DEGREE PROJECT, IN ANALYTICAL CHEMISTRY, SECOND LEVEL

STEHAG, SWEDEN 2015

Calcium Chloride as a Co-Coagulant

WATER TREATMENT

KRISTOFER HÄGG

KTH ROYAL INSTITUTE OF TECHNOLOGY

RINGSJÖVERKET

www.kth.se

i

Acknowledgements

I would like to express my gratitude to everyone who assisted me during this project. There were

many who showed great interest in this work, which made the study that much more interesting to

do.

First, I would like to thank my main supervisor, Kenneth Persson, at Lund Universitet and research

manager at Sydvatten, who gave me the opportunity to work on this thesis and who supported me

during this study.

Thanks to my second supervisor, Britt-Marie Pott, process engineer at Sydvatten, for helping me a

great deal during the experiments conducted at the water treatment facility.

Thanks to everyone at TETRA Chemicals for showing me around the CaCl2 manufacturing facilities

and for supporting this project. A special thanks to Fabrice Dutiel and Olof Norrlöw at TETRA

Chemicals for showing great interest and for all the positive feedback.

I would also want to thank everyone at Ringsjöverket for all the help I received and making my daily

work easier. In particular, Agneta Jönsson for helping me in the laboratory. Also, thanks to Marianne

Franke, laboratory manager for making sure I had everything I needed to conduct the experiments

and for laughing with me when things went wrong.

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Preface

This thesis is a result of a collaboration between Sydvatten AB, a municipal drinking water producer,

TETRA Chemicals, a CaCl2 producer and distributor and Lund Universitet. The hypotheses was

formulated by TETRA Chemicals, based on pre-studies they conducted in June 2013.

The studies were conducted at Ringsjöverket, a water treatment facility in Stehag, Sweden. The work

was financed by Sydvatten AB, Lund Universitet and TETRA Chemicals.

The work focused on CaCl2 as an adjunct in iron and aluminum assisted coagulation and flocculation.

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Abstract

As populations continue to grow, the demand for fresh drinking water is increasing. This puts a lot of

pressure on drinking water producers to strive for more efficient solutions and techniques. Many

producers worldwide use surface water as a raw water source, which they often treat through

coagulation and flocculation techniques. This is done by adding coagulant (e.g. metal coagulants),

creating instability in the suspension, causing flocculation. In this work, PIX-311 (a FeCl3 coagulant

produced by Kemira) and Al2(SO4)3 (ALG) were used as primary coagulants and CaCl2 (produced by

TETRA Chemicals) as an adjunct in a coagulation and flocculation study.

The goal of this work was to study the effects of CaCl2 additions to Fe(III) and Al(III) flocculation. The

experiments were conducted at Ringsjöverket (a water treatment facility), using jar tests to simulate

the treatment process on a laboratory scale. The raw water samples used in this study, were taken

from Bolmen, a lake in southern Sweden. A spectrophotometer was used to monitor the efficiency of

flocculation by UV-VIS absorption.

In the first experiments, various CaCl2 additions were added to Fe(III) flocculation, with FeCl3 as a

primary coagulant. To see if FeCl3 could be substituted with CaCl2, the amount of primary coagulant

was reduced to about 80% of the optimal dosage (the dose used daily by the water treatment plant).

In the next series of experiments, various amounts of CaCl2 were added with an optimal dose of

FeCl3. After that, the effects of CaCl2 additions to Al(III) flocculation were conducted, using Al2(SO4)3

as a primary coagulant. The experiments followed the previous scheme used in Fe(III) flocculation.

The UV-VIS results showed that no CaCl2 additions were effective enough to replace the primary

coagulant. However, reduced amount of primary coagulant benefited slightly from small CaCl2

additions. A likely explanation for this is the ability of Ca2+ to aid in charge neutralization and reduce

the repulsive forces between particles in suspension, aiding coagulation. Furthermore, CaCl2

additions, with reasonable certainty, did not increase the efficiency of Fe(III) flocculation. When the

CaCl2 dose was increased (from about 13µl to 820 µl per liter raw water), the effect became negative.

In other words, high doses of CaCl2 inhibited flocculation by, most likely, occupying adsorption sites

for the primary coagulant. This was observed for an optimal FeCl3 dose, reduced FeCl3 dose and an

optimal dose of Al2(SO4)3. In the more brief study on Al(III) flocculation, low CaCl2 doses did not

appear to have any effect on flocculation at first. However, when a reduced amount of Al2(SO4)3 was

used, the samples with CaCl2 gave better UV-VIS results once the pH was increased from 6 to about

6.15. One explanation for this could be that the shift in flocculation mechanism at higher pH, causes

CaCl2 to have an increased positive effect.

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Abstrakt

Rent färskvatten är nödvändigt för nästintill all mänsklig aktivitet. Detta gäller allt från dricksvatten

och sanitet till industri och agrikultur. I takt med befolkningsökningen, ökar färskvattenbehovet och

vikten av att kunna försörja befolkningen med rent vatten. Det finns många olika tekniker och

metoder att rena vatten som dricksvattenproducenter har till sitt förfogande. En av de vanligaste

reningsmetoderna, som kommer ligga i fokus i detta arbete, inkluderar rening genom koagulering

och flockbildning. Detta åstadkoms genom att ett koaguleringsmedel, vanligen metallkomplex,

tillsätts råvattnet vilket skapar instabilitet i suspensionen och resulterar i flockbildning. I det här

arbetet studeras CaCl2 (producerat av TETRA Chemicals) påverkan på denna process med PIX-311

(FeCl3 ett koaguleringsmedel producerat av Kemira) och Al2(SO4)3 (ALG) som primära

koaguleringsmedel.

Målet med denna studie var att utröna eventuella positiva påverkan av CaCl2 på

koaguleringsprocessen när FeCl3 respektive Al2(SO4)3 användes som primära koaguleringsmedel. För

att simulera processen på liten skala användes en flockulator med 6 stycken enliters bägare med var

sin programmerbar omrörare. Experimenten utfördes på Ringsjöverket och råvattenproven togs från

Bolmen, i Skåne. Efter experimenten undersöktes effektiviteten av koaguleringsprocessen genom att

prov analyserades i en spektrofotometer, där UV-VIS absorptionen mättes.

De första experimenten utfördes på råvattenprov där en reducerad mängd PIX-311 användes

tillsammans med CaCl2, för att testa om det primära koaguleringsmedlet delvis kunde ersättas med

CaCl2. En reducerad respektive optimal mängd koaguleringsmedel är baserat på vad verket använder

i den dagliga driften. I senare experiment användes en optimal mängd PIX-311 tillsammans med en

varierande mängd CaCl2, för att se om CaCl2 hade någon effekt på den optimala driften. Efter det

fortsattes experimenten med Al2(SO4)3 som primärt koaguleringsmedel, där effekten av CaCl2

studerades på samma vis.

Från UV-VIS resultaten visade det sig att det primära koaguleringsmedlet inte kunde ersättas med

någon mängd CaCl2 (varken för PIX-311 eller ALG), däremot hade CaCl2 en positiv effekt vid små

koncentrationer då en reducerad mängd PIX-311 användes. Anledning till dessa effekter kan förklaras

med att Ca2+ har förmågan att bistå med laddningsneutraliseringen och reducera de repulsiva

krafterna mellan partiklar i suspensionen. För en optimal dos PIX-311 hade, med stor säkerhet, en

liten dos CaCl2 ingen effekt på UV-VIS resultaten. När dosen CaCl2 ökade (från ca 13 µl till 820 µl) var

effekten negativ när både PIX-311 och ALG användes (både med reducerad och optimal mängd). En

trolig förklaring är att när dosen Ca2+ ökar börjar adsorptionssäten på partiklar att blockeras från

koaguleringsmedlet och en negativ effekt observeras. För experimenten med ALG upplevdes samma

resultat som för PIX-311, när en reducerad mängd ALG däremot användes tillsammans med CaCl2

observerades en oväntad trend. När pH ökades för dessa prover från 6 till ca 6,15, blev resultaten

gradvis sämre för alla prover tills pH nådde ca 6,15, där prover med CaCl2 uppvisade en plötslig

förbättring i UV-VIS resultat. En möjlig förklaring till detta fenomen är att

flockbildningsmekanismerna förändras med en ökad koncentration av negativa arter i suspension

och att den positiva effekten av CaCl2 därav ökar.

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Abbreviations

ALG Aluminumsulphate, Al2(SO4)3

DLVO Derjaguin, Landau, Verwey and Overbeek theory

DOC Dissolved oxygen content

EDL Electric double layer

HA Humic acid

NOM Natural organic matter

PACl Polyaluminumchloride

PIX, PIX-311 Ferric chloride, FeCl3

TOC Total organic carbon

UV-VIS Ultraviolet-Visible

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Content

1. Introduction .........................................................................................................................................1

1.1 Hypothesis ..........................................................................................................................................2

2. Water treatment ..................................................................................................................................3

2.1 Contaminants in surface water ..........................................................................................................3

2.1.1 Absorption and transmittance spectroscopy ..................................................................................3

2.1.2 Turbidity ..........................................................................................................................................4

2.1.3 Color ................................................................................................................................................5

2.2 Particles in suspension .......................................................................................................................5

2.2.1 Plain sedimentation .........................................................................................................................5

2.2.2 Particle surface charge ....................................................................................................................6

2.2.3 Electric double layer ........................................................................................................................7

2.3 Coagulation and flocculation ..............................................................................................................8

2.3.1 Coagulation and destabilization ......................................................................................................8

2.3.2 Iron and aluminum coagulants ..................................................................................................... 10

2.3.3 Ca2+ as a co-coagulant .................................................................................................................. 11

2.3.4 Jar tests ......................................................................................................................................... 12

2.3.5 Flocculation .................................................................................................................................. 13

3. Experimental ..................................................................................................................................... 15

3.1 Raw water ........................................................................................................................................ 15

3.2 Coagulants and additives................................................................................................................. 15

3.3 Preparation before jar test .............................................................................................................. 15

3.4 Jar tests ............................................................................................................................................ 16

3.5 Ultraviolet-Visible Spectroscopy ..................................................................................................... 16

4. Results and discussion ...................................................................................................................... 17

4.1 Effects of various CaCl2 additions on Fe(III) flocculation ................................................................. 17

4.1.1 Addition of 20 mol% CaCl2 ............................................................................................................ 17

4.1.2 Addition of 40 mol% CaCl2 ............................................................................................................ 18

4.1.3 Addition of 80 mol% CaCl2 ............................................................................................................ 20

4.1.4 Summary of experiments with reduced amount of PIX-311 ........................................................ 20

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4.2 Effects of CaCl2 with an optimal Fe(III) dose .................................................................................... 23

4.2.1 Addition of 20 and 40 mol% CaCl2 ................................................................................................ 23

4.2.2 Addition of 40 and 80 mol% CaCl2 ................................................................................................ 24

4.2.3 Summary of experiments with an optimal PIX-311 dose ............................................................. 24

4.3 Effects of CaCl2 additions on Al(III) flocculation .............................................................................. 27

5. Conclusion ......................................................................................................................................... 29

6. Further work ..................................................................................................................................... 30

References............................................................................................................................................. 31

Appendix ............................................................................................................................................... 33

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1. Introduction

Clean, fresh water is essential in our daily lives, for everything from drinking water and sanitation to industry and agriculture. Less than 0.02% of all water, is fresh liquid surface water, on which we all depend (Cunningham and Cunningham, 2013). Water is a part of a natural cycle, constantly renewed. However, renewal takes time and as the population continues to grow, so does the demand for fresh drinking water. As a consequence, the natural replenishing process isn’t enough to support our current and future needs. To be able to meet this demand, it is important to have a sustainable and a well developed fresh water production. Because ground water is not always enough to support everyone, it is common to use surface water as a fresh water source. Surface water does not undergo the natural infiltration, where a lot of the common contaminant gets reduced, as in ground water. This means that a few extra steps are needed to ensure high quality drinking water. Common contaminants in surface water include, natural organic matter (NOM), humic acid (HA), bacteria, viruses, silt, clay and various inorganic compounds (Trussel and Hand, 2012). One way to reduce these compounds, is through coagulation and flocculation by adding a coagulant. These coagulants are readily available and come in different forms. Often, different iron and aluminum complexes are used as coagulants because of their efficiencies and relatively low cost (Bratby, 1980). However, it is common that adjuncts are used to aid or improve the coagulation and flocculation process. Adjuncts can assist this process in many different ways (e.g. charge neutralization and bridge building) depending on their properties. In beer brewing industry it is well known that Ca2+ is a factor in yeast flocculation and beer clarification. Commonly, it is said that at least 50 ppm (mg/l) Ca2+ is needed in the wort, mainly for yeast to aggregate at the end of fermentation. Studies have shown that flocculation of yeast is improved with a Ca2+ concentrations up to 1 mol/m3 and that yeast cells depend on calcium to flocculate (Amory, Rouxhet and Dufour, 1988). This is because Ca2+ reduces the negative charge on yeast cells, causing them to adsorb onto each other and flocculate over time. This process is similar to what happens when a metal coagulant (FeCl3 or Al2(SO4)3) is added to raw water, which leads us to the focus of this study; can CaCl2 assist in FeCl3 and Al2(SO4)3 flocculation? CaCl2 could potently have several positive effects including, reducing the amount of FeCl3 or Al2(SO4)3 needed for coagulation, which would allow for a more sustainable way to treat water. Also, a reduction of primary coagulant would potentially reduce the cost of producing drinking water.

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1.1 Hypothesis

Hypothesis:

“Raw water treatment through coagulation and flocculation using FeCl3 is more effective if the water

sample is pre-treated with CaCl2.”

The hypothesis is based on studies done by TETRA Chemicals in June 23 2013 at Sydvatten AB’s water

treatment facilities in Stehag, Sweden.

The aim of this thesis is to study the effects on coagulation and flocculation of CaCl2 additions to

conventional raw water treatment using FeCl3 and Al2(SO4)3.

The objectives are as follows:

Is it possible to replace FeCl3 or Al2(SO4)3 with any given amount of CaCl2, without

compromising the results?

Determine the effect on water treatment using FeCl3 and Al2(SO4)3 with various CaCl2

concentrations.

Finally, summarize the result of the study taking cost into consideration. Which alternative

gives the best result in comparison with the total cost?

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2. Water treatment

This chapter will discuss common contaminants in natural water sources and give an introduction in

industrial water treatment techniques used today. The focus will be parameters of water quality,

suspension stability and water treatment through coagulation and flocculation.

2.1 Contaminants in surface water

Natural surface water sources (i.e. lakes) contain a variety of different organic and inorganic

contaminants. Organic contaminants consist of dissolved organic elements (proteins, humic acid),

colloids, bacteria, viruses, parasites and amoebas, while inorganic contaminants include silt, clay and

mineral oxides caused by natural erosion. Particles in water will effect water clarity, color and can be

infectious (i.e. bacteria and viruses). So to achieve high quality drinking water, removal of

containments is required. A common way to remove most of the contaminants in surface water is to

treat the raw water by coagulation and flocculation followed by filtration or sedimentation which will

be described later on. (Trussel and Hand, 2012) The following section will describe what unwanted

physical characteristics contaminants cause and common techniques to assess water quality used

today.

