AWWA RESEARCH FOUNDATION6666 West Quincy Avenue Denver, Colorado 80235

GUIDANCE MANUALSUBJECT AREA: Water Treatment and Operations

Procedures Manual for Selection of Coagulant, Filtration, and Sludge Conditioning Aids in Water Treatment

PROCEDURES MANUAL

FOR

SELECTION OF

COAGULANT. FILTRATION. AND

SLUDGE CONDITIONING AIDS

IN WATER TREATMENT

Steven K. Dentel

Todd A. Eober

Prasanna V. Shetty

John J. Resta

Department of Civil Engineering

University of Delaware

Newark, DE 19716

DISCLAIMER

This study was funded by the American Water Works Association Research Foundation (AWWARF). AWWARF assumes no responsibil ity for the content of the research study reported in this publication, or for the opinions or statements of fact expressed in the report. The mention of tradenames for commercial products does not represent or imply the approval or endorsement of AWWARF. This report is presented solely for informational purposes.

Although the research described in this document has been funded in part by the United States Environmental Protection Agency through a Cooperative Agreement, CR-811335-01, to AWWARF, it has not been subjected to Agency review and therefore does not necessarily reflect the views of the Agency and no official endorsement should be inferred.

Copyright 1986by

American Water Works Association Research FoundationPrinted in U.S.

ISBN 0-915295-14-8

ii

FOREWORD

This report is part of the on-going research program of the AWWA Research Foundation. The research described in the following pages was funded by the Foundation in behalf of its members and subscribers in particular and the water supply industry in general. Selected for funding by AWWARF's Board of Trustees, the project was identified as a practical, priority need of the industry. It is hoped that this publication will receive wide and serious attention and that its findings, conclusions, and recommendations will be applied in communities throughout the United States and Canada.

The Research Foundation was created by the water supply industry as its center for cooperative research and development. The Foundation itself does not conduct research; it functions as a planning and management agency, awarding contracts to other institutions, such as water utilities, universities, engineering firms, and other organizations. The scientific and technical expertise of the staff is further enhanced by industry volunteers who serve on Project Advisory Committees and on other standing committees and councils. An extensive planning process involves many hundreds of water professionals in the important task of keeping the Foundation's program responsive to the practical, operational needs of local utilities and to the general research and development needs of a progressive industry.

All aspects of water supply are served by AWWARF's research agenda: resources, treatment and operations, distribution and storage, water quality and analysis, economics and management. The ultimate purpose of this effort is to assist local water suppliers to provide the highest^ possible quality of water, economically and reliably. The Foundation's Trustees are pleased to offer this publication as contribution toward that end.

This procedures manual is designed to be a guide for the utility operator and laboratory analyst in improving the performance of their plant while providing the same or better water quality. Coagulants, filtration, and sludge conditioning aids can often provide significant benefits for utility operation, but their selection is too frequently haphazard at best. This procedures manual will guide the user through the steps necessary to select the most appropriate polymer for his unique set of raw water quality conditions, plant layout and design, and finished water quality requi re;nents.

'ome B. Gilbert (^Jaroes F. Manwaring, P.E.Sairman, Board of Trustees ^-fxecutive Director

'AWWA Research Foundation AWWA Research Foundation

The authors would like to thank the American Water

Works Association Research Foundation for the financial

support of this project. Helpful suggestions were provided

by Jon DeBoer, Project Officer, as well as by the Project

Advisory Committee consisting of Keith Cams, Ray Letterman,

and Gary Logsdon.

TABLE OF CONTENTSx

I. INTRODUCTION

A. Purpose of this Manual .................. 1

B. What Are Coagulant and Filtration Aids? ......... 3

C. Improving Water Quality with Coagulant and Filtration Aids 7

D. Possible Drawbacks to Coagulant and Filtration Aids ... 9

E. Effect of Chemical Additives on Sludge Handling Processes. 10

II. HOW TO USE THIS MANUAL

A. Examining Your Treatment Processes ............ 12

B. Locating Potential Suppliers and Products. ........ 15

C. Assistance You Can Get from Vendors. ........... 16

D. Preparing to Evaluate the Products ............ 17

E. The Module Format: Determining Modules to Use. ...... 18

F. Quality Control and Analysis of Results. ......... 25

III. MODULES FOR SPECIFIC SELECTION PROCEDURES

A. Preparation of Polymer Solutions ............. 28

B. Rapid Screening Procedure for Coagulant Aids ....... 32

C. The Jar Test ....................... 34

D. Turbidity Measurement for Jar Test Assessment. ...... 53

E. Particle Size Analysis for Jar Test Assessment ...... 55

F. Paper Filter Test. .................... 57

G. Bench Filter Test. .................... 77

H. Analytical Methods for Filter Tests. .......... .102

I. Determination of Sludge Volume Following Jar Tests . . . .105

J. Preparation of Sludge Samples ..............110

K. Time to Filter Test. .................. .112

L. The Capillary Suction Time Test. ............ .120

M. Sludge Jar Test. .................... .127

IV. USING MODULE RESULTS FOR CHEMICAL AID SELECTION

A. Results Evaluation ................... .129

B. Cost Estimating. .................... .129

VI

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I. INTRODUCTION

A. Purpose of this Manual

An increasing variety of chemical additives have become available for improving the removal and management of particulate matter in water treatment. However, many of these coagulant aids, filtration aids, and sludge conditioning aids are proprietary products and, consequently, cannot be selected for use based on their chemical composition or other fundamental properties. Instead, empirical selection procedures are necessary. These would ideally involve the application of each possible chemical in the full-scale plant under controlled conditions. Obviously, this is not practical, especially considering the large number of such products on the market. The alternative is to utilize small-scale tests which will predict the full-scale performance of these additives as well as possible.

This manual sets forth recommended procedures for performing such small-scale tests. They provide a practical means of selecting the most effective coagulant aid, filtration aid, or sludge conditioning aid for a given water and treatment scheme. These procedures are organized for maximum flexibility. For example, you can use an entire sequence of them to comprehensively evaluate the impact of a coagulant aid on sedimentation, filtration, and sludge handling processes. Or, you can select just one procedure for use in an initial screening of products under consideration, and then evaluate the most promising ones in the plant.

The procedures given in this manual will be familiar in some cases; for example, Section III.C covers use of the jar test. However, since the most common chemical aids are organic polyelectrolytes (or "polymers"), you will also find that adjustments have been made which address handling and testing difficulties associated with the evaluation of these materials.

In other cases, test procedures have been adopted either from wastewater treatment applications or from methods more common in research laboratories. In these instances, the recommended test methods have been selected or developed based on extensive comparisons with other variations and procedures, and after assessing the method's capability for adequately predicting scale-up performance.

It should be stressed, however, that none of the procedures in this manual are foolproof. Unavoidable effects of scale and the inevitable complexities of actual plant operation (for example, the possibility of hydraulic short-circuiting in the sedimentation basin) will always limit the extent to which laboratory test results can be trusted in predicting plant results. Some compromise has also been necessary in keeping to the goals of utility and relative simplicity for these procedures. In general, the results of these tests can be relied upon to give a reason able prediction of which chemical additive will give the best results,

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and at what dose. Quantitative prediction of full-scale performance, unfortunately, is beyond the ability of these procedures. For example, the methods for selecting a filtration aid will indicate a filtration aid dose that should do the best job of reducing your filtered tur bidity, but can't be relied on to give a good prediction of what this improved turbidity will be.

The remaining sections of this Chapter will provide you with a brief introduction to coagulation aids, filtration aids, and sludge conditioning aids. This includes some consideration of when their use may or may not be beneficial. More in-depth information can be found in references such as the AWWA publications Polyelectrolytes - Aids to Better Water Quality (AWWA 20121) and Use of Organic Polyelectro lytes in Water Treatment (AWWA 20173).

Chapter II then gives a general idea of how to go about evaluating these chemical products for use in your plant, and how this manual will assist you. The detailed testing procedures are then presented in Chapter III, with Chapter IV explaining how results from several dif ferent procedures can be integrated into an overall analysis of how a given polymer will affect plant processes.

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B. What Are Coagulant and Filtration Aids?

Figure I.B gives a generalized flow chart for water treatment that includes coagulation, filtration, and solids handling processes. Coagulation, flocculation, and sedimentation first remove the bulk of the suspended matter contained in the raw water; filtration then takes out most of the remaining particulates. In some cases, a raw water is low enough in turbidity that sedimentation and sometimes flocculation can be eliminated; this is then termed direct filtration. No matter how the suspended impurities are removed, however, they must then be concentrated and disposed of in some manner, and the solids handling processes for this purpose can include lagoons, drying beds, vacuum filters, centrifuges, and a variety of other mechanical processes.

Basically, all of the processes shown in Figure I.B are concerned with the separation of solid particles from the water which contained them. The efficiency of such processes can be improved by the use of various additives which alter the manner in which particles interact with water and with other particles. These additives are called coagulants, coagulant aids, filtration aids, and conditioning aids. This manual is concerned with all of these except coagulants. Figure I.B also indicates where these substances might be added in a water treatment plant.

The term "coagulant aid" has been defined as "a chemical or sub stance used to assist in coagulation." Thus, in the most general sense, a coagulant aid is any additive used in conjunction with a primary coagulant such as alum. This would include such products as activated silica, sodium alginate, bentonite clay, and synthetic organic poly- electrolytes ("polymers").

By far the most significant of these, however, are the polymers, which have met with widespread use in water treatment plants. Over one thousand of these products have been approved by the U.S. EPA for use in potable water/treatment, and they are used not only as coagulant aids but also as primary coagulants.

These polymers are chains of individual monomer units, linked together in a linear or branched configuration, with functional groups attached periodically along the chain. The functional groups may pos sess a negative charge (anionic polymers), positive charge (cationic polymers), or an overall neutral charge (nonionic polymers). The length of the polymer chain (including branches) is indicated by the molecular weight of the polymer, although it should be remembered that this is actually an overall average for the many individual polymer molecules.

Polymers are most likely to improve coagulation by either coating individual particles or by acting as bridges between particles. In both cases, functional groups and molecular weight are both important factors in the removal of turbidity. Polymers also can help in color reduction

Coagulant Coagulant aid

V

Filtration aid

RAPID MIX

FLOCCULATION

SEDIMENTATION

FILTRATION

Conditioning aid

DEWATERING

Figure I.E.

Points in water treatment for

addition of various additives.

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in water treatment, and this too is dependent on the polymer's func tional groups.

Marketers of polymers typically provide you with the type of charge and the molecular weight range (medium, high, very high) for a given polymer product. Other characteristics of the substance may also be important, such as the type of molecule acting as the "backbone" of the polymer chain, the actual molecular formula of the functional groups, and the spacing of the functional groups along the chains. However, even knowing all of this information does not make it possible to predict which polymer will work the best under a given set of conditions. This means it is necessary to perform on-site tests of polymers for each specific application. In addition, an optimum dosage level should exist for a given polymer, with lower doses having less effect and higher doses either giving unfavorable results or leading only to slight improvements in water quality which are not,worth the additional chemical expense. It is then important not only to find the best polymer but also to find its best dosage level. This will provide a cost estimate for use of the given polymer as well, which then can be compared to the cost of alternative products. Thus the proper procedure for polymer selection should ultimately allow both improved water quality and reduced operational costs to be realized.

Unfortunately, an important distinction between the polymers and other coagulants and coagulant aids is that they are particularly difficult to work with. They may come as powders, liquids, or emulsions (which appear as milky liquids) and must be prepared, diluted, and dosed in the proper manner. Some are particularly sensitive to light, freezing, or biodegradation. Extreme turbulence (such as flash mixing) may cause them to break apart and lose their effectiveness.

Therefore, specific procedures are called for when testing polymers for possible use in a water treatment plant. The test methods in this manual have been developed to meet the particular requirements for polymer evaluation, and can be used not only to assess polymer effect iveness as a coagulant aid, but also as a primary coagulant. (In this case, where instructions call for alum or ferric chloride addition, this is simply replaced by polymer addition at the appropriate step.) The procedures can also be used to evaluate other types of coagulant aids, but if they are not polymers, much of the procedure addressing polymer preparation and application can be ignored.

Filtration aids, unlike coagulant aids, are usually used as the sole chemical additive rather than in conjunction with other substances. Filtration aids most often are polymers which are added to the water following sedimentation, but prior to filtration. In the direct fil tration process, they can be fed prior to a flocculation step which is then directly followed by filtration. In the case of contact or in-line filtration, they are added prior to filtration with no flocculation or sedimentation step. In any of these cases, some provision for rapid mix must be provided.

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Just as for coagulant aids, filtration aids vary by type of charge and molecular weight range. They appear to function much as do the coagulant aids (coating or bridging of particles) but also may affect the way in which particles interact with the filter media (sand, carbon, etc.) surfaces. This includes the way that the water-born particles adhere to the media and the extent to which they penetrate or clog the filter.

Consequently, in the case of filtration aid selection, the dif ficulties associated with handling and dispensing polymers are coupled with the problem of how to duplicate the filtration process and the effect upon it of the filtration aid. Also important in any evaluation procedure for direct or contact filtration is the simulation of rapid mix and/or flocculation processes. As with coagulant aids, a dosage level should exist for a given filtration aid which will provide the needed effluent quality at the most favorable price. (Excessive filtration aid doses will usually decrease the filter run length by increased resistance to flow through the filter).

All of these considerations suggest that exacting procedures should be followed if a filtration aid is to be evaluated in small-scale tests. Adding to the difficulty in this case is the fact that filtration mechanisms are not completely understood, so the similarity between laboratory and full-scale filter performance cannot always be assured. However, experiments have shown that trends in performance are usually duplicated. What this means for the evaluation of filtration aids is that polymer additions indicated by lab tests will be adequate for initial product selection, but that some "fine tuning" may be necessary when plant application is implemented.

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C. Improving Water Quality With Coagulant and Filtration Aids

The procedures in this manual should be useful in a variety of applications, but they are mainly intended for the evaluation of polyelectrolyte additives which have not been previously used at a given treatment facility. For such evaluations, it will be advantageous if one first identifies the primary objectives of a possible change in chemicals used. This in turn will enable the most appropriate test procedures to be chosen for the polymer selection process.

The personnel at a well-run water treatment plant are always on the lookout for ways of upgrading the operation; thus the objective of evaluating different additives might be the general desire to improve finished water quality and cost-effectiveness of the treatment pro cesses. However, it may also be the case that specific problems exist at a plant, and different polymers are being evaluated in order to alleviate these particular difficulties. For example, if the primary coagulant is functioning poorly at low water temperatures, coagulant aids might be evaluated in their ability to accelerate and complete flocculation under these conditions. Here, the proper test procedure would be a series of jar tests with the water temperature kept low using a water or ice bath.

In fact, there are numerous situations in which polymer application might be beneficial. These include:

-Settled or finished turbidity consistently too high (for example, due to inadequate retention time in the flocculator or sedimentation basin). Polymers can help to produce larger, tougher floe which is easier to settle or filter. If finished water quality is inadequate because the plant is operating above design capacity, use of coagulant or filtration aids can therefore avoid capital expenses of expansion by allowing acceptable functioning at increased loading rates.

-Turbidity periodically too high, due to fluctuations in influent flow rate, turbidity, alkalinity, or hardness. Because polymers do not act as acids the way inorganic coagulants do, and are also less pH- dependent in their effectiveness range, they may assist in maintaining good water quality under such conditions. "Bridging" polymers can also clean up a poorly coagulated water in a manner that is fairly indepen dent of solids concentration. For the same reasons, a coagulant aid may lessen coagulant and pH control difficulties during fluctuating con ditions.

-Seasonally inadequate color removal. Some polymers improve color removal, and jar or filtration tests followed by color measurements can be used to select the most appropriate product for this purpose. Specific methods are given in this Manual for such an application.

-Treatment costs are too high due to the use of too much or too many additives. If a coagulant aid can reduce the required dose of primary coagulant (and also the amount of lime or other chemicals which may be needed for pH control), a net cost savings may be achieved.

-Excessive frequency of required filter backwashing caused by premature turbidity breakthrough. A coagulant aid can alleviate this

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situation by either reducing the amount of suspended material reaching the filters, or by favorably altering the properties of these solids. A filtration aid can also provide the second of these effects.

-Excessive sludge production or poor sludge properties. Since a smaller dose of coagulant aid can sometimes replace a larger portion of the aluminum or ferric coagulant dose, the volume of sludge produced can also be decreased. The thickening and dewaterability characteristics of such sludges are frequently improved as well.

It should be understood, however, that polymers are not a "cure all" for all treatment problems. Nor are they always effective at improving the performance of a primary coagulant. Other changes in your water treatment plant's facilities or practices may prove to be more effective at solving particular problems. You should consult other AWWA publications for additional means of improving plant operations, such as Upgrading Water Treatment Plants to Improve Water Quality (AWWA 20153) and Upgrading Existing Water Treatment Plants (AWWA 20126).

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D. Possible Drawbacks to Coagulant and Filtration Aids

The use of coagulant and filtration aids can improve water treat ment processes in a number of respects, as detailed in the previous section. However, there may also be disadvantages to the use of these additives which should be considered before the decision is made to employ them. Most of these involve the handling and operational aspects of polymer use:

-Storage, mixing, and feeding systems for polymers are signifi cantly different than those used for inorganic coagulants. These facilities must be purchased and installed. Some polymers are at very high or low pH and appropriate plastic, fiberglass, or stainless steel must be specified. In some cases, polymer must be mixed with warm water and an appropriate hot water heater will be required. Mixing with water containing a high chlorine residual will degrade some types of polymers, so a provision for water other than finished water may also be neces sary. Highly viscous polymers will require heavy-duty pumping equip ment. (These materials also have the disadvantage of being quite hazardous when spilled because they are extremely slippery). More information on proper handling facilities for polymers can be obtained from polymer suppliers. See also Use of Organic Polyeleotrolytes in Water Treatment (AWWA 20173).

-Difficulties may be encountered in insuring product consistency when utilizing synthetic polymers, due both to the complexity of the polymerization processes used in manufacturing them, and to the vulnerability of these products to various aging reactions. Added to this difficulty is the fact that many vendors provide only minimal technical data on their products and often are not directly responsible for the manufacture of them. It may be found necessary to perform laboratory analyses whenever a new batch of polymer is received, in order to assure product consistency. Such analyses might include viscosity determination or jar testing of a control suspension.

-Trace levels of acrylamide monomer are present in many coagulant aid formulations. This substance has been shown to be mutagenic by the Ames test. Concentrations of this impurity likely to be created in finished water are not believed to pose any threat to human health if applied concentrations are less than maximum recommended doses. If a polymer is to be used, make sure that it is approved by the EPA for use in potable water treatment and that any dosage limits are not exceeded.

-Filtration aids have particular disadvantages if the dose is not closely controlled. Overdosing may increase the adhesiveness of solids to the extent that they are difficult to remove from the filter in backwashing. Additional scour may be required in such cases. If a longer backwash period is found necessary, this may offset any advantage gained in attaining longer filter run times. Long-term overdosing may also contribute to the formation of mudballs and consequent short- circuiting in the filter.

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E. Effect of Chemical Additives on Sludge Handling Processes

The treatment and disposal of the sludges and solids generated by water treatment processes is an area of water treatment technology long ignored by regulators, design engineers, and utilities managers. The typical practice in the past was to discharge these sludges to the nearest surface water downstream from the water intake. However, such disposal methods are now prohibited by Federal and State regulations. Consequently, the handling and disposal of water treatment sludges has been receiving considerable attention.

Frequently, the removal of water from these sludges is essential for cost-effective disposal. This reduces both the weight and volume of sludge to be removed to a disposal site. In fact, current federal regulations prohibit the disposal of sludges that contain free moisture in sanitary landfills ("free moisture" being defined as liquid that will drain under the influence of gravity).

Chemical additives such as polymers can have a substantial impact on sludge handling in water treatment. Two types of effects are of importance:

(1) the substitution of a coagulant aid for a coagulant can reduce the amount of sludge to be dealt with, and/or improve the sludge's de- watering characteristics, and

(2) use of a polymer immediately prior to a dewatering process can significantly increase the amount of water removed in the process. In this case the polymer is defined as a sludge conditioner or conditioning aid.

If two coagulant aids provide similar performance in other re spects, the product having the most favorable effect on sludge charac teristics would therefore be the optimal choice. A comprehensive procedure to evaluate and compare coagulant aids might therefore include the option of assessing the amount and behavior of the resulting sludges. This manual provides several such methods, with the most appropriate method for a given situation depending on the time and equipment available, as well as on the plant's dewatering and disposal practices.

The choice of a conditioning aid for use in full-scale dewatering processes can also have a major impact on plant costs. Laboratory procedures which can be used to select the best polymer for such a purpose are given in this manual, although they are probably less familiar in the water treatment field than are many of the procedures recommended for coagulant aid or filtration aid selection. Nonetheless, some of the methods are similar for example, a "sludge jar test" can be employed to help locate the most promising polymer for dewatering processes. Furthermore, the initial polymer measuring, dilution, and addition procedures are the same regardless of the specific polymer application.

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In summary, it may be possible to improve the finished water quality or water production costs through the selective use of synthetic organic polymers. Three specific aspects of water treament may be upgraded with polymer addition: coagulation, filtration, and sludge handling. A preliminary polymer selection should be made based on laboratory product evaluation, and appropriate test methods are given herein for this purpose. Procedures are included for the assessment of coagulant aids, filtration aids, and for sludge conditioning aids, with the option of evaluating the overall impact of a coagulant aid on coagulation, filtration, and sludge processing. The next chapter gives a general overview of the way in which these procedures might best be applied for a given set of plant circumstances.

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II. How to Use This Manual

A. Examiningjifour Treatment Processes

As discussed in Section I.C, the main objective(s) of a change in chemical additives should be identified before proceeding with any evaluations. Frequently the objective is to remedy an obvious under- performance of a specific process, in which case the possible improve ments listed in Sections I.C and I.E would suggest whether a coagulant aid, filtration aid, or sludge conditioning aid should be evaluated for use. Sales representatives for the polymer products may also be helpful in making this determination. The appropriate procedure Modules in this manual can then be consulted, and the chemical additive selected which will best improve finished water quality.

If the goal is a more general attempt to decrease plant operating costs, then the first step should be to examine your plant processes to decide where a different chemical addition might prove most cost- effective. Making this determination properly could save much time and effort in later evaluation work. The paragraphs below give a basic description of how cost savings might be estimated for coagulant aids, filtration aids, and sludge conditioning aids. If these estimates are made, they can then be compared to give an indication of what type(s) of chemical additives could provide the most savings, and the proper procedures Modules can be consulted for actual evaluations of such products.

