ULTRAFILTRATION FOR THE TREATMENT

I N THE CORRUGATED CONTAINER INDUSTRY

Richard Parsons A1 1 i ed Conta iner C o r p o r a t i on

Auburn , Maine

and

B r i a n Donovan and

Mark Hayward Abcor, Inc.

850 Main S t r e e t W i lm ing ton , MA 01887

ULTRAFILTRATION FOR THE TREATMENT OF I N K AND STARCH WASTEWATER I N THE CORRUGATED CONTAINER INDUSTRY

T h i s paper p resents t h e case h i s t o r y o f a 5,000 g a l l o n per day u l t r a - f i l t r a t i o n system o p e r a t i n g a t A l l i e d Conta iner Corpo ra t i on ’ s Auburn, Maine p l a n t . p ress c lean ings as w e l l as waste s t a r c h adhesive f rom t h e c o r r u g a t i n g pro- cess.

The u l t r a f i l t e r t r e a t s d i l u t e waste i n k wash water generated f r o m

Since RECRA (Resource Conservat ion and Recovery Ac t ) has been i n e f f e c t t h e hand l i ng and t rea tmen t o f t h i s waste has become a major concern o f co r ruga ted c o n t a i n e r manufacturers and o t h e r paper conver te rs . Because o f t h e presence o f heavy meta ls , such as l e a d and chrome, many l a n d f i l l o p e r a t i o n s r e f u s e t o accept t h i s m a t e r i a l . ment process i s then requ i red .

A r e c y c l a b l e c losed l o o p t r e a t -

A t A l l i e d Conta iner , u l t r a f i l t r a t i o n meets these needs by p r o v i d i n g a c l e a n water e f f l u e n t which, w h i l e meet ing l o c a l sewer d i scha rge l i m i t s , can be recyc led ; and a concent ra ted i n k / s t a r c h stream which i s bu t a f r a c t i o n o f t h e o r i g i n a l volume. Th is concen t ra te i s e a s i l y worked away i n p l a n t ope ra t i on .

manufac turer o f co r ruga ted con ta ine rs , based i n New England. T h e i r Auburn, Maine p l a n t generates approx imate ly 5,000 g a l l o n s o f wastewater per day. Genera l l y , 2/3 o f t h i s amount i s waste f l e x o g r a p h i c i n k wash water. The remainder o f t h e waste water i s a d i l u t e s t a r c h adhesive s o l u t i o n , used i n t h e c o r r u g a t i n g process.

F lexograph ic i n k i s a water based, r a p i d d r y i n g m a t e r i a l , employed i n a number o f c o n v e r t i n g processes. i n d u s t r y , f l e x o g r a p h i c i n k s a r e i n use i n most paper bag and envelope p l a n t s . a r e complexed w i t h heavy meta ls , lead , chromium, o r barium, and a r e suspended i n an aqueous s o l u t i o n . Ethanol , i n l e v e l s o f 15% - 25%, completes t h e f o r - mu1 a t i on.

A l l i e d Conta iner Corpora t ion , a s u b s i d i a r y o f Union Camp, i s a ma jor

I n a d d i t i o n t o t h e cor rugated box

U s u a l l y run a t a c o n c e n t r a t i o n o f 15% i n t h e presses, t h e pigments

The i n k s a r e run on s i n g l e o r m u l t i - c o l o r e d presses. When c o l o r s o r p roduc t l i n e s a r e changed, o r when t h e systems a r e shut down; t h e presses a r e c leaned and t h e remain ing i n k removed. Waste i n k wash water i s genera ted d u r i n g t h i s c l e a n i n g procedure, A l though most i n k manufacturers now p r o v i d e low l e a d fo rmu la t i ons , t h e waste water u s u a l l y con ta ins l e v e l s o f l e a d and o t h e r me ta l s h i g h e r than those s e t by l o c a l sewer d i scha rge l i m i t s . I n many cases, c o l o r a lone can be a reason f o r mun ic ipa l waste t r e a t m e n t a u t h o r i t i e s t o r e f u s e t h i s m a t e r i a l .