2.1.1 Absorption and transmittance spectroscopy

Spectrophotometers are used to test water samples for iron, organic compounds (e.g. Humic acid

and aromatic compounds) and small colloidal particles (0.45 µm). Iron and organic compounds

(containing double bonds) absorbing UV light, which is a reason why absorbance is often measured

at 254 nm. Different organic and inorganic compounds absorb light at different wavelengths, so the

wavelength used varies with the source water contaminants.

Figure 2.1.1 Schematic of a UV-VIS spectrophotometer (adapted from: Trussell and Hand, 2012).

The intensity of absorption is determined by passing a beam of light through a water sample of

known thickness and measuring the intensity (I) of transmitted light relative to the intensity (I0) that

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would have been if no absorption occurred. A schematic picture of a UV-VIS spectrophotometer can

be seen in figure 2.1.1. The ratio of the intensity I to the intensity I0 is called transmittance (I/I0) and

can be determined at different wavelengths. Lambert developed an equation for the attenuation of

light as a function of the thickness of a homogenous medium and Beer developed the equation to

take concentration in consideration. According to the Beer-Lambert law, the probability that a

photon will be absorbed is directly proportional to the concentration of absorbing molecules and the

thickness of the sample (Alberty and Silbey, 2000). When analyzing water samples, distilled water is

used as a reference due to the fact that pure water will absorb light. Absorbance is defined as

followed:

𝑙𝑜𝑔 (𝐼

𝐼0) = −𝜀(𝜆)𝐶𝑥 = −𝑘𝐴(𝜆)𝑥 = −𝐴(𝜆) (1)

where

𝐼 - intensity of light after passing through a solution [mW/cm2]

𝐼0 - intensity of light after passing through distilled water [mW/cm2]

𝜆 - wavelength [nm]

𝜀(𝜆) - molar absorptivity of light –absorbing solute at a wavelength 𝜆, [l/mol, cm]

𝐶 - concentration of light-absorbing solute [mol/l]

𝑥- cuvette length [cm]

𝑘𝐴(𝜆) - absorptivity at wavelength 𝜆 [cm-1]

𝐴(𝜆) - absorptivity at wavelength 𝜆, dimensionless

A relationship of absorbance and transmittance can be derived and is as follows:

Transmittance, 𝑇,% = (𝐼

𝐼0) ∗ 100 (2)

𝑇 = 10−𝐴(𝜆) (3)

2.1.2 Turbidity

Turbidity is an indication of water clarity and is caused by suspended matter such as, silt, bacteria,

viruses and macromolecules. Turbidity is defined by optical properties that cause light to be

scattered and absorbed (Standard Methods, 2005). The technique for analyzing turbidity is called

nephelometry and is measured in nephelometric turbidity units (NTU). As seen in figure 2.1.1, a light

beem is directed into the water sample and a detector that is positioned at a 90o angle measures the

scattered light. Turbidity measurements are influenced by the suspended particles size, shape and

refractive index, which means that there is no direct correlation between the turbidity of the sample

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and amount of suspended matter in the sample (Bratby, 1980). Furthermore, the size of the particles

in relationship to the incoming lights’ wavelength will have an impact on the intensity of the

scattered light. For small particles (one-tenth of the incoming lights wavelength) the light scattered is

fairly symmetrical. However, when the size of the particle increases it causes the light to be scattered

more in a forward direction. As a consequence, turbidity measurements are more sensitive to

particles in the size range of the used wavelength. Turbidity measurements are very useful in quality

control and is often used as an indicator in process control for increased concentrations of

containments, such as bacteria. (Trussell and Hand, 2012)

2.1.3 Color

Color can derive from different sources and is therefore described in two different ways, as apparent

color and true color. Like turbidity, apparent color is caused by suspended matter and is measured

on unfiltered samples, while true color is caused by dissolved species and is measured on filtered

samples. Water color is a good indication of organic content (such as humic acid), iron content and

turbidity. Color in water is assessed by visually comparing samples to a standard platinum-cobolt

solution and presented in an arbitrary color scale in color units (c.u.). The platinum-cobolt standard

used is yellow in color and resembles the color found in natural water. (Trussell and Hand, 2012 and

Bratby, 1980)

Color in water is an indication of contamination of some form and steps are therefore taken to

remove color from waters during treatment.

2.2 Particles in suspension

The following section will discuss the stability of particles in natural water.

2.2.1 Plain sedimentation

In plain sedimentation, clarification is achieved purely through the help of gravity without any added clarification aids. Given enough time eventually most particles will settle, however the time required wouldn’t be practical on a large scale drinking water production (Cheremisinoff, 2001). The technique is however utilized for primary treatment of raw water from fast flowing rivers, in order to minimize the amount of suspended material passing into the system (Ratnayaka, et. al., 2009). The time it takes for a particle to settle by its own depends on several different parameters. The settling characteristics include weight, shape and size of the particle and temperature of the medium (which affects the viscosity and/or frictional resistance of the water) (Cheremisinoff, 2001). A list of various particles and the settling times can be seen in table 2.2.1. Table 2.2.1 Particle settling time based on size and type (Source: Cheremisinoff, 2001).

Particle diameter (mm) Particle Type Time to settle one foot

10 Gravel 0.3 sec.

1.0 Coarse sand 3.0 sec.

0.1 Fine sand 38.0 sec.

0.01 Silt 33.0 minutes

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0.001 Bacteria 35.0 hours

0.0001 Clay particles 230 days

0.00001 Colloidal particles 65 years

The velocity V (mm/s) with which a particle in water falls can be calculated through:

𝑉𝐶 =𝑔

1.8∗104(𝑟 − 1)

𝑑2

𝛾 (4)

where

𝑔 – gravitation, 9,82 [m/s2]

𝑟 – density of the particle [g/cm3, kg/m3]

𝑑 – diameter of particle [mm]

𝛾 – kinematic viscosity [m2/s]

Equation (4) is valid for slowly moving water (Reynolds number Re < 0,5) and kinematic viscosity 𝛾 is equivalent to absolute viscosity [Ns/m2] divided by the mediums’ density [kg/m3] (Ratnayaka, et. al., 2009). The kinematic viscosity varies with temperature, which can be seen in table 2.2.2. Table 2.2.2 Viscosity of water at various temperatures (Source: Camp, 1946).

Temperture (oC) 0 5 10 15 20 25

Value ϕ (m2/s) 10-6 1.79 1.52 1.31 1.15 1.01 0.90

2.2.2 Particle surface charge

Particles in water are classified as hydrophobic or hydrophilic. Hydrophobic particles in solution are

inherently unstable and will aggregate irreversibly over time. Hydrophilic particles, on the other hand

have polar or ionized functional groups, which allows them to stay in suspension. These particles

include proteins, humic acid (organic particles) and metal oxides (inorganic particles). Suspended

hydrophilic particles stability is caused by their surface charge. However, given enough time

hydrophilic particles will also settle (Trussell and Hand, 2012).

The surface charge of particles have different sources and their properties may change depending on

the environment. Humic acid for instance, has negatively charged surfaces which they acquire from

their functional groups (e.g. carboxylic acid groups). However, the surface charge of humic acid will

change if the pH of the surrounding solution drops below 3. The pH corresponding to the point in

which the surface charge of any given particle changes from negative to positive is defined as the

zero point of charge (ZPC) or isoelectric point (IEP) if no adsorption occurs. In natural surface water

particle-particle adsorption is a common occurrence, which makes pHzpc more applicable in these

systems (Trussell and Hand, 2012). An example of this are particles adsorbing humic acid causing

them to have a negative surface charge for pH values greater than 5 (Stumm and Morgan, 1996). In

the table below some common particles in surface water can be seen with their corresponding pHzpc

values.

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Table 2.2.3 Zero point charge of various particles found in natural waters (adapted from: Parks, 1967 and

Stumm and Morgan, 1981).

Type of Particle Zero Point of Charge, pHzpc

Algae 3–5

Bacteria 2–4

Humic acid 3

Oil droplets 2–5

Al2O3 9.1

CuO3 9.5

MgO 12.4

2.2.3 Electric double layer (EDL)

When negatively charged particles are in suspension in water, they are surrounded by an electric

double layer. As a result of the variation of electrical potential near the surface of the particle,

counterions accumulate around the particle forming two layers. Near the surface a fixed layer of

cations are adsorbed and forms a layer known as the Stern layer (previously known as Helmholtz

layer). This gives rise to another layer with a net charge of zero called the diffuse layer, which

consists of both cations and anions (figure 2.2.1).

Figure 2.2.1 Schematic overview of negative particle in suspension, illustrating the electric double layer

(Adapted from: Trussell and Hand, 2012).

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In a situation where two negatively charged particles approach each other, the double layers overlap

and the electrostatic forces cause them to repel each other and the system is considered stable. The

zeta potential seen in figure 2.2.1, is an indication of the colloidal system stability. The zeta potential

is measured by applying an electric field between two electrodes forcing the negatively charge

particle to migrate. This movement (known as electrophoresis) causes adjacent water molecules to

follow the particle creating a shear plane. The potential between the bulk solution and the shear

planes is the measured zeta potential. So for small particles, a high zeta potential creates an energy

barrier that prevents flocculation. However, if the repulsive forces are reduced so that the attractive

forces can overcome the energy barrier, the system will be destabilized and rapid flocculation will

occur (Trussell and Hand, 2012). The interaction of attractive and repulsive forces between particles approaching each other is described by the DLVO theory. The theory is named after the scientist who developed it, Derjaguin and Landau, 1941 followed by Verwey and Overbeek, 1948.

2.3 Coagulation and flocculation

The emphasis in this chapter is the physical and chemical phenomena in the coagulation and flocculation process. Because the terms coagulation and flocculation are used in different manners in literature it is important to address these definitions. The term coagulation comes from Latin meaning drive together, which La Mer believed to be an appropriate term as he defined coagulation as the process of reducing the electric repulsion between particles with the addition of neutral salts (La Mer, 1964). More recent definitions of coagulation and flocculation will be used and are as follows (Bratby, 1980): “Coagulation is the process whereby destabilization of a given suspension or solution is effected. That

is, the function of coagulation is to overcome those factors which promote the stability of a given system.”

“Flocculation is the process whereby destabilized particles, or particles formed as a result of

destabilization, are induced to come together, make contact and thereby form large(r) agglomerates.”

2.3.1 Coagulation and destabilization

The coagulation process, as described by Bratby, is the destabilizing process of a suspension. This can be achieved by different means. Often in water treatment several mechanism are utilized including, compression of electric double layer, adsorption and charge neutralization, adsorption and particle bridging and sweep coagulation. Compression of electric double layer: One way to promote coagulation is to add ions (with no specific attraction for colloid surfaces) to increase the ionic strength of the solution and forcing the counter-ions closer to the surface of the particle. This compresses the electric double layer which allows the van der Waals forces to overcome the repulsive forces and flocculation will occur. However, this technique is not practiced in water treatment. (Trussell and Hand, 2012)

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Adsorption and charge neutralization: Charged ions or polymers can be used to destabilize particles by adsorption and charge neutralization, while in adsorption and bridge building techniques, polymer is used as a primary coagulant. As discussed before, most particles in natural raw water are negatively charged (e.g. humic acid), as a result hydrolyzed metal salts and cationic organic polymers are often used for destabilization and charge neutralization. Cationic organic polymers are used for charge neutralization. However, they are more often used in combination with an inorganic coagulant in bridge building techniques. An optimal coagulant dose in adsorption and charge neutralization tends to be when the particles are only partially covered and if exceeded, the charge will change and stability will remain. (Trussell and Hand, 2012) Adsorption and particle bridging: In particle bridging, nonionic polymers are partially adsorbed to surfaces of particles leaving a part of the polymer free to be adsorbed onto a second particle. This mechanism is a result of intermolecular forces, e.g. dipole interactions and hydrogen bonding (Hunter, 2001), and allows adsorption to occur at several sites along the polymer chain. For flocculation to take place an adequate amount of polymer needs to be added. If an excessive dose is added, all the adsorption sites will be occupied and flocculation won’t occur (O’Melia, 1972). Sweep Coagulation/flocculation: Metal coagulant (e.g. FeCl3) in aqueous solution can form metal hydroxide precipitates if under the right conditions. This usually occurs when the contamination concentration is low and pH ranges between 6 and 8 (Trussell and Hand, 2012). When a polymetalion is adsorbed to a particle surface hydroxide accumulate and starts to enmesh surrounding particles. As the insoluble precipitate descends the remaining particles will be swept with the hydroxide, hence sweep coagulation/flocculation (Gillberg et. al., 2003). A comparison of the effects of, different colloid concentrations in water and coagulant doses, have on the type of coagulation that occurs can be seen below (figure 2.3.1).

Figure 2.3.1 Residual turbidity after jar tests as a function of particle and coagulant concentration of metal salts at constant pH. Section S1 to S4 indicates colloidal concentration in increasing order in the water samples. S1-low to S4-very high colloid concentration (Adapted from: Trussel and Hand, 2012, and Bratby, 1980).

10

For the lowest concentration levels of colloids (S1), the particles are removed with sweep coagulation (zone 4) once the coagulant dose is high enough. When the colloid concentration is increased (S2), the particles are at first removed by adsorption and charge neutralization (zone 2). As the coagulant dose is increased, the particles stabilize (zone 3) with a reverse charge (from negative to positive), followed by an increase in particle remove by sweep coagulation as the coagulant dose increases. At high colloid concentrations (S3), all zones are clearly defined. Removal of particles, can be seen through charge neutralization in zone 2 and through sweep coagulation in zone 4. Finally, at very high colloid concentration (S4), particle removal from charge neutralization and sweep flocculation merge to form one zone. This is possible because the concentration required for charge neutralization coincides with precipitation of metal hydroxide (Trussel and Hand, 2012).

2.3.2 Iron and aluminum coagulants

Aluminum and iron based coagulants are the most common metal coagulants used today because of their effectiveness and their relatively low cost. These coagulants however, are often produced using ore and hydrochloric acid (e.g. to produce FeCl3), which raises some concern about their sustainability. Iron and aluminum form multi-charged polynuclear complexes, through a series of hydrolytic reactions, which gives them their high efficiency. (Bratby, 1980) When aluminum and iron coagulants are introduced into water, they immediately dissociate and form water-coordinated complexes, Al(H2O)6

3+ and Fe(H2O)63+ (Bratby, 1980). What follows next is a

series ligand substitution, the ligand of interest being OH-. The first step for Al(H2O)63+ could be

described as (Bratby, 1980, Stumm and Morgan, 1962):

Al(𝐻2𝑂)63+

↔ Al(OH)(𝐻2𝑂)5

2+ +𝐻+ (5) Followed by,

Al(OH)(𝐻2𝑂)52+

→𝑂𝐻−

→ → 𝐴𝑙6(OH)15

3+ →𝑂𝐻−

→ →

𝐴𝑙8(OH)20 4+ →𝑂𝐻−

→ → 𝐴𝑙(𝑂𝐻)3(𝑠)

𝑂𝐻−

→ 𝐴𝑙(𝑂𝐻)4− (6)

The OH- ligand can act as bridges between metal atoms forming polynuclear complexes. Both iron and aluminum has the ability to form such complexes, the simplest being bi-nuclear complexes. (Bratby, 1980) Bi-nuclear species are the first step, as seen below, of the formation of polynuclear complexes (Trussell and Hand, 2012).