Coagulant aids; The first step in cost estimation is gathering of the required data. Here, costs of present coagulant and accompanying additives which might be affected (lime, chlorine for reduction of ferrous iron, etc.) are needed, along with average dosages employed. Straightforward multiplication of each chemical's unit cost times its dosage gives will give chemical cost per volume of water treated; sum these up to get total chemical cost. This should be in units such as dollars per million gallons of water produced. Tables and conversion factors to use in these "baseline" calculations are given in Section IV.B. A check on this figure can be obtained if it is multiplied by the average flow rate to give cost per day, and then compared with purchase records for the chemicals.

A similar cost calculation can be done for projected conditions utilizing a coagulant aid, again using the tables in Section IV.B. Additional data are required for each polymer under consideration: probable dose level, cost, and estimated decrease in required primary coagulant dose. Add the polymer cost to your previous calculations, but subtract savings in primary coagulant cost. Also subtract any expected savings in other chemicals. For example, if ferrous sulfate is presently used as a primary coagulant, with chlorine used to oxidize the iron, and a particular coagulant aid is predicted to decrease the ferrous requirement by 25$, then both the ferrous sulfate and chlorine costs would be decreased by 25$.

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The above approach will give a very rough estimate of cost savings which may (or may not) be attained through use of a coagulant aid. The extent to which primary coagulant dose may be cut can be estimated by prospective suppliers of the respective coagulant aids, although a better source of such information would be other treatment plants using the same product and treating a similar raw water. Other cost aspects not considered in this initial calculation include:

-savings which may accrue through improved filter performance (longer filter runs and thus less backwash).

-decreased cost of solids handling due either to the production of fewer solids or to the generation of a more dewaterable sludge.

Filtration Aids; The use of a polymer prior to filtration will generally decrease effluent turbidity and increase head loss through the filter. This has a number of implications when considering the use of these products.

Most importantly, filtration aids will be of most use when filtered turbidity is to be improved or turbidity breakthrough limits filter run length. If head loss development determines when filters must be back- washed, then it is unlikely that introduction of a filtration aid will increase run length unless a. currently used filtration aid is to be replaced by a more satisfactory product. For conventional treatment configurations, decreased head loss may best be accomplished by improve ments in coagulation, flocculation, and/or sedimentation processes which will reduce the amount of turbidity to be handled by the filters.

However, if filtered turbidity is seen to increase long before a limiting head loss is observed, then a filtration aid may be successful in balancing these two trends. A preliminary estimate of expected improvements might be made as follows.

If it is feasible to observe the performance of a filter in the plant beyond the run length normally dictated by turbidity breakthrough, then the run length limit due to head loss may be found. This is the maximum possible run length, i.e. the run length which would be achieved using a polymer that significantly decreased the effluent turbidity but had no effect on head loss.

(If such an extended filter run would lead to unacceptable deterioration of overall finished water quality, then a rough prediction of this run length may be done graphically. Plot head loss vs. time for the period available and extend the line forward until the maximum acceptable head loss is reached. Read off the time at which this occurs. This estimate is valid for constant rate filters; for declining rate systems, plot flow rate vs. time instead, extrapolating to the minimum acceptable average flow rate.)

Actually, it is unlikely that this maximum run length will be attained because a filtration aid usually causes an increased rate of

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head-loss development. The amount of this increase will depend on the polymer used and many other factors as well. As an estimate, a run length halfway between the head-loss and turbidity-based run lengths might be attained with a filtration aid. Literature reports have shown a doubling of run length in some cases when a filtration aid was utilized.

The estimated increase in run length can then be converted into a projected cost reduction by the computational method given in Section IV.B. If this is estimated in dollars per million gallons, the potential savings can be compared to the potential savings using a coagulant aid. The greater possible savings suggests which type of polymer application might save you the most money, and thus the procedures to use from this Manual.

Sludge Conditioning Aids; The proper use of a sludge con ditioning aid will increase the solids concentration of the dewatered sludge. This can have obvious implications for sludge disposal costs, which typically are in rough proportion to the sludge volume disposed. Increasing the solids concentration in a dewatered sludge by a given factor will decrease the sludge volume and the sludge disposal costs (dollars per day) by the same factor. For example, if a better conditioning aid will enable a dewatering process to achieve 2^% solids instead of the present 20%, the factor is 2V20 or 1.2, so the present sludge disposal costs divided by this factor gives the projected sludge disposal costs. Subtraction gives the savings, and dividing by average plant water production rate (MGD) gives approximate savings in dollars per million gallons. Again, this figure can be compared to those calculated for possible savings with coagulant aid and filtration aid use, to indicate which type of polymer would save you the most money. The projected solids concentration is the difficult quantity to get in this calculation, and should be approximated based on opinions of technical representatives and treatment plant personnel who use conditioners in comparable processes and facilities.

Obviously, these are all very rough calculations and should be interpreted with caution.

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B. Locating Potential Suppliers and Products

It is not generally difficult to locate sales representatives for the larger polymer distributors, who maintain occasional contact with most water treatment facilities. However, if a wider range of suppliers is preferred, additional effort will be necessary in locating further product sources.

The best contact to make for this purpose is with the Drinking Water Branch of your EPA Regional Office. This office can provide you with a list of polymers currently approved for use in water treatment, including the names and addresses of distributors, either within the EPA Region or nationwide. The EPA's maximum recommended dose for each polymer is also given. (As of this writing, responsibility for the approval of polymer additives used in potable water treatment is to be transferred to the National Sanitation Foundation in Ann Arbor, Michi gan. It is expectd that this organization will then make available a similar polymer listing).

Additional "word of mouth" information on polymers and suppliers might be obtained from other water utilities in your area. National and Section Conferences of the AWWA may provide good opportunities for this.

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C. Assistance You Can Get from Vendors

A primary role of sales representatives is advising potential

may therefore be available from such personnel towards determining which polymers in their product line would be most successful in your par ticular application. In some cases this service may include comparison testing of their own products, either on site or at the company's laboratories. Such assistance might therefore be of considerable use in the initial screening of chemical additives under consideration.

On the other hand, evaluations done by treatment plant staff may be more useful because:

-the use of consistent procedures will allow quantified comparisons between polymers from different suppliers' product lines, in cluding cost comparisons.-tests can be performed during various raw water conditions (turbidity, temperature, color, etc.) to assess the range of situations in which a given polymer will be helpful.

-plant personnel know about any unusual aspects of their treatment processes, and can incorporate this into the testing procedures (for example, if short residence times are a problem at high flow rates, the time used for each stage of the jar test can be reduced correspondingly) .

Consequently, the most productive approach may be to utilize recommendations of the suppliers only to develop an initial list of potential products, and then to proceed with evaluations performed by plant staff. Small samples of the additives to be tested will usually be provided for evaluation purposes at no charge. Suppliers will also furnish technical literature for each product. Check the specifications for (a) EPA approval for use in potable water treatment, (b) maximum recommended dosage level, and (c) instructions concerning product storage and preparation. All of these should be heeded, although preparation procedures are also given in this Manual in case none are provided. Of course, the approximate unit cost of each polymer should also be obtained. Finally, polymer distributors can be of assistance once you have made a preliminary polymer selection. They can usually offer advice on proper storage, mixing, and feed facilities and may be able to loan equipment to the plant for a final full-scale polymer evaluation, such as pumps and dose control systems.

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D. Preparing to Evaluate the Products

Before actual testing begins, a number of preliminary actions are necessary:

1. As suggested in the previous section, discuss with sales representatives which of their products would be most suc cessful in the application at hand. List these additives as candidate products.

2. Using cost and technical data provided, go through preliminary cost estimates for these products as described in Section II.A and Chapter IV. Rank your product list according to each additive's estimated cost.

3. Obtain samples of all these polymers. Testing should not begin until all products are on hand, since comparisons of test results are only possible when raw water conditions were fairly similar.

4. According to what is known of problem conditions in the plant, determine what "worst case" conditions should also be used in testing. For instance, some testing may be advisable under high raw water turbidity conditions if this is when plant operation is usually least satisfactory. If seasonal difficulties are encountered, it may be necessary to delay some evaluations until this time period.

5. Determine which evaluation procedures should be used (See Section II.E). If any equipment must be purchased or fab ricated, allow sufficient time for this to be done. Become familiar with the appropriate Module in Chapter III for each procedure, and perform the quality control steps recommended in Section II.F.

6. Some test methods for specific objectives may be desired beyond what is presented in this Manual. For example, if removal of THM precursors is of concern, an appropriate method for measuring these would be needed, such as TOC (Total Organic Carbon) or UV absorbance. Acceptable methodologies for these additional tests must then be selected.

7. Finally, assemble the required data sheets for all required tests. The Modules in this Manual include suggested formats, and these tables can simply be photocopied as required. If other procedures or information are desired, more appropriate data sheets should be designed.

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E. The Module Format; Determining Modules to Use

As indicated in Chapter I, the procedures in this Manual have been divided into separate sub-procedures or "Modules." Each of these is presented in Chapter III as a separate Section: for example, Section III.C, "The Jar Test," is also referred to as "Module C."

The division into Modules has been done to allow maximum flex ibility of use. There are many ways of combining these Modules into a sequence which will be of most use in a given situation. Each user of this Manual can select a proper set of Modules to use based upon the specific:

-type of additive being considered

-process(es) to be improved

-water quality objectives

-equipment available

-expertise and available time of the personnel to be performing the tests.

The type of additive being considered, if not already determined, can be decided upon referring to Sections I.C, I.E, and II.A. This decision also relates to the process(es) to be improved: for example, better filtration might best be achieved with a filtration aid. This might seem obvious, but as suggested in Figure II.E.1, a coagulant aid might also affect filtration and sludge characteristics as well.

These types of interactions may be quite important, and the Module arrangement enables them to be investigated. For instance, if a coagu lant aid is to be evaluated, assessment of the possible impacts on down stream processes (filtration and sludge handling) may also be of inter est. Figure II.E.1 indicates which Modules are designed to simulate the various water treatment processes and the effect of polymers on them; for the present example, this Figure shows that Module A could be used to prepare and dose the coagulant aid in a manner similar to that in full-scale application, Modules B, C, D, and/or E would predict the effect on flocculation and sedimentation. If the impact on filtration is of concern, Modules F, G, and/or H could be used to evaluate this. Finally, any of Modules I through M might be appropriate in analyzing changes to be expected in sludge thickening, dewatering, or disposal. Thus, depending on the situation, only one Module might be used, or a combination of several might be combined.

Most of the Modules shown in Figure II.E.1 describe procedures designed to simulate the corresponding water treatment processes. However, several also present water quality analysis methods which can be performed on the water following these simulation procedures. For

Coagulant Coagulant ai

d

(Module

A)

V

RAPID MIX

FLOCCULATION

SEDIMENTATION

(Modules B, C, D, and E)

Conditioning aid

(Module A)

DEWATERING

(Modules I, J, K,

L, an

d M)

Filtration ai

d

(Mod

ule

A)

FILTRATION

(Modules F, G, and H)

Figure II.E.1. Typical water treatment process diagram, and the Modules which

simulate chemical effects on these processes.

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example, Module D gives instructions on how to properly measure turbidity following a jar test, and would be used along with Module C which describes the jar test method itself. Obviously, other references such as turbidimeter manuals and Standard Methods are already available for this purpose, and the main reason for such a Module is to relate such methods to the most suitable sampling techniques following a jar test (in this case).

It would not be possible to include a Module for every water quality analysis which might be of interest to a user of this Manual. Instead, the user should decide on these depending on the specific water quality goals and then locate appropriate methods. The same sampling techniques suggested in this Manual's Modules (such as for turbidity) should be incorporated into these methods. For instance, if improved color removal is hoped for through the use of a filtration aid, then a method for true color from Standard Methods or the AWWA Intro duction to Water Quality Analyses (1982) might be appropriate.

Other important factors in selecting Modules to use are the equip ment, time, and expertise requirements. A description of necessary apparatus is given in each Module along with an indication of the test's relative level of complexity, and an initial reading of the Modules under consideration will thus help in making the best selection from among them for the situation at hand.

The user should not be immediately dissuaded by the specific equip ment or a significant testing effort required in some Modules. The possible cost savings estimated in Section II.A may indicate that such an investment will be amply returned. Moreover, once testing procedures are developed, they will be available in the future for maintaining optimal plant operation. Specifications which may seem arbitrary have usually been made with good reason; as an example, testing has indicated that square "plexiglass" jars are superior to the more traditional glass beakers in several respects when evaluating coagulant aids.

Figures II.E.2, II.E.3, and II.E.4 illustrate possible Module sequences when evaluating coagulant aids, filtration aids, or sludge conditioning aids. Note that Module A is used in all cases for the proper preparation of polymer working solutions. Figure II.E.2 also indicates that an optional Module B (a "rapid jar test") may be used if initial screening of a large number of coagulant aids is desired. The more elaborate jar test (Module C) can then be used on the most promising polymers. As previously discussed, many other Modules can then be used to more fully characterize coagulant aid performance as it may affect filtration or sludge management.

The Modules shown in Figure II.E.3 for filtration aid evaluation include several levels of complexity and ability to simulate full-scale filtration. These Modules should all be studied prior to choosing one. Both the paper filtration test (Module F) and the bench scale filtration test (Module G) are applicable to a variety of process configurations,

Procedure

for

thLe

Sele

ctio

n of Co

acul

ant

Aids

III.B

Preliminary

screening

(rapid jar

test)

/III.C

Detailed

jar

test

III.

EParticle

size

analysis

ro

III.F,.G,oH

Determine

coagulant

aid's

impact on filtration.

^ -A

III.I,-J,.K,.L,.M

Determine

coagulant

aid's

impact on sludge management .

IVSelection

of

coag

ulant

aid

Figure II.E.2

SELECTION

OF F

ILTRATION

AIDS

(or

impact of coagulant

aids on filtration)

III.

A Preparation

of

working

solutions

III.

F Paper

filter test

III.

G Bench

filter test

Pil

ot

filt

er

eval

uat

ion

\

ro

ro

III.

H

Turb

idit

y m

easu

rem

ents

III.

H

Part

icle

si

ze

anal

yse

sIV

Evaluation of

re

sult

s

Figure II.E.3

PROC

EDUR

E FOR

EVALUATING SL

UDGE

PR

OPER

TIES

A.

Impact of coagulant

aids on sludge properties;

III.C

Detailed Jar

Test

III.I

Sludge Volume

Determination

III.K

Time To Filter

Test (small

volume)

III.L

Capillary

Suction

Time Test

LO

B.

Evaluation of Sludge Conditioning Aids

III.A

Preparation

of

Working

Solutions

III.J

Sludge Sample

Preparation

III.M

Sludge Jar

Test

III.K

Time To Filter

Test_________

III.L

Capillary

Suction

Time Test

Figure II.E.

-24-

including the evaluation of filtration aids in conventional treatment, contact filtration, or direct filtration with prior flocculation. These tests can also be used following a jar test if a coagulant aid's effect on filtration is to be assessed.

Figure II.E.4 depicts a variety of sludge characterization methods. Coagulant aid use can alter sludge properties, and diagram A in this figure shows how such effects can be evaluated. Module I enables changes in sludge volume resulting from a coagulant aid to be measured if this is of concern; it is also required procedure in obtaining sludges for Modules K or L if one of these is to be run. Module K provides information on the dewaterability of a sludge through a "Time To Filter" (or Buchner funnel) test. Module L is an alternate Capillary Suction Time test for dewaterability which is faster than Module K but requires more sophisticated equipment.

Diagram B suggests possible Module sequences when polymers are to be analyzed for direct use as sludge conditioning aids, in which case Module J is needed for proper sludge sample preparation. Module M describes a sludge jar test, which differs from the conventional jar test in that it is used as a quick, qualitative method for determining sludge thickenability or dewaterability. It can be used independently or as a screening procedure prior to the use of Module K or L.

All evaluation sequences then utilize Chapter IV, "Using Module Results for Chemical Aid Selection." It gives means of comparing results and developing cost estimates which will indicate the chemical aid of most benefit to the treatment plant.

Once a choice of Modules has been made, a flow chart similar to these can be drawn which will only show the methods to be used. (A copy of Figure II.E.1 may be used for this purpose by just crossing out the Modules which will not be used.) This may help in organizing the equip ment and procedures which will be required. Also see the following section for important considerations regarding quality control and analysis of results.

Following the evaluation of all prospective products, it may appear that one product is the most promising. Full-scale evaluations in the plant are then recommended in order to validate the product's success prior to the purchase and installation of permanent storage, mixing, and feeding devices. If more than one product exhibited good performance at the same cost in small-scale tests, they may also be compared on a full-scale basis before a final choice is reached. Due to the wide variation in process and plant characteristics, a method of implementing full-scale evaluations is beyond the scope of this manual. Consult "System Design for Polymer Use" in Use of Organic Polyelectrolytes in Water Treatment (AWWA 20173) and consult with technical represent atives of the polymer suppliers.

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F. Quality Control and Analysis of Results

It is of utmost importance that the procedures in this Manual be performed in a correct and reproducible manner. Otherwise, variability in results may prevent any meaningful conclusions from being drawn. The following steps should be taken prior to actual evaluation of polymers in order to assure that rigorous and methodical experimental techniques are employed:

1. Personnel who are to run the tests should practice each procedure until sufficiently familiar with it.

2. Data sheets should be completed in full, dated, and stored in a loose-leaf notebook. Additional tables, graphs, and related records should be kept in this notebook as well.

3. All analytical methods used should be calibrated with accepted standards for the test. This should be done periodically to insure consistent accuracy. Standard Methods is the preferred reference in this regard.

4. Precision of analytical methods should be assessed byperiodically performing replicate analyses. This includes replicate sampling. For example, multiple jar test turbidity measurements would be done by taking different supernatant samples from the same jar and comparing measured turbidities.

5. Tests on replicate polymer doses should be done. Continuing with the jar test example, this would mean also running several jars with the same polymer dose to check for consistent final turbidities. Variability indicates inconsistent procedure.

6. The ability to reproducibly prepare polymer solutions should be assessed in a similar manner. Again, this would be done in jar testing by comparing jar test turbidities after using equal polymer doses taken from different preparations of polymer stock and working solutions.

7. If more than one person is to be performing tests to be compared, each person should run an identical test. If a comparison of results indicates significant deviation, each person's technique should be examined and compared.

8. Calculations done in analyzing results should be performed with care. Units associated with each value should always be indicated. It is advisable to initially have two persons use the required computation method and compare answers to catch any methodical errors.

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-27-

III. MODULES FOR SPECIFIC

SELECTION PROCEDURES

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Module A. Preparation of Polymer Solutions

1. General Discussion.

a. The initial step in evaluating chemical aids is the preparation of the chemical aid or polymer solutions. This is required since most polymer samples are available only in powdered, concentrated liquid or emulsion forms.

b. The resources required for polymer solution preparation are minimal. Test materials and apparatus, as outlined below, are readily available and are located in most water treatment plants. The analytical skills required are fairly simple, though extra care should be employed when weighing or measuring the small amounts of chemical aids using in preparing stock and working solutions. Any inaccuracies during stock solution preparation will affect the subsequent lab determinations. As such, the most accurate equipment available (i.e. balance, pipets, etc.) should be employed.

2. Apparatus.

a. Jar test stirrer (Phipps and Bird type) or magnetic mixer and stirrer bars.

b. Analytical balance or scale (preferably accurate to 0.01 grams) if using powdered polymers.

c. Several 1 or 2-liter beakers.

d. Large bore pipet. This can be constructed by breaking off the tip of a glass pipet after scoring the break with a file. The broken end is then polished with a flame to remove any sharp edges. If available, a calibrated, digital piston-type pipet should be used.

e. 3 valve, rubber pipet bulb.

f. Water for polymer dilution. This should be the same water as that which would be used to prepare the polymer for full-scale plant use. Special care should be taken to avoid freshly chlorinated water for both lab and full-scale use as high chlorine doses can degrade some polymers, reducing their effectiveness.

3. Reagents. Samples of numerous polymers are typically available free of charge from most commercial suppliers of water treatment chemicals.

U. Procedure. The preparation of any conditioning aid solution involves a basic rule of thumb: the less accurate the measuring device, the larger the volume of solution that should be prepared. For most evaluations, 500 mL of stock solution will be more than adequate. For special situations, increase or decrease the stock solution volume accordingly within the accuracy of the available analytical equipment, The procedures are divided according to polymer types, as such the recommended concentrations of the working solutions differ in value but should yield similar results when used. Emulsion polymers

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are different from liquid polymers in that they are dissolved in an oil-based solvent instead of water. When preparation procedures are provided by the polymer supplier those procedures should be used in place of these outlined here. For additional information regarding laboratory procedures see the references.

a. Powdered or Dry Polymers.

(1) Accurately measure 500 mL (milliters) of warm (less than 100 deg F) tap water into a 2-L (liter) beaker. This tap water should be same as that which would be used to prepare the polymer for full-scale plant use.

(2) Place the beaker under the jar test stirrer or on a magnetic stirrer. If a magnetic stirrer is used place a stirring bar into the beaker.

(3) Start the stirrer and adjust the mixing speed until a mild vortex isachieved. The vortex should be at least 1/2 inch deep. If the water issplashing, then the mixer speed is too high.

(4) Accurately weigh 0.5 grams of dry or powdered polymer.

(5) Sprinkle the powder into the beaker over a period of 10-20 seconds. Adding the polymer too quickly will cause large lumps of undissolved polymer to be formed. Adding the polymer too slowly will cause a film of undissolved polymer to form on the surface, reducing mixer effectiveness.

(6) Continue mixing until the solution appears clear (1-3 hours). It may be necessary to increase the mixer speed to maintain adequate turbulence, since the solution will become more viscous over time.

(7) Following mixing, the polymer should be "aged" for at least 1 or more hours before using. The solution should be gently mixed again immediately prior to use.

(8) If the polymer solution has a large number of visible clumps of undissolved polymer, it should be discarded and the procedure repeated. If the polymer cannot be completely dissolved, contact the supplier for additional information.

(9) This procedure will yield 500 mL of a 1 g/L stock solution. Stock solutions can be stored for approximately 1-2 weeks if refrigerated. Allow the stock solution to come to room temperature prior to use.

(10). Immediately prior to use, take 50 mL of the 1 g/L stock solution and dilute it into 450 mL of warm tap water in a 1 L beaker by mixing gently for 5 minutes. This is now a 0.1 g/L working solution. Working solutions should be made up only as needed. They can be stored approximately 1 day if refrigerated. Allow the working solution to come to room temperature prior to use. 20 mL of this solution added to a 2 L sample will yield a chemical aid dose of 1 mg/L.

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b. Emulsion Polymers.

(1) Accurately measure 200 mL of warm (less than 100 deg F) tap water into a 500 mL beaker. This tap water should be same as that which would be used to prepare the polymer for full-scale plant use.