The starch solution i s a biodegradable adhesive w h i c h binds f l a t paper stock t o a corrugated sheet. The adhesive i s applied a t temperatures of approximately 2 5 O C in the corrugator. generated from mixing t a n k washing and corrugator cleaning.. A l t h o u g h some corrugated container manufacturers employ a b i o l o g i c a l treatment system t o handle starch waste, most prefer t o include this stream w i t h the i n k waste, a non-biodegradable material, and dispose of b o t h waste streams together.

The dilute starch waste water i s

During the winter of 1980 - 1981, Allied Container Corporation faced a dilernma now common i n the converting industry. The local sewer com- mission, c i t i n g the new R E C R A Act, was unable t o accept the large quan- t i t i e s of waste generated a t the p l a n t . The nearest sanitary landfi l ls which c o u l d handle the waste were located i n New Jersey and Alabama. Landfill fees were $1 per g a l l o n p l u s mileage. I n a d d i t i o n , the s ta te of Maine classified the p l a n t as a generator or hazardous waste._ This c i t a - tion required a permit a long w i t h a $7,000 annual fee.

Before deciding on u l t ra f i l t ra t ion , Allied Container investigated a number o f alternative solutions t o the problem. A t f i r s t , the di lute waste water was recycled directly, as starch adhesive make-up water. The wastewater, between 1% and 3% i n t o t a l solids caused added problems when used i n t h i s manner. Corrugator speed slowed causing delays i n meeting production schedules. Poor b i n d i n g between the f l a t stock and the corru- g a t e d sheet resulted i n an o f f grade product and increased paper waste. Overall , the recycyling decreased efficiency as we1 1 as p l a n t capaci ty .

A drum dryer evaporation process was a1 so discounted. Boiler capaci ty was already pushed t o i t s limits by corrugator requirements. Energy costs were high and continued t o r ise a t unpredictable rates. In addition t o the capital cost o f the dryer, the installation required a vent from the dryer through the roof of the building, expensive from b o t h a materials and l a b o r s t a n d p o i n t .

A chemical treatment system carried h i g h operating costs in terms of flocculating polymer, lime, and carbon requirements. of the operation posed question as t o the cost of maintenance and down time.

Also, the complexity

Ultraf i l t ra t ion is a process in which a semi-permeable membrane separates and concentrates the suspended s o l i d s , colloids and h i g h molecu- l a r weight materials t h a t are in solution. As shown in Figure 1, the feed s o l u t i o n flows under turbulent conditions through a membrane tube. The permeate (c lear , f i l t e red water) passes thorugh the membrane and i s collected in an a n n u l a r space between the membrane and i t s housing. The permeate i s then a v a i l a b l e for recycle as starch make-up water, or for discharge t o a sewer.

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F i g u r e 1

Tubu la r U1 t r a f i 1 t r a t i on Membrane

Fiberglass-reinforced

. .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...... ):*...:Permeate 0. ....... : . . . ... . . . . . . . . . . . . . . . . . . . . . . a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . e.

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,

Process D e s c r i p t i o n

F i g u r e 2 shows a genera l i zed f l o w schematic o f an Abcor u l t r a f i l t r a - t i o n system. No p h y s i c a l or chemical p re t rea tment i s necessary f o r Abcor 's one- inch d iameter u l t r a f i l t r a t i o n membrane. A basket s t r a i n e r ( r a t e d a t 5 /64") removes l a r g e suspended and f i b r o u s m a t e r i a l i n o rde r t o p r o t e c t t h e c i r c u l a t i o n pump i m p e l l e r .