2(𝐴𝑙(𝐻2𝑂)5(𝑂𝐻)) 2+

−2𝐻2𝑂 → (7)

11

All species of iron and aluminum (mono or polynuclear) interact with the surrounding particles in different ways. Because of the difficulty of controlling which species of metal complexes that form, prehydralyzed metal salts as coagulants have been developed. These coagulants are prepared by reacting the metal with water and various salts. By doing this, control is gained over the species formed during the coagulation process and other benefits such as, lower dosage required and stronger floc-formation are achieved (Trussel and Hand, 2012).

Because Al2SO4 (ALG) and FeCl3 (PIX-311) are exclusively used as primary coagulants in this thesis, it is important to mention the operational requirement when using these coagulants. Iron and aluminum complexes react readily with different species in natural water. These reactions include ligand substitution with natural occurring phosphates and sulphates, which will impact the overall success of coagulation. This is a reason why it is important to use the right coagulant dose and why the dose varies with different natural waters. Also, as seen in (5), adding metal coagulants to water will lower pH and will have an impact on the waters alkalinity. (Trussel and Hand, 2012) An example of FeCl3 added to natural water can be described as (Bratby, 1980): 2𝐹𝑒𝐶𝑙3 + 3𝐶𝑎(𝐻𝐶𝑂3)2

↔ 2𝐹𝑒(𝑂𝐻)3 + 3𝐶𝑎𝐶𝑙2 + 6𝐶𝑂2 (8)

2𝐹𝑒𝐶𝑙3 + 3𝐶𝑎(𝑂𝐻)2

↔ 2𝐹𝑒(𝑂𝐻)3 + 3𝐶𝑎𝐶𝑙2 (9)

The reactions that metal coagulants participate in (e.g. hydration and stepwise substitution) are very rapid, which makes initial mixing of coagulant in raw water very important (Bratby, 1980). This will be discussed in more detail later on.

2.3.3 Ca2+ as a co-coagulant

The focus of this thesis is the effects that CaCl2 might have as a co-coagulant. It is unclear if CaCl2 has any effects on coagulation and flocculation when using commercially available coagulants such as FeCl3 (PIX-311) and Al2SO4 (ALG). There are however studies that indicate that calcium does have a positive effect on flocculation in some cases. R. H. Smellie, Jr., and V. K. La Mer discovered that phosphyrol esters, found in potato starch, rapidly flocculated colloidal dispersions of fine clay in presence of calcium. This was achieved by calcium (or other phosphate binding ions) crosslinking particles that already had adsorbed starch molecules. However, no flocculation occurred with non-phosphate binding ions like Na, K. (La Mer, 1964) In recent studies it has been shown that alkali-earth metal ions can assist in coagulant-humic acid (HA) adsorption by reducing the repulsive forces (Wang et. al., 2010). It was argued that the Ca2+ and Mg2+ ions would assist in charge neutralization of humic acid. At the same time, high concentration of alkali-earth metals would reduce adsorption by blocking adsorption sites for the coagulant, in this case bi-functional resin JN-10 (figure 2.3.2).

12

Figure 2.3.2 The action mechanism of the influence of high concentration of the alkaline-earth metal 258 ions on JN-10’s adsorption capacity for the HA (adapted from: Wang et al., 2010)

In another study, positive effects of calcium on polyaluminumclhloride (PACl) flocculation were observed. In the study, HA samples were pretreated with calcium and flocculated using PACl with different basicities (OH/Al ratios). The results indicated that calcium could enhance the size and strength of the flocs by reducing the zeta potential of HA. Furthermore, when studying floc breakage and re-growth, the floc size was larger for HA-calcium water than HA water, suggesting that calcium could neutralize the negatively charged HA chain and form bridges between adjacent molecules, and thereby promoting the aggregation of HA. (Dong, 2012)

2.3.4 Jar tests

Conducting jar tests is a good way of testing different procedures on a laboratory scale before tests are conducted on pilot scale. It can be used for testing coagulant dosage, optimal pH range and kinetic studies (e.g. initial mixing conditions). The jar test is supposed to simulate the conditions in the coagulation and flocculation process of the large scale plant. The flocculators utilized have programmable kinetic programs, this includes mixing speeds and duration. Usually, the kinetic program is set to simulate different phases by starting an initial rapid mixing phase (coagulation phase), slow mixing (flocculation phase) followed by no mixing (sedimentation phase). Once the program is finished, many different parameters can be tested to see the efficiency of the process. This might include, dissolved organic carbon (DOC), residual metal content and UV-VIS absorbance (indication of removed organic matter). All results are tied to the raw water in the jar test, which means that the results can’t always be applied to different waters. However, some trends seen in a series of tests can give an indication of, for example, new coagulant efficiencies (Trussel and Hand, 2012). A photo of a flocculator can be seen below (figure 2.3.3):

13

Figure 2.3.3 Photo of Kemira Flocculator 2000 used during this thesis project.

As discussed in section 2.3.2, the initial mixing speed is very important for a successful coagulation process. The time it takes to form mononuclear complexes such as AlOH2+ is in the order of 10-10 s, while polynuclear complexes could take up to 1 s to form (Bratby, 1980). Adsorption to particle of these complexes is very rapid (order of 10-10 s) (O’Melia, 1969) and time needed for the structural adjustments to the double layer is of the order 10-10 (Bratby, 1980). As a result, there is no benefit of having the rapid mixing exceeding 5 s in jar tests (Griffith and Williams, 1972). It is possible that longer mixing time will impair coagulation and flocculation results (Letterman, Quan and Gemmell, 1973).

2.3.5 Flocculation

(Essentially from Bratby, 1980, Trussell and Hand, 2012)

The process of flocculation is the stage where particles approach each other, adsorb and form larger agglomerates. Flocculation is divided into two stages, perikinetic flocculation and orthokinetic flocculation. Perikinetic flocculation is a naturally random process that comes from Brownian movement (random motion of particles suspended in fluid), which start immediately after destabilization and is complete within seconds. As the small particles (<0.1 µ) progressively become larger, the energy barrier proportionally increases with the floc area. Once the flocs reach a size of 1 to 100 µm the Brownian motion has little to no effect. The second stage, orthokinetic flocculation, continues with forced convection for particles larger than 1 µm. The mixing causes collisions between particles, however this also erodes and causes flocs to break up. If the forced convection is constant, a steady state of floc breakup and formation will occur given enough time (Parker et al., 1972). Another factor in flocculation is the differences in floc growth, which causes flocs to settle at different times. The difference in size and density also cause flocs to settle at different velocity. As a result, flocs collide promoting additional flocculation. This mechanism is called differential settling and will have an impact on sedimentation, assuming enough time is given.

14

The rate of flocculation is determined by particle collision and breakup in all three mechanisms mentioned above. In other words, the total rate of flocculation is a function of all three rates of flocculation. The rate of flocculation rij, is defined as:

𝑟𝑖𝑗 = 𝛼𝛽𝑖𝑗𝑛𝑖𝑛𝑗 (10)

Where, α – collision efficiency β – collision frequency factor (particles of size i and j) n – particle concentration (i and j particles)

The collision efficiency α, depends on the destabilization factor. So if particles are completely destabilized, the collision efficiency will be 1 (α ranges from 0 to 1). The collision frequency factor βij, depends on all collision frequencies of the different flocculation mechanisms and is as followed:

𝛽𝑖𝑗 = 𝛽𝑃𝑒𝑟𝑖𝑘𝑖𝑛𝑒𝑡𝑖𝑐 + 𝛽𝑂𝑟𝑡ℎ𝑜𝑘𝑖𝑛𝑒𝑡𝑖𝑐 + 𝛽𝐷𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑡𝑖𝑎𝑙 𝑠𝑒𝑡𝑡𝑙𝑖𝑛𝑔 (11)

There are three different models describing the flocculation process: spherical particles in a linear flow field, spherical particles in a nonlinear flow field, and fractal-based models. The floc growth prediction is what differentiates these models from each other. They are all based on different assumptions about particle-particle interactions, particle geometry and so on. The spherical particles in a linear flow field model assumes that particles are spherical and that the total floc volume is constant. The model doesn’t account for collision efficiency and van der Waals forces, which neglects the importance of perikinetic flocculation to some degree. These forces and interactions are more accurately described in the nonlinear model developed by Han and Lawler (1992). Flocculation theory was later developed in the fractal flocculation model. In this model the floc volume isn’t considered to be constant over time, which results in a more accurate depiction of the flocculation rate.

15

3. Experimental

3.1 Raw water

The raw water samples used in this study were taken from a lake, Bolmen in southern Sweden. The

water is transported through an 80 km long underground tunnel followed by a 25 km long raw water

pipeline to the municipal water treatment plant in Stehag southern Sweden. The incoming water

consists of up to 10% stormwater that was filtered through the soil into the tunnel. The raw water

quality used varied daily depending on previous conditions at the water source. The variation of the

water quality also depends on the current season. The experiments in this study were conducted

from January to April 2015 and during this time the water quality was as followed:

Table 3.1.0 Average raw water quality from January to April 2015. The temperature ranged from 2 oC to 5oC

during this period.

Date 20150113 to 20150212 20150212 to 20150314 20150314 to 20150413

Min Max Average Min Max Average Min Max Average

Turbidity 3.11 3.75 3.26 3.05 3.40 3.30 3.37 3.50 3.43

NO3-Neq 1.11 1.21 1.15 1.12 1.24 1.20 1.22 1.25 1.23

TOCeq 9.26 10.75 9.82 9.78 10.88 10.47 10.78 11.17 10.93

DOCeq 13.40 14.39 13.81 13.23 14.62 14.29 14.50 14.83 14.66

UV 40.2 43.8 41.6 40.0 44.1 43.1 43.9 44.8 44.2

3.2 Coagulants and additives

All coagulants used in the study were of food grade quality and were used directly without further

preparation with the exception of Al2(SO4)3 (Kemira ALG, Sweden). A 0.36% NaOH (Akzo Nobel,

Sweden) solution was used to control the resulting pH due to the decrease in pH caused by PIX-311

and ALG. The 36% by weight CaCl2 solution used was produced and provided by TETRA chemicals

(Helsingborg, Sweden). The first primary coagulant used was PIX-311, a 40% by weight FeCL3 solution

produced by Kemira (Helsingborg, Sweden) and provided by Sydvatten AB (municipal drinking water

producer). In later experiments, ALG was used as a primary coagulant, that was provided by

Sydvatten AB in pellet form. In the experiments, the primary coagulants and CaCl2 dose was

presented in percent. For PIX-311 and ALG, the percent was be based on the daily optimal dose (see

Appendix) used by Ringsjöverket, and for CaCl2 the percent was based on an optimal coagulant dose

of 61mg/l.

3.3 Preparation before jar test

Samples of raw water with added coagulant were pH-tested (using a WTW pH-197, pH meter) before

jar tests were conducted to ensure that the resulting pH would be within the optimal (or targeted)

range. NaOH (0.36% by weight) solution was added accordingly. In the experiments when PIX-311

was used no preparations were required. When Al2(SO4)3 was used as the primary coagulant

16

granulates of Al2(SO4)3 were dissolved in distilled water under rapid mixing to create a 200g/l

solution.

3.4 Jar tests

Jar tests were conducted in the water treatment plant in Stehag, Sweden using a program-controlled

flocculator (Flocculator 2000, Kemira; Helsingborg, Sweden). The setup consisted of six 1 liter glass

beakers and the jar test procedure was as follows:

1. The flocculator was programmed to 30 seconds rapid mixing (400 rpm), 20 min slow mixing

(50 rpm) and 30 min sedimentation (0 rpm). Each beaker was filled with one liter raw water.

2. Before the program was started CaCl2 and 0.36% NaOH were added to the beakers while

mixing (50 rpm).

3. The program was started and when 3 seconds remained of the rapid mixing, coagulant was

added. Once the rapid mixing was finished and slow mixing had started, the samples were

pH-tested.

4. When sedimentation was finished samples were taken with a 50 ml syringe 3 cm below the

surface.

The program was altered to its current method above after results indicated that brief rapid mixing

after the addition of FeCl3 gave better UV-VIS results (see Appendix).

3.5 Ultraviolet-Visible Spectroscopy

All samples were tested for residual natural organic matter (NOM) in a spectrophotometer (Hach

Lange, DR 5000) using a 5 cm cuvette. The absorption was measured at λ=245 nm and λ=436nm.

These wavelength were used by the water treatment plant for daily process control. In table 3.5.1

seen below, the average UV-VIS results are displayed, measured by the water treatment plant. The

measurements taken after the filters, are samples that have already gone through the process of

flocculation.

Table 3.5.1 Measured UV-VIS absorption results from 010215 to 100415, conducted by the water treatment

facility (Ringsjöverket). Samples were taken after quick filter 1 and 7 (after flocculation).

UV-VIS measurements Quick filter 1 Quick filter 7 Incoming raw water

Average UV-abs (λ=254 nm) 4.97 4.83 43.89

Average VIS-abs (λ=436 nm) - - 3.13

17

4. Results & Discussions

4.1 Effects of various CaCl2 additions on Fe(III) flocculation

During these experiments two samples acted as a control group with 100% PIX, two samples had 80%

PIX and two samples had 80% PIX and various amounts of CaCl2. The convections program was as

follows: 30s rapid mixing (400 rpm), 20min slow mixing (50 rpm) and 30 min sedimentation (0 rpm).

CaCl2 and NaOH were added before the program during slow mixing (50 rpm). PIX was added when 3

seconds of rapid mixing remained. Explanation for this can be seen in Appendix (Experiment 1 and 2).

4.1.1 Addition of 20 mol% CaCl2

The Aim of these experiments was to see if a low dose of CaCl2 (20 mol% of the optimal PIX dose)

would have any effect on flocculation when using a reduced amount of PIX (in this case 83 to 86%

PIX). As seen in figure 3.1, the effects of 103 to 107% PIX, 83- 86% PIX and 83- 86% PIX with added

CaCl2 were studied. These early results show that an addition of CaCl2 seem to have a positive effect

on UV-VIS results in some cases when comparing with samples without CaCl2 and the same amount

of PIX. However, it is not clear from these results if PIX can be substituted with CaCl2.

Figure 3.1 Results from Experiment 3 (2015-02-03, 2015-02-04 and 2015-02-05).

8

9

10

11

12

13

14

15

0,6

0,7

0,8

0,9

1

1,1

1,2

1,3

1,4

4,7 4,8 4,9 5 5,1 5,2 5,3

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

103 to 107% PIX VIS

83 to 86% PIX VIS

83 to 86% PIX with CaCl2 VIS

103 to 107% PIX UV

83 to 86% PIX UV

83 to 86% PIX with CaCl2 UV

18

4.1.2 Addition of 40 mol% CaCl2

In the following experiments the setup was the same however the CaCl2 dose was increased to 40

mol%. Results seen in figure 4.1 show that a reduced amount of PIX with CaCl2 gave better results at

pH below 4.9 compared with 108% PIX at the same approximate pH. This was also true for samples

with a reduced amount of PIX without CaCl2 (figure 4.2). At the same time samples with 108% PIX

produce better results when pH was above 5 in both cases (figure 4.1 and 4.2). The explanation for

this is that the optimal pH-range is altered based on the coagulant dose. If pH is reduced, the amount

of negative species in suspension will be reduced, and organic contaminants (e.g. humic acid and

protein) will obtain fewer negative charges on the surface. As a result, the optimal coagulant dose

will also be reduced. In other words, a reduced amount of PIX will transfer the optimal pH to a lower

range. (Gillberg et al., 2003)

Figure 4.1 Results from Experiment 4 A and B (2015-02-06 and 2015-02-09).

