Multiyear Experience with Oily and Organic ... - ACS Publications

14 Multiyear Experience with Oily and Organic Chemical Waste Treatment Using Reverse Osmosis

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D. D E A N SPATZ Osmonics, Inc., 15404 Industrial Road, Hopkins, MN 55343

I appreciate this opportunity to speak at the same time on the last day of this symposium just as my close friend and mentor, Dr. Sourirajan spoke on the f i r s t day of this symposium. In concluding his talk, Dr. Sourirajan said, "The inherent potential of reverse osmosis processes and reverse osmosis membrane to contribute s i g n i f i c a n t l y to the health and welfare of all being and also to the progress of many f i e l d s of science, engineering, biology and medicine is far more than what one can comprehend at any time." Whether we c a l l the process we have talked about during this week reverse osmosis or hyperfiltration or u l t r a f i l t r a t i o n is of little importance. The important thing is that the membrane invented by Loeb and Sourirajan s l i g h t l y over 20 years ago is a marketable product and has a fantastic future. Too often we allow semantics to act as a barrier to our mutual understanding of this technology.

After listening to these other fine papers, I guess I should feel lucky to be able to attend this symposium and even luckier to present a paper. My paper has no fancy equations. Yes, I studied Mass Transport by Byrd, Stewart and Lightfoot, but it has been a few years since I could understand the equations which have been projected on the screen in the last three days. I do not consider myself a scientist perhaps a technologist and most definitely an entrepreneur of reasonable success. Dr. Sourirajan has had much to do with my success and to the success of our technology. I feel that a short history of one of those successes would be a fitting tribute to this man who has lived "reverse osmosis" for the last 24 years of his life. In 1964, while studying at Dartmouth College and considering what would be the best method of removing salt from brackish water, I had the great opportunity to meet with Dr. Loeb and later on with Dr. Sourirajan. This was in 1964, and at that time my colleagues and I decided that reverse osmosis had to be the

0097-6156/81/0154-0221$05.00/0 © 1981 American Chemical Society

In Synthetic Membranes: Volume II; Turbak, A.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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most e c o n o m i c a l way t o remove t h e s a l t s from b r a c k i s h w a t e r . C e r t a i n l y t h e commitment t o t h i s t e c h n o l o g y t h a t Dr. S o u r i r a j a n had was i n s t r u m e n t a l i n making me d e c i d e t o w o r k i n t h i s f i e l d . W i t h t h e h e l p o f Dr. S o u r i r a j a n and Dr. Myron T r i b u s , we o b t a i n e d a c o n t r a c t from t h e O f f i c e o f S a l i n e Water w h i c h c a r r i e d t h r o u g h


1968.

In 1 9 6 9 , I founded Osmonics, Inc. t o c a r r y the technology o f r e v e r s e o s m o s i s and u l t r a f i l t r a t i o n t o t h e m a r k e t p l a c e . We o r i g i n a l l y p u r c h a s e d membrane from Eastman Kodak Company and made o u r own s p i r a l e l e m e n t s . We c o n t i n u e d p u r c h a s i n g membrane u n t i l Kodak d e c i d e d not t o remain i n t h e membrane b u s i n e s s and we d e c i d e d t o b e g i n t h e m a n u f a c t u r e o f membrane. By 1 9 7 3 , we were i n f u l l p r o d u c t i o n m a n u f a c t u r i n g c e l l u l o s e a c e t a t e membrane using the L o e b - S o u r i r a j a n approach. One y e a r l a t e r , we w e r e m a n u f a c t u r i n g p o l y s u l f o n e membrane f o r u l t r a f i l t r a t i o n . Last y e a r , 1 9 7 9 , Osmonics m a n u f a c t u r e d o v e r one m i l l i o n s q u a r e f e e t o f RO/UF membrane. Osmonics became a p u b l i c c o r p o r a t i o n i n 1 9 7 1 , and s i n c e becoming p u b l i c we have grown a t an a v e r a g e r a t e i n e x c e s s o f 33% per year. T h i s i s e q u i v a l e n t t o i n c r e a s i n g i n s i z e twenty times o v e r a t e n y e a r p e r i o d . Osmonics has been p r o f i t a b l e i n e v e r y y e a r s i n c e 1 9 7 3 , t h e y e a r we f i r s t s t a r t e d t o p r o d u c e membrane. S i n c e 1 9 7 3 , o u r s a l e s and p r o f i t s have i n c r e a s e d i n each s u c c e s s i v e y e a r . We now o c c u p y 4 6 , 0 0 0 s q u a r e f e e t o f m a n u f a c t u r i n g s p a c e and we a r e i n t h e p r o c e s s o f b u i l d i n g a new 8 5 , 0 0 0 s q u a r e foot manufacturing f a c i l i t y t o c o n s o l i d a t e our business. ALL OF THIS SUCCESS I OFFER TO THIS MEETING AS A TRIBUTE TO THE PIONEER OF OUR TECHNOLOGY, MY ESTEEMED MENTOR-—DR. S. SOURIRAJAN. Di s c u s s i on Now t h a t t h e most i m p o r t a n t p a r t o f my t a l k i s f i n i s h e d , I w o u l d l i k e t o t e l l you about two c a s e h i s t o r i e s where RO/UF was used t o s a t i s f y a w a t e r p o l l u t i o n c o n t r o l p r o b l e m . But b e f o r e we g e t i n t o t h e c a s e h i s t o r y , l e t us r e v i e w some o f t h e b a s i c c r i t e r i a we use i n an RO/UF s y s t e m . F i g u r e 1 w i l l g i v e you an i d e a o f RO/UF e q u i p m e n t . T h i s i s a p h o t o g r a p h we c a l l t h e " l a r g e s t t o t h e s m a l l e s t " . It w i l l give you an i d e a o f one o f t h e s m a l l e s t R 0 u n i t s on t h e m a r k e t b e i n g h e l d i n t h e e n g i n e e r ' s hand and n e x t t o t h e e n g i n e e r one o f t h e l a r g e s t R 0 u n i t s put o n t o a s i n g l e s k i d . There are l a r g e r R0 u n i t s t h a n t h e one shown but most o f t h e s e o c c u p y two s k i d s o r a r e f a b r i c a t e d on t h e j o b s i t e . In a d d i t i o n t o t h e s m a l l e s t and l a r g e s t m a c h i n e i s a medium s i z e d c a b i n e t R 0 u n i t f o r t h e p r o d u c t i o n of medical pure w a t e r . F i g u r e 2 shows a g e n e r a l i z e d v i e w o f r e v e r s e o s m o s i s / u 1 t r a filtration. You w i l l n o t e t h a t t h e a r t i s t has p u r p o s e l y shown t h e membrane h a v i n g an i s o t r o p i c n a t u r e , i . e . , a dense t o p s k i n w i t h s m a l l pores w i t h a very porous s u p p o r t l a y e r . The f e e d