(2) Place the beaker under the jar test stirrer or on a magnetic stirrer. If a magnetic stirrer is used place a stirring bar into the beaker.

(3) Start the stirrer and adjust the mixing speed until a mild vortex is achieved. The vortex should be at least 1/2 inch deep. If the water is splashing, then the mixer speed is too high.

(4) Using a large-bore pipet or syringe, accurately measure 1.0 mL of the emulsion polymer and inject it into the vortex. Continue mixing for 30 minutes, for a magnetic stirrer increase the mixing time to 60 minutes. If necessary, increase the mixer speed to maintain adequate turbulence without splashing. This is now a 0.5? stock solution (5 mL/L). Stock solutions can be stored for approximately 2-3 days if refrigerated. Allow the stock solution to come to room temperature prior to use. Pipets and other glassware can be cleaned by rinsing with kerosene or other organic solvent.

(5) Immediately prior to use, take 100 mL of the 0.5% stock solution and dilute into 400 mL of warm tap water in a 1 L beaker by mixing gently for 5 minutes. This is now a 0.1$ working solution (1 mL/L). Working solutions should be made up only as needed. They can be stored for approximately 1 day, if refrigerated. Allow the working solution to come to room temperature prior to use. 20 mL of this solution added to a 2 L sample will yield a chemical aid dose of 0.01 mL/L.

c. Liquid Polymers

(1) Accurately measure 150 mL of warm (less than 100 deg F) tap water into a 2-L beaker. This tap water should be same as that which would be used to prepare the polymer for full-scale plant use.

(2) Place the beaker under the jar test stirrer or on a magnetic stirrer. If a magnetic stirrer is used place a stirring bar into the beaker.

(3) Start the stirrer and adjust the mixing speed until a mild vortexis achieved. The vortex should be at least 1/2 inch deep. If the water issplashing, then the mixer speed is too high.

Accurately measure 50 mL of the liquid polymer in a graduated cylinder or pipet.

(5) Slowly pour the polymer into the vortex; if a pipet is used, insert the tip about 1/2 inch below the water surface and swirl the tip to achieve better dispersion. Continue mixing for 30 minutes (60 minutes if a magnetic stirrer is used).

(6) Following mixing, the stock solution should be "aged" for at least 1 hour prior to use .

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(7) This procedure will yield 500 mL of a 10$ (100 mL/L) stock solution. Stock solutions can be stored for approximately 2-3 days if refrigerated. Allow the stock solution to come to room temperature prior to use.

(8) Immediately prior to use, take 50 mL of the 10$ stock solution and dilute into 1*50 mL of warm tap water in a 1 L beaker by mixing gently for 5 minutes. This is now a 1$ working solution (10 mL/L). Working solutions should be made up only as needed. They can be stored for approximately 1 day, if refrigerated. Allow the working solution to come to room temperature prior to use. 20 mL of this solution added to a 2 L sample will yield a chemical aid dose of 0.1 mL/L.

5. Variables. The most significant variables that affect the preparation of conditioning aids are the various errors associated with weighing and measuring the conditioning aids. As the ultimate selection of a conditioning aid will be based on its cost, it is crucial that conditioning aid doses be calculated and prepared accurately.

REFERENCESSTANDARD METHODS FOR THE EXAMINATION OF WATER AND WASTEWATER. 15th Edition, 1980, American Public Health Association, American Water Works Association and The Water Pollution Control Federation.

AWWA. INTRODUCTION TO WATER QUALITY ANALYSES. American Water Works Association, 1982.

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Module B. Rapid Screening Procedure For Coagulant Aids

1 . General Discussion

In general, all coagulant aid testing will involve some jar test procedure as discussed in Module C. However, since "jar testing" requires a great deal of time and a somewhat elaborate procedure, a simple screening test can first be utilized which is rapid and requires less equipment. In this test, a polymer dose is used which is likely to be much higher than the "optimal" dose; if well-defined floes are observed, smaller doses should be evaluated using the more elaborate jar test procedure given in Module C. If no floe develops, the polymer can be eliminated from consideration. Because this is only a rough, initial procedure for estimating polymer performance, a visual inspection of the extent of flocculation is the only "analytical method" required.

2. Apparatus

-Magnetic mixer and stir bar. One paddle on a bench stirrer, as described in Module C, may be substituted.

-2-L beaker or 2-L "square jar" as described in Module C. If necessary, smaller size containers can be used with appropriate adjustments to all dosages. For example, if 1-L containers are used, all dosages in this procedure should be cut in half.-3-valve rubber pipette bulb.-Graduated pipette, 25 mL or as appropriate for the polymer volume to be dispensed.

-Small beakers (e.g. 50 mL) if chemicals are to be pre-dispensed.-Plastic bucket for obtaining water samples.

3. Reagents

-Working polymer solutions prepared according to the instructions in Module A, or according to the manufacturer's instructions. If the manufacturer furnishes a range of recommended doses, calculate the volume of polymer solution required to provide the highest recommended dose to the jar. The formula given in Module C, Section 3 can be used for this purpose. If no recommended doses are given, use the volumes specified below.

4 . Procedure

1. With a bucket, obtain a sample of the water to be tested. This water should be obtained from a point directly after the rapid mix chamber so that the coagulant has already been added. This water should be taken immediately prior to testing so that the temperature has not changed.

2. Pour a 2-L sample from the bucket into the beaker. Drop a2-inch stir bar into the beaker and rapidly mix the contents on a magnetic mixer. A 1-inch vortex should be present in the beaker to assure good mixing conditions.

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3. Dose the sample with 20 mL (or a volume calculated as described above) of the working polymer solution, and continue mixing for 20 seconds to allow for dispersion.

4. Slow down the mixing speed (so there is a 1/4-inch vortex) and continue mixing for 5 minutes.

5. If large floes form, the polymer should be further investigated. For each test, note the time at which floes form, their general size after 5 minutes, and whether the fluid between the floes appears clear.

5. Interpreting Results

This test is useful to determine which aids will probably enhance or increase flocculation. It does not provide conclusive results as to which aids and doses are effective, but rather gives an indication as to those that should be tested first in the more time-consuming jar test procedure.

Generally, when floe size increases due to the addition of a polymer, it can be safely concluded that flocculation is being enhanced, and that the polymer warrants further investigation. A proper dose should also lead to the water between the larger floes being essentially free of turbidity or smaller particles, but determination of this optimum dose is best done in subsequent testing with the more elaborate jar test procedure (Module C).

The subjective results of this initial test can be used to later estimate doses to be evaluated in detail. Polymers which did not form any floe should be dropped; polymers forming well defined floes (i.e. discrete floes) with clear water between the particles should be tested near the dose used in the screening test. Polymers forming large "globs" surrounded by unflocculated particles should be evaluated at much lower doses.

REFERENCES

INTRODUCTION TO WATER QUALITY ANALYSES. American Water Works Association Publication (1982).

Conduct and Use of Jar Tests. H.E. Hudson and E.G. Wagner in AWWA SEMINAR PROCEEDINGS-UPGRADING EXISTING WATER TREATMENT PLANTS. American Water Works Association Publication 20126 (1980).

Module C. The Jar Test

1. General Discussion

The jar test procedure basically involves filling 2-L (liter) containers with the water to be treated, placing them under a multipaddle stirring machine (bench stirrer), dosing the jars during a high paddle speed (rapid mix), flocculating at a lower speed, and finally, allowing sedimentation to occur under quiescent settling conditions.

The jar test has seen substantial use in the water treatment industry due to its ability to simulate rapid mix, flocculation, and sedimentation in one vessel. The key consideration in the running of a jar test is to simulate the physical conditions in the treatment plant as closely as possible. These conditions include such parameters as detention times, velocity gradient (mixing intensity), temperature, pH, and order of addition of all coagulants, pH control chemicals, and polymeric aids. Varying any of these parameters during a jar test may significantly alter the final results and produce poor correlations with actual full-scale plant processes.

2. Apparatus

-Containers or "jars": When the jar test was originally devel oped, any glass jar was acceptable. Since then, however, research has shown that the jar type can have a significant effect on success of the test. Although there are a number of different jar configurations available, a 2-L acrylic plastic square jar is recommended. This type of jar is essentially unbreakable and is less heat conductive than glass. The 2-L volume enables filtra tion and sludge characterization tests given in later modules to be incorporated in this procedure. It can either be purchased (Hach Chemical Company, Loveland, CO) or easily constructed. Con struction requires a table saw with a fine toothed blade, 1/U inch thick acrylic plastic ("Plexiglass"), and acrylic plastic solvent. Details as to construction techniques may be obtained from most glass dealers. Figure C.1 gives the approximate dimensions for the jars. They should be provided with a calibrated 2-L mark. Other container types, although less preferable, may be substi tuted. However, do not mix or compare results between different types of jars.

-Variable speed multistirring machine (bench stirrer) with at least 5 paddles. Make sure there is adequate clearance for the jars: if not, the legs may need to be modified.

-Plastic pail to collect enough sample to fill all the jars.-Glass pipettes to dispense coagulant, polymer, limewater, or other chemical.-3-valve rubber pipette bulb.

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4.5"-4.5-

Figure C.1. Dimensions of 2-liter "square" jar. Material is 1/M inch acrylic plastic ("Plexiglass").

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-Magnetic mixer, stir bars, and stir bar retriever for mixing solutions prior to dispensing into jars.

-Plastic syringe, large "turkey baster", or similar device to withdraw sample from jars for further analysis. This device should have a mark at some distance from the tip (e.g. 5 cm) so that the sample is taken from a constant distance below the surface in every jar. Alternatively, a hole may be drilled about 2.5 inches from the bottom of the jar to insert a sampling port with flexible tubing and a pinch clamp as shown in Figure C.1. The distance at which the port is located should be identical for all jars.

-Stopwatch or timer to time the periods of rapid mix, flocculation, and sedimentation.

-Beakers, 100 mL or larger to collect samples for further analysis (turbidity, particle size analysis, color, alkalinity, etc).

-Thermometer.

3. Reagents

a. Coagulant aids to be evaluated, in proper working solution strengths. If instructions for the preparation of such solutions are not provided for a given product, see Module A.

b. Coagulants and Other Chemicals

In general, all chemicals (coagulants, lime, etc.) should be identical to those used in the plant and preferably should be taken directly as supplied, since the actual concentrations are often not accurately known. For example, lime slurry should be obtained directly from the lime dosing line. Chemicals can also be prepared according to the procedure outlined in AWWA Introduction To Water Quality Analyses . However, alum or ferric solutions should not be diluted more often than necessary beforehand, since this may alter their effective dose. Alum stock solutions should be at least 30 g/L and ferric chloride solutions stock solutions should have a concentration of at least 200 g/L. Due to the solution chemistry of of these chemicals, concentrations less than the values mentioned above may be less effective than those which are more more concentrated, even when identical doses are used. Conse quently, liquid ferric chloride and alum should be used in the concentrated form whenever possible. If dilution is necessary, it should be done just prior (within seconds) to jar testing.

To determine the final concentration of a solution after dilution, use the following formula:

Concentration of X mL of solution added = final cone, initial solution(mg/L) Total vol. of new solution(mL) (mg/L)

where 1 mg/L = 1 ppm.

For example, if the initial concentration of a stock solution is 900 ppm and 25 mL are added to a flask and diluted to 500 mL, then the final concentration is (900 X 25)/500 or H5 ppm = 45 mg/L. If

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coagulants are purchased as liquids, information concerning the concentration may be obtained from the manufacturer. General concentration ranges are also given in AWWA Introduction to Water Treatment.

4. Procedure

a. General Considerations

Before performing the jar test, label all reagents and mix them thoroughly with magnetic stirrer and stir bar. Place the beakers of reagents near the multi-stirrer in the order that they are to be used. Label all glass pipettes and put them in the corresponding reagent beakers. Decide on chemical dosages including any lime, activated carbon, permanganate, etc. before the jar test begins, record them on the data sheet, and put the sheet in a highly visible location. (Note: to estimate chemical dosages, see the section on cost analysis. Also see steps 1 and 2 below for determination of lime and coagulant aid doses). If chemicals are to be predispensed into small beakers, label and locate these appropriately. Analysis equipment such as turbidi- meters or spectrophotometers should be ready for use, since initial measurements such as turbidity and color should be taken prior to the initiation of the jar test.

The 2-L jars and paddles from the multi-stirrer should be cleaned by wiping with a damp cloth and rinsing with warm tap water in between each test to remove any polymer residue. Similarly, pipettes used for dispensing a polymer should be thoroughly rinsed once a day or immediately if a different polymer is used. This may be accomplished by inserting the tip of a large squeeze bottle filled with hot water into the large end of the pipette and flushing with large amounts of water. Occasionally, it may be necessary to acid wash the pipettes with 1 Normal acid to remove any residual polymer.

When pipetting any particular chemical to a large number of jars, it is convenient to use one or two large pipettes (which are filled prior to the start of the jar test). Each pipette should have a 3-valve rubber bulb so that a number of accurate doses can be dispensed before refilling the pipette. There may be a need to dilute a chemical to decrease the likelihood of measurement error when pipetting. If possible, however, the chemicals used in jar tests should be identical both in origin and concentration to those in the plant.

Another method which allows rapid addition of chemicals (coagulants such as alum or ferric, lime, activated carbon, etc.) during the jar test is to pre-dispense them into small beakers (appropriately labelled). These are then lined up for each jar test container and added at the corresponding stage of the test. A squirt bottle can be used for rinsing residual chemical from the beaker, with the rinse water also being added to the jar. This method helps prevent pipetting error and is especially recommended when a large number of different chemicals are to be added to the jars. It is not recommended to add polymers to the jar test containers using this method since their dispersion would

-38-

be adversely affected. Additionally, polymers tend to adhere to glass and large volumes of rinse water would be required to completely remove the polymer from the walls of the small dosing beakers.

Jar testing should be conducted at similar temperatures to those of the water in the actual treatment process. If the water sampled is cold (as in winter), the jar test must be performed before the sample warms appreciably. The optimal coagulant aid dose may differ substantially at different temperatures. To best simulate coagulation, flocculation, and sedimentation at colder temperatures,it may be necessary to place the jars in a water bath, i.e. a container or tray which is filled with cold water or actual plant water so that most of the jar is immersed and held close to process temperatures. If the purpose of a coagulant aid is to improve performance under difficult conditions, such as high turbidity, then an attempt should be made to run jar tests when raw water in this condition can be obtained.

Regardless of the jar test procedure used, there may still be dif ferences between jar test results and plant results. The most important consideration is not whether bench-scale and full-scale systems provide identical results, but that the bench-scale jar tests predict the poly mer dose that is optimal for the plant. The following are possible causes why optimum dose may be falsely predicted:

-Deposition of coagulant aid on the mixing blade of the bench stirrer or walls of the jar.

-Improper preparation of the reagents.-Excessive aging of the reagents.-Incomplete dispersion of polymers added to jars.-Measurement error (particularly with viscous polymers).-Use of reagents from a different source than those used in full- scale plant processes.

-Mixing conditions during flocculation in the jar test are drastically different from those in the plant.

b. Procedure Using Raw Water

1. Determine the coagulant aid doses to be evaluated in this jar test series. Generally, because polymers are expensive but usually work well at low concentrations, the maximum dose should be less than 1.5 mg/L and doses as small as 0.05 mg/L may prove effective as an aid for coagulation. If the supplier of a polymer can provide you with a range of recommended doses, try these in the jar tests. Otherwise, a good range of doses to try first might be 0, 0.1, 0.25, 0.5, 0.75, and 1.0 mg/L. The proper volume of polymer solution can then be calculated for each jar. For example, assuming that the polymer to be tested is at a concentration of 0.1g/L (0.1 mg/mL), the amounts of polymer to be added for the above doses would be 0, 2, 6, 10, 15, and 20 mL. Once these doses are evaluated, further series of jar tests can be performed with different dosages to more exactly locate the optimal polymer dose.

-39-

2. If lime or other chemicals are used for pH control in the plant, check that the jar test dose will produce the desired final pH. Usually this is the pH in the flocculators. Fill a 2-L glass beaker with the water to be tested. Add a 2-inch magnetic stir bar, place the jar on a magnetic mixer, and turn up the mixing speed so as to form a 1/2 inch vortex. With a pipette, dose the jar with coagulant (identical to the full-scale plant dose). Insert the pH electrode into the jar and add small doses of lime or other chemical to adjust the pH to the desired level. (If limewater is used, it is important to shake it up just prior to addition so that the settled lime is uniformly dispersed). Note the volume of lime or other chemical added since an identical volume will be used in all subsequent jar tests. These volumes can also be pre-dispensed into small beakers for rapid addition during the jar test.

3. If coagulant, lime, or other chemicals (carbon, permanganate, etc.) are to be pre-dispensed into small beakers, complete this step of the procedure and organize these beakers before beginning the jar test. Collect enough water to fill the jars. Measure and record all initial parameters of interest (pH, turbidity, color, etc.) from the head of the treatment plant.

4. Pour 2-L of sample into each square jar.

5. Position the jars under the multi-stirrer so they are centered with respect to the shaft of the paddles.

6. Lower the paddles so that the top of each paddle is equidistant from the surface of the water and the bottom of the jar.

7. Begin rapid mix. If no other paddle speed is otherwisespecified, the maximum RPM is recommended (about 125 RPM on most bench stirrers).

8. Using a 25 mL graduated pipette, dispense identical doses of coagulant as rapidly as possible to each of the jars. The coagulant dose should be the same as used in the plant although the solution may need to be diluted prior to the jar test. For the purpose of accuracy, the volume of coagulant dispensed to each jar should be at least 3 mL. For smaller alum doses use a smaller graduated pipette (e.g. 5 mL).

9. To each of the jars, add any lime or other chemical used for pH control. The dose to be added was predetermined in step 2. (Note: Steps 9, 10, and 11 may be reordered depending on the point of lime or anticipated coagulant aid addition.)

10. Bypassing the first jar (which is the zero polymer dose), apply increasing coagulant aid doses to the remaining jars. As with the alum, dosing is achieved by using a large graduated pipette and inserting the tip 1/2 inch below the water surface of each

-MO-

jar while releasing the polymer. Continue rapid mix for 15 seconds after the last jar has been dosed to facilitate good dispersion.

11. Decrease mixing speed (e.g. 25 RPM) to simulate mixing cond itions during flocculation in the full-scale process.

12. Flocculate for a period similar to the estimated flocculatordetention time (e.g. 20 minutes). Visually observe floe size in the first jar (where only the primary coagulant has been added and no polymer) and compare to the actual floe size observed in the plant. If the floe size in the jar is much larger than in the plant, the mixing speed in the jar may be too low. If the floe size in the jar is significantly smaller than in the plant, the mixing speed in the jar may be too high. If the difference is substantial, the jar test should be revised and repeated. If the floe size is larger than in the plant, determine a better paddle speed by increasing the paddle speed until floe size re sembles that in the plant. If floes have settled to the bottom during flocculation, readjust paddle level lower in the con tainer and allow floes to be redispersed. (Note: More elaborate methods of establishing the times and RPMs which best simulate plant conditions may be found in Schull (1967) and Cornwell and Bishop (1983). See References at the end of this Module).

13. Stop the mixer, pull up the paddles, and allow sedimentation to occur. If this is the first jar test series to be run, this step must be adjusted to simulate plant settling as much as possible. To do this, periodically measure turbidity in the first jar (with no coagulant aid). Take care not to signifi cantly disturb jar contents while taking these samples. When the jar's turbidity is approximately equal to the settled plant turbidity, this time should be recorded and used for all subsequent jar test settling periods. (Depth of sampling may also be adjusted for this purpose).

14. Withdraw samples for desired analyses (turbidity, particle size analysis, true color, pH, etc). Sample withdrawal may be accomplished either by the use of a syringe or sampling port. When using a syringe, samples should be taken from a specific depth. For example, a piece of tape 5 cm from the end of the syringe serves as a reliable marker for depth. The syringe should be rinsed with distilled water before sampling from different jars. The first 150 mL taken from a fixed port, however, should be discarded before using to measure for turbidity, color, or particle size analysis.

o. Procedure for Water from Rapid Mix

This procedure is applicable to water which has been sampled after coagulants such as alum or ferric chloride have been added, but before polymer addition. This is useful only when the goal is to improve water

-41-

quality using a polymer without modifying the alum or ferric dose. The procedure is similar to the one given previously, but is easier to per form since the water to be tested has already been dosed with one or more chemicals during rapid mix. All steps are the same, except Step 8 is omitted. If chemicals for pH control have been added in the plant prior to the sampling point, Steps 2 and 9 are also omitted.

d. Procedure to Determine if Alum/Ferric Dose May Be Decreased as a Result of Coagulant Aid Addition

This procedure is applicable to situations where it is desirable to approximate the degree to which the primary coagulant, e.g. ferric or alum dose, may be reduced as a result of adding a coagulant aid. It differs from the preceding procedures in that the coagulant dose is varied while the previously selected aid dose is held constant. The range of doses which will be used will be determined by the dose which is presently being used in the plant. For example, if the plant operates at 100 mg/L alum under highly turbid conditions which are being assessed in the jar tests, then a good range of doses to try might be 10, 30, 40, 60, 80, and 100 mg/L alum. In this example the first jar would be dosed with 10 mg/L and increasing doses in subsequent jars until 100 mg/L is reached.

If lime or other pH controlling chemical is presently employed, this dose must also be adjusted since its addition is meant to counteract pH changes due to the coagulant. The amount added to achieve a particular pH should be adjusted to be proportional to the coagulant dose. For example, if 60 mg/L of lime was used to arrive at a certain pH for a coagulant dose of 100 mg/L, then if the coagulant dose was reduced to one half of 100 (i.e. 50 mg/L), the lime dose would also be reduced by the same factor to 30 mg/L (i.e. 1/2 x 60 mg/L). The different lime and coagulant doses would therefore be known before the jar test begins and could be pre-dispensed into small beakers. The Procedure Using Raw Water (Section C.4.b.) is then used with the above modifications In addition, the final pH of each jar test should be measured. If these pH values are not within 0.5 pH units of the settled water in the plant, readjust the lime doses and repeat the jar test.

A more time-consuming procedure can be used if the precise combination of optimal coagulant and coagulant aid doses is to be located. An entire set of coagulant aid additions can be evaluated at each coagulant dose, thus covering many combinations of dosages. For example, six polymer doses of 0, 0.1, 0.25, 0.5, 1.0, and 1.5 mg/L could be employed in each jar test set, with a constant alum dose. The procedure would be repeated using alum doses (in all six jars) of 10, 25i 50, 75i and 100 mg/L alum. The optimal dose combination can then be determined as illustrated in the next section. The disadvantage of this approach is obviously the large number of jar tests that must be run; note that a very large raw water sample should be obtained so that all of these tests are run on the same water. This is particularly important if coagulation is being evaluated under storm or other rapidly changing conditions.