The usual method f o r waste t rea tment , as shown i n F i g u r e 2 , i s t h e mod i f i ed ba tch opera t ion . t h rough t h e membrane tubes and back t o t h e process tank. I n t h e i n i t i a l phase o f t h e opera t i on , as permeate i s removed by t h e u l t r a f i l t e r , f r e s h feed o f equal volume i s added t o t h e process tank. I n t h i s manner, t h e c o n c e n t r a t i o n o f t h e process t a n k i s kept a t a minimum, a l l o w i n g t h e u l t r a - f i 1 t r a t i o n membranes t o opera te a t maximum e f f i c i e n c y . volume o f m a t e r i a l has been processed, t h e f r e s h feed t o t h e process tank i s stopped and s t r a i g h t ba tch c o n c e n t r a t i o n begins. Th is a l l ows many days o f f r e s h waste t o be added t o t h e process tank be fore feed a d d i t i o n i s d iscont inued. Once t h e change has been made from m o d i f i e d batch t o ba tch o p e r a t i o n t h e u l t r a f i 1 t e r w i l l con t i nue t o concen t ra te t h e process f l u i d u n t i l f l u x d e c l i n e s t o a p o i n t where c l e a n i n g i s necessary,

Wastewater i s c i r c u l a t e d from t h e process tank

A f t e r a predetermined

A1 l i e d Conta iner Corpo ra t i on operates t h e Abcor model UF-158 u l t r a - f i l t r a t i o n system. A t t h e Auburn, Maine p l a n t ; waste i n k from t h e two f l e x o presses i s c o l l e c t e d i n sumps. From t h e sumps, t h e waste i s g r a v i t y f e d t o a 1,000 g a l l o n underground h o l d i n g tank, Level c o n t r o l s on t h e 2,500 g a l l o n u l t r a f i l t r a t i o n process tank a c t u a t e a pump i n t h e h o l d i n g t a n k which p rov ides a f r e s h feed, as needed t o t h e u l t r a f i l t r a t i o n system. Four c o r r u g a t o r p i t s g r a v i t y feed s t a r c h waste d i r e c t l y t o t h e process tank. The i n k / s t a r c h concen t ra te i s r e t a i n e d i n t h e process tank, w h i l e permeate i s d e l i v e r e d t o t h e s t a r c h mark-up area f o r re-use or d ischarge th rough t h e s torm d r a i n .

M a t e r i a l Balance

An o v e r a l l m a t e r i a l ba lance f o r t h e process i s shown i n F igu re 3. On t h e b a s i s o f 5,000 g a l l o n s o f feed a t 1% t o t a l s o l i d s an u l t r a f i l t r a t i o n system w i l l produce 4,800 ga l l o n s o f a c lean permeate stream and 200 g a l l o n s o f a 25% i n k / s t a r c h concent ra te . Th is concen t ra te stream represents a 96% volume r e d u c t i o n when compared w i t h t h e i n i t i a l waste feed,

Chemical a n a l y s i s found t h a t t h e permeate con ta ins < 0.1 mg/l Pb and << 0.1 mg/l Cr, w e l l below t h e s t a t e o f Maine l i m i t a t i o n s o f t o t a l s o l i d s 5.0 mg/l f o r b o t h Pb and C r . Table 1 shows t y p i c a l average permeate q u a l i t y f rom samples taken over t h e course o f a p rocess ing day, Comparison between raw wastewater and permeate q u a l i t y shows s i g n i f i c a n t removal o f a number o f components, b o t h o rgan ic and ino rgan ic . As p r e v i o u s l y mentioned, t h e m a j o r i t y of t h e permeate i s reused i n b o t h t h e p r imary and secondary s t a r c h adhesives. Under these c o n d i t i o n s t h e c o r r u g a t o r operates a t a maximum e f f i c i e n c y and speed. When t h e remainder o f permeate i s combined w i t h o t h e r p l a n t waste, t h e t o t a l e f f l u e n t becomes q u i t e d i l u t e and i s w e l l i n compl iance w i t h Maine r e g u l a t i o n s .