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Figure 1. RO/UF equipment. This photograph contains one of the smallest RO units on the market and one of the largest RO units. There are larger RO units than the one shown but most of these occupy two skids or are fabricated on the fob site. In addition to the smallest and largest machines, there is a medium-sized cabinet RO unit for the production of medical pure water.

Figure 2. A generalized view of RO/UF. Note that the artist purposely has shown the membrane having an isotropic nature, i.e., a dense topskin with small pores with a very porous support layer. The feed solution flows between the two membranes and as the pressurized feed solution passes over the membranes, permeate passes through the membranes and concentrate exits from between the membranes. The artist has made an effort to show that the impurities in the water are being concentrated as the permeate is being removed.



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s o l u t i o n flows between the two membranes and as the p r e s s u r i z e d feed s o l u t i o n passes over the membranes, permeate passes through the membranes and concentrate e x i t s from between the membranes. You w i l l a l s o note that the a r t i s t has made an e f f o r t to show that the i m p u r i t i e s i n the water are being concentrated as the permeate i s being removed. Stepping from the g e n e r a l i z e d concept of RO/UF to the more s p e c i f i c mechanism we have Figure 3. Figure 3 shows the mechanism of u l t r a f i l t r a t i o n . This i s u l t r a f i l t r a t i o n as defined i n the marketplace. Note that t h i s membrane has pores which are too large to e f f e c t d e s a l t i n g but are small enough t o remove pract i c a l l y a l l of the organic molecules l a r g e r than 1000 molecular weight. Figure h shows the mechanism of what i s g e n e r a l l y r e f e r r e d to as reverse osmosis in the marketplace. As you can see, the pore s i z e i s approximately equal to twice the thickness o f the pure water layer over the membrane which i s v o i d o f any ions. This membrane, when constructed o f c e l l u l o s e a c e t a t e , w i l l t y p i c a l l y remove over 33% o f the organics in excess of 200 molecular weight and removes over 3&% of monosaccharides such as dextrose end glucose. But look aren't these membranes r e a l l y the same w i t h the exception o f the f a c t that the pores are s m a l l e r f o r the one we consider an R0 membrane and l a r g e r f o r the one we consider a UF membrane? Yes, they are b a s i c a l l y the same membrane and they are made i n p r a c t i c a l l y the same manner. However, most users f e e l uncomfortable in c a l l i n g both o f these membranes by one name and those o f us in the marketplace have t h e r e f o r e , i n f o r m a l l y agreed to c a l l a membrane which r e j e c t s s a l t s a reverse osmosis membrane and a membrane which does not r e j e c t s a l t s but i s o f a pore s i z e s m a l l e r than 0.05 microns an u l t r a f i l t r a t i o n membrane. I purposely picked two a p p l i c a t i o n s t o discuss where an R0 membrane i s being used f o r what i s considered a UF a p p l i c a t i o n . In other words, a membrane w i t h very small pores i s being used to remove organic matter g e n e r a l l y l a r g e r than 500-1000 molecular weight. Do we c a l l i t reverse osmosis o r do we c a l l i t u l t r a f i l t r a t i o n ? Let's compromise and c a l l i t RO/UF. These two a p p l i c a t i o n s were a l s o purposely chosen because too many researchers are o v e r l y concerned about the RO/UF membrane used f o r water p u r i f i c a t i o n . At t h i s meeting others have t a l k e d some about RO/UF used i n food processing and my d i s c u s s i o n should help you see the d i v e r s i t y o f our technology. The key to the s u c c e s s f u l use of the RO/UF membrane i s i n the packaging o f the membrane. U n t i l economical, e a s i l y f a b r i cated and s t a b l e packages were developed, membranes were of l i t t l e commercial value. We use the s p i r a l wound type of membrane element f o r a l l of our equipment. Other packages such as the tube, the hollow f i b e r w i t h bore flow and the hollow f i b e r w i t h o u t s i d e flow are a l l v a l u a b l e and useful packages. However, the s p i r a l package i s by f a r the most u n i v e r s a l in i t s a b i l i t y t o



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Figure 3. Mechanism of UF as defined in the marketplace. This membrane has pores that are too large to effect desalting but are small enough to remove practically all of the organic molecules larger than 1000 mol wt.