-42-

5. Interpreting Results

Most importantly, the quality control steps described in Section II.F should be followed before any jar test results are used to determine actual plant dosages. This will insure that the data used for chemical selection is statistically meaningful. In addition, the procedure should be repeated with varying raw water conditions to get some idea of the range of dosages that may be required.

Use of the overall procedure will be illustrated in the following example, including the tabulation and graphical analysis of results. To predict optimum polymer dose for a given sample, procedure C.4.b or C.4.C. would be used. Table C.1 shows data that might result and how it could be tabulated. The turbidity versus polymer dose could then be plotted such as on Figure C.2 connecting the points with a straight edge. From this graph, an optimum dose of 0.4 mg/L of the polymer might be chosen. This value might be preferable to 0.3 mg/L to provide a factor of safety. Although in this example, the coagulant aid significantly improved turbidity removal, it would also be desirable to learn if the coagulant dose could be decreased to save chemical costs while maintaining similar turbidity removal. Following procedure C.4.d., the results could be recorded as on Table C.2, and graphed on Figure C.3. The coagulant dose could be decreased to 90 mg/L in this case, a 10 percent decrease in primary coagulant, while having about the same turbidity removal. A 90 mg/L dose might be chosen rather than 80 mg/L to provide a factor of safety.

To warrant the use of a coagulant aid, it should significantly re duce the turbidity, color, or some other measure of performance. For example, if a coagulant aid only reduces the turbidity by about 20 per cent at optimum dose it probably isn't economically feasible to use, unless it reduces the primary coagulant dose enough to save signifi cantly on chemical costs. Other factors, such as sludge disposal costs, may also be significant factors.

Figure C.4 shows a different set of jar test results obtained by the more lengthy procedure of varying both polymer and coagulant dos ages. The point is located on the graph for each coagulant and coagu lant aid combination, and the resulting turbidity is noted. After all the data is on the graph, lines of equal turbidity (contour lines) are drawn. This produces an "isoturbidity topogram" which can be examined to help select a dose combination (Log-log graph paper is most satis factory for such graphs because a wide range of concentrations can easily be included). In the example Figure C.4, it appears that a polymer addition of 0.15-0.25 mg/L generally gives the lowest turbidity for a given alum dose, and that the alum dose would be set depending on the desired settled turbidity. Again, other considerations such as relative cost and effects on filtration and sludge handling may also be important.

-43-

To calculate the total pounds of dry polymer needed per day, multiply the optimum dose in mg/L times 8.34 times the number of MGD that the plant treats. For example, if a 10 MGD plant uses an optimum polymer dose of 0.5 mg/L, then the total pounds of polymer needed per day is 0.5 x 8.34 x 10 = 41.7 pounds per day.

6. Data Tabulation and Analysis

Tables C.3 and C.4 and Figures C.4, C.5, and C.6 are provided to illustrate how results can be recorded and analyzed.

REFERENCES

INTRODUCTION TO WATER QUALITY ANALYSES. American Water Works Association (1982).

Conduct and Use of Jar Tests. H.E. Hudson and E.G. Wagner in AWWA SEMINAR PROCEEDINGS-UPGRADING EXISTING WATER TREATMENT PLANTS. American Water Works Association Publication 20126 (1980).

Coagulation Testing: A Comparison of Techniques. R.J. TeKippe and R.K. Ham. Journal AWWA. 62., 594 (1970).

Determining Velocity Gradients in Laboratory and Full-Scale Systems. D.A. Cornwell and M.M. Bishop. Journal AWWA. JJL, ^70 (1983).

Filtrability Techniques for Improving Water Clarification. K.E. Schull. Journal AWWA. 59_, 1164 (1967).

Prototype Studies. P. 455 in Water Treatment Principles & Design. James M. Montgomery, Consulting Engineers, Inc. NY: Wiley Interscience (1985).

-UP

OPERATOR

COAGULANT AID POLT 999

COAO. AID CONCENTUTIOH 0.1 K/L

ALUM/FERRIC DOSE 100 mm/L

LIME DOSE ________________

RAW WATER CHARACTERISTICS

PH ________________

TURBIDITT

TEMPERATURE

TRUE COLOR _

COMMENTS

JAR *

POLTKEB DOSE(B8/L)

1NAL TURBOITT

riNAL PH

nHAL TEMP.

1HAL COLOR

0

5

6.5

0.1

3

6.6

0.3

0.9

6.4

0.5

0.8

6.5

0.75

1.1

6.6

1.0

1.5

6.3

OBSERVATIONS

Table C.1. Example tabulation of jar test results varying coagulant aid dose.

Q

U z h-l r at u »- u. a: ca a:

TURBIDITY vs POLYMER DOSE

OPERRTOR

, DRTE

, WRTER TEMP.

1

B.B

8.2

8.4

0.6

B.B

i.a

POLYMER DOSE <mg/l)

(POLYMER NRME

POLY 939

, RLUM/FERRIC DOSE 100 mg/l)

(ROW MRTER TURBIDITY____, FINflL pH OF JRRS -

6.5)

°f Jar

varyin

g

-46-

OATE

OPERATOR

COAGULANT AID POLT 999

COAO. AID CONCEHTRATIOII 0.1 g/L

COAG. AID DOSE Q.< K/L

RAH WATER CHARACTERISTICS

PH ________________

TURBIDIT7

TEMPERATURE

TRUE COLOR

COMMENTS

JAR

U.OM/RBRXC DOSE

(u/L)

LIME DOSE

niAL TORBIDITX

rZBAL pB

1HAL COLOR

riHAL TEMP.

TIKE STARTED

TIME AT ED or rue.TIME TO TAKE SAMPLE

10

8

6.5

0

20

90

30

6

6.6

3

23

53

40

'

6.5

6

26

56

60

1.5

6.*

9

29

59

80

1

6.7

12

32

62

100

1

6.7

15

35

65

OBSERVATIONS

Table C.2. Example tabulation of jar test results varying coagulant dose with constant coagulant aid dose.

TURBIDITY vs

. PLUM/FERRIC DOSE

OP

ER

flT

OR

_

__

,

DR

TE

.

Wfl

TE

R

TE

MP

.IB

Q

U in z l-l r u H

U. o: ca

a:

20

48

60

B0RLUMXFERRIC DOSE (mgXl)

(POLYMER NRMEXDOSE

POLY 999

x 0.4 mgXl)

(RRH WflTER TURBIDITY____, FINRL pH OF JRRS -

6.5)

100

Figu

re C

.3.

Example

of graphed results

of jar

tests

varying

coag

ulan

t do

se w

ith

cons

tant

co

agul

ant

aid

dose.

Same

dat

a as in T

able

C.2.

-MS-

0.25 -£ a:

10 20 30 15100

Figure C.4. Example of graphed results of multiple jar tests with coagulant aid dose varied in each set, and coagulant dose varied between sets. Turbidities are indicated at each dose combination, and lines of constant turbidity are interpolated between the data points.

-49-

DATE

OFER1TOR

RAW WATER CHARACTERISTICS

PH ________________

COAGULANT AID TURBIDITI

COAC. AID CORCEKTRATIOH

ALUM/FERRIC DOSE _____

LIME MSB ___________

TEMPERATURE

TRUE COLOR

COMMENTS

JAR *

POLTMER DOSE(«g/L)

FINAL T0BBIDITI

FINAL pB

1NAL TEMP.

FINAL COLOR

l«l«I<«*ll*l*ll*l>ltMttfl««tl>l*l«««t«*lll<««tllllllll<l till ttl«tl»lf« til tt !••••(

)BSERVATIOKS

Table C.3. Blank data sheet for jar tests varying coagulant aid dose with constant coagulant dose. Photocopy for lab use.

-50-

BATE

OPERATOR

COiOOUHT AID

COAG. AID CONCEKTRATIOH

COAO. AID DOSE ______

RAW HATER CHARACTERISTICS

PH ________________

TURBIDITT

TEMPERATURE

TRUE COLOR

COMMENTS

JAR #

ALUM/FERRIC DOSE

(B8/L)

LIME DOSE

(BS/L)

FINAL TDRBIDITT

riHAL pH

'IHAL COLOR

1HAL TEMP.

FINS STARTED

TIME AT END OF FLOC,

TIME TO TAKE SAMPLE

OBSERVATIONS

Table C.4. Blank data sheet for jar tests varying coagulant dose at a constant coagulant aid dose. Photocopy for lab use.

TU

RB

IDIT

Y

vs.

PO

LY

ME

R

DO

SE

OP

ER

RT

OR

,

DR

TE

,

MR

TER

T

EM

P.

a U in z »-« r tt

U U. a: a 1-4 m

B.B

8.2

(POLYMER NRME

0.4

0.6

0.8

CRHH HRTER TURBIDITY

POLYMER DOSE (mg/I)

______, RLUM/FERRIC DOSE ___mgXl)

, FINRL pH OF JRRS -

)

Figu

re C

.5.

Blank

graph

for

jar

test

s vary

ing

coag

ulan

t aid

dose w

ith

cons

tant

co

agul

ant

dose.

Photocopy

for

lab

use.

TURBIDITY vs. PLUM/FERRIC DOSE

OP

ER

RT

OR

,

Dfl

TE

,

WH

TER

T

EM

P.

IB

Q

U

U)

Z

1-1 r IK U

GC CP

(E

ro i

28

48

68

88RLUMXFERRIC DOSE (mg/l )

(POLYMER NRME/DOSE __________ X ___ mg/l )

(RRW MRTER TURBIDITY____, FINRL pH OF JRRS - _

188

Figu

re C

.6.

Blan

k gr

aph

for

jar

tests

varying

coag

ulan

t dose at a

cons

tant

co

agul

ant

aid

dose.

Photocopy

for

lab

use.

-53-

Module P. Turbidity Measurement for Jar Test Assessment

1. General Discussion

Turbidity measurement, in most cases, is sufficiently sensitive for evaluation of coagulant and coagulant aid effectiveness. Limitations and specific procedures will vary according to the model of turbidimeter employed. General points concerning turbidity for jar test assessment follow; for more specific instructions, refer to the operating manual for the individual turbidimeter and to publications listed at the end of this Module under References.

2. Apparatus

-laboratory turb id imet er.-sample cells for the appropriate turbidimeter. Cells to be used should be clean and free from scratches.-turbidity standards to calibrate the instrument.

3. Reagents

If the appropriate turbidity standards are not provided with the turbidimeter, it will be necessary to prepare them. Proper calibration using such standards is necessary if results are to be compared between past and present jar test analyses. Instructions for preparing these standards may be found in Standard Methods for the Examination of Water and Wastewater .

Procedure

Pipettes and syringes should be well rinsed between samples. The most accurate turbidity readings will be obtained if the same turbidity cell is used for all samples and it is marked to be oriented in the same direction each time it is placed in the turbidimeter. Be sure that the sample cell is well cleaned between samples. This insures accurate readings. Lens paper is recommended for the final cleaning.

Collected samples should be carefully poured into the turbidity cells immediately before measuring the turbidity. There should be no visible bubbles in the turbidity cell since these interfere with light transmittance . If more than a minute passes between collecting the sample before pouring it into the cell, it will be necessary to gently swirl the sample before adding it to the turbidity cell.

-51-

6. Data Interpretation

In most cases, interpretation of turbidity measurements is straight forward. However, if the readings appear to be lower than the sensi tivity range of the instrument, it will be difficult to confidently evaluate coagulation results. The following changes may then be considered:

-use a more sensitive turbidimeter.-increase the sampling depth in the jar test container.-decrease the settling period.-use a particle size analyzer instead of a turbidimeter (refer to Module E which follows).

REFERENCES

STANDARD METHODS FOR THE EXAMINATION OF WATER AND WASTEWATER. American Public Health Association, American Water Works Association, and Water Pollution Control Federation.

INTRODUCTION TO WATER QUALITY ANALYSES. American Water Works Association (1982).

METHODS FOR CHEMICAL ANALYSIS OF WATER AND WASTES. U.S. EPA. Technology Transfer Series. EPA-625-/6-74-003 (1974).

-55-

Module E. Particle Size Analysis for Jar Test Assessment

This Module is concerned with general aspects of particle size analysis of concern for jar test assessment. Refer also to the manual for the particular particle size analyzer being used.

1. General Discussion

The particle size analyzer is a very sensitive instrument capable of characterizing water quality based on particle number and particle size in a given sample. This information can be used to locate the optimal coagulant or coagulant aid dose in cases where turbidity is not suffic iently sensitive. However, the equipment required is expensive and its use would generally be economically justified only if used for other purposes as well. In some cases, research laboratories or vendors may provide access to such equipment.

2. Apparatus

-Particle size analyzer with appropriate sensor.-Glass sample bottles. Although these are commercially avail able, nearly any clean glass container that will fit into the analyzer is acceptable (e.g. beakers or small juice bottles).-Small magnetic stir bars (1/2 inch or less).-250 mL and 50 mL graduated cylinders.-1-liter plastic reagent bottles to store filtered water.-Filtering apparatus (e.g. Millipore) including vaccuum pump.-0.45 micron filter papers.

3. Reagents

-Distilled, filtered (O.MS micron) water or electrolyte solution.

4. Procedure

Particle size analyzers vary substantially in their capabilities and operating procedures. Thus, the manufacturer's recommendations should be followed for the use of each specific instrument. Some general rules are provided here which should assure reliable results.

1. All glassware should be thoroughly cleaned and rinsed prior to use. If possible, water filtered through a 0.45 micron filter should be used for the final rinse. Glassware should be stored upside down and rinsed again immediately prior to use.

-56-

Samples should be taken from the jar test using a device that will not break up flocculated particles. The tip of a pipette can be cut off, or a piece of flexible plastic tubing fitted over a syringe, to prevent floe rupture by passage through a small orifice. The volume of sample to be taken will depend on the particular analyzer requirements and whether or not the sample is to be diluted.

Samples may require dilution if they are highly turbid because particle size analyzers are usually limited in the particle size concentrations they can handle. Consult your analyzer's manual for specific limitations. If samples must be diluted, dilution water should be prepared by filtering a portion of the sample through a 0.45 micron filter. Some types of particle size analyzers require concentrated electrolyte instead of water, and this should be prepared in a similar manner. This may then be used to dilute the original sample. Volumes of sample and dilution water to be combined should be measured with graduated cylinders.

A particle size analysis should also be performed on the dilution water (or electrolyte solution). If this water has substantially lower particle counts than do the diluted samples, then the particle counts for the original, undiluted sample can be obtained simply by multiplying the diluted sample counts by the dilution factor. The dilution factor is the volume of the diluted sample divided by the original sample volume. For example, if a 50 mL sample is diluted with 150 mL of dilution water, the dilution factor equals 200/50 or 4.0. The diluted sample counts would be multiplied by four. Some particle size analyzers are equipped to do these dilution calculations (background calculations) automatically.

REFERENCES

A Comparison of Particle Counting and Nephelometry. J.D. Beard and T.S. Tanaka. Journal AWWA. 6_9_ (1977).

The Use of Particle Counting in Developing Plant Design Criteria. C.H. Tate and R.R. Trussell. Journal AWWA. 7_P_, 698 (1978).

-57-

Module F. Paper Filter Test

This Module describes a paper filtration procedure which can be used for two purposes: determination of an optimal filtration aid dose, or optimizing coagulant aid selection with regard to its effects on filtration. These applications are described respectively in Sections I and II.

I) DETERMINING OPTIMUM FILTRATION AID DOSE

1) General discussion

A filter aid can be used to enhance filter performance either in direct filtration or in conventional water treatment (flocculation and sedimentation followed by filtration). Direct filtration has been defined by the Committee on Coagulation- Filtration of AWWA's Water Quality Division as being any water treatment scheme in which there is no in-plant sedimentation prior to filtration (McCormick and King, 1982). There may or may not be a flocculation basin prior to filtration. Direct filtration without the flocculation step is called in-line filtration or contact flocculation-filtration (contact filtration), since the flocculation occurs during contact with the filter media as opposed to volume flocculation in a flocculation chamber (Adin and Rebhun, 1974).

There are two tests that can be performed to evaluate the effect of a filtration aid on filter performance: the paper filter test and the bench filter test (described in Module G). The former is more rapid and easy to perform, and is the recommended test. The paper filter test is intended to simulate the process of filtration in a water treatment plant, just as a jar test is meant to simulate the flocculation and sedimentation processes. It assesses the impact of a filtration aid on the filtration process and is used to qualitatively predict the variation of the plant effluent quality with filtration aid dosage. An indication of the head loss that would develop across the plant filter bed is provided by the filtration time in this test.

This method is applicable both when the filter aid under test is to be used in a direct filtration process and when it is to be added at the end of the sedimentation basin in a conventional treatment plant. The major pieces of equipment needed to run this test are: a multipaddle stirrer, square jars, filtering flasks, filter holders and a vacuum pump. Approximately one and a half hours are required for running this test. This test does not require any special skills and can easily be performed by an operator or laboratory personnel.

-58-

2) Apparatus

a) Multiple stirring apparatus. Phipps and Bird type, variable speed.

b) Illuminator base, for optional use with stirrer. Enhancesobservation of floe formation by providing effective glare-free illumination of floe samples. Consists of fluorescent lamp mounted below translucent plastic plate. Test jars and support posts of stirrer rest directly on diffuser top plate.

c) Jars. 2-L capacity, square, acrylic plastic, either with orwithout side outlet, for preparation of samples to be filtered.

d) Bucket. for collection of sufficient sample to fill all jars.

e) Pipets, glass, for dispensing the filtration aid solution, alum or ferric solutions and any other chemicals.

f) Pipet filler, bulb type, rubber.

g) Magnetic stirrer. variable speed, for preparation of filtration aid solutions.

h) Other. stir bars, stir bar retriever, and stopwatch (with buzzer), pH meter (for direct filtration tests).

i) Filtering flasks. 1-L, pyrex glass.Side-arm accepts standard 1A" I.D. flexible hose for vacuum connection, neck fits #8 perforated stopper.

j) Filter holders. 300-mL funnel capacity, pyrex. Pyrex funnel and base with coarse frit glass support for filter, anodized aluminum spring clamp, neoprene stopper, 47 mm diameter filter size.

k) Filter paper, diameter 5.5 cm, Whatman #40.

1) Vacuum pump, capable of generating a vacuum of at least 15" of mercury.

m) Vacuum hose, flexible, 1M" I.D., length 2-3 feet.

3) Reagents

a) Filtration aid working solution, made according to the instructions in Module A.

b) Coagulants and other chemicals (in case of direct filtration).

In general, all chemicals (primary coagulant, lime, etc.) should be identical to those used in the plant and preferably

-59-

should be taken directly as supplied, since the actual concentrations are often not accurately known. For example, lime slurry should be obtained directly from the lime dosing line. Chemicals can also be prepared according to the procedure outlined in AWWA Introduction to Water Quality Analyses. However, alum or ferric solutions should not be diluted more often than necessary beforehand, since this may alter their effective dose. Alum stock solutions should be at least 30 g/L and ferric at least 200 g/L. If dilution is necessary, it should be done just prior (within seconds) to testing.

The concentration of a diluted solution can be calculated as follows:

c 1 = c2 » v2 / Vl

where C.. = concentration of dilute solution (mg/L)

Cp = concentration of stock solution (mg/L)

Vp = volume of concentrated solution used (mL)

V1 = total volume of dilute solution (mL)

(Note 1 mg/L = 1 ppm)

If coagulants are purchased as liquids, information concerning their concentration may be obtained from the manufacturer. General concentration ranges are also given in AWWA Introduction to Water Treatment.

4) Procedure

a) Preparation of working solutions of filtration aids

The procedure to be followed is identical to that used for making coagulant aid solutions. Refer to Module A.

If the product data sheet on the polymer is available try different dosage levels in the recommended range. If not, recommended values of filtration aid doses are: 0, 0.01, 0.03, 0.05, 0.07, and 0.1 mg/L. To calculate the volume of the filtration aid solution needed for each jar use the formula given below.

V = C 1 « V / C

where V = volume required (mL)C'= desired concentration (mg/L or mL/L)V'= volume of sample (should be 2L)C = concentration of working solution (mg/L or mL/L)

-60-

Record the volumes needed for the six doses,

b) Preparation of samples for filtration

i. Contact filtration

1. Use the bucket to collect about 15 L (4 gal) of the plant influent raw water. Assemble the filtration apparatus as shown in Figure F.1.

2. Pour 2 L of the water into a jar, and place the jar in the multiple stirrer unit. Begin rapid mix. If no other paddle speed is otherwise specified, the maximum RPM is recommended (about 125 RPM on most bench stir- rers). Using a pipet dose the jar with the primary co agulant. The coagulant dose should be the same as that used in the plant. Insert the pH electrode into the jar and add small doses of lime or other chemical to adjust the pH to the level presently existing in the plant fil ter influent. Note the volume of lime or other chemical added. Allow 1 minute for good dispersion of chemicals.

3. Gently stir the sample water to ensure that a uniform sample will be obtained. Then pour 2 L of the water into a jar and place the jar in the multiple stirrer unit. Begin rapid mix. Using a pipet, dose the jar with the primary coagulant (identical to the plant dose). Also add lime or any other chemical used for pH control. The dose to be added was determined in step 2. For the first run with zero polymer dose, proceed directly to step 5.

4. Using the pipet dispense the filtration aid solution in to the contents of the jar, keeping the tip of the pipet half an inch below the water level. The volumes required for different doses were calculated in step (a) above.

5. Allow 1 minute for proper dispersion of added chemicals. Switch off the stirrer and remove the jar from the stirrer unit.

ii. Direct filtration with flocculation

1. Use the bucket to collect about 15 L (4 gal) of the plant influent raw water.

2. Pour 2 L of the water into a jar, and place the jar in the multiple stirrer unit. Begin rapid mix. If no other paddle speed is otherwise specified, the maximum RPM is recommended (about 125 RPM on most bench stirrers). Using a pipet dose the jar with the primary coagulant. The coagulant dose should be the same as

-61-

FUNNEL

FILTER PAPER

BASE

VACUUM PUMP

VACUUM GAUGE

SPRING CLAHP

FILTF.RING FLASK

Figure F.1 Paper filter test assembly

-62-

that used in the plant. Insert the pH electrode into the jar and add small doses of lime or other chemical to adjust the pH to the level presently existing in the plant flocculators. Note the volume of lime or other chemical added- Allow 1 minute for proper dispersion of chemicals.

Reduce mixing speed to simulate mixing intensity during flocculation in the full-scale process (e.g. 20 RPM). Visually observe floe size in the jar and compare to the actual floe size observed in the plant. If the floe size in the jar is much larger than in the plant, the mixing speed in the jar may be too low. Similarly, if the floe size in the jar is significantly smaller than in the plant the mixing speed in the jar may be too high. If the difference is substantial repeat until the floe size is approximately the same as that in the plant. Make a note of this mixing speed.