Figure 4.2 Results from Experiment 4 C to E (2015-02-10 and 2015-02-11).

8

9

10

11

12

13

14

15

16

17

0,6

0,7

0,8

0,9

1

1,1

1,2

1,3

1,4

1,5

1,6

4,7 4,8 4,9 5 5,1 5,2 5,3 5,4

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

108% PIX VIS

87% PIX VIS

87% PIX with CaCl2 VIS

108% PIX UV

87% PIX UV

87% PIX with CaCl2 UV

8

9

10

11

12

13

14

15

16

17

0,6

0,7

0,8

0,9

1

1,1

1,2

1,3

1,4

1,5

1,6

4,8 4,9 5 5,1 5,2 5,3 5,4

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

108% PIX VIS

86% PIX VIS

86% PIX with CaCl2 VIS

108% PIX UV

86% PIX UV

86% PIX with CaCl2 UV

19

At this point the used PIX dose was changed to match the optimal dose used by the water treatment

plant. The results of this can be seen in figure 5.1.

Figure 5.1 Results from Experiment 5 (2015-02-12, 2015-02-13 and 2015-02-17).

From these results it is quite clear that a 40 mol% addition of CaCl2 does not match the results from

samples with 100% PIX at pH around 5.1. However, as seen in figure 4.1, 4.2 and figure 5.1, a

reduced amount of PIX gave better UV-VIS results at pH below 4.9.

8

10

12

14

16

18

20

0,6

0,7

0,8

0,9

1

1,1

1,2

1,3

1,4

1,5

1,6

4,7 4,9 5,1 5,3 5,5U

V-a

bs

(λ=2

54

nm

/m)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

100 to 101% PIX VIS

80 to 81% PIX VIS

80 to 81% PIX with CaCl2 VIS

100 to 101% PIX UV

80 to 81% PIX UV

80 to 81% PIX with CaCl2 UV

20

4.1.3 Addition of 80 mol% CaCl2

During these experiments the CaCl2 dose was doubled to 80 mol%, which gave similar results (figure

6.1). At the optimal pH-range for 100% PIX, the reduced amount of PIX (with and without CaCl2)

produced poorer UV-VIS results. This can also be seen in table 6.8 below, where the average UV-VIS

results are clearly better for 100% PIX than 81% PIX with CaCl2. When comparing results from

samples with 81% PIX, the samples with CaCl2 does give better results. However, they don’t match

the results for 100% PIX.

Table 6.8 Average UV-VIS results for experiment 6.

Experiment 6 pH Range Average pH Average VIS-abs Average UV-abs

81% PIX without CaCl2 4.81-5.26 5.22 1.37 17.35

81% PIX with 80 mol% CaCl2 4.98-5.27 5.22 1.28 16.20

100% PIX 5.00-5.57 5.17 0.79 10.61

CaCl2 Effect 6.6% 6,6%

Figure 6.1 Results from Experiment 6 2015-02-18, 2015-02-19 and 2015-02-23.

4.1.4 Summary of experiments with reduced amount of PIX-311

When combining all results from experiment 5 to 11 (see Appendix) the effects of PIX dose and CaCl2

dose becomes clear (figure 6.2 and 6.3). The optimal pH for 100% PIX ranges from approximately 4.9

to 5.2 while the optimal pH range for 80% PIX is slightly lower. Lowering pH might cause corrosion

issues for drinking water producers and as a result it is more advantageous to keep pH above 5. As

seen in figure 6.2 and 6.3, the samples with reduced amount of PIX (with or without CaCl2) do not

share comparable results with samples of 100% PIX in that pH range. When the CaCl2 dose is

increased to 0.4g/l (over 64 times increase) the results appear to get worse. However, there are

8

10

12

14

16

18

20

0,6

0,7

0,8

0,9

1

1,1

1,2

1,3

1,4

1,5

1,6

4,7 4,9 5,1 5,3 5,5

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

100% PIX VIS

81% PIX VIS

81% PIX with CaCl2 VIS

100% PIX UV

81% PIX UV

81% PIX with CaCl2 UV

21

positive effects when a lower CaCl2 dose (40 to 80 mol%, or 13.72 resp. 27.4µl 36% CaCl2 (aq) per liter

raw water) is combined with 80% PIX. Based on literature data (Wang et al., 2010) Ca2+ does lend

support in coagulation by reducing repulsion forces between humus in solution and humus adsorbed

to coagulant. Also, when Ca2+ concentration reaches a certain point, the Ca2+ ions block the primary

coagulants’ (in this case FeCl3) adsorption sites and poorer results are observed.

Figure 6.2 The combined VIS-absorption results from experiment 5 to 11.

Figure 6.3 The combined UV-absorption results from experiment 5 to 11.

0,5

0,7

0,9

1,1

1,3

1,5

4,7 4,8 4,9 5 5,1 5,2 5,3 5,4 5,5 5,6

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

VIS

100% PIX VIS 80 to 81% PIX VIS

80 to 81% PIX with 40% CaCl2 VIS 80 to 81% PIX with 80% CaCl2 VIS

80% PIX with 0,4g/l CaCl2 VIS 100% PIX UV

Poly. (100% PIX VIS) Poly. (80 to 81% PIX VIS)

Poly. (80 to 81% PIX with 80% CaCl2 VIS)

8

10

12

14

16

18

20

4,7 4,8 4,9 5 5,1 5,2 5,3 5,4 5,5 5,6

UV

-ab

s (λ

=25

4 n

m/m

)

pH

UV

100% PIX VIS 100% PIX UV80 to 81% PIX UV 80 to 81% PIX with 40% CaCl2 UV80 to 81% PIX with 80% CaCl2 UV 80% PIX with 0,4g/l CaCl2 UVPoly. (100% PIX VIS) Poly. (100% PIX UV)Poly. (80 to 81% PIX UV) Poly. (80 to 81% PIX with 80% CaCl2 UV)

22

At the same time, when comparing results from experiment 4 (table 4.6), that same benefit doesn’t

appear. This could be explained by the increase of PIX in that experiment (from 80 to 87%) and/or

that the slight benefit of adding CaCl2 to 80% PIX is within the margin of error. It is important to

mention that the average results seen in table 4.6, are based on all the results within that specific pH

range and the distribution is not accounted for.

Table 4.0 Summary of Experiment 4 showing pH range, average pH, average UV-VIS results.

Experiment 4 pH Range Average pH Average VIS-abs Average UV-abs

86 to 87% PIX without CaCl2 4.86-5.04 4.95 0.783 10.4

86 to 87% PIX with 40 mol% CaCl2 4.88-5.03 4.95 0.785 10.5

CaCl2 Effect -0.3% -0.4%

A reason why the benefits are not observed in experiment 4, could also be that the pH only ranges to

5.04. As seen in table 6.8 and figure 6.2 and 6.3, where the pH is higher, a benefit of adding CaCl2 is

observed. This can also be seen in table 5.0 below, where a 40 mol% CaCl2 dose appear to improve

the UV-VIS results by 2.6 resp. 3.1%. So a benefit of adding CaCl2 could be that the optimum pH range

is shifted to higher pH or that the optimal pH range is broadened. As discussed previously, when pH

is increased, the negative species in the suspension increase and coagulation by charge neutralization

is reduced. As a result, when pH increases, the positive Ca2+ ions assist in charge neutralization, and

the UV-VIS results are improved. (Gillberg et al., 2003)

Table 5.0 Summary of Experiment 5 showing pH range, average pH, average UV-VIS results.

Experiment 5 pH Range Average pH Average VIS-abs Average UV-abs

81% PIX without CaCl2 5.01-5.15 5.07 1.03 13.67

81% PIX with 40 mol% CaCl2 4.98-5.13 5.07 1.00 13.31

CaCl2 Effect 3.1% 2.6%

In table 6.0, the standard deviation was considered for experiment 5 and 6, showing that the

observed positive effects of adding CaCl2 to a reduced amount of PIX, were reasonable.

Table 6.0 Summary of the standard deviations of Experiment 5 and 6. The standard deviation was calculated,

taking pH in consideration for each individual data point.

Experiment 5 Standard deviation VIS Standard deviation UV

81% PIX without CaCl2 0.02 0.29

81% PIX with 40 mol% CaCl2 0.02 0.28

Experiment 6 Standard deviation VIS Standard deviation UV

81% PIX without CaCl2 0.04 0.43

81% PIX with 80 mol% CaCl2 0.03 0.27

23

4.2 Effects of CaCl2 additions with an optimal Fe(III) dose

In these experiments CaCl2 was added to samples with 100% PIX. Similar to the previous section, one control group was used with only 100% PIX and the other samples with various amounts of CaCl2. The CaCl2 doses are presented in percent (20, 40 and 80 mol%) based on a 56.5g/m3 PIX dose. The setup varied throughout these experiments.

4.2.1 Addition of 20 and 40 mol% CaCl2

In this set of experiments 20 and 40 mol% CaCl2 were added to 100% PIX. The results in figure 7.3

appear to follow the same trend as previously observed, where a decrease in pH below 4.95

drastically degrades the UV-VIS-results. When comparing the different results it doesn’t seem like

CaCl2 has any impact. Again, there are individual samples with CaCl2 that give better results but it

isn’t systematic.

Figure 7.3 Results from Experiment 7A to N (2015-03-10, 2015-03-11 and 2015-03-12).

8

9

10

11

12

13

14

0,6

0,7

0,8

0,9

1

1,1

1,2

4,7 4,8 4,9 5 5,1 5,2 5,3

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV -VIS

100% PIX VIS

100% PIX with 20% CaCl2 VIS

100% PIX with 40% CaCl2 VIS

100% PIX UV

100% PIX with 20% CaCl2 UV

100% PIX with 40% CaCl2 UV

24

4.2.2 Addition of 40 and 80 mol% CaCl2

In the following experiments the CaCl2 dose was doubled to 40 and 80 mol%. The results from these experiments can be seen in Figure 8.1. An increase in CaCl2 dose appears to have very limited effects on UV-VIS absorption results. One thing to keep in mind is that the raw water quality varies day to day and these experiments are conducted over a period of days. Nonetheless, if CaCl2 had any impact (positive or negative), the results should show a trend to that effect.

Figure 8.1 Results from Experiment 8A to G (2015-03-17, 2015-03-18, 2015-03-19 and 2015-03-20).

4.2.3 Summary of experiments with optimal PIX-311 dose

When combining all the results from experiment 5 to 11 there appears to be a slight benefit by adding CaCl2 (figure 9.2). However, as mentioned before, the raw water quality changes over time (table 3.0). The early experiments were conducted in February and the later in March, which makes it difficult to be certain that the CaCl2 additions had any positive effects. In figure 9.3, the UV results appear to be independent of calcium dose. An interesting observation is that the inclinations of the trend lines in figure 10.2 seem to be similar and that they reveal a pH optimum around 5.2-5.25, while the UV results in figure 9.3 indicate that the pH optimum is lower. Based on that, average UV-results are slightly improved at a lower pH and average VIS-results are slightly improved at higher pH. In any case, a benefit of adding calcium could come from electric double layer compression described earlier (Trussell and Hand, 2012, Wang et al., 2010) or due to calcium’s ability to neutralize the HA’s negative charge and/or calcium’s bridged building abilities (Dong, 2012). As seen in the earlier experiments, a high calcium dose (0.4g/l 36% CaCl2 (aq)) gives worse UV-VIS results, however not to the same degree (figure 9.2 and figure 9.3).

8

9

10

11

12

13

14

0,5

0,55

0,6

0,65

0,7

0,75

0,8

0,85

0,9

0,95

1

4,7 4,8 4,9 5 5,1 5,2 5,3

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

100% PIX VIS

100% PIX with 40% CaCl2 VIS

100% PIX with 80% CaCl2 VIS

100% PIX UV

100% PIX with 40% CaCl2 UV

100% PIX with 80% CaCl2 UV

25

Figure 9.2 VIS Results from experiment 5 to 11. Trend lines are generated from samples between pH 4.9 and 5.2 resp. pH 5.2 and 5.6.

Figure 9.3 UV Results from experiment 5 to 11. Trend lines are generated from samples between pH 4.9 and 5.2 resp. pH 5.2 and 5.6.

R² = 0,0706 y = 1,5801x - 7,6152R² = 0,9387

y = 1,5736x - 7,5514R² = 0,8648

R² = 0,0768

0,4

0,6

0,8

1

1,2

1,4

1,6

4,7 4,8 4,9 5 5,1 5,2 5,3 5,4 5,5 5,6

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

VIS

100% PIX VIS 100% PIX with 40% CaCl2 VIS 100% PIX with 0,4g/l CaCl2 VIS

8

10

12

14

16

18

20

4,7 4,8 4,9 5 5,1 5,2 5,3 5,4 5,5 5,6

UV

-ab

s (λ

=25

4 n

m/m

)

pH

UV

100% PIX UV 100% PIX with 40% CaCl2 UV 100% PIX with 0,4g/l CaCl2 UV

26

Table 9.7 shows the results from experiments 7, 8 and 9, where a positive effect can be seen from CaCl2 additions (3% for average VIS and 1% for average UV). The positive effect could be, as discussed earlier, that the optimal pH range is broadened. However, the standard deviations displayed in table 9.7, suggest that these results are not significant. Table 9.7 Average UV-VIS absorption results from experiment 7 to 9. The standard deviation for data points from 4.9 to 5.2 pH are also displayed.

100% PIX

Experiment pH Range Average pH Average VIS-abs Average UV-abs

9 4.93-5.26 5.14 0.618 9.30

8 4.89-5.12 4.96 0.656 9.16

7 4.79-5.24 4.98 0.819 10.27

Total average 5.02 0.697 9.58

Standard deviation 4.9-5.2 0.087 0.53

100% PIX with 40 mol% CaCl2

Experiment pH Range Average pH Average VIS-abs Average UV-abs

9 5.01-5.26 5.18 0.631 9.50

8 4.9-5.16 4.99 0.636 9.08

7 4.75-5.2 5.01 0.761 9.93

Total average 5.06 0.676 9.50

Standard deviation 4.9-5.2 0.075 0.49

CaCl2 effect 3% 1%

The confidence level was tested for experiment 7 to 9 and the results can be seen in table 9.8. It is safe to say that the results from these experiments are significant and not generated by chance. Table 9.8 Regression analysis from experiment 7 to 9. States the confidence level (95%) of observed results.

Statistics Confidence VIS Confidence UV

100% PIX 3.97E-08 9.35E-06

100% PIX with 40 mol% CaCl2 1.68E-07 2.63E-04

One thing to reflect on, is that all the observed UV-VIS results compared to the UV-VIS results

received from the water treatment plant (table 3.5.1), are significantly poorer. Granted, the samples

from the water treatment plant were taken after the quick filters, however it serves well as an

indication of the observed results. With this in mind, if the experiments would be applied to the pilot

scale, the slightly positive effect of adding CaCl2 might be insignificant.