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Unl ike ordinary f i l t r a t i o n , the waste stream flows parallel t o the membrane surface, no t perpendicular. on the membrane. Moreover, the structure of the membrane i t s e l f wi l l no t become plugged because the retained materials cannot penetrate the membrane. Turbulence a t the membrane surface caused by the circulating waste stream carries retained materials from the membrane.

As a resul t , no f i l t e r cake b u i l d s u p

Membrane permeation ( f l u x , gallons per day per f t 2 o f membrane a r e a ) i s a function of f low, pressure, temperature and concentration.

Increased f low rates through the membrane tubes generally result i n increased permeation rates. Because of energy considerations, however, the o p t i m u m flow rate i s between 30 and 3 5 gpm per pass of membranes.

Because pressures above 1.5 a tm produce on ly sl ight increases i n per- meation rates, the operating pressure i s set by the desired f low conditions w h i c h are usually 3.4 atm (50 psig) inlet and 1.4 atm (20 p s i g ) outlet.

Permeation rates increase w i t h increasing temperature. Operating tem- perature i s limited by membrane material and configuration. This limit ranges from 5°C t o 8 O O C . The normal recommended operating temperature i s 30°C t o 50°C.

.Permeation rates decline w i t h increasing concentration of t o t a l solids i n the process f l u i d . , resul t of a b u i l d - u p of ink s o l i d s on the membrane surface. cleaning i s required t o remove these build-ups from the surface of the membrane and t o restore the i n i t i a l process flux of the system.

Flux decline i n low concentration i n k waste i s a A weekly

Cleaning consists of washing the u l t ra f i l t ra t ion system w i t h a detergent solution for one t o two hours. flushed through the tubes , mechanically cleaning the membranes. membrane cleaning has been completed, the detergent solution i s displaced back t o the feed t a n k . generated .

Rubber spongeballs are then After

T h u s , no a d d i t i o n a l solid o r l i q u i d wastes are

A ten f o o t membrane tube contains 2 .2 square feet of membrane area. Normally, there are eight tubes connected in series per pass and as many passes as needed are placed in parallel t o obtain the proper amoun t o f membrane area.

Since the constraints imposed by solids concentration and membrane f l u x are similar for most waste ink streams, membrane area i s primarily a function of the size of the waste stream.

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Figure 2

Ultrafiltration System Typical Flow Schematic

Permeate Return Line

4

ABCOR SUPPLIED 1 1 I I

CUSTOMER SUPPLIED f

Permeate Didlarge 95-98% of Orinind Volume

c

Figure 3

,Typical Material Balance U l t r a f i l t r a t i o n o f Waste Ink And

Starch Adhesive Wash Water

i

Concentrate 200 gpd

- _ _ -

Permeate UF System Feed Washwater 4,800 gpd 5,000 gpd 'L 1% Ink and Starch

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Waste Component

Arsenic Barium Cadmium Chromium Copper Iron Lead idanganes e Mercury Nickel Selenium S i 1 ver T i n Zinc Ammonia as N BOD Boron Phenol i cs Phosphorous Dissolved Solids Suspended Solids Oi 1 PH

TABLE 1

COMPARISON BETWEEN WASHWATER FEED A N D UF PERMEATE Q U A L I T Y

Allied Container, Auburn, Maine

U F* Feed Pe rmea t e

Concentration Concentration ( m g / l ) “1 )

0010 54.0 0110 J 447 24.3 8.34 1.56 -27 001

02 <.01 <. 1 <7

2.27 190

3,340 9.9 .15

82.7 7,038 10,163

923 5.6

<.001 . 77 <.005

001 a 0 9

3.99 . 07 -097

- 0 1 <.03

<.002 <o. 1 <1 .Q

0 34 158

1,570 7.5 .04

25.1 1,125 9.3 45

6.2

% Removal

90 98.6 95 98

99.6 53.2 95.5 54 0 85 80 90 86 85 17 53 24 73 70 84

99.9 95 --

* Average permeate q u a l i t y during the course o f normal concentration.