3. Gently stir the sample water to ensure that a uniform sample will be obtained. Then pour 2 L of the water into a jar and place the jar in the multiple stirrer unit. Begin rapid mix. Using a pipet, dose the jar with the primary coagulant (identical to the plant dose). Also add lime or any other chemical used for pH control. The dose to be added was determined in step 2. For the first run with zero polymer dose, proceed directly to step 5.

U. Using the pipet dispense the filtration aid solution in to the contents of the jar, keeping the tip of the pipet a half-inch below the water level. The volumes required for different doses were calculated in step (a) above.

5. Allow 1 minute for proper dispersion of added chemicals. Reduce mixing speed to that recorded in step 2. Set the timer for the estimated flocculator detention time (e.g. 20 mins) and start the timer.

6. Assemble the filtration apparatus as shown in Figure F.1. Switch off the stirrer when the buzzer goes off and remove the jar from the stirrer unit.

iii. Conventional treatment

1. Use the bucket to collect about 15 L (4 gal) ofunfiltered water from the plant. If a filter aid is presently being used, withdraw the sample from the end of the sedimentation basin prior to the injection point of the aid. If no aid is being used, the sample can be taken from above the filter media.

2. Assemble the filtration apparatus as shown in Figure

-63-

F.1. Gently stir the sample water to ensure that a uniform sample will be obtained. For the first run with zero polymer dose, pour 2 L of the water into a jar and proceed directly to (c).

3. Gently stir the sample water to ensure that a uniform sample will be obtained. Then pour 2 L of the water into a jar and place the jar in the multiple stirrer unit. Begin rapid mix. If no other paddle speed is otherwise specified, the maximum RPM is recommended (about 125 RPM on most bench stirrers). Using the pipet, dispense the filtration aid solution into the contents of the jar, keeping the tip of the pipet half an inch below the water level. The volumes required for different doses were calculated in step(a).

-5K 4. Allow 1 minute for proper dispersion of added chemicals. Switch off the stirrer and remove the jar from the stirrer unit.

c) Filtration of samples

1. Pour out 100 mL from the jar into the funnel (The markings on the funnel may sometimes be inaccurate and so it is advisable to recalibrate them, using a graduated cylinder).

s

2. Turn on the vacuum pump, and simultaneously start the timer (The pump should not be started before pouring in the sample, since filtration starts immediately and more than the required volume would then be poured in while bringing the liquid level up to the 100 mL mark).

3. When all of the sample has filtered through the paper, stop the timer, disconnect the vacuum hose, and turn off the pump. Sometimes the time taken for filtration of the entire sample is excessively long, especially at higher doses of the coagulant aid. In such cases terminate the test after four minutes. Make sure that the pump is vented to the atmosphere on shutdown. This prevents the oil in the pump from getting into parts where it can do damage.

4. Determine the quality of the filtered water by measuring its turbidity, according to the directions given Module H. See also:

-Standard Methods for the Examination of Water and Wastewater (APHA, AWWA, WPCF).

-Introduction to Water Quality Analyses (AWWA).

-the instruction manual for the turbidimeter to be used.

5. Make any other measurements (color, particle size analyses

-64-

etc.) as desired. If the filtered water turbidities are below the sensitivity range of the turbidimeter, a particle size analyzer will have to be used to evaluate filtration results.

d) Testing for different doses

Repeat the above procedure six times, starting from step 3 in (b), using a different dose for each run. Take care to main tain the same mixing time, mixing speed and vacuum for all runs.

5) Interpreting results

The example below illustrates the use of paper filter test data to predict an optimum dose of a filtration aid. Table F.1 and Figure F.2 show how experimental results could be tabulated and plotted. The graph of filtered water turbidity versus polymer dose suggests that a dose of 0.01 mg/L would give the best finished water quality. However, the filtration time, which is an indicator of the head loss developed across the filter media, is extremely high for this dose of the filtration aid. Increasing the dose to 0.03 mg/L would only marginally affect the quality of product water and substantially cut down on the rate of head loss development as compared to using a dose of 0.01 mg/L. Hence, in this case, a filtration aid dose of 0.03 mg/L could be chosen to make a significant improvement in finished water quality without drastically affecting the head loss developed across the filter bed.

6) Data tabulation and analysis

Table F.2 and Figure F.3 show the recommended format for recording and plotting test results.

II) Optimizing coagulant aid selection with regard to filtration

1) General discussion

Production of high-quality filtered water can sometimes be achieved with a coagulant aid dose far less than that required for a floe that settles well (Hudson and Wagner, 1980). This lower dose would result in a decrease in chemical costs and the quantities of sludge generated and in many instances, increased filter run lengths as well. A floe that settles well may not have good filtration characteristics, and a floe that has poor settleability may have good filterability; hence, a compromise will have to be made. Selection of a coagulant aid dose that will optimize overall plant performance can be done by taking into account results from both the jar test and filterability studies (Ives, 1981).

-65-

Table F.I

DATE __ OPERATOR

MIXING TIME 20 rru/»

MIXING SPEED 41?. T P ~

POLYMER 130 N

POLYMER CONCENTRATION o i ryl*

PAPER FILTER USED: WHATMAN NO.

SETTLED HATER CHARACTERISTICS

TURBIDITY -2-2-7

TEMPERATURE ITC

TRUE COLOR ____

4°

Jarno.

Polymer dose(mg/1)

Polymer volume foreach Jar (ml)

Paper filterturbidity

Paper filtercolor

Paper filtration time (sees)

1

o

o

i- J3

24

2

0 2_

c. -47

ni

3

o o3

0-6

0 Si,

51

H

c-o$

t

o-SS

31

5

0 P^

'4

O-S'I

6-7

6

c • I

2.

o-48

-7,'

COMMENTS

n H •m

o:

I-S 1-6

1-4-

0-8 "< 0-4

\

0.0

00

.01

0.0H

0.0

30

.05

0.0

6B

.B7

0.0

8

SECS FILTRflTION

TIMEer>

<y

> i

0.0

30.1

0

PO

LYM

ER

D

OS

E

(mg

/U.

PO

LY

ME

R

Figu

re F

,2

Gra

ph o

f pa

per

filt

er

test

res

ult

s

-67-

Table F.2

DATE __ OPERATOR

MIXING TIME

MIXING SPEED

POLYMER ___

POLYMER CONCENTRATION

SETTLED WATER CHARACTERISTICS

TURBIDITY _____

TEMPERATURE ____

TRUE COLOR ____

PAPER FILTER USED: WHATMAN NO.

Jar no.

Polymer dose (ng/1)

Polymer volume for each jar (ml)

Paper filter turbidity

Paper filter color

Paper filtration time (sees)

1 2 3 4 5 6

COMMENTS

U) u

u

in

>-

i- O) o: Z)

H

u z: •z.

o (E

Qi

oo

3.80

B.

B1B

.02

B.B

3Q

.B4

B.B5

0.0

6B

.07

B.BB

0.B

9B

. IB

PO

LYM

ER

D

OS

E

(mg/L

)P

OL

YM

ER

Figu

re F

.3

Gra

ph f

or p

lott

ing

pape

r fi

lter

tea

t re

sult

s

-69-

The paper filter test assesses the impact of a coagulant aid on the filtration process by evaluating the filterability of a suspension and is performed subsequent to the jar test, which measures the settleability of the suspension. This procedure is used to qualitatively predict the variation of the plant effluent quality with coagulant aid dosage. An indication of the head loss that would develop across the plant filter bed is provided by the filtration time in this test.

Besides the equipment needed to run the jar test, this procedure requires filtering flasks, filter holders and a vacuum pump. After the completion of the jar test, an additional hour is required for running the paper filter test. This test does not require any special skills and can easily be performed by an operator or laboratory personnel.

2) Apparatus

a) Jar test apparatus

All apparatus required for conducting a jar test is needed, since the paper filter test is conducted using the jar test supernatant. However, an additional requirement is that the jars must have a side outlet for withdrawal of supernatant (lifting up the jars to pour the supernatant would resuspend sludge into the filtration samples). See Figure F.4 for dimensions.

b) Beakers

2-L capacity, for collection of samples to be filtered. This allows sufficient excess volume to allow swirling of contents prior to filtration. If sludge characteristics are not to be evaluated, or a 1-L jar volume was used, beakers as small as 500 mL can be substituted.

c) Filtration aid apparatus

All the apparatus listed under filtration aid selection from (i) to the end.

3) Reagents

a) Jar test reagents

Besides the reagents needed for the jar test, no additional reagents are required.

-70-

4.5"'

Figure F.U Jar type needed for filtration studies subsequent to the jar test

-71-

4) Procedure

a) Jar test procedure

Since this test is run subsequent to the jar test, first follow the procedure for conducting a jar test, as outlined in Module C. However, the settled water quality is to be measured in a different manner as described in (b) below. While the jar test is in progress, wash the beakers and filtering apparatus with distilled water and keep them ready to collect and filter jar test samples. If distilled water is not available, then use the effluent from the plant filters. Keep all washed glassware upside down to let wash water drain out, and to keep internal surfaces free from dust.

b) Collection of samples

At the end of the settling period of the jar test, remove the pinch clamps on the side outlet tubings and let the supernatant drain into a 2-L beaker. Clamp the tubing again when the liquid level is 1/2" above the side outlet. Take a turbidity measurement (and color or other measurements as desired) from this withdrawn volume.

c) Filtration of samples

Follow the same procedure as that for filtration aid selection.

d) Testing for different doses

Since the contents of each beaker have been dosed with different levels of the coagulant aid, repeat the filtration step for each beaker.

5) Interpreting results

To select a coagulant aid dose that will optimize overall plant performance, results from both the jar test and the paper filter test have to be taken into consideration. The example below illus trates the general procedure to be followed. Table F.3 and Figure F.5 show how experimental results could be tabulated and plotted.

The optimum polymer dose for coagulation, as suggested by the graph of jar test turbidity versus polymer dose, is 0.25 mg/L in this example. However, the plot of paper filter turbidity versus polymer dose implies that decreasing the polymer dose from 0.25 mg/L to 0.05 mg/L would only marginally increase the turbidity of the filtered water. In addition, the effects of the lower poymer dose on filter run length can be estimated, since the filtration time in this test is a general indicator of the rate of head loss devel opment across the filter bed. Shorter filtration times imply

-72-

slower head loss build up and hence longer filter runs before terminal head loss is reached. The plot of filtration time versus polymer dose predicts that filter run lengths may be drastically reduced if doses higher than 0.05 mg/L are employed.

As compared to using only the primary coagulant, a dose of 0.05 mg/L of the coagulant aid together with the primary coagulant would improve filtered water quality and at the same time increase filter run length. This dose would cut down on chemical costs and quantities of sludge generated as compared to using a dose of 0.25 mg/L. Hence, by using both the jar test and paper filter test results, a dose of 0.05 mg/L could be chosen to optimize both coagulation and filtration.

6) Data tabulation and analysis

Table F.4 and Figure F.6 are provided to show how results, can be recorded and analyzed.

REFERENCES

STANDARD METHODS FOR THE EXAMINATION OF WATER AND WASTEWATER. American Public Health Association, American Water Works Association, Water Pollution Control Federation.

INTRODUCTION TO WATER QUALITY ANALYSES. American Water Works Assoc iation (1982).

High-Rate Contact Flocculation-Filtration with Cationic Polyelectro- lytes. A. Adin and M. Rebhun. Journal AWWA. 68., 109 (197*0.

Optimizing Coagulants and Flocculent Aids for Settling. J.R. Bratby. Journal AWWA. 7J. (1981).

Conduct and Use of Jar Tests. H.E. Hudson, Jr. and E.G. Wagner. AWWA Seminar Proceedings-Upgrading Water Treatment Plants to Improve Water Quality. AWWA Publication 20153 (1980).

Deep Bed Filtration. K.J. Ives in Solid-Liquid Separation. L. Svarosky, ed. (2nd edition). London: Butterworths (1981).

Factors That Affect Use of Direct Filtration in Treating Surface Waters. R.F. McCormick and P.H.King. Journal AWWA. 7JL» 23 1* (1982).

-73-

Table F.3

DATE 11/3 A OPERATOR

-ALUM/FERRIC DOSE ,2 (,

LIME DOSE J j r

pH adjusted to 8 c>

POLYMER /O2I AIM We

POLYMER CONCENTRATION

PAPER FILTER USED: WHATMAN NO. 44

RAW WATER CHARACTERISTICS

PH 7'-5"

TURBIDITY ' 2-

TEMPERATURE l°

TRUE COLOR

Jarno.

Polymer dose(mg/I)

Polymer volume foreach Jar (ml)

Jar teatturbidity

Jar testcolor

Paper filterturbidity

Paper filtercolor

Paper filtration tine (sees)

1

O

o

f-fc

o 4.0

11

2

o-oS

2.

o-(,

O-LS

+ S

3

o 10

4o-$

o IS

K3

n

0'2S"

10

0-2.

O-IO

7140

5

o-&>

2-0

o -4

0 1 1

>^40

6

| -00

40

o -.r

o-/i"

>2.^o

COHHEOTS

DQ o:

2o U

Q 7

2 -

)»

5.

ny

U)

U

U

LH X^f

U 21 Z

O CE/o

o

4=-

I

a.a

e.i

B.2

B.3

0.5

0

.E

0.7

0

.B

0.3

1

.0

PO

LYM

ER

D

OS

E

(mg/1

)P

OLY

ME

R

ion

A

^.o^

-c

Fig

ure

F

.5

Gra

ph o

f p

aper

fi

lter te

st

resu

lts

-75-

Table F.I

DATE __ OPERATOR

ALUM/FERRIC DOSE

LIME DOSE

pH adjusted to

POLYMER

POLYMER CONCENTRATION

RAW WATER CHARACTERISTICS

PH _____

TURBIDITY _____

TEMPERATURE ____

TRUE COLOR ____

PAPER FILTER USED: WHATMAN NO.

Jar no.

Polymer dose (mg/1)

Polymer volume for each Jar (ml)

Jar test turbidity

Jar test color

Paper filter turbidity

Paper filter color

Paper filtration time (sees)

1 2 3 'I 5 6

COMMENTS

PQ

Qi Z)

B.0

Q

.I

0.2

0

.3

0.4

0.5

B

.G

0.7

0.

B

0.9

1

.0

POLYMER DOSE (mg/1 )

POLYMER

u Ul in u H-1

I— o t-H I— cr

Figure F

.6

Grap

h for

plotting p

aper

fil

ter

test

results

-77-

Module G. Bench Filter Test

This Module describes a bench filtration procedure which can be used for two purposes: determination of an optimal filtration aid dose, or optimizing coagulant aid selection with regard to its effects on filtration. These applications are described respectively in Sections I and II.

I) DETERMINING OPTIMUM FILTRATION AID DOSE

1) General discussion

A filter aid can be used to enhance filter performance either in direct filtration or in conventional water treatment (flocculation and sedimentation followed by filtration). Direct filtration has been defined by the Committee on Coagulation- Filtration of AWWA's Water Quality Division as being any water treatment scheme in which there is no in-plant sedimentation prior to filtration (McCormick and King, 1982). There may or may not be a flocculation basin prior to filtration. Direct filtration without the flocculation step is called in-line filtration or contact flocculation-filtration (contact filtration), since the flocculation occurs during contact with the filter media as opposed to volume flocculation in a flocculation chamber (Adin and Rebhun, 1974).

The bench filter test, like the paper filter test, evaluates the filterability of a suspension. The sample under test is filtered through a bed of sand at a constant rate and various parameters are measured. A dimensionless number called the filterability index (which incorporates the initial water quality, the filtrate quality, the rate of rise of head loss, and the velocity of filtration), is used as an indicator of the effect of the filter aid on the filtration process. This method's advantages over the paper filtration method are that it uses the actual filter bed media, and a direct measure of head loss is obtained. However, it also requires more sophisticated equipment.

This method is applicable both when the filter aid under test is to be used in a direct filtration process and when it is to be added at the end of the sedimentation basin in a conventional treatment plant. The major pieces of equipment required are: a multiple stirrer, square jars, a flowmeter and a weighing balance. Approximately two hours are needed for conducting this test. Although the test procedure is time-consuming, precise results can be obtained with only minimal experience with the apparatus.

-78-

2) Apparatus

a) Multiple stirring apparatus. Phipps and Bird type, variable speed.

b) Illuminator base, for optional use with stirrer.Enhances observation of floe formation by providing effective glare-free illumination of floe samples. Consists of fluorescent lamp mounted below translucent plastic plate. Test jars and support posts of stirrer rest directly on diffuser top plate.

°) Jars. 2-L capacity, square, acrylic plastic, either with orwithout side outlet, for preparation of samples to be filtered.

d) Bucket, for collection of sufficient sample to fill all jars.

e) Pipet. glass, for dispensing the filtration aid solution, alum or ferric solutions and any other chemicals.

f) Pipet filler, bulb type, rubber,

h) Stopwatch. with buzzer.

i) Weighing balance, range 100 grams, accuracy up to 1/10 of a gram, for measuring out the required amount of sand for each run.

j) Beakers. 1-L, for collection of filtered samples.

k) Bench filter apparatus. This may be purchased as a unit(Filterability Index System, Technovate Inc., 910 Southwest 12th Avenue, Pompano Beach, FL 33060) or may be constructed as shown in Figure G.1 from the following components:

- Funnel. 1-L capacity, should be translucent or transparent that the water level is visible.

- Support ring. For holding up feed funnel.

- Test filter cell. Cylinder, clear acrylic plastic, 1-1/2" I.D., 1-3A" O.D., length 4".

- Rubber stoppers. Two, size 8; one-hole, hole size 3/16".

- Cell Holder. Clear acrylic plastic, for holding the filter cell in place. Refer to Figure G.2.a. for dimensions.

- Supporter. Disk, clear acrylic plastic, 1-1/2" O.D., with holes 1/8" diameter, to let the filtrate flow through while supporting the sand. See Figure G.2.b.

-79-

\^ Sample, *^

-L Funnel

Filter cell 1-1/2" I.D.

Supporter

Spacer

Filtrate collection

Figure G.1 Bench filter test apparatus

-80-

Figure o.2.a Cell holder

Figure G.2.b SupporterFigure G.2.C Spacer

-81-Spacer. Ring, placed between the supporter and the rubber stopper, to provide some space for collection of filtrate before it flows out of the filter column (See Figure G.2.c).

Wire gauze . Circular, 1-1/2" diameter, placed between supporter and spacer, 50 meshes to the inch, wire diameter

", available in tobacco store as pipe screen.

Flowmeter. Rotameter (variable area meter), range 0.002- 0.25 L/min, positioned in the outlet line from the cell for observing the rate of filtration.

Day pinchcock. Three > holds tubing up to 3/8", can be put on. or removed without dismantling the apparatus .

Hoffman opep-side pinchcock. For flow regulation, one side is open, opening 3/4".

Tubing clamps. For tubing size 1-9/16" to 2-1/2" O.D., for fastening flowmeter to wooden frame.

Tygon tubing. Clear, flexible, 1/4" I.D., 3/8" O.D., length 10 feet.

Bubble tubing. Reduces need for connectors; tubing I.D. 1/4", O.D. 3/8"; bubble I.D. 1/2", length 10 feet.

Graph paper. For head loss readings, quadrille 4 squares to the inch.

Tubing connectors. Four, T-shaped, O.D. 1/4", either glass or polypropylene (Nalgene, translucent).

Vacuum grease. Helps to slide tubing onto connectors and funnel end, not only lubricates but forms leakproof seals.

Wood . For constructing the frame that supports the various components of the apparatus and the board that holds up the manometer tubes, the size of the frame and board is not crit ical and can be built out of any available pieces of wood so long as the overall dimensions are approximately the same as that indicated in Figure G.1.

Other. Threaded rods, two, diameter 1/4", length 8"; rod with threaded end, diameter 1/4", length 13"; nuts, four, hole diameter 1/4", wingnuts, two, hole diameter 1/4"; washers, six, metal, hole diameter 1/4"; copper wire, length 2 feet; wood saw, power drill, pliers, nails, and marking tape.

3) Reagents

a) Filtration aid working solution, made according to thesupplier's recommendations or the instructions in Module A.

-82-b) Coagulants and other chemicals (in case of direct filtration).

In general, all chemicals (primary coagulant, lime, etc. ) should be identical to those used in the plant and preferably should be taken directly as supplied, since the actual concentrations are often not accurately known. For example, lime slurry should be obtained directly from the lime dosing line. Chemicals can also be prepared according to the procedure outlined in AWWA Introduction to Water Quality Analyses. However, alum or ferric solutions should not be diluted more often than necessary beforehand, since this may alter their effective dose. Alum stock solutions should be at least 30 g/L and ferric at least 200 g/L. If dilution is necessary, it should be done just prior (within seconds) to testing.

The concentration of a diluted solution can be calculated as follows:

c 1 = c2 • v2 / v,where C, = concentration of dilute solution (rng/L)

Cp = concentration of stock solution (mg/L)

Vp = volume of concentrated solution used (mL)

V. = total volume of dilute solution (mL)

(Note 1 mg/L = 1 ppm)

If coagulants are purchased as liquids, information concerning their concentration may be obtained from the manufacturer. General concentration ranges are also given in AWWA Introduction to Water Treatment.

c) Filter media. Best taken directly from filter beds to besimulated. If the plant utilizes multi-media filters, use the uppermost media.

Procedure

a) Preparation of working solutions of filtration aids

The procedure to be followed is identical to that used for making coagulant aid solutions. Refer to Module A.

If the product data sheet on the polymer is available try different dosage levels in the recommended range. If not, recommended values of filtration aid doses are: 0, 0.01, 0.03, 0.05, 0.07, and 0.1 mg/L. To calculate the volume of the filtration aid solution needed for each jar, use the following formula:

-83-

V = C 1 « V / C

where V = volume required (mL)C'= desired concentration (mg/L or mL/L)V'= volume of sample (should be 2L)C = concentration of working solution (mg/L or mL/L)

Record the volumes needed for the six doses.

b) Assembling the apparatus (if the unit is to be constructed).

The bench filter apparatus assembly is shown in Figure G.1. Build the wooden frame using a wood saw, a power drill and nails. Cut the graph paper into strips 2" wide and glue them onto the wooden board to form a continuous strip 2 tlx20 tl . Number the inches on the graph paper lengthwise along both sides for head loss readings. The manometer tubes are held up by passing pieces of copper wire through holes (diameter 1/16", at inter vals of 6", drilled in the wooden board on either side of the tube) and twisting the wire from behind with pliers to press the tubing against the board. Fasten the flowmeter to the frame with the help of tubing clamps.