27

4.3 Effects of CaCl2 additions on Al(III) flocculation

In these experiments (experiment 12 and 13, see Appendix), 40% by weight CaCl2 (35.4 µl/l raw

water) and 0.4g/l CaCl2 (820µl/l raw water) was added to Al2(SO4)3 (ALG) flocculation. The percent

calcium was based on a 43g/m3 ALG dose. Only two sets of experiments were done with ALG, which

will make it difficult to draw any definite conclusions, however the experiments gave some

interesting results. As seen in figure 12.1, a high CaCl2 dose (0.4g/l) provides worse results and a low

CaCl2 dose (40%) does not appear to have any impact at all. As pH increases, the results start

wavering greatly. One possible explanation could be, that when pH increases, a predominance of

negative hydrolysis species occur. Furthermore, this could result in a gradual increase of flocculation

due to precipitate enmeshment or sweep flocculation (Bratby, 1980).

Figure 12.1 Results from Experiment 12A to L (2015-04-14, 2015-04-15, 2015-04-16, 2015-04-17, 2015-04-20,

2015-04-22 and 2015-04-23).

Table 12.13 shows the effect of CaCl2 additions and the average UV-VIS results. A high calcium dose

(0.4g/l) gave a -29% VIS result and a -13% UV result. At the same time, a low dose (40%) did not have

any significant impact on the results. These results are comparable with previous results, a high

calcium dose giving worse results and a low calcium dose having little to no effect on the results.

Table 12.13 Average UV-VIS absorption results from Experiment 12.

Experiment 12 pH Range Average pH Average VIS-abs Average UV-abs

ALG 5.93-6.50 6.21 0.790 13.22

ALG w 40% Ca 5.97-6.47 6.20 0.807 13.19

ALG w 0.4g/l Ca 5.97-6.46 6.22 1.022 14.91

CaCl2 effect VIS UV

ALG w 40% Ca -2% 0%

ALG w 0.4g/l Ca -29% -13%

10

11

12

13

14

15

16

17

18

19

20

0,6

0,7

0,8

0,9

1

1,1

1,2

1,3

1,4

5,9 6 6,1 6,2 6,3 6,4 6,5 6,6

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

ALG VIS

ALG with 40% CaCl2 VIS

ALG with 0,4g/l CaCl2 VIS

ALG UV

ALG with 40% CaCl2 UV

ALG with 0,4g/l CaCl2 UV

28

In the next experiment, the ALG dose was reduced to 79% (34g/m3) and the calcium additions were

40 and 80% by weight, based on 43g/m3 ALG dose. The results can be seen in figure 13.1. The

calcium addition does not have any effect until pH reaches about 6.15, where the sample with added

calcium suddenly improve the results significantly. According to Trussell and Hand, 2012, sweep

coagulation is one of the mechanisms that are possible at a pH range of 6 to 8 (due to metal

hydroxide formation in this range). As pH increases, the negative species increases and the

flocculation due to enmeshment increases. Once that happens CaCl2 might act as an adjunct in

sweep flocculation or aiding by bridge building (Dong, 2012).

Figure 13.1 Results from Experiment 13A to G (2015-04-28, 2015-04-29, 2015-04-30 and 2015-05-04).

The average UV-VIS result was calculated for all data points from pH 6.14 and 6.18, the results can be seen in

table 13.0 below. The samples with 80% CaCl2 appear to improve the average UV-VIS results the most, when

compared to samples with only reduced amount of ALG. These results are very interesting because they might

allow for water treatment at higher pH however, these experiments were limited and further studies need to

be conducted.

Table 13.0 Average UV-VIS results from Experiment 13. Results range from pH 6.14 to pH 6.18.

Experiment 13 pH Range Average pH Average VIS Average UV

79% ALG with 40% CaCl2 6.15-6.17 6.16 1.35 18.8

79% ALG with 80% CaCl2 6.14-6.17 6.16 1.16 17.3

79% ALG 6.16-6.18 6.17 1.43 19.8

CaCl2 Effect VIS UV

79% ALG with 40% CaCl2 5.7% 5.1%

79% ALG with 80% CaCl2 18.6% 12.7%

10

12

14

16

18

20

22

0,6

0,8

1

1,2

1,4

1,6

1,8

5,9 5,95 6 6,05 6,1 6,15 6,2 6,25 6,3

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

79% ALG VIS 79% ALG with 40% CaCl2 VIS 79% ALG with 80% CaCl2 VIS

79% ALG UV 79% ALG with 40% CaCl2 UV 79% ALG with 80% CaCl2 UV

29

5. Conclusions

When using a less than optimal PIX-311 dose, CaCl2 additions do not assist enough in coagulation and

flocculation to replace the effect of the reduced PIX-311 dose. From the results it was possible to see

that CaCl2 had a positive effect on flocculation when pH was above 5 at low dosage (40 to 80 mol%)

however, the UV-VIS results were inadequate and would not insure acceptable water quality . When

the CaCl2 dose was increased from 80 mol% to 0.4g/l (an equivalent of increasing the CaCl2 dose from

about 25µl to 820µl per liter raw water), a clear negative effect was observed due to coagulant-HA

hindrance, caused by hydrates formed by calcium.

The addition of 12.7µl CaCl2 per liter raw water (40 mol%) to an optimal amount of PIX-311 had an

3% positive VIS result and 1% positive UV result, based on those numbers. If that is correct, the water

treatment plant would need to add 19ml of 36% by weight CaCl2 per second (based on a water

production of 1500l/s) in order to improve the UV-VIS results by 1 and 3%. Which adds up to 1640 l

CaCl2 per 24 h. If cost is taken in consideration, the improved results would cost 2214 SEK per 24h

(based on a CaCl2 cost of 1000 SEK per 1000 kg and ρcalicum=1.35g/cm3). However, because of the

deviation in the results, the observed positive effects are within the margin of error, and hence, CaCl2

might not have any positive effect on the water quality.

When it comes to CaCl2 additions in Al(III) flocculation it appears that the results are, in some cases,

comparable with those of PIX-311. A high dose of CaCl2 (0.4g/l), seem to effect flocculation in the

same way. However, a low calcium dose (40% by weight), did not appear to be of any significant

impact on the results. If anything, it had a slightly negative effect.

When a non-optimal dose ALG was used with two different CaCl2 doses (40 and 80%), there did not

appear to be any impact except when pH was increased to about 6.15. At this point, the UV-VIS

results improved and the samples with CaCl2 gave better results than the sample without CaCl2

(figure 13.1). The most likely explanation is the increase of pH causing a shift in flocculation

mechanism. The result of this could be that the coagulation process could be conducted at higher pH

without compromising the results. At full scale, this would be very advantages due to the reduced

potential of concrete corrosion. That in mind, there could be a good reason to extend these studies.

30

6. Further work

In this thesis, coagulation and flocculation studies were conducted using FeCl3 and Al2(SO4)3 as

coagulants and CaCl2 as a co-coagulant. However, there are other coagulant such as, PACl that could

benefit from calcium additions, as seen in other experiments (Dong, 2012).

Even though calcium did not have much effect on NOM reduction, there are reasons to suspect that

CaCl2 could aid in enhancing floc strength and thereby reducing sludge (Peeters et al., 2011 and Yu et

al., 2014). Also, it might be interesting to see if calcium is effective at reducing specific

contaminations, such as bacteria or viruses.

Finally, because of the limited experiments done in this thesis, more studies could be conducted on

Al2(SO4)3. A more extensive study on this, might reveal if CaCl2 has any positive effects on aluminum

flocculation or if the result are comparable with FeCl3.

31

References

Alberty R. A., Silbey R. J., 2000. Physical Chemistry. 3rd edition. New York: John Wiley & Sons, inc. ISBN: 0-471-

38311-2

Amory, D. E., Rouxhet, P. G. and Dufour, J. P., 1988. Journal of the Institute of Brewing, 94(2), 79. Bache, D. H., Gregory, R. 2007 Flocs in water Treatment. IWA Publishing 2007, ISBN: 1843390639,

9781843390633

Bratby, J. 1980. Coagulation and flocculation, Uplands Press Ltd, Croydon, UK, pp 5

Camp, T. R. 1946. Sedimentation and the Design of Settling Tanks. Trans ASCE, III.

Cheremisinoff, N. P. 2001. Handbook of water and wastewater treatment technologies. Butterworth

Heinemann, ISBN: 978-0-7506-7498-0

Derjaguin, B. V., and Landau, L. D. 1941 ‘‘Theory of Stability of Strongly Charged Lyophobic Soles and Coalesance of Strongly Charged Particles in Solutions of Electrolytes,’’ Acta Physicochim. URSS, 14, 733–762. Dong M., Gao B., Xu W., Wang Y., Mao R. 2012 Effect of calcium on floc properties and membrane foulings in coagulation–ultrafiltration process by polyaluminum chloride (PACl) of different OH/Al3+ values, Desalination, Volume 294, 15 May 2012, Pages 30-35, ISSN 0011-9164 Gillberg L., Hansen B., Karlsson I. 2003. Konsten att rena vatten. Kemira Kemwater. Helsingborg, Sverige. ISBN: 91-631-4353-4 Griffith J.D., Williams R.G. 1972 Application of Jar Teat Analysis at Phoenix, Ariz., Jour. AWWA, 64, 12, Dec. , 825-830. Han, M., and Lawler, D. 1992 ‘‘The (Relative) Insignificance ofGin Flocculation,’’ J. AWWA, 84, 10, 79–91. Hunter, R. J. 2001 Foundations of Colloid Science, Vos. 1 and 2, Oxford University Press, Oxford, UK La Mer, V. K. 1964. La Mer VK. J Colloid Interface Science New York Academic Press, 1964:19:291

Letterman R.D., Quon J.E., Gemmell R.S. 1973. Influence of Rapid Mix Parameters on Floaculation, Jour. AWWA, Nov., 716-722. O'Melia C.R. 1969 A Review of the Coagulation Process, Public Wks., 100, May, 87 O’Melia, C. R. 1972 Coagulation and Flocculation, in W. J. Weber, Jr. (ed.), Physicochemical Processes for Water Quality Control, Wiley-Interscience, New York. O’Melia, C. R. 1978 Coagulation in Wastewater Treatment, in K. J. Ives (ed.), Scientific Basis of Flocculation, Noordhoff International, Leyden, Netherlands. Parker, D. S., Kaufmann, W. J., and Jenkins, D. 1972 Floc Breakup in Turbulent Flocculation Processes, J. Sanit. Eng. Div., 98, 79–99. Parks, G. A. 1967 Aqueous Surface Chemistry of Oxides and Complex Oxide Minerals; Isolectric Point and Zero Point of Charge, in Equilibrium Concepts in Natural Water Systems, Advances in Chemistry Series, No. 67, American Chemical Society, Washington, DC. Peeters B., Dewil R., Lechat D. & Smets I. Y. 2011. Quantification of the exchangeable calcium in activated sludge flocs and its implication to sludge settleability. Separation And Purification Technology, 83, pp. 1-8.

32

Ratnayaka, D. D., Brandt, M. J. and Johnson K. M. 2009. Chapter 7 - Storage, Clarification and Chemical Treatment, In Water Supply (Sixth Edition), edited by Don D. Ratnayaka, Malcolm J. Brandt, K. Michael Johnson, Butterworth-Heinemann, Boston, Pages 267-314, ISBN: 9780750668439 Standard Methods 2005 Standard Methods for the Examination of Water and Waste Water, 21st ed., American

Public Health Association (APHA), American Water Works Association (AWWA), and Water Environment

Federation (WEF), Washington, DC.

Stumm, W., and Morgan J.J. 1962 Chemical Aspects of Coagulation, Jour.AWWA, 5A_, 8, Aug., 971-991. Stumm, W., and Morgan, J. J. 1981 Aquatic Chemistry, 2nd ed., Wiley-Interscience, New York. Stumm, W., and Morgan, J. J. 1996 Aquatic Chemistry, 3rd ed., Wiley, New York.

Trussell, R. R. and Hand, D. W. 2012, MWH's Water Treatment Principles and Design (3rd Edition), John Wiley &

Sons, Hoboken, NJ, USA.

Verwey, E. J. W. and Overbeek, J. T. G. 1948 Theory of the Stability of Lyophobic Colloids, Elsevier, Amsterdam. Wang J., Zhou Y., Li A., Xu L. 2010, Adsorption of humic acid by bi-functional resin JN-10 and the effect of alkali-earth metal ions on the adsorption, Journal of Hazardous Materials, Volume 176, Issues 1–3, 15 April 2010, Pages 1018-1026, ISSN 0304-3894. Yu J., Guo M., Xu X., Guan B., 2014 The role of temperature and CaCl2 in activated sludge dewatering under hydrothermal treatment, Water Research, Volume 50, 1 March 2014, Pages 10-17, ISSN 0043-1354

33

Appendix

Experiment 1 - 20mol% CaCl2-addition

Setup: Optimum PIX dosage: 58.67g, m-3 (2015-01-30). Used PIX dosage: 61g, m-3. 20mol% CaCl2 based on

61g/m3 PIX dose. Addition of PIX with 20 seconds remaining of rapid mixing. However PIX was added

to beaker 6 when 7 seconds remained.

Table 1.1 Results from Experiment 1 (2015-01-30).

Beaker 1 2 3 4 5 6

104% PIX (µl) 43 43 - - - -

83% PIX (µl) - - 34.4 34.4 34.4 34.4

NaOH 0.36% (µl) 950 950 220 220 220 220

CaCl2 (µl) - - - - 6.86 6.86

pH 4.98 4.98 5.08 5.10 4.97 4.95

VIS 13.3 11.5 18.5 14.4 16.5 9.60

UV 1.22 1.02 1.66 1.24 1.64 0.705

Figure 1.1 Results from Experiment 1 (2015-01-30).

As seen in Table 1.1 and Figure 1.1, the best results were observed from beaker 6. This is almost

certainly the result of a shorter rapid mixing time. This becomes especially clear if these results are

compared with the results from beaker 5 with the same CaCl2 and PIX additions. This lead to further

experiments with PIX added at different times.

0,6

2,6

4,6

6,6

8,6

10,6

12,6

14,6

16,6

18,6

20,6

0,6

0,8

1

1,2

1,4

1,6

1,8

4,9 4,95 5 5,05 5,1 5,15

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

104% PIX VIS

83% PIX VIS

83% PIX with CaCl2 VIS

104% PIX UV

83% PIX UV

83% PIX with CaCl2 UV

34

Experiment 2 – Effects of PIX additions at various time

Setup: Optimum PIX dosage: 58.67g, m-3 (2015-02-02) and 58.5g, m-3 (2015-02-03). Used PIX dosage: 61g,

m-3. No addition of CaCl2.

a) Addition of PIX when 20, 10, 5s remaining of rapid mixing.

Figure 2.1 Results from Experiment 2A (2015-02-02).

It is difficult to draw any conclusions when comparing the results from the samples because of the

variation of pH. However, it is clear that the samples from the 10 second additions resulted in a

better outcome compared with the samples from the 20 second additions.

Table 2.1 Results from Experiment 2A (2015-02-02).