Figure 4. Mechanism of RO in the marketplace. The pore size is approximately equal to twice the thickness of the pure water layer over the membrane which is void of any ions. This membrane, when constructed of CA, typically will remove over 99% of the organics in excess of 200 mol wt and removes over 98% of monosaccharides such as dextrose and glucose.



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t r e a t a l l t y p e s o f w a t e r , w a s t e w a t e r , and i n d u s t r i a l s o l u t i o n s . We have h a n d l e d many s o l u t i o n s w h i c h a r e n o r m a l l y n o t c o n s i d e r e d a p p r o p r i a t e f o r s p i r a l wound membrane e l e m e n t s s i m p l y by a p p l y i n g good c h e m i c a l e n g i n e e r i n g p r a c t i c e . L e t ' s t a k e a q u i c k l o o k a t t h e s p i r a l membrane e l e m e n t s o t h a t a l l o f us have t h e o p p o r t u n i t y t o u n d e r s t a n d i t s makeup. T h i s i s a f i g u r e o f a p a r t i a l l y u n r o l l e d s p i r a l membrane e l e m e n t w h i c h we c a l l a s e p r a l a t o r ( F i g u r e 5 ) . The s e p r a l a t o r has a permeate t u b e f o r c o l l e c t i n g t h e p e r m e a t e , t h e membrane i s l a i d o n t o a permeate c a r r i e r m a t e r i a l and t h e edges o f t h e membrane and t h e permeate c a r r i e r a r e g l u e d t o g e t h e r . The membrane i s i n t e g r a l l y c a s t o n t o a b a c k i n g m a t e r i a l as shown i n t h e f i g u r e . F i g u r e 6 i s an e n l a r g e m e n t o f c r o s s s e c t i o n s o f t h e s e p r a l a t o r . You c a n s e e t h e two l a y e r s o f membrane w h i c h a r e s i m i l a r t o t h e i d e a l i z e d RO/UF d r a w i n g i n F i g u r e 1. In o r d e r t o c o n s t r u c t t h e s e p r a l a t o r , a mesh s p a c e r i s used t o keep t h e membranes f r o m t o u c h i n g each o t h e r . T h i s mesh s p a c e r i s a l s o used as a t u r b u lence promoter. The mesh s p a c e r i s t y p i c a l l y 3 0 m i l s ( 0 . 7 6 2 mm) i n t h i c k n e s s b u t can be e i t h e r t h i n n e r o r t h i c k e r as r e q u i r e d . I t i s n o t u n u s u a l t o go as t h i n as 2 0 m i l s ( 0 . 5 0 8 mm) n o r as t h i c k as 6 0 m i l s ( 1 . 5 3 mm) o r even 120 m i l s ( 3 - 0 5 mm). We have f o u n d t h a t a 30 mi 1 t h i c k n e s s a l l o w s us t o o p t i m i z e t u r b u l e n c e , m a i n t a i n r e l a t i v e l y low f l o w s and r e d u c e t h e pumping e n e r g y r e q u i r e d t o have m i n i m a l f o u l i n g o f t h e membrane. Once t h e permeate goes t h r o u g h t h e membrane i t e n t e r s t h e permeate c a r r i e r which i s a r e l a t i v e l y porous s y n t h e t i c m a t e r i a l . The permeate c a r r i e r i s c o n n e c t e d t o t h e permeate t u b e and s m a l l h o l e s c a r r y the permeate from t h e permeate c a r r i e r t o t h e permeate t u b e and f i n a l l y t o t h e permeate c o l l e c t i o n m a n i f o l d . The end c r o s s s e c t i o n shows how t h e permeate p r o c e e d s t h r o u g h t h e permeate c a r r i e r s p i r a l l y t o t h e permeate t u b e . S p i r a l wound e l e m e n t s have been used by a number o f companies i n the water p u r i f i c a t i o n area s i n c e 1968. Osmonics has been u n i q u e i n t h a t we have used s p i r a l s on a v e r y l a r g e number of n o n - w a t e r p u r i f i c a t i o n a p p l i c a t i o n s , i n c l u d i n g o i l c o n c e n t r a t i o n , l a t e x c o n c e n t r a t i o n and o f c o u r s e , t h e c o n c e n t r a t i o n and f r a c t i o n a t i o n o f c h e e s e whey. In f a c t , o u r i n s t a l l e d c a p a c i t y on c h e e s e whey i s a p p r o x i m a t e l y 3 2 4 , 0 0 0 s q . f t . ( 2 9 , 1 6 0 m ) o f memb r a n e o r 2 0 m i l e s ( 3 2 km) o f membrane as i t comes o f f o f o u r m a c h i n e r y 3 f t . (1 m e t e r ) w i d e . Or, i f you p r e f e r the i n s t a l l e d c a p a c i t y i s c a p a b l e o f h a n d l i n g 8 0 0 , 0 0 0 l b s ( 3 6 0 , 0 0 0 kg) o f c h e e s e whey p e r h o u r . 2

Case H i s t o r y - W h i t e s t o n e C h e m i c a l Co. The f i r s t c a s e h i s t o r y we w i l l d i s c u s s i s a medium s i z e d c h e m i c a l company, W h i t e s t o n e C h e m i c a l Co. w h i c h i s a d e p a r t m e n t of BASF W y a n d o t t e C o r p o r a t i o n . They m a n u f a c t u r e s p e c i a l t y o r g a n i c c h e m i c a l s and a r e l o c a t e d i n S p a r t a n b u r g , S o u t h C a r o l i n a . W h i t e s t o n e manufactures p r i m a r i l y a l k o x y l a t e s ; s u r f a c t a n t s from



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Figure 5. A partially unrolled spiral membrane element known as a sepralator. The sepralator has a permeate tube for collecting the permeate; the membrane is laid onto a permeate carrier material and the edges of the membrane and the permeate carrier are glued together. The membrane is integrally cast onto a backing material as shown in the figure.