Paste a strip of marking tape lengthwise along the outside of the test filter cell. Plug the bottom of the cell with one of the stoppers and mark the position to which the stopper extends into the filter cell. The perimeters of both the supporter and the spacer require a smooth finish for a close fit with the inside walls of the filter cell. This enables the supporter, wire gauze and spacer to move as one unit when the spacer is being prodded into the cell as described later. Remove the stopper and insert the supporter, about a quarter of an inch, into the cell. Use any flat surface like the end of a screwdriver handle to tap on the supporter to drive it into the cell. Drop the wire gauze on the supporter and push the spacer into the cell until the gauze is held tightly between the supporter and the spacer. Continue pushing until the bottom of the spacer coincides with the mark made on the tape.

Make a mark on the tape 1-1/2" above the top of the supporter. Pour sand into the filter cell up to this mark, and determine the weight of the sand added. For each run, weigh out this amount of dry sand, add it to the filter cell, and bring the sand level up to the same depth mark. Connect the various components of the assembly, as shown in Figure G.1, using tubing, tubing connectors and vacuum grease.

c) Setting up the apparatus

1. Before the sample can be filtered, the apparatus has to be filled with clean water to saturate the sand bed and remove any air bubbles. Close all the three pinchcocks: above the

-84-manometers, on the drain line, and on the filtrate line (see Figure G.1).

2. Pour 200 to 300 mL into the feed funnel and open the pinch- cock on the outlet line. Let about 100 mL flow through and close the pinchcock again.

3. Eliminate any air bubbles that are present in the horizontal passages of the apparatus by opening the filtrate, drain, or manometer pinchcocks and letting the water out in spurts. Remove bubbles that have been carried into vertical passage ways by tapping that particular component.

4. Adjust the pinchcock above the manometer tubes and let the water level rise to about half the length that has been calibrated, with graph paper, for measuring headloss. This ensures that the water level in either tube does not rise above or fall below the calibrated length at the end of the filter run.

5. Remove the air pocket in between the walls of the cell and the sides of the top rubber stopper by squeezing the stopper and letting the air escape.

6. Draw the water level down to the neck of the funnel, by using the pinchcock on the filtrate line.

7. Note the water level in the manometer limbs. If the above procedure has been followed rigorously, there should not be more than a 1/4" difference between the heights in the two limbs.

8. Conversion from the plant filtration rate (in an individual filter) in MOD to the required flowrate in the apparatus in L/min can be done as follows.

C = F • I.D. 2 « 14.34 / A

where C = flowrate to be maintained in L/min,F = plant filtration rate in MGD,

I.D. = internal diameter of bench filter cell in inches, A = cross-sectional area of the plant filter in ft2 ,

14.34 = conversion factor.

d) Preparation of samples for filtration

i. Contact filtration

1. Use the bucket to collect about 15 L (4 gal) of the plant influent raw water. Assemble the filtration apparatus as shown in Figure F.1.

2. Pour 2 L of the water into a jar, and place the jar in

-85-

the multiple stirrer unit. Begin rapid mix. If no other paddle speed is otherwise specified, the maximum RPM is recommended (about 125 RPM on most bench stir- rers). Using a pipet dose the jar with the primary coagulant. The coagulant dose should be the same as that used in the plant. Insert the pH electrode into the jar and add small doses of lime or other chemical to adjust the pH to the level presently existing in the plant filter influent. Note the volume of lime or other chemical added. Allow 1 minute for proper dispersion of chemicals.

3. Gently stir the sample water to ensure that a uniform sample will be obtained. Then pour 2 L of the water into a jar and place the jar in the multiple stirrer unit. Begin rapid mix. Using a pipet, dose the jar with the primary coagulant (identical to the plant dose). Also add lime or any other chemical used for pH control. The dose to be added was determined in step 2. For the first run with zero polymer dose, proceed directly to step 5.

4. Using the pipet dispense the filtration aid solution into the contents of the jar, keeping the tip of the pipet half an inch below the water level. The volumes required for different doses were calculated in step (a) above.

5. Allow 1 minute for proper dispersion of added chemicals. Switch off the stirrer and remove the jar from the stirrer unit.

ii. Direct filtration with flocculation

1. Use the bucket to collect about 15 L (4 gal) of the plant influent raw water.

2. Pour 2 L of the water into a jar, and place the jar in the multiple stirrer unit. Begin rapid mix. If no other paddle speed is otherwise specified, the maximum RPM is recommended (about 125 RPM on most bench stirrers). Using a pipet dose the jar with the primary coagulant. The coagulant dose should be the same as that used in the plant. Insert the pH electrode into the jar and add small doses of lime or other chemical to adjust the pH to the level presently existing in the plant flocculators. Note the volume of lime or other chemical added. Allow 1 minute for proper dispersion of chemicals.

Reduce mixing speed to simulate mixing intensity during flocculation in the full-scale process (e.g. 20 RPM). Visually observe floe size in the jar and compare to the actual floe size observed in the plant. If the floe

-86-

size in the jar is much larger than in the plant, the mixing speed in the jar may be too low. Similarly, if the floe size in the jar is significantly smaller than in the plant the mixing speed in the jar may be too high. If the difference is substantial repeat until the floe size is approximately the same as that in the nlant= Make a note of this mixing speed,

3. Gently stir the sample water to ensure that a uniform sample will be obtained. Then pour 2 L of the water into a jar and place the jar in the multiple stirrer unit. Begin rapid mix. Using a pipet, dose the jar with the primary coagulant (identical to the plant dose). Also add lime or any other chemical used for pH control. The dose to be added was determined in step 2. For the first run with zero polymer dose, proceed directly to step 5.

4. Using the pipet dispense the filtration aid solution into the contents of the jar, keeping the tip of the pipet half an inch below the water level. The volumes required for different doses were calculated in step (a) above.

5. Allow 1 minute for proper dispersion of added chemicals. Reduce mixing speed to that recorded in step 2. Set the timer for the estimated flocculator detention time (e.g. 20 mins) and start the timer.

6. Assemble the filtration apparatus as shown in Figure F.1. Switch off the stirrer when the buzzer goes off and remove the jar from the stirrer unit.

iii. Conventional treatment

1. Use the bucket to collect about 15 L (4 gal) ofunfiltered water from the plant. If a filter aid is presently being used, withdraw the sample from the end of the sedimentation basin prior to the injection point of the aid. If no aid is being used, the sample can be taken from above the filter media.

2. Assemble the filtration apparatus as shown in Figure F.1. Gently stir the sample water to ensure that a uniform sample will be obtained. For the first run with zero polymer dose, pour 2 L of the water into a jar and proceed directly to (e).

3. Gently stir the sample water to ensure that a uniform sample will be obtained. Then pour 2 L of the water into a jar and place the jar in the multiple stirrer unit. Begin rapid mix. If no other paddle speed is otherwise specified, the maximum RFM is recommended (about 125 RPM on most bench stirrers). Using the

-87-

pipet, dispense the filtration aid solution into the contents of the jar, keeping the tip of the pipet half an inch below the water level. The volumes required for different doses were calculated in step(a).

Allow 1 minute for proper dispersion of added chemicals. Switch off the stirrer and remove the jar from the stirrer unit.

e) Running the test

Take the first jar, swirl the contents, and pour the sample into the feed funnel.

Commence flow by opening the outlet pinch clamp, and simultaneously start the timer.

Maintain a constant flowrate by means of the Hoffman open-side pinchcock. This flowrate should be equal to the rate of filtration in the plant filters and has been calculated in c.8.

Discard the first 100 mL since this is just the displaced clean water.

Collect the remaining sample that filters through in a clean beaker.

When the sample level falls down to the neck of the funnel, stop the timer and record the liquid levels in the two manometer limbs (do this with the sample still flowing).

Determine the quality of the filtered water by measuring its turbidity, according to the directions given in:

-Standard Methods for the Examination of Water and Wastewater (APHA, AWWA, WPCF).

- Introduction to Water Quality Analyses (AWWA).

-the instruction manual for the turbidimeter to be used.

-see also Module H.

Make any other measurements (color, particle size analyses, etc.) as desired. If the filtered water turbidities are below the sensitivity range of the turbidimeter, a particle size analyzer will have to be used to evaluate filtration results.

-88-f) Resetting the apparatus

1 . Remove the pinchcock above the manometers and drain the water from the apparatus by removing the pinchcock on the drain line.

2. Loosen the wing nuts above the holder and pull the test filter cell forward until it is free of the filter holder.

3. Detach the test filter cell by removing the stoppers from either side. Discard the filter media and clean the inside of the cell to remove any media particles that may still be present .

M. Weigh out the amount of dry sand previously determined, pour it into the cell and bring it up to the 1-1/2" level marked on the tape.

5. Seal both ends of the cell with the stoppers and install the cell in its position by placing it beneath the holder and tightening the wing nuts.

g) Testing for different doses

Repeat the above procedure six times, starting from step 3 in d), using a different dose for each run. Take care to maintain the same mixing time, mixing speed and rate of filtration for all runs.

5) Interpreting results

The filterability index, F, is defined as (Ives, 1981)

F = (H « C) / (CQ « v * t)

where: H = head loss developed across the filter media, t = time taken for filtration,C = filtrate quality (turbidity or other desired indicator), CQ= inlet quality (same units as C), and v = velocity of filtration.

With the parameters having consistent units, e.g., with H in inches, v in inches/ second, t in seconds, and with C/C a ratio, the resulting filterability index number F is a dimensionless number.

H = H (final) - H (initial)

where H (final) = headless when the sample reaches the neck of thefunnel, and

H (initial) = headless at the start of the run (should be less than

t = filtration time (measured) - x

where x = time taken for the sample to reach the filter media.

-89-

Calculate this time by filling the apparatus with water up to the neck of the funnel, and then draining the water until it reaches the top of the filter media. Collect and measure the volume of the drained water and divide it by the flowrate maintained during the course of a run (calculated in H.c.8 of the protocol for filtration aid selection) to obtain x.

x (sees) = volume collected (mL) • 0.06 / flowrate (L/min)

v (inches/sec) = flowrate (L/min) • 1.3 / I.D.

where I.D. = inner diameter of bench filter cell in inches.

The meaning of this filterability index can be understood as follows. Low values of rate of headless buildup (H/t) and outlet concentration (C) are both desirable. However, higher values of C and v are advantageous because they indicate that the filter can operate at worse inlet conditions and higher loading rates. Therefore, according to the above equation, a low F number indicates good filterability, both in terms of cost (head loss and required frequency of backwash) and product water quality (if specific information regarding these factors is desired, the parameters comprising F can be also be evaluated individually).

Selection of a filtration aid dose that will optimize filter performance is illustrated by the following example. Table G.1 and Figure G.3 show how experimental results could be tabulated and plotted. The plot of filterability index versus polymer dose suggests an optimum dose of 0.05 mg/L. Increasing or decreasing the filtration aid dose would adversely affect the filtration characteristics of the filter influent.

The graph of bench filter turbidity versus polymer dose also indicates an optimum dose of 0.05 mg/L. Increasing the dose beyond this point would only increase the cost of the polymer without further improving filtered water quality. Hence, a dose of 0.05 mg/L could be chosen to improve filter performance.

6) Data tabulation and analysis

Table G.2 and Figure G.4 are provided to show how results can be recorded and analyzed.

-90-

Table 0.1

DATE

OPERATOR

MIXING TIME 2-° *~~*

MIXING SPEED 4° if*

POLYMER

SETTLED WATER CHARACTERISTICS

TURBIDITY (CJ ^•2.^

TEMPERATURE __\~> ' <-

POLYMER CONCENTRATION o 1 ^ /"<- TRUE COLOR

VELOCITY OF FILTRATION (v) o -I (inches/sec)

Jarno.

Polymer dose(mg/L)

Polymer volume foreach jar (ml)Bench filterturbidity (C)Bench filtercolor

Filtrationtimet (sees)

Head lossH (inches)

measured

corrected

final

initial

correctedFilterability index

F = (H-C)/(C,-v.t)

1

0

0

I-TJ

3i> 4

288

3 f/t'•s

3^

^•U/o' r

2

0 0 I

o -i

, 31

211JTi'

5'It

4 \

l-l Xio"'

3

0 Oi

06

I 3 ^

ill

^4^

3%'<•

3 '4

g-TXIo" 1

4

o rs"

1

1 !(,

306

^TO

3 3 /s

''«

3'/4

fe-i xio"*'

5

OP 7

1-4

i n

3C 1)

iT3

^3/4

7S

5V,

i-ixio"'

6

0 1

2.

1-2-1

3C4

i8 SC''A

'/t

t\

I iXlo' '

COMMENTS

12-

S

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2 m a:

1-1

U

1-5 1-4-

13 1-2.

\ A\

\,

10 1 S 1 C 5

X Ld

Q M m a: DC. LJ

VD

1

0.00

0.01

0.02

0.

03

0.04

0.0

50.

06

0.07

0.08

0.09

0.10

PO

LYM

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D

OS

E

(mg

/L)

POLYMER

Figure G.3

Grap

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ben

ch f

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teat

res

ults

-92-

DATE

OPERATOR

Table G.2

MIXING TIME

MIXING SPEED

POLYMER

POLYMER CONCENTRATION __

VELOCITY OF FILTRATION (v)

SETTLED WATER CHARACTERISTICS

TURBIDITY (CJ ______

TEMPERATURE _____

TRUE COLOR ______

(inches/sec)

Jar no.

Polymer dose (mg/L)

Polymer volume for each Jar (ml)Bench filter turbidity (C)Bench filter color

Filtration tine t (sees)

Head loss H (inches)

measured

corrected

final

initial

correctedFilterability index

F = (H-C)/(C.-v.t)

1 2 3 4 5 6

COMMENTS

X LJ

O

Z) t- n f-H m

m

cc

ct

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3

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40.8

58

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8.8

78

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8.1

8

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Cm

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-gu

Optimizing coagulation aid selection with regard to filtration

1) General discussion

Production of high-quality filtered water can sometimes be achieved with a coagulant aid dose far less than that required for a floe that settles well (Hudson and Wagner, 1980). This lower dose would result in a decrease in chemical costs and the quantities of sludge generated and in many instances, increased filter run lengths as well. A floe that settles well may not have good filtration characteristics, and a floe that has poor settleability may have good filterability; hence, a compromise will have to be made. Selection of a coagulant aid dose that will optimize overall plant performance can be done by taking into account results from both the jar test and filterability studies (Ives, 1981).

The bench filter test, like the paper filter test, evaluates the filterability of a suspension. The sample under test is filtered through a bed of sand at a constant rate and various parameters are measured. A dimensionless number, called the filterability index (which incorporates the initial water quality, the filtrate quality, the rate of rise of head loss, and the velocity of filtration), is used as an indicator of the effect of the coagulant aid dose on the filtration process.

The major pieces of equipment required, besides that needed for the conduction of the jar test, are a flowmeter and a weighing balance. At least one and a half hours are needed after the completion of the jar test for conducting this test. Although the test procedure is time-consuming, precise results can be obtained with only minimal experience with the apparatus.

2) Apparatus

a) Jar test apparatus

All apparatus required for conducting a jar test is needed, since the jar test supernatant is used as the sample to be filtered in the bench filter test. However, an additional requirement is that the jars must have a side outlet for the withdrawal of supernatant (lifting up the jars to pour the supernatant would resuspend sludge into the filtration samples). See Figure F.4.

b) Containers for sample collection

2-L beakers, for collection of samples to be filtered (though only 1-L samples are collected, 2-L beakers provide sufficient volume for swirling of the contents just prior to filtration).

-95-

c) Filtration aid apparatus

All the apparatus listed under filtration aid selection starting from (i) to the end.

3) Reagents

a) Jar test reagents.

b) Filter media. Best taken directly from filter beds to besimulated. If the plant utilizes multi-media filters, use the uppermost media.

4) Procedure

a) Jar test procedure

Since the bench scale filtration procedure is run subsequent to the jar test, first follow the procedure for conducting a jar test, as outlined in Module C. However the settled water quality is to be measured in a different manner as described in (c) below. While the jar test is in progress, wash the beakers with distilled water and keep them ready to collect jar test samples and filtered volumes. If distilled water is not available, then use the effluent from the plant filters. Keep all washed glassware upside down to let wash water drain out, and to keep internal surfaces free from dust.

b) Collection of samples

At the end of the settling period of the jar test, remove the pinch clamps on the side outlet tubings and let the supernatant drain into a 2-L beaker. Clamp the tubing again when the liquid level is about 1/2 " above the side outlet. Take a turbidity measurement (and color or other measurements as desired) from this withdrawn volume.

c) Filtration of samples and resetting the apparatus

The procedure to be followed is the same as that outlined in sections 4. e) and f) of filtration aid selection.

d) Testing for different doses

Since the contents of each beaker have been dosed with different levels of the coagulant aid repeat c) for each beaker.

-96-

5) Interpreting results

The filterability index, F, is defined as (Ives, 1981)

F = (H * C) / (Co « v « t)

where: H = head loss developed across the filter media, t = time taken for filtration,C = filtrate quality (turbidity or other desired indicator), C = inlet quality (same units as C), and v = velocity of filtration.

With the parameters having consistent units, e.g., with H in inches, v in inches/ second, t in seconds, and with C/C a ratio the resulting filterability index number F is a dimensioniess number .

H = H (final) - H (initial)

where H (final) = headless when the sample reaches the neck of thefunnel, and

H (initial) = headless at the start of the run (should be less than

t = filtration time (measured) - x

where x = time taken for the sample to reach the filter media.

Calculate this time by filling the apparatus with water up to the neck of the funnel, and then draining the water until it reaches the top of the filter media. Collect, and measure the volume of the drained water and divide it by the flowrate maintained during the course of a run (calculated in M.c.8 of the protocol for filtration aid selection) to obtain x.

x (sees) = volume collected (mL) * 0.06 / flowrate (L/min)

v (inches/sec) = flowrate (L/min) * 1 .3 / I.D.2

where I.D. = inner diameter of bench filter cell in inches.

The meaning of this filterability index can be understood as follows. Low values of rate of headless buildup (H/t) and outlet concentration (C) are both desirable. However, higher values of C and v are advantageous because they indicate that the filter can ° operate at worse inlet conditions and higher loading rates. There fore, according to the above equation, a low F number indicates good filterability, both in terms of cost (head loss and required fre quency of backwash) and product water quality (if specific infor mation regarding these factors is desired , the parameters comprising F can be also be evaluated individually) .

-97-

Selection of a coagulant aid dose that will optimize overall plant performance can be done by taking into account results from both the jar test and the bench filter test. The example below illustrates the general procedure to be followed. Table G.3 and Figure G.5 show how experimental results could be tabulated and plotted.

The optimum polymer dose for coagulation, as suggested by the graph of jar test turbidity versus polymer dose, is 0.45 mg/L in this example. However, the plot of bench filter turbidity versus polymer dose implies that decreasing the polymer dose from 0.45 mg/L to 0.25 mg/L would not deleteriously affect the quality of the filtere'd water. The value of the filterability index is also lowest at a dose of 0.25 mg/L, indicating that this dose produces a suspen sion with the best filtration characteristics. As compared to using only the primary coagulant, a dose of 0.25 mg/L of the coagulant aid together with the primary coagulant would substantially improve filtered water quality and at the same time increase filter run lengths. This dose would cut down on chemical costs and quantities of sludge generated as compared to using a dose of 0.45 mg/L. Thus, by using both the jar test and bench filter test results, a dose of 0.25 mg/L could be chosen to optimize both coagulation and filtration.

6) Data tabulation and analysis

Table G.4 and Figure G.6 are provided to show how results can be recorded and analyzed.

REFERENCESSTANDARD METHODS FOR THE EXAMINATION OF WATER AND WASTEWATER.

American Public Health Association, American Water WorksAssociation, Water Pollution Control Federation.

/INTRODUCTION TO WATER QUALITY ANALYSES. American Water Works Assoc

iation (1982).

INTRODUCTION TO WATER TREATMENT. American Water Works Association (1982).

High-Rate Contact Flocculation-Filtration with Cationic Polyelectro- lytes. A. Adin and M. Rebhun. Journal AWWA. 68., 109 (1974).

Conduct and Use of Jar Tests. H.E. Hudson, Jr. and E.G. Wagner. AWWA Seminar Proceedings-Upgrading Water Treatment Plants to Improve Water Quality. AWWA Publication 20153 (1980).

Deep Bed Filtration. K.J. Ives in Solid-Liquid Separation. L. Svarosky, ed. (2nd edition). London: Butterworths (1981).

Factors That Affect Use of Direct Filtration in Treating Surface Waters. R.F. McCormick and P.H.King. Journal AWWA. 74. 234 (1982).

DATE __

OPERATOR

-98-

Tabla 0.3

ALUM/FERRIC DOSE 2.S

LIME DOSE *) i~V2/ '.*+.

pH adjusted to 3'3

POLYMER IQZI /Wo'n.'c.

POLYMER CONCENTRATION o -Q6

VELOCITY OF FILTRATION (v) "7-

RAH WATER CHARACTERISTICS

pH 7-3

TURBIDITY

TEMPERATURE

TRUE COLOR

(inches/sec)

Jar no.

Polymer dose (mg/L)

Polymer volume for each jar (ml)Jar teat turbidity (C, )Jar teat colorBench filter turbidity (C)Bench filter color

Filtration time t (sees)

Head loss* H (inches)

measured

corrected

final

initial

correctedFilterability index

HCF - c"5t o

1

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COMMENTS

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-100-

DATE __

OPERATOR

Table 0.4

ALUM/FERRIC DOSE

LIME DOSE ____

pH adjusted to

POLYMER ___

POLYMER CONCENTRATION

VELOCITY OF FILTRATION (v)

RAW WATER CHARACTERISTICS

PH ____

TURBIDITY

TEMPERATURE

TRUE COLOR

(Inches/sec)

Jar no.

Polymer dose (mg/L)

Polymer volume for each Jar (ml)Jar test turbidity (C,,)Jar test colorBench filter turbidity (C)Bench filter color

Filtration time t (sees)

Head loss> H (inches)

measured

corrected

final

Initial

correctedFilterability index

F .-B£_ Covt

1 2 3 U 5 6

COMMENTS

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0.2

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POLYMER DOSE (mgXl)

POLYMER

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Figure G

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esults

-102-

Module H. Analytical Methods for Filter Tests

This module describes two different means of filtrate quality assessment that can be performed in conjunction with either the paper filter test (Module F) or the bench filter test (Module G). These two methods—turbidity measurement and particle size analysis—are outlined in Sections I and II respectively.