Beaker 1 2 3 4 5 6

104% PIX (µl) 43 43 43 43 43 43

NaOH 0.36% (µl) 950 950 950 950 950 950

Time remaining (s) 20 20 10 10 5 5

pH 4.81 4.83 4.82 4.85 4.98 4.98

VIS 1.66 1.51 1.29 1.17 0.886 1.02

UV 15.8 15.4 13.8 12.8 10.7 11.7

9,5

10,5

11,5

12,5

13,5

14,5

15,5

16,5

0,8

0,9

1

1,1

1,2

1,3

1,4

1,5

1,6

1,7

1,8

4,8 4,85 4,9 4,95 5

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

PIX addition at 20s VIS

PIX addition at 10s VIS

PIX addition at 5s VIS

PIX addition at 20s UV

PIX addition at 10s UV

PIX addition at 5s UV

35

b) Addition of PIX when 7, 5, 3s remaining of rapid mixing.

Figure 2.2 Results from Experiment 2B, 2015-02-03.

The results seen in figure 2.2 show little variation in UV-absorption and VIS-absorption when

comparing the 7 seconds addition and 3 seconds addition. The results from the 5 second additions

seem to be slightly poorer. This can be explained by the lower corresponding pH-values for the

samples. Based on these results, the PIX addition was added when 3 seconds remained of the rapid

mixing in following experiments. The results also agree with Griffith and Williams, 1972, that stated

that rapid mixing times above 5 seconds may not improve flocculation efficiencies.

Table 2.2 Results from Experiment 2B (2015-02-03).

Beaker 1 2 3 4 5 6

104% PIX (µl) 43 43 43 43 43 43

NaOH 0.36% (µl) 950 950 950 950 950 950

Time remaining (s) 7 7 5 5 3 3

pH 4.95 4.95 4.9 4.89 5.02 4.97

VIS 0.804 0.902 1.02 0.877 0.799 0.894

UV 9.82 10.7 11.6 10.3 9.85 10.6

9,5

10

10,5

11

11,5

12

0,75

0,8

0,85

0,9

0,95

1

1,05

4,85 4,9 4,95 5 5,05

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

PIX addition at 7s VIS

PIX addition at 5s VIS

PIX addition at 3s VIS

PIX addition at 7s UV

PIX addition at 5s UV

PIX addition at 3s UV

36

4.1.3. Experiment 3 – Using 20mol% CaCl2

Setup: Optimum PIX dosage: 58.5 g, m-3 (2015-02-03), 59 g, m-3 (2015-02-04) and 57 g, m-3 (2015-02-05).

Used PIX dosage: 61g, m-3. 20mol% CaCl2 based on 61g/m3 PIX dose. Addition of PIX when 3 seconds

remaining of rapid mixing.

Figure 3.1 Results from Experiment 3 (2015-02-03, 2015-02-04 and 2015-02-05).

Table 3.1 Results from Experiment 3A (2015-02-03).

Beaker 1 2 3 4 5 6

104%PIX (µl) 43 43 - - - -

83%PIX (µl) - - 34.4 34.4 34.4 34.4

NaOH 0.36% (µl) 950 950 220 220 220 220

CaCl2 (µl) - - - - 6.86 6.86

pH 4.86 4.93 5.04 4.97 4.99 4.97

VIS 0.77 0.85 0.722 0.691 0.709 0.819

UV 9.37 10.1 9.93 9.42 9.69 10.1

Table 3.2 Results from Experiment 3B (2015-02-04).

Beaker 1 2 3 4 5 6

103%PIX (µl) 43 - - - -

83%PIX (µl) - - 34.4 34.4 34.4 34.4

NaOH 0.36% (µl) 950 950 220 220 220 220

CaCl2 (µl) - - - - 6.86 6.86

pH 5.02 5.04 4.77 4.92 4.95 4.97

8,4

9,4

10,4

11,4

12,4

13,4

14,4

0,6

0,7

0,8

0,9

1

1,1

1,2

1,3

1,4

4,7 4,8 4,9 5 5,1 5,2 5,3

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

103 to 107% PIX VIS

83 to 86% PIX VIS

83 to 86% PIX with CaCl2 VIS

103 to 107% PIX UV

83 to 86% PIX UV

83 to 86% PIX with CaCl2 UV

37

VIS 0.657 0.684 0.814 0.886 0.727 0.709

UV 8.81 8.9 9.97 10.8 9.91 9.62

Table 3.3 Results from Experiment 3C (2015-02-05).

Beaker 1 2 3 4 5 6

107%PIX (µl) 43 - - - -

86%PIX (µl) - - 34.4 34.4 34.4 34.4

NaOH 0.36% (µl) 950 950 220 220 220 220

CaCl2 (µl) - - - - 6.86 6.86

pH 4.77 4.83 4.97 4.85 4.94 5

VIS 1.15 1.2 0.768 0.788 0.765 0.711

UV 12.6 12.9 10.3 10.8 9.84 10

Table 3.5 Results from Experiment 3D (2015-02-05).

Beaker 1 2 3 4 5 6

107% PIX (µl) 43 - - - -

86%PIX (µl) - - 34.4 34.4 34.4 34.4

NaOH 0.36% (µl) 950 950 220 220 220 220

CaCl2 (µl) - - - - 6.86 6.86

pH 4.77 5 5.05 4.76 4.9 4.91

VIS 1.32 0.667 0.699 0.78 0.773 0.747

UV 14.1 8.96 10 9.85 9.91 9.94

38

4.1.3. Experiment 4 – 40mol% CaCl2

Setup: Optimum PIX dosage: 56.3 g, m-3 (2015-02-06 and 2015-02-09) and 56.5 g, m-3 (2015-02-10 and

2015-02-11). Used PIX dosage: 61g, m-3. 40mol% CaCl2 based on 61g/m3 PIX dose. Addition of PIX

when 3 seconds remaining of rapid mixing.

Figure 4.1 Results from Experiment 4 (2015-02-06 and 2015-02-09).

9

10

11

12

13

14

15

16

17

0,6

0,7

0,8

0,9

1

1,1

1,2

1,3

1,4

1,5

1,6

4,7 4,8 4,9 5 5,1 5,2 5,3 5,4

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

108% PIX VIS

87% PIX VIS

87% PIX with CaCl2 VIS

108% PIX UV

87% PIX UV

87% PIX with CaCl2 UV

39

Figure 4.2 Results from Experiment 4 (2015-02-10 and 2015-02-11).

Table 4.1 Results from Experiment 4A (2015-02-06).

Beaker 1 2 3 4 5 6

108% PIX (µl) 43 43 - - - -

87% PIX (µl) - - 34.4 34.4 34.4 34.4

NaOH 0.36% (µl) 950 950 220 220 220 220

CaCl2 (µl) - - - - 13.72 13.72

pH 4.88 4.79 5.04 4.97 4.88 4.89

VIS 1.1 1.49 0.779 0.769 0.724 0.83

UV 12.6 16.3 10.9 10.3 9.77 10.7

Table 4.2 Results from Experiment 4B (2015-02-09).

Beaker 1 2 3 4 5 6

108% PIX (µl) 43 43 - - - -

87% PIX (µl) - - 34.4 34.4 34.4 34.4

NaOH 0.36% (µl) 960 960 220 220 230 230

CaCl2 - - - - 13.72 13.72

pH 5.35 5.03 4.97 5.18 4.88 4.95

VIS 0.611 0.724 0.753 0.962 0.755 0.775

UV 9.3 9.22 10.2 13.1 9.95 10.4

Table 4.3 Results from Experiment 4C (2015-02-10).

Beaker 1 2 3 4 5 6

108% PIX (µl) 43 43 - - - -

8,5

9,5

10,5

11,5

12,5

13,5

14,5

15,5

16,5

0,6

0,7

0,8

0,9

1

1,1

1,2

1,3

1,4

1,5

1,6

4,8 4,9 5 5,1 5,2 5,3 5,4

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

108% PIX VIS

86% PIX VIS

86% PIX with CaCl2 VIS

108% PIX UV

86% PIX UV

86% PIX with CaCl2 UV

40

86% PIX (µl) - - 34.4 34.4 34.4 34.4

NaOH 0.36% (µl) 960 960 220 220 230 230

CaCl2 (µl) - - - - 13.72 13.72

pH 4.84 4.84 4.97 4.86 5.03 4.97

VIS 1.44 1.46 0.831 0.837 0.886 0.841

UV 15.5 15.8 10.9 10.6 11.6 11

Table 4.4 Results from Experiment 4D (2015-02-10).

Beaker 1 2 3 4 5 6

108% PIX (µl) 43 43 - - - -

86% PIX (µl) - - 34.4 34.4 34.4 34.4

NaOH 0.36% (µl) 965 965 220 220 230 230

CaCl2 (µl) - - - - 13.72 13.72

pH 5.2 5.32 4.9 5.25 4.9 4.98

VIS 0.709 0.613 0.785 1.08 0.746 0.778

UV 9.55 9.21 10.3 14.5 9.98 10.5

Table 4.5 Results from Experiment 4E (2015-02-11).

Beaker 1 2 3 4 5 6

108% PIX (µl) 43 43 - - - -

86% PIX (µl) - - 34.4 34.4 34.4 34.4

NaOH 0.36% (µl) 965 965 220 220 230 230

CaCl2 (µl) - - - - 13.72 13.72

pH 5.05 4.98 4.94 4.92 5.01 5.01

VIS 0.726 0.921 0.76 0.746 0.738 0.777

UV 9.36 11 10.2 10 10.3 10.5

Experiment 5- 40 mol% CaCl2

Setup: Optimum PIX dosage: 56.5 g, m-3 (2015-02-12 and 2015-02-17) and 56 g, m-3 (2015-02-13). Used PIX

dosage: 56.5 g, m-3. 40mol% CaCl2 based on 61g/m3 PIX dose. Addition of PIX with 3 seconds

remaining of rapid mixing.

41

Figure 5.1 Results from Experiment 5 (2015-02-12, 2015-02-13 and 2015-02-17).

Table 5.1 Results from Experiment 5A (2015-02-12).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 0 0 0 0

80% PIX (µl) 0 0 31.8 31.8 31.8 31.8

NaOH 0.36% (µl) 700 700 0 0 10 10

CaCl2 (µl) 0 0 0 0 13.72 13.72

pH 5.14 5.05 5.13 4.83 5.05 4.98

VIS 0.745 0.799 1.16 0.865 0.922 0.86

UV 10 10.2 15.1 11.1 12.5 11.6

Table 5.2 Results from Experiment 5B (2015-02-13).

Beaker 1 2 3 4 5 6

101% PIX (µl) 39.8 39.8 0 0 0 0

81% PIX (µl) 0 0 31.8 31.8 31.8 31.8

NaOH 0.36% (µl) 700 700 0 0 10 10

CaCl2 (µl) 0 0 0 0 13.72 13.72

pH 5.07 5.05 4.94 4.86 5.12 5.12

VIS 0.627 0.715 0.89 0.834 1.07 1.04

UV 8.76 9.43 11.7 10.9 14.1 13.8

8

10

12

14

16

18

20

0,6

0,7

0,8

0,9

1

1,1

1,2

1,3

1,4

1,5

1,6

4,7 4,9 5,1 5,3 5,5

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

100 to 101% PIX VIS

80 to 81% PIX VIS

80 to 81% PIX with CaCl2 VIS

100 to 101% PIX UV

80 to 81% PIX UV

80 to 81% PIX with CaCl2 UV

42

Table 5.3 Results from Experiment 5C (2015-02-13).

Beaker 1 2 3 4 5 6

101% PIX (µl) 39.8 39.8 0 0 0 0

81% PIX (µl) 0 0 31.8 31.8 31.8 31.8

NaOH 0.36% (µl) 700 700 0 0 10 10

CaCl2 (µl) 0 0 0 0 13.72 13.72

pH 5.16 4.9 5.05 5.01 5.13 5.11

VIS 0.666 0.989 0.99 0.892 1.13 1.07

UV 9.29 11.4 13.2 11.8 14.8 14.1

Table 5.4 Results from Experiment 5D (2015-02-17).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 0 0 0 0

81% PIX (µl) 0 0 32.2 32.2 32.2 32.2

NaOH 0.36% (µl) 700 700 0 0 10 10

CaCl2 (µl) 0 0 0 0 13.72 13.72

pH 5.1 5.07 5.15 5.03 5.09 5.21

VIS 0.689 0.744 1.27 0.894 1.03 1.36

UV 9.4 9.76 16.4 12.3 13.7 17.6

Table 5.5 Results from Experiment 5E (2015-02-17).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 0 0 0 0

81% PIX (µl) 0 0 32.2 32.2 32.2 32.2

NaOH 0.36% (µl) 700 700 0 0 10 10

CaCl2 (µl) 0 0 0 0 13.72 13.72

pH 4.98 5 4.92 5.07 5.03 4.98

VIS 0.763 0.771 0.858 0.976 0.91 0.952

UV 9.85 9.78 11.5 13.2 12.5 12.7

4.1.3. Experiment 6- 80 mol% CaCl2

Setup: Optimum PIX dosage: 56.5 g, m-3 (2015-02-18, 2015-02-19 and 2015-02-23). Used PIX dosage: 56.5 g,

m-3. 80mol% CaCl2 based on 61g/m3 PIX dose. Addition of PIX with 3 seconds remaining of rapid

mixing.

43

Figure 6.1 Results from Experiment 6 2015-02-18, 2015-02-19 and 2015-02-23.

Figure 6.3 Results from experiment 5 and 6.