Figure 6. An enlargement of the cross-sections of the sepralator. Note the two layers of membrane which are similar to the idealized RO/UF drawing in Figure 1. In order to construct the sepralator, a mesh spacer is used to keep the membranes from touching each other and is used also as a turbulence promoter.



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p r o p y l e n e and e t h y l e n e o x i d e , and e s t e r s f o r t h e t e x t i l e i n d u s t r y . The p l a n t has t h e c a p a c i t y t o m a n u f a c t u r e 35 m i l l i o n pounds ( 1 5 . 8 m i l l i o n kg) o f p r o d u c t p e r y e a r and g e n e r a t e s a p p r o x i m a t e l y 3 0 , 0 0 0 g a l l o n s (114 m3) o f w a s t e w a t e r p e r day. Because Whitestone i s a manufacturer o f s p e c i a l t y o r g a n i c chemicals the waste w a t e r i s composed p r i m a r i l y o f o r g a n i c s . The p r i m a r y s o u r c e s o f p o l l u t i o n a r e r e a c t o r and e q u i p m e n t w a s h o u t s and some s p i l l a g e . These p o l l u t a n t s cause problems i n meeting the b i o c h e m i c a l oxygen demand (BOD), t o t a l s u s p e n d e d s o l i d s ( T S S ) , ammonia, p h e n o l , and petroleum hydrocarbon standards. From 1971 t h r o u g h 1 9 7 7 , Whites t o n e C h e m i c a l had r e l i e d on b i o l o g i c a l d i g e s t i o n o f the o r g a n i c s i n i t s w a s t e w a t e r i n o r d e r t o meet t h e EPA g u i d e l i n e s . However, w i t h more s t r i n g e n t g u i d e l i n e s and s i n c e W h i t e s t o n e was d i s c h a r g i n g i t s w a s t e a f t e r t r e a t m e n t d i r e c t l y t o a s t r e a m , i t was d e c i d e d t o i n s t a l l an RO s y s t e m on t h e f i n a l a e r a t i o n pond. A p i l o t t e s t o f a p p r o x i m a t e l y 1000 h o u r s showed t h e usef u l n e s s o f r e v e r s e o s m o s i s and a l l o w e d Osmonics t o s p e c i f y t h e membrane e l e m e n t s and s y s t e m l a y o u t w i t h s u f f i c i e n t c e r t a i n t y t o g u a r a n t e e a r e a s o n a b l e l i f e and o p e r a t i n g c h a r a c t e r i s t i c s t o Whi t e s t o n e . W h i t e s t o n e d i d e v a l u a t e many a l t e r n a t i v e s p r i o r t o c h o o s i n g RO. They d e c i d e d t o use RO b e c a u s e t h e i n i t i a l c o s t was low, m a i n t e n a n c e r e q u i r e m e n t s were low and o p e r a t o r a t t e n t i o n was m i n i m a l compared t o t h e a l t e r n a t i v e s . Whitestone a l s o c a l c u l a t e d t h a t t h e o p e r a t i n g c o s t s , b o t h i n manpower needs and i n a c t u a l c h e m i c a l s and membrane r e p l a c e m e n t , was l e s s t h a n o t h e r a l t e r n a tives. S i n c e t h e RO s y s t e m w o u l d be o p e r a t i n g on b i o l o g i c a l l y a c t i v e m a t e r i a l s i t was d e c i d e d t h a t c l e a n i n g e v e r y 8 h o u r s w o u l d be a p p r o p r i a t e . T h e r e f o r e , an a u t o m a t i c C l e a n - I n - P l a c e (CIP) s y s t e m was d e v e l o p e d and i n s t a l l e d w i t h t h e RO u n i t . There i s t y p i c a l l y a k0% r e d u c t i o n i n p e r m e a t e r a t e due t o f o u l i n g p r i o r t o t h e t i m e t h a t W h i t e s t o n e c l e a n s t h e RO u n i t . The b a s i c w a s t e t r e a t m e n t s y s t e m a t W h i t e s t o n e i n c l u d e s : Feed pumps from t h e c o l l e c t i o n a r e a Bag f i l t e r s The RO u n i t Permeate s t o r a g e tank M i x i ng p i t D i s c h a r g e pumps CIP s y s t e m . The s y s t e m i s housed i n a p r e - e n g i n e e r e d m e t a l b u i l d i n g o f s u f f i c i e n t s i z e t o add a d d i t i o n a l t r e a t m e n t c a p a c i t y i f and when t h e need a r i s e s . The e n t i r e s y s t e m was b u i l t and i n s t a l l e d f o r l e s s t h a n $ 1 0 0 , 0 0 0 and has been i n o p e r a t i o n s i n c e J u n e o f 1977. The R0 m a c h i n e c o n s i s t s o f 78 s e p r a l a t o r s u s i n g S E P A ® - 9 7 membrane. A 50 Hp m o t o r i s t h e o n l y e n e r g y r e q u i r e d and i t runs a pump s u p p l y i n g p r e s s u r e t o t h e membranes a t 4 5 0 t o 480 p s i g (3041-3243 kPa). The most common f e e d w a t e r t e m p e r a t u r e t o t h e R0 i s 8 0 - 8 5 ° F ( 2 7 - 3 0 ° C ) but t h e t e m p e r a t u r e w i l l f l u c t u a t e dep e n d i n g on t h e s p e c i f i c t i m e o f t h e y e a r . The m a c h i n e i s r u n n i n g