I) TURBIDITY MEASUREMENT

1) General Discussion

A turbidimeter is not as sensitive as a. particle size analyzer to particles smaller than 5 microns in size which are the first to break through the filter (Kavanaugh, et al., 1978; Tunison, 1985). Hence, it would have limited use for accurately estimating filter run lengths. However, in both the filter tests only a fixed amount of sample is filtered and the test is not continued until break through occurs. Turbidity measurements correlate well with particle count for the filtrate from the two tests and is a sufficiently accurate means of evaluating the effectiveness of a filtration aid. Its low cost and simplicity of operation make it the recommended method.

Detailed instructions on the operation of the instrument can be found in the manual for the particular turbidimeter being used. Additional information can be obtained from publications listed at the end of this module under References.

2) Apparatus

a) Turbidimeter, sensitivity of 0.01 NTU or better.

b) Sample cells, supplied with the equipment.

c) Cleaning tissue, Kimwipes.

d) Lens paper.

3) Reagents

a) Turbidity standards.If they are not supplied with the instrument, they can be made according to the instructions in Standard Methods.

b) Distilled water

4) Procedure

-103-

1. Turn on the turbidimeter and calibrate it using either the prepared or supplied standard.

2. Gently swirl the contents of the container holding the filtered water, hold the sample cell at an angle, and carefully pour the filtrate into the cell to the level specified in the turbidimeter manual.

3. Eliminate any air bubbles by gently tapping the sides of the cell.

M. Wipe the outside of the cell, first with cleaning tissue and then with lens paper.

5. Place the cell in the sample compartment of the turbidimeter and note the reading.

6. Before using the cell for the next sample, clean it thoroughly with distilled water and place it upside down to let the wash water drain out, and to keep internal surfaces free from dust.

II) PARTICLE SIZE ANALYSIS

1) General discussion

A particle size analyzer furnishes information regarding not only the number of particles in a given sample but also categorizes these particles into their respective size ranges. It is more sen sitive than a turbidimeter to low particle concentrations likely in filter effluent (Tate and Trussel, 1978). However, since a highly sensitive turbidimeter is sufficiently accurate for evaluating the clarity of filtrate from the two filter tests, acquiring this instrument solely for the purpose of evaluating a filtration aid is not justifiable due to its prohibitively high cost.

2) Apparatus

a) Particle size analyzer with appropriate sensor.

b) Sample bottles. Any clean bottle that can fit into the sample compartment is acceptable.

c) Magnetic stir bars, 1" or less

d) Stir bar retriever

3) Reagents

-10M-

a) Demineralized water. Available in most supermarkets.

b) Distilled water. Also at supermarkets.

4) Procedure

Refer to the manual for the particular instrument being used for detailed instructions on operating the unit. A few general rules to follow are listed below.

1. Fill a sample bottle with demineralized water and place it in the sample compartment. When the unit is being used after a long time, run the demineralized water through the instrument's sensor three or four times, since falsely high readings are obtained in the first few runs.

2. Gently swirl the contents of the container holding the filtered water, hold the sample bottle at an angle, and carefully pour the filtrate into the bottle. Drop a stir bar into the bottle and place it in the sample compartment.

3. Turn on the magnetic stirrer, run the sample through, and record the particle count readings.

M. After each run with a sample, perform one run with the demin eralized water. In between samples, thoroughly clean the sample bottle with distilled water, use the demineralized water for a final rinse and place the bottle upside down to let the wash water drain out, and to keep internal surfaces free from dust.

REFERENCES

STANDARD METHODS FOR THE EXAMINATION OF WATER AND WASTEWATER.American Public Health Association, American Water Works Association, and Water Pollution Control Federation.

INTRODUCTION TO WATER QUALITY ANALYSES. American Water Works Association (1982).

METHODS FOR CHEMICAL ANALYSIS OF WATER AND WASTES. U.S. EPA. Technology Transfer Series. EPA-625-/6-7U-003 (197*0.

A Comparison of Particle Counting and Nephelometry. J.D. Beard and T.S. Tanaka. Journal AWWA. 65. (1977).

The Use of Particle Counting in Developing Plant Design Criteria. C.H. Tate and R.R. Trussell. Journal AWWA. 7JL, 698 (1978).

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Module I. Sludge Volume Determination

1. General Discussion

a. This test is applicable to the determination of relative sludge volumes produced by differing doses of coagulants or coagulant aids. It is used in conjunction with a jar test. This information is required where the impact of a coagulant or coagulant aid on subsequent sludge volume generation must be taken into consideration- for example, when sludge handling capacity is limited by the sludge storage volume or dewatering process capacity. This procedure may also be used to collect and concentrate sludge generated during jar tests for subsequent dewaterability testing using methods outlined in modules K or L.

b. The resources (equipment, time analytical expertise, etc.) required for this test are minimal. Test materials and apparatus, as outlined below, are readily available and inexpensive. Imhoff cones are suggested for volume measurement as they are more accurate than beakers and can be modified to permit sludge removal for subsequent testing.

2. Apparatus

a. 3 to 6 one L (1-L) Imhoff cones (Figure I), with a support rack or ring stands. Multiple Imhoff cones will allow the contents of all jars from a jar test (typically 6 jars) to undergo sludge volume determinations simultaneously. If the removal of the collected sludge for subsequent testing is desired, the Imhoff cones can be modified by replacing the drain plugs with sections of flexible tubing and squeeze clamps as shown in Figure I. One-L, graduated cylinders may be substituted for Imhoff cones if desired; however, these usually cannot be modified to permit sludge removal. Do not compare sludge volumes determined with different container types (i.e. Imhoff cones, graduated cylinders) as the container shape has an effect on the sludge compaction and final volume.

b. Stopwatch

c. Stirring rod or laboratory spatula.

d. Thermometer

3. Reagents. Jar test contents.

4. Procedure.

a. Following completion of a 2-L jar test, transferthe contents of each jar to an Imhoff Cone. If the jar testsupernatant has not been removed for filtration testing,

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1-Liter Imhoff Cone

.Flexible Tubing

FIGURE I. IMHOFF CONE.

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decant 1 L from the top of each jar or from the sampling ports if the jars are equipped with ports.

b. At 15 minute intervals, gently stir the cone contents for 10 to 15 seconds to dislodge the solids adhering to the cone sides. Do this by scraping the cone sides with a stirring rod or spatula.

c. After 60 minutes, record the volume of sludge in mL from the cone graduates. See Table I for a suggested data sheet. Multiply the sludge volume by 0.5. This can be reported as gal/1000 gal water treated (L sludge/1000 L water treated). If a 1 L jar test was used, do not multiply the sludge volume by 0.5. If the settled sludge contains large pockets of water entrained in the sludge zone, estimate the volumes of these pockets and subtract from the total volume. The practical lower limit of measurement is approximately 1mL/L.

d. Plot sludge volume vs. coagulant aid dose.

5. Data Analysis. From the sludge volume/coagulant dose plot, jar test results,and filterability results (if these procedures were performed) determine the coagulant or coagulant aid dose which provides acceptable settled water quality while minimizing the volume of sludge produced.

6. Results Interpretation. Test results should be interpreted cautiously, as only relative sludge volumes are estimated by this method. Correlations between the estimated sludge volumes and actual sludge volumes can only be determined through operational experience .

7. Variables. Variations in water temperature and agitation while transferring the jar test contents can affect results. Therefore, ensure that all tests are run under similar conditions.

8. Precision and Accuracy. Triplicate analyses of 10 sample sets resulted in an average method precision of 2.3 mL/L. Method precision refers to the standard deviation of the results of a series of replicate samples. Method accuracy, which refers to the agreement between the value determined by the test method and

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the actual value present, could not be determined as there is no independent means of determining sludge volume. If an optimum coagulant aid dose is to be chosen based on the results of this method, it is recommended that replicate tests (3 or more) be conducted because of the relatively high inherent imprecision.

REFERENCES

STANDARD METHODS FOR THE EXAMINATION OF WATER AND WASTEWATER. 15th Edition, 1980, American Public Health Association, American Water Works Association and the Water Pollution Control Federation .

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TABLE I. SUGGESTED SLUDGE VOLUME TEST DATA RECORDING SHEET

Date:____________

Analyst:______________________________

Coagulant Aid:

Cone Ho.

Coagulant Aid Dose (mg/L)

Sludge Volume (mL/L)

Sludge Volume x 0.5 (gal/1000 gal)

Remarks:

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Module J. Preparation of Sludge Sampies

1. General Discussion.

a. This method is applicable to the preparation of sludge samples for the subsequent evaluation of conditioning aid effectiveness. It is used in conjunction with the methods outlined in Modules 0 or P.

b. The resources required for this test are minimal. Test materials and apparatus, as outlined below, are readily available and are located in most water treatment plants.

2. Apparatus.

a. Jar Test stirrer (Phipps and Bird type with maximum speed of 130 RPM). Substitution of a different type of mixer (i.e. magnetic stirrer or high speed mixer) will require modification of recommended mixing durations due to differences in mixer velocity gradients. For a magnetic stirrer, double the recommended mixing times. For a high speed mixer, halve the recommended mixing times. See the reference for modification methods for other stirrer types.

b. Large bore pipet. This can be constructed by breaking off the tip of a glass pipet after scoring the break with a file and then polishing the broken end with a flame to remove any sharp edges.

3. Reagents.

a. Sludge samples.

b. Miscellaneous conditioning aids. (See Section II.A for conditioning aid preparation methods).

Procedure.

a. In order to insure uniformity of sludge samples, obtain one large sample (5-10 gal for several tests) and gently stir it to insure a homogenous consistency throughout. Then immediately measure equal volumes (typically 1-L) of sludge to the mixer jars (typically 2-L jars). Since subsequent tests are influenced by such variables as sludge solids concentrations, and temperature differences it is imperative that these differences be minimized by ensuring uniformity between samples.

b. Start mixer at maximum speed (minimum 100 RPM). For magnetic stirrers or high speed mixers operate the mixer at

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the highest speed possible without splashing the sludge out of the containers.

c. Add the chosen conditioning aid at various dosages to the jars. One jar should be a control (no conditioning aid added ).

d. Mixing duration is dependent upon the type of dewatering process to be used. For low-stress dewatering processes such as drying beds, the minimum recommended mixing time is 2 minutes (4 minutes for magnetic stirrers, 1 minute for high speed mixer). For medium-stress processes such as vacuum filters, the minimum recommended mixing time is 15 minutes (30 minutes for magnetic stirrers, 7 minutes for high speed mixers). For high-stress dewatering processes such as centrifuges or belt-filter presses, the minimum recommended mixing time is 1 hour (2 hours for magnetic stirrers, 30 minutes for high speed mixers).

e. Following rapid mixing completion, reduce the mixer speed to (30 RPM) and allow the sludge to flocculate for 5 minutes.

f. Remove the sludge from the mixer and proceed with the dewaterability evaluations outlined in Modules 0 or P. For a rapidly settling sludge, gently stir at slow speed (10-20 RPM) while awaiting testing.

g. Conditioning aid doses are dependent upon the type of conditioning aid used (i.e. dry, emulsion, liquid). Any comparison between different conditioning aids will have to be based on the amount of the polymer and its cost as supplied by the manufacturer. Consequently, all conditioning aid doses should be reported in terms of the form that the polymer is available (i.e. pounds of dry products, gallons of liquid or emulsion products).

5. Variables. The variables in this procedure that affect the subsequent sample properties are mixing intensity and duration. Low intensity, low duration mixing has been shown to underpredict the optimum conditioning aid dose for high stress dewatering processes such as centrifuges. Consequently ensure that all samples undergo the same preparation procedures prior to comparison. Particular attention should be paid to ensuring homogenity among samples (i.e. same solids concentration and temperature).

REFERENCES

Werle, C.P., Novak, J.T. , Knocke, W.R. and Sherrard, J.H., "Mixing Intensity and Polymer Sludge Conditioning", ASCE-Journal of Environmental Engineering. 110. 5, 919 (198M).

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Module K. Time To Filter Test

1 . General Discussion

a. This test is applicable to the determination of thefilterability or dewaterability of sludges. It can be used:

(1) To evaluate various sludge conditioning aids and dosages (large-volume test).

(2) To evaluate the impact of coagulant aids on sludge dewaterability in conjunction with a jar test and the sludge volume determination procedure (small-volume test).

(3) To assist in the daily operation of sludge dewatering processes (large-volume test).

b. The resources required for this test are moderate. Test materials and apparatus, as outlined below, are widely available. Test duration and required analytical expertise are minimal.

c. The test consists of placing a sludge sample in a Buchner funnel with a paper support filter,applying a vacuum and measuring the time required for a fixed volume of filtrate (usually 50$ of the sample volume) to collect in the graduated cylinder. While similar to the better known Specific Resistance to Filtration test (SRF), the Time to Filter test (TTF) is superior for these purposes because of its ease and simplicity of use.

2. Apparatus

a. Large volume TTF (see Figure K-1 for apparatus setup).

(1) Vacuum pump or other vacuum source.

(2) 5-9 cm diameter Buchner funnel.

(3) 24-40 fritted glass side arm.

(4) 250 mL graduated cylinder with a 24-40 fritted glass neck.

(5) Filter paper (Whatman No. 1 or 2 or equivalent)

(6) Assorted corks, vacuum tubing, vacuum flasks and glass tubing. The number used depends on how many Buchner funnels are with the assembly.

(7) Stopwatch.

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9 cm diameter

Buchner Funnel

Whatman No . 1 or 2

\.<v

24-40 Side Arm

250 mL Graduated Cylinder

w/24-40 neck.\

/

^ cJ<- — *

—

X^ s-,. Pressure Gage7 O-"""'' Pinch Clamo Vj>, n—— ̂r —— is^^l '

N. To Vacuum-, \Flexible Tubine

\

FIGURE K-1. LARGE VOLUME TTF EQUIPMENT.

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b. Small-Volume TTF (see Figure K-2 for apparatus setup).

(1) Vacuum pump or other vacuum source.

(2) 2.5 cm diameter Buchner funnel.

(3) 10 mL graduated cylinder equipped with side arm or 10 mL graduated cylinder with funnel adaptor (Figure K-2).

(4) Filter paper (Whatman No. 1 or 2 or equivalent).

(5) Stopwatch.

3. Reagents.

a. Sludge samples.

b. Miscellaneous conditioning aids. If method is to be used to evaluate sludge conditioning aids, see Module A for conditioning aid preparation methods.

4. Procedure.

a. Large-volume TTF.

(1) Assemble apparatus as shown in Figure K-1 .

(2) Place paper support filter into funnel.

(3) To seal filter, pre-wet the filter with a small volume of water. Drain any excess water.

(4) Accurately measure 100-200 mL of conditioned sludge into a graduated cylinder or beaker. See Module J for conditioning aid addition and mixing procedures. The sample volume is dependent upon Buchner funnel diameter. A volume should be used that will almost fill funnel completely. This will be 200 mL for a 9 cm diameter funnel. Ensure that all tests are conducted at the same initial sample volume.

(5) Start vacuum pump.

(6) Pour conditioned sludge sample into the funnel.(7) Start stopwatch or timer.

(8) Record the time required for 50% of the sample volumeto collect in the graduated cylinder. A suggested datasheet is shown as Table K.

(9) If possible, repeat for a minimum of three determinations per conditioning aid dose.

(10) Repeat for different conditioning aids or doses.

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2.5 cm. Diameter

Buchner Funnel

Side Arm Adaptor

10 mL Graduated Cylinder

Pinch Clamp Pressure Ga?e

To Vacuum

Flexible Tubing

FIGURE K-2. SMALL VOLUME TTF EQUIPMENT WITH SIDE ARM ADAPTOR.

-lie-

fa. Small-Volume TTF

(1) Assemble apparatus as shown in Figure K-2.

(2) Place paper support filter into funnel.

(3) To seal filter, pre-wet the filter with a small volume of water. Drain any excess water.

(4) Following sludge volume determination as outlined in Module I, remove the collected sludge from the bottom of the Imhoff Cones. Minimize the dilution of the sludge with the supernatant by decanting as much supernatant as possible from the Imhoff Cones prior to sludge withdrawal.

(5) Accurately measure 7-10 mL of sludge into a graduated cylinder or beaker (7 mL the minimum sample volume required by this method). Ensure that all tests are conducted at the same initial sample volume.

(6) Start vacuum pump.

(7) Pour sludge sample into the funnel.

(8) Start stopwatch or timer.

(9) Record the time required for 50% of the sample volume to collect in the graduated cylinder. A suggested data sheet is shown as Table K.

(10) If possible, repeat for a minimum of three determinations per coagulant aid dose.

(11) Repeat for different coagulant aids or doses.

5. Data Analysis. From the data sheet, plot TTF vs. conditioning or coagulant aid dose for the aids evaluated (See Figure K-3). Determine which conditioning or coagulant aid and dose give the optimum results. Optimum conditioning occurs at the dose which results in the minimum TTF for the least cost (i.e. lowest dose of conditioning aid). In order to complete the detailed cost estimates outlined in Section IV it is necessary to conduct a sludge jar test as outlined in Module M at the current conditioning aid dose and optimum conditioning aid dose. Refer to Module M for procedure instructions.

6. Results Interpretation. Test results can be interpreted fairly confidently as the TTF test is a variation of the more familiar Specific Resistance to Filtration test which has been used to model most full-scale dewatering processes.

900

o O

O Lu

800 -

700 -

600 -

500 -

400 -

300

40

n P

oly

mer

A

80

120

1 6O

200

240

Poly

mer

Dose

(m

g/L

or

mL/L

)+

Poly

mer

B

o P

oly

mer

C

FIGURE K-3.

SAMPLE TTF100 DATA PLOT.

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7. Variables. Variations in the vacuum pressure, support filter type, sludge temperature and sample volume can affect test results.

a. Sludge suspended solids concentration has a significant effect on the test results. This effect can be avoided, when using the TTF procedure to evaluate sludge conditioning aids or assist in the operation of a dewatering process by adhering to the sample preparation procedures outlined in Module J, particulary ensuring homogenity between samples. Comparison of TTF data between different original samples (especially if taken on different days), cannot be made with confidence unless suspended solids concentrations are comparable. A rough correction for different solids contents can be made by dividing the TTF value by its corresponding solids concentration.

b. When using the small-volume TTF test to evaluate the impact of coagulant aids on sludge dewaterability, variations in sludge solids content are to be expected, since different coagulant aid doses will have different effects on sludge settling and compaction in the Imhoff cones. Because these differences occur in full-scale applications as well, the TTF results should be interpreted as reflecting the overall impact of the different coagulant aid doses including the different solids concentrations of the settled sludge.

8. Precision and Accuracy. Triplicate analyses of 18 sample sets of conditioned and unconditioned alum sludge resulted in an average method precision of 19 seconds (approximately 4$ of the average value) for the large-volume TTF test. Triplicate analyses of 9 sample sets of conditioned and unconditioned alum sludge resulted in a method precision of 9 seconds (approximately 6% of the average value) for the small-volume TTF test. Method precision refers to the standard deviation of the results of a series of replicate samples. Method accuracy, which refers to the agreement between the value determined by the test method and the actual value present could not be determined as there is no independent means of determining Time to Filter.

REFERENCES

Knocke, W.R and Wakeland, D.L., "Fundamental Characteristics of Water Treatment Plant Sludges", Journal of the American Water Works Association. 113. 10, 516, (1983).

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TABLE K. SUGGESTED TIME TO FILTER TEST DATA RECORDING SHEET.

Date:

Analyst:

Conditioning or Coagulant Aid

Sample Volume:________

Filtrate Volume:

Conditioning or Coagulant Aid Dose Time to Filter (sec)(mg/L) 11 #2 #3 Avg TTF

Remarks:

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Module L. The Capillary Suotion Time Test

1. General Discussion

a. This test is applicable to the determination of thefilterability or dewaterability of sludges. It can be used:

(1) To evaluate various sludge conditioning aids and dosages .

(2) To evaluate the impact of coagulant aids on sludge dewaterability in conjunction with a jar test and the sludge volume determination.

(3) To assist in the daily operation of sludge dewatering processes .

b. The resources required for this test are moderate. Test materials and apparatus, as outlined below (see Figure L-1), is only available from one manufacturer located in Great Britain and thus are somewhat difficult to obtain (approximately $900, 1986). Test duration and required analytical skill, however, are quite minimal, offsetting the cost of the test apparatus.

c. The test consists of placing a sludge sample in a small cylinder on a sheet of chromatography paper, which extracts the liquid from the sludge by capillary action. The time required for the liquid to travel one centimeter is recorded.

2. Apparatus

a. Capillary Suction Time Apparatus (available from Triton Electronics Ltd., Bigods Hall, Dunmow, Essex, England, CM63BE).

b. CST paper available from Triton Electronics Ltd. (7 cm x 9 cm sheets of Whatman No. 17, chromatography grade paper cut with the grain parallel to the 9 cm side can be substituted available through Fischer Porter or Arthur Thomas).

c. Large bore pipet.

3. Reagents.

a. Sludge samples.

b. Miscellaneous conditioning aids. If the method is to be used to evaluate sludge conditioning aids, see Module A for conditioning aid preparation methods.

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SLUDGE RESERVOIR^

ci i \r\ftf

BLOCK HOLDING PROBES — i

n —— *-

?

r nFILTER PAPER — (44— 1 1 |

DIGITAL TIMER

TO TIMER

REFERENCE MARKS ON BLOCK

(PLAN)

Capillary Suction Time Apparatus (Triton Electronics Ltd., England )

Figure L.I

-122-

4. Procedure.

a. Turn CST meter on.

b. Reset meter.

c. Place the CST paper into the test cell with the rougher side up and the grain parallel to the 9 cm length side.

d. If the test is to be used to evaluate sludge conditioning aids, refer to Module J for conditioning aid addition and mixing procedures.

e. If the test is to be used to evaluate the effect of coagulant aids on sludge dewaterability following sludge volume determination as outlined in Module I, remove the collected sludge from the bottom of the Imhoff Cones. Minimize the dilution of the sludge with the supernatant by decanting as much supernatant from the Imhoff Cones as possible prior to sludge withdrawal.

f. If the test is to be used to assist in the operation of a sludge dewatering process by optimizing conditioning aid dose, refer to the conditioning aid preparation procedures outlined in Module A. However, since the dosage range is known from past operation, restrict the evaluation to smaller intervals of conditioning aid doses, (30, 35, 50, M5, 50 mg/L instead of 0, 10, 25, 50, 100 mg/L).

g. Remove 5-7 mL from the sample jar and pour the sludge into the test cell reservoir. This can be done easily with a large bore pipett of the type used to add the conditioning aid. Record CST shown on digital display. A suggested data recording sheet is shown as Table L-1. An example data recording sheet is shown as Table L-2.

h. Repeat for a minimum of three determinations per sample,

i. Repeat for different conditioning aids or doses.