Table 6.1 Results from Experiment 6A (2015-02-18).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 0 0 0 0

81% PIX (µl) 0 0 32.2 32.2 32.2 32.2

8

10

12

14

16

18

20

0,6

0,7

0,8

0,9

1

1,1

1,2

1,3

1,4

1,5

1,6

4,7 4,9 5,1 5,3 5,5

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

100% PIX VIS

81% PIX VIS

81% PIX with CaCl2 VIS

100% PIX UV

81% PIX UV

81% PIX with CaCl2 UV

8

10

12

14

16

18

20

0,5

0,7

0,9

1,1

1,3

1,5

4,7 4,9 5,1 5,3 5,5

UV

VIS

pH

UV-VIS

80 to 81% PIX VIS

80 to 81% PIX with 40% CaCl2 VIS

80 to 81% PIX with 80% CaCl2 VIS

80% PIX with 0,4g/l CaCl2 VIS

80 to 81% PIX UV

80 to 81% PIX with 40% CaCl2 UV

80 to 81% PIX with 80% CaCl2 UV

80% PIX with 0,4g/l CaCl2 UV

44

NaOH 0.36% (µl) 715 715 0 0 12 12

CaCl2 (µl) 0 0 0 0 27.4 27.4

pH 5.22 5.57 4.94 4.95 5.06 5

VIS 0.698 1.17 0.842 0.929 1.07 0.968

UV 9.71 15.9 11.4 12.3 13.9 12.8

Table 6.2 Results from Experiment 6B (2015-02-18).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 0 0 0 0

81% PIX (µl) 0 0 32.2 32.2 32.2 32.2

NaOH 0.36% (µl) 680 680 0 0 12 12

CaCl2 (µl) 0 0 0 0 27.4 27.4

pH 5.37 5.25 5.18 4.99 5.09 5.05

VIS 0.735 0.705 1.39 0.887 1.07 0.965

UV 10.8 10.1 17.7 12.1 14.2 13.1

Table 6.3 Results from Experiment 6C (2015-02-19).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 0 0 0 0

81% PIX (µl) 0 0 32.2 32.2 32.2 32.2

NaOH 0.36% (µl) 560 560 0 0 12 12

CaCl2 (µl) 0 0 0 0 27.4 27.4

pH 5 4.92 4.81 4.85 5.05 5

VIS 1.03 1.03 0.871 0.863 0.981 0.959

UV 12.1 12.1 11.3 11.3 13.1 12.7

Table 6.4 Results from Experiment 6D (2015-02-19).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 0 0 0 0

81% PIX (µl) 0 0 32.2 32.2 32.2 32.2

NaOH 0.36% (µl) 560 560 8 8 12 12

CaCl2 (µl) 0 0 0 0 27.4 27.4

pH 5.1 5.25 5.06 5.05 4.98 5.06

VIS 0.685 0.718 0.978 0.955 0.838 0.928

UV 9.26 10.3 13.2 12.9 11.5 12.6

Table 6.5 Results from Experiment 6E (2015-02-23).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 0 0 0 0

45

81% PIX (µl) 0 0 32.2 32.2 32.2 32.2

NaOH 0.36% (µl) 560 560 8 8 12 12

CaCl2 (µl) 0 0 0 0 27.4 27.4

pH 5 5.08 5.02 5.17 5.08 5

VIS 0.743 0.71 0.885 1.13 0.908 0.848

UV 9.74 9.68 12.2 15.1 12.5 11.6

Table 6.6 Results from Experiment 6F (2015-02-23).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 0 0 0 0

81% PIX (µl) 0 0 32.2 32.2 32.2 32.2

NaOH 0.36% (µl) 560 560 8 8 12 12

CaCl2 (µl) 0 0 0 0 27.4 27.4

pH 5.18 5.15 5.25 4.97 5.11 5.08

VIS 0.815 0.759 1.44 0.972 1.09 1.04

UV 10.3 9.95 18 12.7 14.3 13.9

Table 6.7 Results from Experiment 6G (2015-02-23).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 0 0 0 0

81% PIX (µl) 0 0 32.2 32.2 32.2 32.2

NaOH 0.36% (µl) 560 560 8 8 12 12

CaCl2 (µl) 0 0 0 0 27.4 27.4

pH 5.12 5.22 4.92 5.26 5.27 5.17

VIS 0.753 0.688 0.904 1.51 1.47 1.09

UV 10.2 9.89 11.9 18.6 18.2 14.2

6.1.1 Experiment 7 - 100%pix + 20 resp. 40 mol% CaCl2 based on 56.5g/m3

Setup:

Optimum PIX dosage: 56.5 g, m-3 (2015-02-25, 2015-02-26, 2015-03-10, 2015-03-11 and 2015-03-

12).Used PIX dosage: 56.5g, m-3. 20 and 40mol% CaCl2 based on 56.5g/m3 PIX dose. Addition of PIX

with 3 seconds remaining of rapid mixing.

46

Figure 7.1 Results from Experiment 7A to F (2015-02-25 and 2015-02-26).

Figure 7.2 Results from Experiment 7G to N (2015-03-10, 2015-03-11 and 2015-03-12).

8,5

9

9,5

10

10,5

11

11,5

12

12,5

13

13,5

0,6

0,7

0,8

0,9

1

1,1

1,2

1,3

4,7 4,8 4,9 5 5,1 5,2 5,3

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

100% PIX VIS

100% PIX & 20% CaCl2 VIS

100% PIX & 40% CaCl2 VIS

100% PIX UV

100% PIX & 20% CaCl2 UV

100% PIX & 40% CaCl2 UV

8,5

9

9,5

10

10,5

11

11,5

12

12,5

13

13,5

0,6

0,7

0,8

0,9

1

1,1

1,2

4,7 4,8 4,9 5 5,1 5,2 5,3

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV -VIS

100% PIX VIS

100% PIX with 20% CaCl2 VIS

100% PIX with 40% CaCl2 VIS

100% PIX UV

100% PIX with 20% CaCl2 UV

100% PIX with 40% CaCl2 UV

47

Figure 7.3 Results from Experiment 7A to N (2015-03-10, 2015-03-11 and 2015-03-12).

Table 7.1 Results from experiment 7A (2015-02-25).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 560 560 560 560 560 560

CaCl2 (µl) 0 0 6.36 6.36 12.72 12.72

pH 5.11 5.03 4.99 5.09 5.19 4.96

VIS 0.725 0.79 0.762 0.715 0.823 0.869

UV 9.64 10.1 9.8 9.47 10.8 10.4

Table 7.2 Results from experiment 7B (2015-02-25).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 560 560 560 560 560 560

CaCl2 (µl) 0 0 6.36 6.36 12.72 12.72

pH 4.97 5.02 5.02 5.05 4.99 5.05

VIS 0.817 0.73 0.721 0.74 0.701 0.729

UV 9.87 9.34 9.28 9.7 9.26 9.72

Table 7.3 Results from experiment 7C (2015-02-25).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 560 560 560 560 560 560

CaCl2 (µl) 0 0 6.36 6.36 12.72 12.72

pH 5.2 5.24 4.98 4.9 5.07 5.09

VIS 0.773 0.745 0.823 0.948 0.757 0.726

UV 10.3 10.3 10.2 11.3 9.99 9.89

8,5

9

9,5

10

10,5

11

11,5

12

12,5

13

13,5

0,6

0,7

0,8

0,9

1

1,1

1,2

4,7 4,8 4,9 5 5,1 5,2 5,3

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV -VIS

100% PIX VIS

100% PIX with 20% CaCl2 VIS

100% PIX with 40% CaCl2 VIS

100% PIX UV

100% PIX with 20% CaCl2 UV

100% PIX with 40% CaCl2 UV

48

Table 7.4 Results from experiment 7D (2015-02-26).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 560 560 560 560 560 560

CaCl2 (µl) 0 0 6.36 6.36 12.72 12.72

pH 4.79 4.94 4.93 4.95 4.97 4.98

VIS 1.05 0.999 0.788 0.835 0.766 0.802

UV 11.9 10.9 9.97 10.5 9.86 10.1

Table 7.5 Results from experiment 7E (2015-02-26).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 560 560 560 560 560 560

CaCl2 (µl) 0 0 6.36 6.36 12.72 12.72

pH 4.79 5.12 5.03 5.13 5.2 5.14

VIS 1.23 0.796 0.684 0.712 0.66 0.674

UV 13.2 10.4 9.13 10 9.7 9.67

Table 7.6 Results from experiment 7F (2015-02-26).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 560 560 560 560 560 560

CaCl2 (µl) 0 0 6.36 6.36 12.72 12.72

pH 4.88 4.83 5.03 5.13 4.94 4.86

VIS 0.928 1.03 0.706 0.758 0.77 0.83

UV 10.7 11.5 9.33 10.5 10.1 10.5

Table 7.7 Results from experiment 7G (2015-03-10).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 570 570 570 570 570 570

CaCl2 (µl) 0 0 6.36 6.36 12.72 12.72

pH 4.81 4.86 4.85 5.09 5.12 4.94

VIS 0.941 0.841 0.793 0.658 0.668 0.731

UV 11.3 10.5 10.1 9.38 9.63 9.66

Table 7.8 Results from experiment 7H (2015-03-10).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 570 570 570 570 570 570

CaCl2 (µl) 0 0 6.36 6.36 12.72 12.72

49

pH 4.82 4.99 4.99 4.98 5.03 4.75

VIS 0.895 0.77 0.798 0.81 0.719 1.19

UV 10.7 10.1 10.2 10.2 9.51 12.8

Table 7.9 Results from experiment 7I (2015-03-11).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 640 640 640 640 640 640

CaCl2 (µl) 0 0 6.36 6.36 12.72 12.72

pH 4.95 5.04 5.18 4.83 4.97 5

VIS 0.8 0.675 0.71 0.873 0.666 0.654

UV 9.97 9.27 10.1 10.5 9.07 9.08

Table 7.10 Results from experiment 7J (2015-03-11).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 640 640 640 640 640 640

CaCl2 (µl) 0 0 6.36 6.36 12.72 12.72

pH 5.03 4.96 4.93 5.11 4.96 5.05

VIS 0.689 0.749 0.687 0.728 0.757 0.739

UV 9.36 9.75 9.11 9.74 9.55 9.71

Table 7.11 Results from experiment 7K (2015-03-11).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 640 640 640 640 640 640

CaCl2 (µl) 0 0 6.36 6.36 12.72 12.72

pH 4.93 4.9 4.98 5.13 4.92 5

VIS 0.762 0.878 0.783 0.714 0.755 0.683

UV 9.73 10.6 9.94 10.1 9.86 9.48

Table 7.12 Results from experiment 7L (2015-03-12).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 640 640 640 640 640 640

CaCl2 (µl) 0 0 6.36 6.36 12.72 12.72

pH 4.98 5.16 4.92 4.94 5.05 5.02

VIS 0.643 0.733 0.825 0.803 0.768 0.694

UV 8.93 10.3 10.2 10.1 10.2 9.47

50

Table 7.13 Results from experiment 7M (2015-03-12).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 640 640 640 640 640 640

CaCl2 (µl) 0 0 6.36 6.36 12.72 12.72

pH 4.97 5.18 5.15 5.07 5.02 4.99

VIS 0.738 0.7 0.745 0.709 0.773 0.818

UV 9.62 10 10.3 9.25 9.76 10.1

Table 7.14 Results from experiment 7N (2015-03-12).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 640 640 640 640 640 640

CaCl2 (µl) 0 0 6.36 6.36 12.72 12.72

pH 4.95 4.93 5 4.93 4.98 5.04

VIS 0.759 0.744 0.81 0.843 0.793 0.788

UV 9.73 9.63 10.4 10.3 9.97 10.1

51

4.2.2 Experiment 8 - 100% PIX + 40 resp. 80 mol% CaCl2

Setup:

Optimum PIX dosage: 56.5 g, m-3 (2015-03-17, 2015-03-18, 2015-03-19 and 2015-03-20).Used PIX

dosage: 56.5g, m-3. 40 and 80mol% CaCl2 based on 56.5g/m3 PIX dose. Addition of PIX with 3 seconds

remaining of rapid mixing.

Figure 8.1 Results from Experiment 8A to G (2015-03-17, 2015-03-18, 2015-03-19 and 2015-03-20).

Table 8.1 Results from experiment 8A (2015-03-17).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 680 680 680 680 680 680

CaCl2 (µl) 0 0 12.72 12.72 25.4 25.4

pH 4.93 4.9 4.9 4.9 5.01 5.02

VIS 0.647 0.753 0.737 0.713 0.673 0.694

UV 8.99 10 9.77 9.52 9.33 9.61

Table 8.2 Results from experiment 8B (2015-03-18).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 700 700 700 700 680 680

CaCl2 (µl) 0 0 12.72 12.72 25.4 25.4

pH 4.92 5.12 5.03 4.98 4.92 4.98

VIS 0.707 0.671 0.636 0.675 0.662 0.71

UV 9.47 9.72 9.03 9.42 9.24 9.71

8

9

10

11

12

13

14

0,5

0,55

0,6

0,65

0,7

0,75

0,8

0,85

0,9

0,95

1

4,8 4,9 5 5,1 5,2

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

100% PIX VIS

100% PIX with 40% CaCl2 VIS

100% PIX with 80% CaCl2 VIS

100% PIX UV

100% PIX with 40% CaCl2 UV

100% PIX with 80% CaCl2 UV

52

Table 8.3 Results from experiment 8C (2015-03-18).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 700 700 700 700 680 680

CaCl2 (µl) 0 0 12.72 12.72 25.4 25.4

pH 4.98 5.01 4.98 5.16 4.92 5.15

VIS 0.667 0.632 0.668 0.613 0.657 0.64

UV 9.06 8.9 9.08 9.45 9.06 9.67

Table 8.4 Results from experiment 8D (2015-03-19).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 700 700 700 700 680 680

CaCl2 (µl) 0 0 12.72 12.72 25.4 25.4

pH 4.89 5.07 5.07 4.95 4.92 5.04

VIS 0.639 0.64 0.596 0.694 0.645 0.592

UV 8.92 9.31 8.93 9.44 9 8.83

Table 8.5 Results from experiment 8E (2015-03-20).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 700 700 700 700 680 680

CaCl2 (µl) 0 0 12.72 12.72 25.4 25.4

pH 4.92 4.93 4.95 4.97 4.98 4.87

VIS 0.58 0.613 0.533 0.567 0.548 0.662

UV 8.63 8.98 8.33 8.7 8.58 9.17

Table 8.6 Results from experiment 8F (2015-03-20).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 700 700 700 700 680 680

CaCl2 (µl) 0 0 12.72 12.72 25.4 25.4

pH 4.96 4.91 5.01 5.03 5 5.07

VIS 0.669 0.671 0.604 0.593 0.61 0.62

UV 9.15 9.11 8.75 8.7 8.82 9.07

Table 8.7 Results from experiment 8G (2015-03-20).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 700 700 700 700 680 680

CaCl2 (µl) 0 0 12.72 12.72 25.4 25.4

pH 4.91 4.92 4.93 4.98 4.94 4.87

VIS 0.637 0.651 0.633 0.638 0.683 0.721

53

UV 8.93 9.07 8.92 9.11 9.34 9.59

Table 8.3 Average UV-VIS results from Experiment 8.

Experiment 8 pH Range Average pH Average VIS Average UV

100% PIX 4.89-5.12 4.96 0.656 9.16

100% PIX with 80% CaCl2 4.87-5,15 4.98 0.651 9.22

CaCl2 Effect -1% 1%

Experiment 9 - 100% PIX + 100% PIX with 40 % CaCl2

Setup:

Optimum PIX dosage: 56.5 g, m-3 (2015-03-26 and 2015-03-27).Used PIX dosage: 56.5g, m-3. 40mol%

CaCl2 based on 56.5g/m3 PIX dose. Addition of PIX with 3 seconds remaining of rapid mixing.

Figure 9.1 Results from Experiment 9A to F (2015-03-26 and 2015-03-27).

Table 9.1 Results from experiment 9A (2015-03-26).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 800 800 800 800 800 800

CaCl2 (µl) - - - 12.72 12.72 12.72

pH 4.93 5.02 5.02 5.01 5.09 5.04

VIS 0.637 0.566 0.571 0.596 0.659 0.639

UV 8.97 8.65 8.63 8.78 9.64 9.27

8,5

8,7

8,9

9,1

9,3

9,5

9,7

9,9

10,1

10,3

0,5

0,55

0,6

0,65

0,7

0,75

4,9 5 5,1 5,2 5,3

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

100% PIX VIS

100% PIX with 40% CaCl2 VIS

100% PIX UV

100% PIX with 40% CaCl2 UV

54

Table 9.2 Results from experiment 9B (2015-03-26).

