Application Note

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Background

The manufacture of corrugated box-board and paper bags is a major in-dustry in the United States and else-where. There are about 1,500 corru-gated box plants and a similar num-ber of bag plants in the United States.Because of its relatively low cost andhigh strength characteristics, corru-gated board has become the primestructural material for the manufactureof boxes and shipping containers.Linerboard materials and paper areused to manufacture corrugated boxesand paper bags. Corrugated paper-board is a sandwich structure formedby gluing a fluted corrugating mediumply to two linerboard facings. Thedisposal of wastewater generated in abox or bag plant has become a prob-lem due to the high levels of organicsprimarily resulting from glue starchand heavy metals. These contaminants

result in a discharge stream not meetingthe regulatory requirements.

Objective

To meet the requirements of both ecol-ogy and economy, the filtration of ef-fluent streams allows a box or a bagplant to meet discharge requirementsand/or provide a clean source of reus-able water. The treatment of the efflu-ent is in most cases required for dis-charge and/or reuse.

Solution

Technological advances in membranefiltration systems have created an op-portunity for box and bag plants to treatwastewater effluent streams in order tomeet stricter environmental constraints.The “Vibratory Shear Enhanced Pro-cessing” or VSEP , developed by NewLogic International makes it possible to

filter effluent streams without the foul-ing problems exhibited by conventionalmembrane systems. The VSEP mem-brane system will significantly reduceBOD, COD, TDS, TSS and color bod-ies from effluent streams dischargedfrom box and bag plants as well as pulpand paper mills, thus minimizing treat-ment cost.

The VSEP treatment system usesnanofiltration membrane modules totreat the box and bag plant effluent inorder to generate a permeate stream thatmeets the water discharge or reuse cri-teria for the required concentration oforganics and heavy metals. The clearpermeate can then be discharged or re-cycled to the process. In addition,VSEP preconcentrates solids (starch,ink and TDS) prior to the final evapo-ration or drying step. Reverse osmosisfiltration can also be used if dissolvedsolids or color is an issue. In summary,the VSEP treatment system can be usedto treat box plant effluent, supplementthe dryer at the facility, and thus in-

Effluent Treatment for Box and Bag PlantsA cost-effective and environmentally-sound solution

Figure 1Treatment of Box Plant Effluent Using VSEP

PLC

V✧ SEP Unit

CleaningSolution

Tank

FM P

P FM

P

open during normal

operationonly open

during cleaning

cycle

CleaningChemical

100 gal.

PermeateTank

AgitatedFeed

StorageTank

Wastewater from Box Plant5 to 10 GPM0.5% to 1.5% TS12,000 mg/L COD930 µS conductivity9.2 pH

Cleaning Solution

PumpConcentrated Solution 0.5 to 1 GPM5% to 15%+ TS470 psig

V1

V2

Feed Pump(500 psig)

Permeate Transfer Pump

Permeate to Recycleor Discharge4.5 to 9.5 GPM<5 mg/L TSS120 mg/L COD250 S cond.15 psig

To DrainLegend:

Valve Normally Open

Valve Normally Closed

Flow Indicator/Meter

Pessure Indicator/Monitor

Programmable Logic Controller

FM

PLC

NC

FreshWater

P

Inclined Filter

40 Mesh Screen

AgitatedConcentrate

Storage Tank

Dryer Solids To Disposal60%+ TS

500 psig

Dryer FeedPump

Application Note

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crease the plant energy efficiency (re-duce dryer load).

In the box and bag plant industry, as wellas the pulp and paper industry, VSEPmembrane systems can now be utilizedwhere traditional cross-flow membranetechnologies faced substantial mem-brane fouling problems in the past. TheVSEP is an attractive alternative to con-ventional filtration methods due to itsvibrational, shear-enhanced design.

Process Conditions

A process schematic for treatment of abox plant effluent using a VSEP sys-tem is presented in Figure 1. A paperbag plant effluent treatment would besimilar. When the residual ink and

starch is washed from the printer pressand the glue preparation equipment, theresult is a wastewater effluent, at 0.5 to1.5% by weight total solids (TS). Thiswastewater effluent is typically sent toa chemical treatment step followed by afilter press, dryer or an evaporator in or-der to concentrate the solids to 60 to65% by weight. The concentrated sol-ids are sent off-site to be disposed at asolid waste disposal facility. As you can

see in the diagram, the addition of VSEPahead of the dryer to preconcentrate thewastewater effluent reduces the load onthe dryer significantly, thus improvingthe process efficiency. The permeate canbe reused in the process or discharged.

Figure 1 also includes a material bal-ance and illustrates the performance asenhanced by VSEP. Effluent from thefeed storage tank is fed to the VSEP unitat an average rate of 5 to 10 gpm. OneVSEP unit, using a nanofiltration mem-brane module, processes the feed wa-ter.

The VSEP produces a concentratedwaste stream at a flow rate of 0.5 to 1.5gpm which is then sent to the dryer. Theconcentrated stream contains approxi-

mately 5-15% by weight of total solids(TS). The VSEP treatment system alsogenerates a permeate stream of about 4.5to 9.5 gpm which is recycled to the pro-cess or disposed to the sewer. The con-centration of solids is less than 5 mg/Lof TSS, well below the design criteriafor process recycle or discharge require-ments.