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at 35% r e c o v e r y o f t h e f e e d as p e r m e a t e . In o t h e r w o r d s , 35% o f the w a t e r t h a t e n t e r s t h e m a c h i n e comes o u t as permeate and 5% i s concentrate. The permeate i s m e e t i n g a l l o f t h e EPA r e q u i r e m e n t s for d i s c h a r g e t o the stream. The s y s t e m does g e t d i r t y and r e q u i r e s CIP c l e a n i n g about e v e r y 8 h o u r s . A l g a e blooms have p e r i o d i c a l l y c a u s e d a p r o b l e m but c h l o r i n e f e e d c o u p l e d w i t h a d d i t i o n a l c l e a n i n g u s i n g a p r o p r i e t a r y c l e a n e r has a l w a y s r e s t o r e d t h e permeate r a t e . Sepral a t o r l i f e a p p e a r s t o be about 2k months and W h i t e s t o n e has changed t h e i r s e p r a l a t o r s once i n t h e l a s t 3 y e a r s . Even though c l e a n i n g e v e r y 8 h o u r s may a p p e a r t o be e x c e s s i v e t o some o f y o u who have s p e n t most o f y o u r t i m e i n t h e b r a c k i s h o r s e a w a t e r p u r i f i c a t i o n a r e a , i t i s economical f o r Whitestone t o clean that o f t e n r a t h e r t h a n s p e n d i n g e x c e s s i v e t i m e t r y i n g t o d e v e l o p some t y p e o f u n i q u e method f o r p r e t r e a t m e n t t h a t w o u l d r e d u c e t h e c l e a n i n g f r e q u e n c y . A t t h i s time t h e system i s p e r f o r m i n g w e l l , membrane l i f e i s r e a s o n a b l e and t h e p o l l u t i o n c o n t r o l r e q u i r e ments a r e b e i n g met. Case H i s t o r y #2 - Cummins E n g i n e Company, C h a r l e s t o n , C a r o l i na

South

A n o t h e r i n s t a l l a t i o n i n S o u t h C a r o l i n a b u t o f much l a r g e r p h y s i c a l s i z e i s t h e Cummins C h a r l e s t o n D i v i s i o n o f Cummins E n g i n e Company. T h i s l o c a t i o n has o v e r 900,000 s q u a r e f e e t (81,000 s q . m.) o f m a n u f a c t u r i n g f a c i l i t y . The m a n u f a c t u r i n g o p e r a t i o n s a r e c e n t e r e d a r o u n d m a n u f a c t u r e , a s s e m b l y and t e s t i n g of d i e s e l engines. V a r i o u s u n i t o p e r a t i o n s i n c l u d e g r i n d i n g , machining, parts washing, parts c l e a n i n g , assembly, p a i n t i n g , t e s t i n g and s t o r a g e . The n a t u r e o f t h e o p e r a t i o n s i s s u c h t h a t c o n s i d e r a b l e volumes o f o i l o r o i l y compounds a r e u s e d . The m a j o r c o n t r i b u t o r t o t h e w a s t e w a t e r a t Cummins i s t h e t e s t i n g f a c i l i t y where t h e e n g i n e s a r e t e s t e d p r i o r t o s h i p m e n t . A l l of the w a s t e w a t e r p r o d u c t i o n a t Cummins amounts t o a p p r o x i m a t e l y 180,000 g a l / d a y (681 m3/day). The w a s t e w a t e r i s composed o f c o o l a n t s , c u t t i n g o i l s , d i e s e l f u e l , l u b r i c a t i o n o i l s , h y d r a u l i c o i l s , wash t a n k s o l u t i o n s , deg r e a s e r s , and p h o s p h a t e r i n s e from t h e p a i n t i n g o p e r a t i o n . A t y p i c a l a n a l y s i s o f t h e w a s t e w a t e r shows: pH = 8 T o t a l d i s s o l v e d s o l i d s = 1106 mg/1 T o t a l suspended s o l i d s = 76 mg/1 BOD = 325 mg/1 T o t a l p h o s p h a t e = 15 mg/1 I r o n = 3.7 mg/1 Aluminum = k.O mg/1 Lead = L e s s t h a n 0.01 mg/1 O i l and G r e a s e = 700 mg/1