5. Data Analysis. From the data sheet, plot CST vs. conditioning or coagulant aid dose for the aids evaluated (Figure L-2). Determine which conditioning or coagulant aid and dose gives the optimum results. Optimum conditioning occurs at the dose which results in the minimum CST for the least cost. In order to complete the detailed cost estimates outlined in Section IV it is necessary to conduct a sludge jar test as outlined in Module M at the current conditioning aid dose and optimum conditioning aid dose. Refer to Module M for procedure instructions.

u OJ en Ul

O

80

70

-

60 -

50 -

40

-

30

-

20

-i

10

04

0

N)

W I

8O1

20

1 6

0

n P

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me

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o

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200

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240

FIGURE L-2.

SAMPLE CST

DATA PLOT.

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TABLE L-1. SUGGESTED CAPILLARY SUCTION TIME TEST DATA RECORDING SHEET.

Date:______________

Analyst:.

Conditioning or Coagulant Aid:

Conditioning or Coagulant Aid Dose Capillary Suction Time (sec)

(mg/L) #1 #2 #3 Avg CST

Remarks:

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TABLE L-2. EXAMPLE CAPILLARY SUCTION TIME TEST DATA RECORDING SHEET.

Date:

Analyst:.

Conditioning or Coagulant Aid:

Conditioning or Coagulant Aid Dose Capillary Suction Time (sec)

(mg/L) #1 #2 #3 Avg CST

o

/CO

no Mfio

at7Z4 ?/•*>

fa*/

Remarks:

-126-

6. Results Interpretation. Test results can be interpreted fairly confidently as the CST test has been used successfully to predict the performance of most sludge dewatering processes. Correlations between CST and full-scale dewatered solids content can be developed for each individual dewatering process.

7. Variables. Variations in sludge temperature and sample volume can affect CST results. Consequently, ensure that all analyses are run under similar conditions.

a. Sludge suspended solids concentration has a significant effect on the test results. This effect can be avoided, when using the CST procedure to evaluate sludge conditioning aids or assist in the operation of a dewatering process by adhering to the sample preparation procedures outlined in Module J, particulary ensuring homogenity between samples. Comparison of CST data between different original samples (especially if taken on different days) cannot be made with confidence unless suspended solids concentrations are comparable. A rough correction for different solids contents can be made by dividing the CST value by its corresponding solids concentration.

b. When using the CST test to .evaluate the impact of coagulant aids on sludge dewaterability, variations in sludge solids content are to be expected, since different coagulant aid doses will have different effects on sludge settling and compaction in the Imhoff cones. Because these differences occur in full-scale applications as well, the CST results should be interpreted as reflecting the overall impact of the different coagulant aid doses including the different solids concentrations of the settled sludge.

8. Precision and Accuracy. Triplicate analyses of 30 sample sets of conditioned and unconditioned alum sludge resulted in an average method precision of 1.0 seconds. Method precision refers to the standard deviation of the results of a series of replicate samples. Method accuracy, which refers to the agreement between the value determined by the test method and the actual value present could not be determined as there is no independent means of determining capillary suction time.

REFERENCESBaskerville, R.C. and Gale, R.S., "A Simple Automatic Instrument for Determining the Filtrability of Sewage Sludges", Water Pollution Control. 67, 233 (1968).

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Module M. Sludge Jar Test

1 . General Discussion

a. This method is applicable to the qualitative determination of the effectiveness of sludge conditioning aids. It can be used to screen several different conditioning aids quickly as well as to obtain qualitative estimates on optimum .conditioning aid doses. It is also used to generate data required to estimate any cost savings involved with using sludge conditioning aids. Use of this test alone to choose a conditioning aid and estimate any cost savings is not recommended.

b. The resources required for this test are moderate, Test materials and apparatus, as outlined below, are already located in most water treatment plants. Test duration and required analytical skill are low. The test accuracy is highly variable, depending on site specific conditions and operator experience. The main disadvantage of the test Is that it actualy assesses conditioning aid effects on sludge settleabllity and thickening behavior, not on sludge dewaterability. Conditioning aids'impact on the sludges* tendency 'to "blind" a filter media, reducing dewaterability and any adverse impacts on operational costs are not determined .

2. Apparatus

a. Jar Test stlrrer Or other mixing device,

b. Miscellaneous beakers or Jars.

3. Reagents.

a. Sludge samples.

b. Mlsoellaneous conditioning aids. See Module M for conditioning aid preparation methods.

4. Procedure.

a. Place equal volumes of sludge samples into jar test beakers or containers.

b. Add conditioning aids in accordance with procedures outlined in Module J. As this method is to be used only for

, qualitative screening, use larger conditioning aid dose intervals than that used for other methods (i.e. 0, 10, 25, 50, 100, 200 mg/L instead of 0, 35, 40, 45, 50, 55 mg/L). When using this method to obtain cost information conduct the test with the current conditioning aid and dose and

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compare the results to the projected conditioning aid and dose as determined by Module K or L results.

c. Rapidly mix the sludge and conditioning aid at maximum mixer speed. Mixing duration is dependent upon dewatering process. See Module J for additional information.

d. Reduce mixing speed to 30 RPM and allow the sludge to flocculate for 5 minutes.

e. Stop mixing and allow the sludge to settle for 15 minutes.

f. Observe the floe size, sludge depth and supernatant depth and clarity.

g. Record observations.

5. Data Analysis. From the observation record, determine which conditioning aid gives the best results at the minimum dose. Optimum conditioning should occur with the aid that yields the largest floe size, largest supernatant volume, and/or clearest supernatant. Additional testing with the methods outlined in Modules K or L will confirm which parameter (floe size, sludge depth or supernatant depth and clarity) is the most important.

6. Results Interpretation. Test results should be interpreted cautiously as this method only yields qualitative results suitable for choosing which conditioning aid warrants additional testing .

7. Variables. Variations in the sludge suspended solids concentrations, mixing intensity and duration all affect results Consequently, all tests should be conducted under similar conditions to minimize methodology errors.

8. Precision and Accuracy. Method precision and accuracy were not evaluated as this method is intended to be used for qualitative screening only.

REFERENCES

Vesilind, P.A.Treatment and Disposal of Wastewater Sludges. Ann Arbor Science (1974).

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CHAPTER IV. USING MODULE RESULTS FOR CHEMICAL AID SELECTION.

A. Results Evaluation.

1. Baseline Data. The most important step in evaluating test results is the collection of accurate baseline operating data prior to chemical aid selection. While the current coagulant dose, filter run duration, backwash frequency, sludge generation rates or operating costs may appear to be readily available, most treatment plants are probably deficient in this baseline information. Common causes of these deficiencies include poorly calibrated flow meters and chemical metering pumps, inaccurate and inadequate operational analyses, changing chemical consistency, insufficient operation and maintenance records, inadequate operational cost information, and too much reliance on "operator experience" in place of detailed historical records and analyses. Without first obtaining this information, it is improbable that a chemical aid could be selected rationally.

2. Simple Approach. The simplest approach to evaluating test results is to concentrate on a single treatment process without regard to any other processes that may be affected. An example would be using jar tests to determine the optimum coagulant aid without evaluating its impact on filtration or sludge generation rates. Choosing the optimum chemical aid in this case is fairly easy since the optimum aid/dose is the one that gives the best settled water quality at the lowest cost. Methods for determining chemical costs are outlined below in Section IV.B. Advantages of this approach are fairly obvious, given its simplicity. Disadvantages can include possible detrimental impacts on subsequent treatment processes like decreased filter run duration or increased sludge volume. These disadvantages will most likely vary from plant to plant. This approach is most suitable for small to medium size water treatment plants where the costs of a comprehensive process evaluation could not be justified by the savings yielded from such an evaluation. Where detailed accurate baseline information is unavailable, this approach is the only method that should be used.

3. Comprehensive Approach. A more complicated approach to evaluating test results is to evaluate the effect of a chemical aid on the entire treatment process. An example of this approach would be coagulant aid evaluation using jar tests, paper filtration tests, sludge volume tests, and time to filter tests to evaluate the subsequent impact of the coagulant aid on coagulation, filtration, sludge volume, and sludge characteristics respectively. The advantages of this comprehensive approach are obvious, given the sometimes uncertain impacts of chemical additives on subsequent processes like filtration or sludge management. The disadvantages are also quite obvious given the large number of tests that need to be conducted, as well as the required existence of detailed, accurate baseline data. As a result, this approach is most likely restricted to use in larger water treatment plants where even small reductions in coagulant doses can lead to significant savings.

B. Cost Estimating. Estimating the costs when choosing a chemical aid are critical, because performance is rarely the sole criteria in the selection process. A number of factors must be considered in ultimately determining

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whether using a chemical aid to improve treatment will be cost effective. These include the cost of the chemical aid, any savings due to decreases in other process chemicals, reduced operational costs, and other miscellaneous costs. The following procedure outlines a method of estimating the chemical costs associated with using a chemical aid such as an organic polymer. It is assumed that the required physical facilities (mixing tanks, pumps, piping, etc.) are already in place. The procedure does not include any estimates of increases or decreases in labor or energy costs. For estimating those costs and the construction costs of the required facilities consult the Environmental Protection Agency's Estimating Water Treatment Costs. EPA 600/2-79-162c, August 1979.

a. The first step in estimating the costs of using a chemical aid is to determine the current chemical costs prior to selection of a chemical aid. This is outlined in Section 1 of Table VI.1. Chemical unit costs can be obtained from the purchase orders. Chemical doses should be known from the treatment plant records. It is important that the chemical costs for the current conditions (i.e., the ones under which the lab tests are conducted) be used. Using the annual average alum dose may alter the final decisions because of seasonal variations not considered in the lab tests.

b. The second step is to determine the costs of the chemical aids selected from the lab tests (jar tests, filtration tests, etc). It is very important that lab test doses be calculated accurately. All chemical doses should be expressed in terms of product as supplied, (prior to any dilution) per volume of water treated. For a powdered polymer, the dose in mg/L should be converted to pounds of polymer per MG (millon gallons) of water treated. Conversion factors are included on Table IV.1. For a liquid or emulsion polymer the dose of mL/L should be converted to gallons of polymer as supplied per MG of water treated. For sludge conditioning aids doses should be reported as pounds or gallons of product supplied per ton of dry solids conditioned. This requires that the solids concentration of the sludge be known. If sludge solids concentration is assumed to be fairly consistent then these doses can be reported as pounds or gallons of product per 1000 gallons of sludge conditioned or MG of water treated. An example of these calculations is shown in Table IV.2.

c. The third step is to determine the savings from any reduction in chemical requirements allowed by the use of a chemical aid. For example, if a coagulant aid dose of 1 mg/L allows the alum or ferric chloride dose to be reduced by 5 mg/L and the lime dose by 10 mg/L then the cost savings should be included as well.

d. The fourth and final step is to determine any savings in operation and maintenance costs attributable to use of the chemical aid. For example, if the use of a coagulant aid reduces the sludge volume and hence disposal costs by 20 percent, or a filtration aid increases the filter run duration by 24 hours, the savings associated with reduced sludge disposal costs or backwash costs should be included. These final savings can sometimes be the most significant benefit of using a chemical aid. Without detailed baseline data, however, it is difficult to quantify any realized savings. Nonetheless, estimates of these costs may at least permit relative cost-effectiveness to be computed when

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several different chemical additives are being considered. These estimates also require that appropriate modules were used to generate the needed values.

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TABLE IV.1 CHEMICAL COST ESTIMATING WORKSHEET(Photocopy and revise as necessary: at least one copy per chemical aidevaluated)

1. Current Chemical Costs

Average Treated Water Flow Rate (MGD): ___ (MOD = millon gallons per day)

Conversion Factors:

mg/L x 8.3^ x MGD = Ib/day

Average Chemical Usage

Alum (mg/L):

(Ib/day):

Ferric Chloride (mL/L):

(gal/day):

Lime (mg/L):

(Ib/day):

Polymer (mg/L or mL/L):

(Ib/day or gal/day):

Other* (mg/L or mL/L):

(Ib/day or gal/day):

mL/L x 1000 x MGD = gal/day

Chemical Unit Cost

Alum ($/lb): _

Ferric Chloride ($/gal):

Lime ($/lb):

Polymer ($/lb or $/gal):

Other* ($/lb or $/gal):

Average Chemical Cost (Chemical usage x unit cost / treated water flow rate):

Alum ($/MG): ___

Ferric Chloride ($/MG): ___

Lime ($/MG): ___

Polymer ($/MG): ___

Other ($/MG): ___

TOTAL CURRENT CHEMICAL COSTS ($/MG): ____

Include only chemicals with dosage changes under new conditions.

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2. Projected Chemical Costs;(Requires results from Modules C,F,G,K,L,and/or M)

Conversion Factors:

mg/L x 8.34 = lb/MG

mL/L x 1000 = gal/MG

a. Projected Chemical Aid Doses:

Alum Dose (mg/L): ___ (lb/MG):

Ferric Chloride Dose (mL/L): ___ (gal/MG):

Lime Dose (mg/L): ___ (lb/MG):

Polymer Dose (mg/L or mL/L): ___ (lb/MG or gal/MG):

Other* (mg/L or mL/L): ___ (lb/MG or gal/MG):.

b. Projected Chemical Costs lb/MG or gal/MG x unit cost);

Alum U/MG): ___

Ferric Chloride ($/MG): ___

Lime ($/MG): ___

Polymer ($/MG): ___

Other*($/MG): ___

TOTAL PROJECTED CHEMICAL COSTS:

* Include only chemicals which are changed from present doses,

3. Net Chemical Cost Savings;

TOTAL CURRENT CHEMICAL COSTS (from above) ($/MG):

TOTAL PROJECTED CHEMICAL COSTS ($/MG):

TOTAL PROJECTED CHEMICAL SAVINGS ($/MG): (Current Costs - Projected Costs)

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H. Operational Cost Savings;

a. Coagulation/Sedimentation Processes: (Requires results from Modules C & I)

Average Daily Treated Water Flow Rate (MOD):

Average Annual Treated Water Flow Rate (MG): (Average Daily Flow Rate x 365)

Total Annual Cost of Sludge Management and Disposal:

Unit Cost of Sludge Management and Disposal ($/MG): (Total Cost/Average Annual Treated Water Flow Rate)

Current Sludge Volume at Current Chemical Dose (from Module I results) (mL/L):

Projected Sludge Volume at Projected Chemical Dose (from Module I results) (mL/L):

Projected Sludge Volume to Current Sludge Volume Ratio (PSV/CSV):

Projected Unit Cost of Sludge Management and Disposal (Unit Cost x PSV/CSV) ($/MG):

PROJECTED PROCESS SAVINGS (Current Unit Costs - Projected Unit Costs) ($/MG):

b. Filtration Processes

Unit Cost of Filtered Water ($/MG):

Average Filtration Rate for a given filter (MGD):

Current Filter Run Duration for a given filter (hours):

Average Filtered Volume for a given filter (MG): (Filtration rate x filter run duration/24)

Backwash Flow Rate (gpm):

Backwash Duration for a given filter (min):

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Current Backwash Volume for a given filter (MG): ___ (Backwash flow rate (gpm) x backwash duration (min)/1,000,000)

Backwash Volume to Filtered Volume Ratio: ___ (BV/FV)

Current Backwash Cost for a given filter ($/MG): ___ (BV/FV x unit cost of treated water)

Projected Filter Run Duration (hours): ___ (from Module F or G results)

Current Filter Run Duration to Projected FilterRun Duration Ratio (CFR/PFR): ___

Projected Backwash Cost ($/MG): ___ (Current Backwash Cost x CFR/PFR)

PROJECTED PROCESS SAVINGS($/MG): ___ (Current Backwash Cost - Projected Backwash Cost)

c. Sludge Dewatering and Disposal Processes (Requires results from Modules M and K or L)

Average Daily Treated Water Flow Rate (MGD): ___

Average Annual Treated Water Flow Rate (MG): (Average Daily Flow Rate x 365)

Total Annual Cost of Sludge Dewatering and Disposal:

Unit Cost of Sludge Dewatering and Disposal ($/MG): (Total Cost/Average Annual Treated Water Flow Rate)

Current Sludge Depth (from Module M results)(in):

Projected Sludge Depth (from Module M results)(in):

Projected Sludge Depth to Current Sludge Depth Ratio (PSD/CSD):

Projected Unit Cost of Sludge Dewatering and Disposal (Unit Cost x PSD/CSD)($/MG):

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PROJECTED PROCESS SAVINGS (Current Unit Cost - Projected Unit Cost)($/MG):

TOTAL PROJECTED PROCESS SAVINGS ($/MG): (Coagulation + Filtration + Sludge Savings)

TOTAL PROJECTED CHEMICAL SAVINGS ($/MG):

TOTAL PROJECTED SAVINGS ($/MG):(Projected Process Savings + Projected ChemicalSavings)

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TABLE IV. 2 CHEMICAL COST ESTIMATING EXAMPLE WORKSHEET(Photocopy and revise as necessary: at least one copy per chemical aidevaluated)

1 . Current Chemical Costs

Average Treated Water Flow Rate (MGD): IO (MOD = millon gallons per day)

Conversion Factors:

mg/L x 8.34 x MGD = Ib/day mL/L x 1000 x MGD = gal/day

Average Chemical Usage Chemical Unit Cost

Alum (mg/L):3oy«'

(Ib/day): Alum ($/lb):

Ferric Chloride (mL/L): /Oon& L?$€<}

(gal/day): - •• Ferric Chloride ($/gal):

Lime (mg/L):/t

(Ib/day): /2> Lime ($/lb);

Polymer (mg/L o«*-*b/t): O ,7^ /^/Z-. 6 ,2.5*3, 3^y/0 = (Ib/day OP pal/day); *2./_ Polymer ($/lb oas^gaci):

Other* (mg/L or mL/L): /J&ne^

(Ib/day or gal/day): __ Other* ($/lb or $/gal):

Average Chemical Cost (Chemical usage x unit cost / treated water flow rate):

Alum ( $/MG) : 2Soo x. ^fc. ic /

Ferric Chloride ($/MG):

Lime ($/MG):

Polymer ($/MG):

Other ($/MG):

TOTAL CURRENT CHEMICAL COSTS (&/MG):

"include only chemicals with dosage changes under new conditions.

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2. Projected Chemical Costs;(Requires results from Modules C,F,G,K,L, and/or M)

Conversion Factors:

mg/L x 8.31* = Ib/MG

mL/L x 1000 = gal/MG

a. Projected Chemical Aid Doses:

Alum Dose (mg/L): *2O (Ib/MG):

Ferric Chloride Dose (mL/L): ~" ~ (gal/MG):

Lime Dose (mg/L) : /£ />»//. * f§ = /Q (Ib/MG) :, _

Polymer Dose (mg/L ur uiL/L); ^_f?" ( Ib/M^or^af/MG) ; V> / 7

Other* (mg/L or mL/L): ___ (Ib/MG or gal/MG) ;

b. Projected Chemical Costs Ib/MG or gal/MG x unit cost):

Alum ($/MG):

Ferric Chloride ($/MG):

U.^

Polymer — r /

Other* ($/MG):

TOTAL PROJECTED CHEMICAL COSTS:

* Include only chemicals which are changed from present doses.

3. Net Chemical Cost Savings;

TOTAL CURRENT CHEMICAL COSTS (from above) ($/MG): 37.

TOTAL PROJECTED CHEMICAL COSTS ($/MG): 52 '

TOTAL PROJECTED CHEMICAL SAVINGS ($/MG): T» 8 B> (Current Costs - Projected Costs)

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4. Operational Coat Savings;

a. Coagulation/Sedimentation Processes: (Requires results from Modules C & I)

Average Daily Treated Water Flow Rate (MOD): JO

Average Annual Treated Water Flow Rate (MG): (Average Daily Flow Rate x 365)

Total Annual Cost of Sludge Management and Disposal: ^2^

-±2,000, •,> p .- _ Unit Cost of Sludge Management and Disposal ($/MG): o « ' / (Total Cost/ Average Annual Treated Water Flow Rate)

Current Sludge Volume at Current Chemical Dose (from Module I results) (mL/L):

Projected Sludge Volume at Projected Chemical Dose(from Module I results) (mL/L): /Q

Projected Sludge Volume to Current Sludge Volume Ratio (PSV/CSV):

b. Filtration Processes

Unit Cost of Filtered Water ($/MG):

Average Filtration Rate for a given filter (MGD):

Current Filter Run Duration for a given filter (hours):

Projected Unit Cost of Sludge Management and £ "7 Disposal (Unit Cost x PSV/CSV) ($/MG):

PROJECTED PROCESS SAVINGS (Current Unit Costs - ^ ._ — . Projected Unit Costs) ($/MG): /* /^~

Average Filtered Volume for a given filter (MG): 1* (Filtration rate x filter run duration/24)

Backwash Flow Rate (gpm):

Backwash Duration for a given filter (min):

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Current Backwash Volume for a given filter (MG): (Backwash flow rate (gpm) x backwash duration (min)/1 ,000,000) '

Backwash Volume to Filtered Volume Ratio: &i (BV/FV) 0, IW / /,&£ =.

Current Backwash Cost for a given filter ($/MG): ""V* (BV/FV x unit cost of treated water)

Projected Filter Run Duration (hours): (from Module F or G results)

Current Filter Run Duration to Projected Filter Run Duration Ratio (CFR/PFR):

Projected Backwash Cost ($/MG): (Current Backwash Cost x CFR/PFR)

PROJECTED PROCESS SAVINGS U/MG): /S^32— 9»/*? (Current Backwash Cost - Projected Backwash Cost)

c. Sludge Dewatering and Disposal Processes (Requires results from Modules M and K or L)

Average Daily Treated Water Flow Rate (MGD):

Average Annual Treated Water Flow Rate (MG) : (Average Daily Flow Rate x 365)

Total Annual Cost of Sludge Dewatering and Disposal:32/£>oy /?&&> ~ && ~ -7

Unit Cost of Sludge Dewatering and Disposal ($/MG): o* f /(Total Cost/Average Annual Treated Water Flow Rate)

Current Sludge Depth (from Module M results) (in):

Projected Sludge Depth (from Module M results) (in): * *

Projected Sludge Depth to Current Sludge Depth Ratio (PSD/CSD): ?

Projected Unit Cost of Sludge Dewatering and Disposal (Unit Cost x PSD/CSD )($/MG):

PROJECTED PROCESS SAVINGS (Current Unit Cost - ^Projected Unit Cost)($/MG):.^c -7.7_ ^frUQ -~ ?.%n«5' » / J • / O

TOTAL PROJECTED-PROCESS SAVINGS ($/MG): X^/_2 (Coagulation + Filtration + Sludge Savings)

' *2 *? rK" ^TOTAL PROJECTED CHEMICAL SAVINGS ($/MG): V/^3

TOTAL PROJECTED SAVINGS U/MG): ^/6 , C>O(Projected Process Savings + Projected ChemicalSavings)

ISBN-0-915295-14-8

3P-3C-90515-2/89-SE