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c

The smal l volumes o f i n k / s t a r c h concen t ra te a re worked away i n t h e secondary s t a r c h make-up on an i n f r e q u e n t bas is . A l though c o r r u g a t o r e f f i - c i e n c y and speed a re reduced a t t h i s t ime, t h e s i t u a t i o n i s t o l e r a b l e due t o t h e optimum o p e r a t i o n on UF-permeate a t a l l o t h e r t imes and t h e i n f r e q u e n t need t o d ispose o f concent ra te . On r a r e occasions when s p e c i a l t y s ta rches a r e i n use a t t h e same t i m e as when concen t ra te must be e l i m i n a t e d , t h e waste i s l a n d f i l l e d .

As a d i r e c t r e s u l t o f t h e i n s t a l l a t i o n of t h e u c i t i n g improved e f f l u e n t q u a l i t y and t h e c losed l o o p t h e s t a t e o f Maine no l onger c l a s s i f i e s A l l i e d Conta hazardous waste.

System D e s c r i p t i o n - Economics

t r a f i 1 t r a t i on system, n a t u r e o f t h e process, ne r as a genera tor o f

The Abcor UF-158 system o p e r a t i n g a t A l l i e d Conta iner con ta ins n ine ' p a r a l l e l passes o f e i g h t membrane tubes i n s e r i e s f o r a t o t a l o f 158 m2 o f a c t i v e membrane area. I t s nominal c a p a c i t y i s 5,000 g a l l o n s o f waste per day. The system i s comp le te l y skid-mounted and i n c l u d e s a 1 5 hp c i r - c u l a t i o n pump, 150 g a l l o n tank f o r membrane c lean ing , s a f e t y dev ices a l l o w i n g f o r 24 hours/day unattended opera t i on , e l e c t r i c a l c o n t r o l box and panel , and a l l i n t e r n a l p i p i n g va lves and w i r i n g . I n s t a l l a t i o n o f t h e u n i t was complete one day a f t e r d e l i v e r y , r e q u i r i n g o n l y feed and r e t u r n connect ions t o t h e process tank and e l e c t r i ' c a l power t i e - i n .

Table 1 shows an o p e r a t i n g c o s t es t ima te f o r t h e UF-158 u l t r a f i l t r a -

However, i n t h e 11/2 y e a r s t h a t t h e system

t i o n system. energy c o s t assoc ia ted w i t h system opera t ion . Membrane replacement i s c a l c u l a t e d on a t h r e e yea r bas is . has been i n ope ra t i on , no membrane d e t e r i o r a t i o n has been observed. i s es t imated a t two hours per day, m o s t l y f o r c l e a n i n g t ime. t i o n cos ts f o r t h e system a re approx ima te l y 1.5 cen ts per g a l l o n o f waste processed. a t $O.lO/gallon and evapora t i on ( 1 - e f f e c t , $9/1,000 l b s o f steam) by drum d ry ing .

Conclus ion

found t o be t h e most c o s t e f f e c t i v e method o f t r e a t i n g waste f l e x o g r a p h i c i n k wash water and d i l u t e s t a r c h adhesive waste.

E l e c t r i c a l power t o opera te t h e c i r c u l a t i o n pump i s t h e o n l y

Labor To ta l opera-

Tab le 2 shows a comparat ive investment a n a l y s i s versus h a u l i n g

A t A l l i e d Conta iner Corpo ra t i on i n Auburn, Maine, u l t r a f i l t r a t i o n was

A f t e r u l t r a f i l t r a t i o n , the c lean e f f l u e n t i s re-used as s t a r c h adhe- R e l a t i v e l y smal l amounts of s i v e make-up water or d ischarged t o a sewer.

i n k / s t a r c h concen t ra te may be worked away i n p l a n t opera t ion . S ince t h e i n s t a l l a t i o n o f an Abcor u l t r a f i l t r a t i o n system a t t h e p l a n t , t h e s t a t e of Maine no l o n g e r c l a s s i f i e s A l l i e d Conta iner as a genera tor of hazardous waste.