Beaker 1 2 3 4 5 6

100% PIX (µl) x x 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) x x 920 920 920 920

CaCl2 (µl) x x - 12.72 12.72 12.72

pH x x 5.19 5.22 5.2 5.23

VIS x x 0.584 0.59 0.583 0.598

UV x x 9.03 9.22 9.05 9.35

Table 9.3 Results from experiment 9C (2015-03-26).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 920 920 920 920 920 920

CaCl2 (µl) - - - 12.72 12.72 12.72

pH 5.2 5.18 5.18 5.23 5.2 5.24

VIS 0.589 0.578 0.64 0.629 0.643 0.626

UV 9.22 9.09 9.47 9.46 9.58 9.51

Table 9.4 Results from experiment 9D (2015-03-27).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 940 940 940 940 940 940

CaCl2 (µl) - - - 12.72 12.72 12.72

pH 5.15 5.26 5.13 5.25 5.19 5.26

VIS 0.581 0.646 0.605 0.677 0.606 0.646

UV 8.81 9.92 9.03 10.1 9.25 9.91

Table 9.5 Results from experiment 9E (2015-03-27).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 940 940 940 940 940 940

CaCl2 (µl) - - - 12.72 12.72 12.72

pH 5.23 5.18 5.19 5.16 5.22 5.2

VIS 0.644 0.634 0.663 0.649 0.66 0.702

UV 9.89 9.65 9.86 9.56 9.89 10.2

Table 9.6 Results from experiment 9F (2015-03-27).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 940 940 940 940 940 940

CaCl2 (µl) - - - 12.72 12.72 12.72

pH 5.13 5.07 5.13 5.18 5.14 5.15

55

VIS 0.618 0.655 0.669 0.604 0.59 0.665

UV 9.32 9.47 9.71 9.3 9.08 9.86

Experiment 10 - 100% PIX + 100% PIX with 0.4 g/l CaCl2

Setup:

Optimum PIX dosage: 56.5 g, m-3 (2015-04-09).Used PIX dosage: 56.5g, m-3. Addition of PIX with 3

seconds remaining of rapid mixing.

Figure 10.1 Results from Experiment 10A (2015-04-09).

Table 10.1 Results from experiment 10A (2015-04-09).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 - - -

80% PIX - - - 31.8 31.8 31.8

NaOH 0.36% (µl) 850 850 850 120 120 120

CaCl2 (µl) 820 820 820 820 820 820

pH 5.05 5.05 5.05 4.95 4.95 4.95

VIS 0.766 0.762 0.785 1.02 1.03 1.06

UV 10.1 10.1 10.3 13.2 13.1 13.5

8

9

10

11

12

13

14

0,6

0,65

0,7

0,75

0,8

0,85

0,9

0,95

1

1,05

1,1

4,94 4,96 4,98 5 5,02 5,04 5,06

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

100% PIX with 0,4g/l CaCl2 VIS

80% PIX with 0,4g/l CaCl2 VIS

100% PIX with 0,4g/l CaCl2 UV

80% PIX with 0,4g/l CaCl2 UV

56

Experiment 11 - 100%Pix + 100%PIX with 40% CaCl2 aiming at 5.5ph

Setup:

Optimum PIX dosage: 56.5 g, m-3 (2015-04-10).Used PIX dosage: 56.5g, m-3. 40mol% CaCl2 based on

56.5g/m3 PIX dose. Addition of PIX with 3 seconds remaining of rapid mixing.

Figure 11.1 Results from Experiment 11A and B (2015-04-10).

Table 11.1 Results from experiment 11A (2015-04-10).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 1200 1200 1200 1200 1200 1200

CaCl2 (µl) - - - 12.72 12.72 12.72

pH 5.47 5.56 5.5 5.55 5.58 5.49

VIS 0.923 1.36 1.02 1.09 1.32 1.1

UV 13.1 18.1 14.3 15.1 17.5 15

Table 11.2 Results from experiment 11B (2015-04-10).

Beaker 1 2 3 4 5 6

100% PIX (µl) 39.8 39.8 39.8 39.8 39.8 39.8

NaOH 0.36% (µl) 1200 1200 1200 1200 1200 1200

CaCl2 (µl) - - - 12.72 12.72 12.72

pH 5.48 5.54 5.56 5.55 5.55 5.49

VIS 0.957 1.19 1.28 1.15 1.19 0.928

UV 13.6 16.2 17.2 15.8 16.4 13.4

12

13

14

15

16

17

18

19

0,8

0,9

1

1,1

1,2

1,3

1,4

5,46 5,48 5,5 5,52 5,54 5,56 5,58 5,6

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

100% PIX VIS

100% PIX with 40% CaCl2 VIS

100% PIX UV

100% PIX with 40% CaCl2 UV

57

Experiment 12- 43g/m3 ALG 40% by weight CaCl2 and 0.4g/l CaCl2

Setup:

ALG dose: 43g/m3. CaCl2 dose: 40% by weight based on 43g/m3 ALG dose (17.2mg/l) and 0.4g/l.

Addition of ALG when 3 seconds remain

Figure 12.1 Results from Experiment 12A to L (2015-04-14, 2015-04-15, 2015-04-16, 2015-04-17, 2015-04-20,

2015-04-22 and 2015-04-23).

Table 12.1 Results from experiment 12A (2015-04-14).

Beaker 1 2 3 4 5 6

ALG (µl) 215 215 215 215 215 215

NaOH 0.36% (µl) 1300 1300 1300 1300 1400 1400

CaCl2 (µl) - - 35.4 35.4 820 820

pH 5.93 5.96 5.97 5.95 5.97 6.00

VIS 0.687 0.728 0.777 0.689 1.02 1.06

UV 11.9 12.1 12.5 11.7 14.3 14.6

Table 12.2 Results from experiment 12B (2015-04-15). Flocculation was disturbed in beaker 1 and 2 for 1

minute during slow mixing due to complications with the flocculator. This seemed to effect the results in

limited ways.

Beaker 1 2 3 4 5 6

ALG 215 215 215 215 215 215

NaOH 0.36% (µl) 1300 1300 1300 1300 1400 1400

CaCl2 (µl) - - 35.4 35.4 820 820

pH 5.99 6 5.97 5.96 6.01 6.05

10

11

12

13

14

15

16

17

18

19

20

0,6

0,7

0,8

0,9

1

1,1

1,2

1,3

1,4

5,9 6 6,1 6,2 6,3 6,4 6,5 6,6

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

ALG VIS

ALG with 40% CaCl2 VIS

ALG with 0,4g/l CaCl2 VIS

ALG UV

ALG with 40% CaCl2 UV

ALG with 0,4g/l CaCl2 UV

58

VIS 0.734 0.698 0.686 0.724 1.02 1.06

UV 12.1 11.8 11.5 11.8 14.1 14.3

Table 12.3 Results from experiment 12C (2015-04-15).

Beaker 1 2 3 4 5 6

ALG 215 215 215 215 215 215

NaOH 0.36% (µl) 1300 1300 1300 1300 1400 1400

CaCl2 (µl) - - 35.4 35.4 820 820

pH 5.97 5.96 5.98 5.96 5.99 6.00

VIS 0.74 0.725 0.848 0.806 1.14 1.08

UV 12.1 11.8 12.9 12.4 14.9 14.5

Table 12.4 Results from experiment 12D (2015-04-16).

Beaker 1 2 3 4 5 6

ALG 215 215 215 215 215 215

NaOH 0.36% (µl) 1300 1300 1300 1300 1400 1400

CaCl2 (µl) - - 35.4 35.4 820 820

pH 6.03 6.03 6.04 6.03 6.06 6.05

VIS 0.742 0.766 0.836 0.827 1.08 1.1

UV 12.2 12.4 12.9 12.8 14.7 14.7

Table 12.5 Results from experiment 12E (2015-04-16).

Beaker 1 2 3 4 5 6

ALG 215 215 215 215 215 215

NaOH 0.36% (µl) 1300 1300 1300 1300 1400 1400

CaCl2 (µl) - - 35.4 35.4 820 820

pH 6.01 6.01 6.03 6.08 6.05 6.05

VIS 0.753 0.778 0.837 0.973 1.16 1.13

UV 12.1 12.3 12.8 14.2 15.1 14.9

Table 12.6 Results from experiment 12F (2015-04-17).

Beaker 1 2 3 4 5 6

ALG 215 215 215 215 215 215

NaOH 0.36% (µl) 1700 1700 1700 1700 1800 1800

CaCl2 (µl) - - 35.4 35.4 820 820

pH 6.25 6.23 6.2 6.23 6.24 6.26

VIS 0.897 0.789 0.787 0.82 1.06 1.07

UV 14.2 13.1 12.7 13.3 15.2 15.4

59

Table 12.7 Results from experiment 12G (2015-04-17).

Beaker 1 2 3 4 5 6

ALG 215 215 215 215 215 215

NaOH 0.36% (µl) 1700 1700 1700 1700 1800 1800

CaCl2 (µl) - - 35.4 35.4 820 820

pH 6.26 6.34 6.23 6.25 6.24 6.31

VIS 0.779 1 0.826 0.802 1.02 1.15

UV 13.1 15.7 13.2 13.2 14.9 16.3

Table 12.8 Results from experiment 12H (2015-04-20).

Beaker 1 2 3 4 5 6

ALG 215 215 215 215 215 215

NaOH 0.36% (µl) 1900 1900 1900 1900 2000 2000

CaCl2 (µl) - - 35.4 35.4 820 820

pH 6.35 6.43 6.37 6.36 6.41 6.37

VIS 0.734 1.01 0.852 0.913 1.26 0.938

UV 13.1 16.1 14.1 14.7 17.4 14.9

Table 12.9 Results from experiment 12I (2015-04-22).

Beaker 1 2 3 4 5 6

ALG 215 215 215 215 215 215

NaOH 0.36% (µl) 1900 1900 1900 1900 2000 2000

CaCl2 (µl) - - 35.4 35.4 820 820

pH 6.34 6.34 6.35 6.34 6.33 6.33

VIS 0.788 0.774 0.799 0.824 0.887 1.01

UV 13.5 13.5 13.6 13.9 14.6 15.3

Table 12.10 Results from experiment 12J (2015-04-22).

Beaker 1 2 3 4 5 6

ALG 215 215 215 215 215 215

NaOH 0.36% (µl) 1900 1900 1900 1900 2000 2000

CaCl2 (µl) - - 35.4 35.4 820 820

pH 6.34 6.35 6.34 6.34 6.32 6.32

VIS 0.784 0.817 0.844 0.815 0.988 1.03

UV 13.3 13.8 13.8 13.7 15 15.1

Table 12.11 Results from experiment 12K (2015-04-23).

Beaker 1 2 3 4 5 6

ALG 215 215 215 215 215 215

NaOH 0.36% (µl) 2150 2150 2150 2150 2250 2250

60

CaCl2 (µl) - - 35.4 35.4 820 820

pH 6.45 6.47 6.43 6.45 6.49 6.46

VIS 0.782 0.819 0.794 0.766 0.891 0.773

UV 13.8 14.5 13.8 13.8 15.1 14.1

Table 12.12 Results from experiment 12L (2015-04-23).

Beaker 1 2 3 4 5 6

ALG 215 215 215 215 215 215

NaOH 0.36% (µl) 2150 2150 2150 2150 2250 2250

CaCl2 (µl) - - 35.4 35.4 820 820

pH 6.47 6.5 6.47 6.47 6.45 6.46

VIS 0.761 0.867 0.727 0.784 0.792 0.806

UV 13.8 15 13.5 13.8 14.2 14.2

Experiment 13- 79% ALG 40% resp. 80% by weight CaCl2

Setup: ALG dose: 34g/m3. CaCl2 dose: 40 and 80% by weight CaCl2 based on 43g/m3 ALG dose (17.2mg/l

resp. 34.4g/m3). Addition of ALG when 3 seconds remain

Figure 13.1 Results from Experiment 13A to G (2015-04-28, 2015-04-29, 2015-04-30 and 2015-05-04).

10

12

14

16

18

20

22

0,6

0,8

1

1,2

1,4

1,6

1,8

5,9 6 6,1 6,2 6,3 6,4 6,5 6,6

UV

-ab

s (λ

=25

4 n

m/m

)

VIS

-ab

s (λ

=43

6 n

m/m

)

pH

UV-VIS

79% ALG VIS

79% ALG with 40% CaCl2 VIS

79% ALG with 80% CaCl2 VIS

79% ALG UV

79% ALG with 40% CaCl2 UV

79% ALG with 80% CaCl2 UV

61

Table 13.1 Results from experiment 13A (2015-04-28).

Beaker 1 2 3 4 5 6

ALG 170 170 170 170 170 170

NaOH 0.36% (µl) 1000 1000 1000 1000 1000 1000

CaCl2 (µl) - - 35.4 35.4 70.8 70.8

pH 6.01 5.98 6 6 6.01 6.01

VIS 0.782 0.856 0.895 0.86 0.858 0.885

UV 13 13.4 14 13.6 13.6 13.8

Table 13.2 Results from experiment 13B (2015-04-28).

Beaker 1 2 3 4 5 6

ALG 170 170 170 170 170 170

NaOH 0.36% (µl) 1000 1000 1000 1000 1000 1000

CaCl2 (µl) - - 35.4 35.4 70.8 70.8

pH 5.98 5.98 6 5.99 5.98 6.03

VIS 0.726 0.8 0.979 0.928 0.859 0.986

UV 12.3 13 14.5 14.1 13.5 14.8

Table 13.3 Results from experiment 13C (2015-04-29).

Beaker 1 2 3 4 5 6

ALG 170 170 170 170 170 170

NaOH 0.36% (µl) 1000 1000 1000 1000 1000 1000

CaCl2 (µl) - - 35.4 35.4 70.8 70.8

pH 6.17 6.17 6.15 6.15 6.15 6.14

VIS 1.61 1.56 1.48 1.44 1.25 1.33

UV 21.2 20.8 19.7 19.3 17.9 18.2

Table 13.4 Results from experiment 13D (2015-04-30).

Beaker 1 2 3 4 5 6

ALG 170 170 170 170 170 170

NaOH 0.36% (µl) 900 900 900 900 900 900

CaCl2 (µl) - - 35.4 35.4 70.8 70.8

pH 6.09 6.09 6.12 6.08 6.07 6.09

VIS 1.22 1.29 1.46 1.25 1.06 1.28

UV 17.9 18.5 20.1 17.9 16.3 17.9

Table 13.5 Results from experiment 13E (2015-04-30).

Beaker 1 2 3 4 5 6

ALG 170 170 170 170 170 170

NaOH 0.36% (µl) 900 900 900 900 900 900

CaCl2 (µl) - - 35.4 35.4 70.8 70.8

pH 6.09 6.1 6.08 6.08 6.11 6.07

62

VIS 1.27 1.37 1.22 1.16 1.24 1.22

UV 18.2 19.1 17.6 17.2 18.2 17.6

Table 13.6 Results from experiment 13F (2015-05-04).

Beaker 1 2 3 4 5 6

ALG 170 170 170 170 170 170

NaOH 0.36% (µl) 1100 1100 1100 1100 1100 1100

CaCl2 (µl) - - 35.4 35.4 70.8 70.8

pH 6.17 6.16 6.15 6.16 6.16 6.17

VIS 1.33 1.38 1.3 1.34 1.07 1.25

UV 19.1 19.5 18.3 19 16.7 18.4

Table 13.7 Results from experiment 13G (2015-05-04).

Beaker 1 2 3 4 5 6

ALG 170 170 170 170 170 170

NaOH 0.36% (µl) 1100 1100 1100 1100 1100 1100

CaCl2 (µl) - - 35.4 35.4 70.8 70.8

pH 6.18 6.18 6.17 6.17 6.16 6.17

VIS 1.32 1.36 1.26 1.25 0.958 1.11

UV 18.9 19.3 18.3 18.2 15.5 17