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A f t e r a m i n i m a l amount o f t e s t i n g , an 0SM0® d u a l RO s y s t e m was i n s t a l l e d and s t a r t e d up i n e a r l y 1 3 7 5 . Each o f t h e two RO m a c h i n e s c o n t a i n s 120 s e p r a l a t o r s . Each m a c h i n e i s d e s i g n e d f o r 60 gpm ( 1 3 . 6 m 3 / h r ) p e r m e a t e r a t e a t 4 0 0 - 5 0 0 p s i g ( 2 7 0 2 - 3 0 4 1 kPa) and 9 5 t o 97% r e c o v e r y o f t h e f e e d as p e r m e a t e . F i g u r e 7 shows t h e s y s t e m a t Cummins. The w a s t e w a t e r i s c o l l e c t e d i n d i f f e r e n t h o l d i n g c o n t a i n e r s , pumped t h r o u g h the bag f i l t e r s and c a r t r i d g e f i l t e r s p r i o r t o t h e R0 m a c h i n e and t h e n t o t h e R0 m a c h i n e . On s t a r t - u p i t was r e c o g n i z e d t h a t t h i s s y s t e m s h o u l d have had more e x t e n s i v e p i l o t t e s t i n g . U n f o r t u n a t e l y , t h e e n g i n e manuf a c t u r i n g was not even i n p a r t i a l o p e r a t i o n when t h e p i l o t t e s t s w e r e run and s y n t h e s i z e d w a s t e had t o be used. By t h e t i m e t h e m a c h i n e was s t a r t e d up t h e l a g o o n s used by Cummins f o r w a s t e w a t e r s t o r a g e had d e v e l o p e d a s u b s t a n t i a l a l g a e bloom t h a t was never a n t i c i p a t e d . However, t h i s p r o b l e m d i d a l l o w us t o l e a r n how t o remove a l g a e when i t has f o u l e d t h e R0 s y s t e m . We a l s o l e a r n e d how t o remove o i l f o u l i n g . The a d d i t i o n o f 1 0 0 - 2 0 0 mg/1 of c h l o r i n e i s about t h e o n l y way t o remove s u b s t a n t i a l amounts of a l g a e f r o m t h e R0 m a c h i n e s . Once t h e f i r s t bloom o f a l g a e was taken c a r e of the machines s t a b i l i z e d , r e q u i r i n g c l e a n i n g every 24-36 hours. As l o n g as t h e Cummins o p e r a t o r p r a c t i c e d good c l e a n i n g t e c h n i q u e s and t o o k r e a s o n a b l e c a r e w i t h t h e R0 u n i t , the system performed very w e l l . I f c l e a n i n g was m i s s e d o r done i n c o m p l e t e l y t h e r e s u l t a n t f o u l i n g t o o k two t o t h r e e days t o ove rcome. The e n g i n e e r s a t Cummins had h e a r d t h a t i t was u n u s u a l f o r R0 e q u i p m e n t t o be c l e a n e d as o f t e n as e v e r y 24 t o 36 h o u r s . They d e c i d e d t o i n v e s t i g a t e the p o s s i b i l i t y of p r e t r e a t i n g the waste w a t e r p r i o r t o t h e R0 o r p o s s i b l y r e p l a c i n g t h e R0 w i t h some o t h e r d e v i c e which would r e q u i r e less o p e r a t o r a t t e n t i o n . It is i n t e r e s t i n g a t t h i s p o i n t t o compare t h e a t t i t u d e o f t h e o p e r a t o r s a t W h i t e s t o n e C h e m i c a l , who w e r e p r e p a r e d t o c l e a n t h e R0 u n i t b a s e d on t h e p i l o t t e s t s , t o t h e o p e r a t o r s a t Cummins who were u n p r e p a r e d t o c l e a n t h e R0 u n i t and t h e r e f o r e , were u p s e t by a c l e a n i n g f r e q u e n c y w h i c h was 1/3 as o f t e n as t h e c l e a n i n g frequency at Whitestone. Cummins d i d e x t e n s i v e t e s t i n g w h i c h i s s u m m a r i z e d as f o l l o w s : 1. D i a t o m a c e o u s e a r t h f i l t r a t i o n was used w i t h many t y p e s o f d i a t o m a c e o u s e a r t h (DE) o f b o t h t h e o i l a b s o r b i n g and s t a n d a r d t y p e s . The DE f i l t r a t i o n p r o d u c e d good q u a l i t y w a t e r removing as much as 35% o f t h e t o t a l s u s p e n d e d s o l i d s and 50% o f t h e o i l . However, r a p i d b l i n d i n g o f t h e DE r e q u i r e d f r e q u e n t changes on t h e p r e c o a t and caused c o n c e r n a b o u t t h e d i s p o s a l o f the c o n t a m i n a t e d DE. The DE d i d r e d u c e t h e f o u l i n g on t h e R0 u n i t and w o u l d have e x t e n d e d t h e c l e a n i n g c y c l e f o r t h e R0. Howe v e r , i n o r d e r t o o b t a i n an e c o n o m i c a l f i l t r a t i o n run w i t h t h e DE, p r e f i 1 t r a t i o n p r i o r t o t h e DE w o u l d be r e quired. S i n c e t h e o b j e c t i v e was t o p r e t r e a t t h e R0 and not t o have two p r e t r e a t m e n t s , Cummins d e c i d e d t o d r o p c o n s i d e r a t i o n o f t h e DE f i l t e r s as p r e t r e a t m e n t .



Figure 7. System at Cummins. The waste water is collected in different holding containers, pumped through bag and cartridge filters prior to the RO machine, and then put through to the RO machine.


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Figure 8. A typical RO system with a clean-in-place (CIP) unit adjacent to the RO. The CIP unit is plumbed into the RO unit so that the operator can CIP the RO system by simply changing three valves and making certain that the cleaning chemicals are used.

Figure 9. A bag filter system used for pretreatment prior to an oily waste application. We are using 5-fi-rated bags which we feel are approximately equal to 15-fx cartridge filters. Bags are valuable because the waste that is collected can be thrown away.



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Figure 10. The actual operating installation of a system that uses both spiralwound UF and spiral-wound RO to handle oily waste which also is contaminated with phosphates

Figure 11. A beaker containing the concentrate from an RO unit on oily waste and a second beaker showing the permeate from oily waste processing. Normally the oily wastes can be concentrated until the oil "breaks" due to concentration and separate phases are apparent to the naked eye.