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Primarily due to l o w energy and labor requirements as well as long menbrane life, operating costs for the ultrafilter are only 1.5 cents per gallon o f waste processed. substantial c o s t savings over other methods of waste treatment.

Ultrafiltration provides A l l i e d Container with

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TABLE 2

OPERATING COST ANALYSIS FOR THE PROCESSING OF FLEXOGRAPHIC INK/ -

STARCH AD H E s I v E w AS H W AT ER

BASIS: 5,000 Gal/Day UF-158 t o c o n c e n t r a t e s o l i d s from 1% t o 25% TS 98% vol ume r e d u c t i on 250 days /yea r of o p e r a t i o n

CAPITAL COST

UF-158 System I n s t a l l a t i o n

To ta l

$58,000.00 $ 5,000.00 $63,000.00

OPERATING COST

power $ 2,900.00 (O.OS/absorbed k w - h r )

La bo r $ 7,500.00 (2 hours /day 8 $15/hr )

Membrane Replacement $ 3,200.00 (2 y e a r l i f e )

C1 e a n i n g Chemical s $ 2,700.00 Maintenance $ 500.00

(1% o f non-membrane c a p i t a l ) UF Concen t r a t e Haul i ng $ 2,500.00

(2% o f volume)

To ta l $19,300.00

UF SAVINGS: 25 X c o n c e n t r a t i o n ( 96% vol ume r e d u c t i on)

when compared t o 1 - e f f e c t v s . h a u l i n g drum d r y e r e v a p o r a t i o n

8 $9/1,000 l b s steam

$125,000 $ 91,900 (energy)

@ $O.lO/gal 1 on

$ 2,500 ( h a u l i n g c o n c e n t r a t e ) $ 8,000 (main tenance e s t i m a t e )

To ta l ~m

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. a . . ’

TABLE 3

INVESTMENT ANALYSIS

FLEXOGRAPHIC INK/STARCH WASTEWATER

UF-158 U1 t r a f i 1 t a t i o n System 5,000 g a l l o n s / d a y 98% v o l ume reduc t i on

- - I n s t a l l e d UF-158 System P r i c e C a p i t a l Recovery (5 y e a r s t r a i g h t

1 i ne on non-membrane c a p i t a l equipment) =

$ 63,000

$ 10,6 56/yea r

Savings :

UF Opera t i ng Costs UF Net Income Income Less C a p i t a l

Recovery Less 50% Taxes Cash Flow ( A f t e r Tax

Income P lus C a p i t a l Recovery)

A f t e r Tax R O I Payback P e r i o d

when UF i s compared t o haul i n g a t $O.lO/gal ?on

$ 125,000

(19,300) 105,700

95,044 47,522

$ s

s 58,178 92.3% 1.08 y e a r s

when UF i s compared t o drum d r y e r e v a p o r a t i o n

9 102,300

(19,300) $ 83,900

9 72,344 $ 36,172

9 46,828 74.3% 1.35 y e a r s

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Abcor can solve them and save you money, too.

When disposing waste printing inks, Abcor ultrafiltration systems will:

Remove up to 90% of the water, producing a concentrated ink that can be reused. Produce a clear water effluent that meets current pollution standards and that can be either discharged or recycled for in-plant use.

chemicals, with minimal operator atten- tion, and with only a pump to drive the system.

Treat the waste stream without added

~~ ~

The heart of Abcor's simple and efficient system:

CLEAR WATER

POROUS REINFORCE FIBERGLASS TUBE UP TO 30% INK

CONCENTRATE

CLEAR WATER

To solve ink disposal problems, call or write:

Abcor, inc. 850 Main Street, Wilmington, MA 01887 (617) 657-4250