Figure 2 presents an overall flow chart

for a corrugated box plant includingthe VSEP wastewater treatment sys-tem. Corrugated paperboard sheets areproduced in a continuous manufactur-ing process. The paperboard from aroll of corrugating medium is shapedinto flute form, adhesive is applied toone side of the flute tips, and alinerboard facing is brought into con-tact with the adhesive and bonded tothe medium to produce a single-facedweb. The single-faced web proceedsto the double facer operation where ad-hesive is applied to the opposite sideof the flute tips and a second linerboardfacing is glued to the medium. Thissimplest form of the sandwich struc-ture is called single-wall corrugated fi-berboard. Double-wall and triple-wallcorrugated fiberboard is produced in asimilar fashion. Finally, the corrugatedboard web is scored and slit to the re-quired box size. The finished box isthen formed from the sheets in a dis-crete process operation where the cor-rugated sheets are printed using a print-ing press, slotted to form the top andbottom flap closures, and scored toprovide the required box dimensions.

The materials required for this processinclude the corrugating adhesive, pro-cess steam to provide heat to set thecorrugator adhesive, some possiblecoatings applied to the surface of thelinerboard facings, along with chemi-cals impregnated into the linerboardand/or medium, the manufacturer’s(glue) joint adhesive, and the printingink. The wastewater is generated fromdaily washing of the adhesive rollers,the ink press rollers and the corre-sponding storage tanks.

Using a nanofiltration module in theVSEP system is a commercially viableoption for treatment of box and bagplant effluent streams. Nearly 90 to95% of the wastewater is recovered astreated water suitable for reuse or dis-charge, while less than 5 to 10% is fedto the dryer as concentrate, thereby re-

Printed Corrugated

Boxboard

WastewaterStorage Tank

ConcentrateStorage Tank

Evaporator or Dryer

Solids to Disposal

Treated Waterto Recycle or Discharge

VGSEP Unit

VGSEP Wastewater Tratment System

Box Plant

Water

Ink

Adhesive

Linerboard

Figure 2Corrugated Box Plant Including VSEP Wastewater Treatment System

Washwaterfrom Ink Press &

Storage Tank

Washwaterfrom Adhesive Rollers &

Storage Tank

Application Note

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ducing the load to the dryer by a greatmargin.

Membrane selection is based on mate-rial compatibility, flux rates (capacity)and concentration requirements. In thisexample, the BOD reduction is over90% while the rejects are concentratedfrom 0.5% to 5-15% by weight. Thepermeate quality from the VSEP can becontrolled through laboratory selectionof membrane materials available to fitthe application parameters.

Successful pilot tests have been con-ducted at New Logic for box and bagplant effluent treatment. A commercialproject is also under construction fortreatment of a box plant effluent in Cali-fornia. Depending on process tempera-tures, membrane selection and the re-quirement for concentration or BOD/COD removal for effluent streams, thepermeate flux rate in the VSEP canrange from 40 to over 70 gallons per dayper square foot (GFD). The concentra-tion level out of the VSEP unit is con-trolled by an automatic timed controlvalve. This valve is set such that theconcentration of the solids is held at thedesired level. A multi-stage feed pumpsupplies the VSEP unit at a pressuresuitable for the membrane used. A vari-able frequency electronic drive is usedto set feed pressure through P.I.D. (Pro-portional-Integral-Derivative) controlloop. This kind of drive acts to controlthe rotational speed of the pump, thuscontrolling the flow rate.

Economic Value

New Logic’s VSEP system provides analternative approach for box plant ef-fluent treatment applications. In a singleoperation step, VSEP will reduce BOD,COD, TSS, TDS and color to provide ahigh quality stream for discharge or re-use in the process. In many applications,the addition of VSEP will eliminateconventional treatment process require-ments and technologies without chemi-

cal treatment demands. The justifica-tion for the use of VSEP treatment sys-tem in your process is determinedthrough analysis of the system cost andbenefits including:

· Reduction of BOD, COD, TSS,TDS and color for the effluentstream.

· Reduction of effluent dischargevolume and associated treatmentcost.

· Provision of high quality water forreintroduction into the process.

· Offset fresh water demands andpretreatment cost.

· Retain heat in recycled processwater as a possible method to re-duce energy requirements.

· Elimination of biological growth,and odor in effluent.

· Simplify effluent treatment with acompact, low energy system.

Summary

New Logic International has suppliedVSEP separation technology success-fully into many industrial processes.The box and bag plants as well as thepulp and paper industries effort to meetenvironmental regulations will be en-hanced with the utilization of membranefiltration combined with “VibratoryShear Enhanced Processing”. The de-velopment towards applications for boxplants, along with the availability of newmembrane materials and VSEP technol-ogy make it possible to treat the moredifficult streams with very successful,economic results.

References

Smook, G. A., Handbook for Pulp &Paper Technologists, Second Edition,Angus Wilde Publications, VancouverB.C., Canada, pp. 228-263.

Dexter, R. J., “Industry’s Efforts at Ef-fluent Closure Must Focus on Competi-tive Innovation,” Pulp and Paper, Feb-ruary, 1996, pp. 2-4.

Kroschwitz, J. I., and Howe-Grant, M.,Kirk-Othmer Encyclopedia of Chemi-cal Technology, Fourth Edition, JohnWiley and Sons, 1996, Vol. 17, pp. 995-1017.

For more information on VSEPtechnology and its potential ap-plication to your process, pleasecontact:

New Logic International1295 67th StreetEmeryville, CA 94608

(888) 289-VSEP(8737) toll free(510) 655-7305 tel(510) 655-7307 faxe-mail: info@vsep.com

www.vsep.com