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The n e x t method o f p r e t r e a t m e n t w h i c h was t r i e d was ultrafiltration. P i l o t s i z e UF u n i t s u s i n g t h e h o l l o w f i b e r b o r e f l o w t y p e c a r t r i d g e and t h e 1" t u b e module w e r e t e s t e d . As w o u l d be e x p e c t e d , t h e permeate from the UF u n i t was q u i t e c l e a r and when used as f e e d f o r the RO, a b s o l u t e l y no f o u l i n g was a p p a r e n t . However, t h e UF f o u l e d a t about t h e same r a t e as t h e RO had f o u l e d . The UF c o u l d be c l e a n e d j u s t as t h e RO c o u l d be c l e a n e d . The Cummins e n g i n e e r s d e c i d e d t h a t UF as a p r e t r e a t m e n t t o RO i n t h i s c a s e was n o t e c o n o m i c a l b e c a u s e o f e x c e s s i v e c a p i t a l and o p e r a t i n g c o s t s and s h o u l d n o t be p u r s u e d . As an a s i d e , Osmonics does have some i n s t a l l a t i o n s where UF p r i o r t o RO i s a v i a b l e p r e t r e a t m e n t and can be e c o n o m i c a l l y j u s t i f i e d . I t j u s t d i d not f i t this application. A new p r o c e s s c a l l e d e c l e c t i c t r e a t m e n t was t r i e d . This uses a c o n v e n t i o n a l b e l t skimmer f o r r e m o v i n g f r e e o i l and t h e n t h e a d d i t i o n o f e l e c t r i c i t y t o a i d i n f o r m i n g a f l o e o f t h e suspended o r emulsed o i l s . On-site p i l o t d a t a c o u l d n o t be c o l l e c t e d w i t h i n a r e a s o n a b l e t i m e and Cummins d e c i d e d n o t t o p u r s u e t h e e c l e c t i c s y s t e m . C h e m i c a l t r e a t m e n t and s e t t l i n g i s t h e most commonly used method o f t r e a t i n g w a s t e w a t e r . Alum and p o l y m e r f l o c c u l a t i n g a g e n t s were used and were f o u n d t o be s u c c e s s f u l i n p r e t r e a t i n g the waste water p r i o r t o the RO u n i t . One o f t h e b i g a d v a n t a g e s o f a c h e m i c a l s y s t e m i s t h a t i t can be t a i l o r e d on a d a i l y b a s i s t o meet changing requirements. The o p e r a t o r can c o n s i d e r t h e d i f f e r i n g w a t e r coming t o t h e w a s t e t r e a t m e n t p l a n t . However, t h e p r o c e s s i s o p e r a t o r i n t e n s i v e . Cummins has n o t t o t a l l y d e c i d e d t o go w i t h c h e m i c a l treatment s i n c e the cost o f d i s p o s i n g o f the sludge c o u l d be e x c e s s i v e . A f a i r l y new t e c h n o l o g y w h i c h many p e o p l e i n t h e w a s t e treatment o f o i l s f i r m l y b e l i e v e i n i s d i s s o l v e d a i r f l o t a t i o n (DAF). DAF was o r i g i n a l l y t r i e d a t Cummins but e i t h e r t h e o i l a t Cummins was t o o s o l u b l e o r t h e c o n c e n t r a t i o n was t o o low t o h o l d t o g e t h e r t h e f l o e f o r a l o n g enough p e r i o d t o have r e a s o n a b l e f l o t a t i o n . After the f i r s t r e v i e w , t h e a i r f l o t a t i o n p r o c e s s was c o n s i d ered not a p p r o p r i a t e . S u b s e q u e n t t o t h e g e n e r a l t e s t i n g and c o n t i n u e d o p e r a t i o n o f t h e s y s t e m as o r i g i n a l l y i n s t a l l e d , Cummins d i d a d d i t i o n a l t e s t i n g w i t h DAF. They f o u n d t h a t t h e DAF w o r k e d f i n e i f t h e o i l c o n c e n t r a t i o n i n t h e w a s t e s o l u t i o n was s u f f i c i e n t l y h i g h . A f t e r a program o f w a t e r c o n s e r v a t i o n gave a r e d u c e d t o t a l e f f l u e n t f l o w and an i n c r e a s e d o i l c o n c e n t r a t i o n , a d d i t i o n a l t e s t s w e r e run w i t h DAF. A g a i n , alum and p o l y m e r w e r e added. A t



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t h i s s t a g e t h e DAF p r o v e d t o be a r e a s o n a b l e and a t t r a c t i n g method o f removing a good s h a r e o f t h e h e a v i e r o i l s and o t h e r c o n t a m i n a n t s w h i c h w e r e p r o b a b l y f o u l i n g t h e RO u n i t . At t h e p r e s e n t t i m e , Cummins has d e c i d e d t o i n s t a l l a p r e t r e a t m e n t s y s t e m u s i n g d i s s o l v e d a i r f l o t a t i o n as t h e p r i m a r y t r e a t m e n t f o l l o w e d by an a n t h r a c i t e / s a n d b a c k w a s h a b l e f i l t e r and an a c t i v a t e d c a r b o n p o l i s h i n g f i l t e r . The e f f l u e n t from t h e f i l t e r s t h e n goes t o t h e RO u n i t . The RO w i l l remove t h e l a s t t r a c e s o f the most s o l u b l e o i l s and o r g a n i c s . I t i s Cummins' i n t e n t i o n t o have t h e e f f l u e n t f r o m t h e f i l t e r s a t a t u r b i d i t y o f l e s s t h a n kS JTU's. T h i s s h o u l d keep t h e RO u n i t s f r o m f o u l i n g and w i l l a l l o w t h e RO t o be used w i t h m i n i m a l c l e a n i n g . L i k e a l l u n i t c h e m i c a l p r o c e s s e s , t h e RO i s u s u a l l y n o t c a p a b l e o f s t a n d i n g e n t i r e l y by i t s e l f . The i m p o r t a n t t h i n g t o remember i s t h a t a s y s t e m must be d e v e l o p e d t o g i v e a c o m p l e t e product. In t h e c a s e o f Cummins, t h e c o m p l e t e s y s t e m i n c l u d e s dissolved a i r f l o t a t i o n , anthracite/sand f i l t r a t i o n , activated c a r b o n f i l t r a t i o n and RO. In t h e c a s e o f W h i t e s t o n e C h e m i c a l , t h e c o m p l e t e s y s t e m i n c l u d e s RO and a c l e a n i n g regimen t o m a i n t a i n the RO a t t h e r e q u i r e d p e r m e a t e f l o w r a t e . Time w i l l t e l l w h i c h of t h e s e a l t e r n a t i v e s has t h e b e s t e c o n o m i c s . The e c o n o m i c s and the p r o p e r s y s t e m u s i n g RO a r e b o t h dependent on t h e p r o b l e m t h a t requires a solution. Cone 1 us i o n In

c o n c l u s i o n , I w o u l d l i k e t o l e a v e you w i t h two t h o u g h t s : F i r s t , I am o f t e n a s k e d by i n v e s t m e n t b a n k e r s and t h o s e who f o l l o w o u r t e c h n o l o g y , why t h i s t e c h n o l o g y has n o t grown as f a s t as e v e r y o n e s a i d i t w o u l d . A t f i r s t my i n c l i n a t i o n was somewhat d e f e n s i v e , but t h e n I d i d some r e s e a r c h i n t o t h e g r o w t h o f o t h e r new t e c h n o l o g i e s . I looked a t : - S e m i c o n d u c t o r s w h i c h were i n v e n t e d a t t h e t u r n o f t h e c e n t u r y and have o n l y seen g r o w t h i n t h e l a s t decade. - C o l o r e d t e l e v i s i o n w h i c h was a r o u n d i n 1925 but n e v e r became a v i a b l e p r o d u c t u n t i l I 9 6 0 — 3 5 y e a r s l a t e r . - N u c l e a r r e a c t i o n s , w o u l d we say 1933 f o r t h e i n v e n t i o n ? Is t h e b u s i n e s s r e a l l y t h a t b i g even now? My f e l l o w membrane t e c h n o l o g i s t s , d o n o t become d e f e n s i v e when someone a s k s t h e g r o w t h q u e s t i o n , i n s t e a d a s k them t o t e l l y o u one o t h e r t e c h n o l o g y w h i c h 10 y e a r s a f t e r i t s i n v e n t i o n had more t h a n 10 a c t i v e companies s e l l i n g p r o d u c t s u s i n g t h i s t e c h n o l o g y and now o n l y 2 0 y e a r s l a t e r has p r o b a b l y 3 0 a c t i v e m a n u f a c t u r i n g companies and as many more who are r e s e a r c h i n g t h e p o s s i b i l i t y o f e n t e r i n g t h e f i e l d . S e c o n d l y , I want t o remind a l l o f y o u t h a t t h e o n l y t r u e t e s t o f t h e w o r t h o f any r e s e a r c h i s t h e u l t i m a t e e f f e c t o f t h a t r e s e a r c h on s o c i e t y i n g e n e r a l and i n t h e m a r k e t p l a c e i n particular. Twenty y e a r s a f t e r t h e b e g i n n i n g o f r e v e r s e


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o s m o s i s and u l t r a f i l t r a t i o n , t h e m a r k e t p l a c e has p r o c l a i m e d t h a t t h i s membrane t e c h n o l o g y i s a s u c c e s s . We a l l l o o k forward t o t h e next twenty y e a r s which w i l l see t h i s t e c h n o l o g y emerge as one o f t h e g r e a t e s t b a s i c i n v e n t i o n s o f the 20th Century.


Acknow1edgemen t s I w i s h t o e x t e n d my d e e p e s t a p p r e c i a t i o n t o Dr. S. S o u r i r a j a n who f o r o v e r 16 y e a r s has h e l p e d me t o g a i n a b e t t e r u n d e r s t a n d i n g o f t h i s u n i q u e f i e l d o f r e v e r s e o s m o s i s and u l t r a f i l t r a t i o n and t o t h e f o l l o w i n g f o u r i n d i v i d u a l s whose p e r s o n a l a t t e n t i o n t o my r e q u e s t s f o r i n f o r m a t i o n on t h e c a s e s t u d i e s h e l p e d me i n p r e p a r i n g this talk. B e a l , Thomas W., O p e r a t i o n s M a n a g e r , W h i t e s t o n e BASF W y a n d o t t e C o r p . , S p a r t a n b u r g , SC

Chemical D i v . ,

F r a n k l i n , P a t r i c i a V., P.E., Cummins C h a r l e s t o n , I n c . , C h a r l e s t o n , SC K a r a s i e w i c z , W. R i c h a r d , P.E., M c N a i r , G o r d o n , J o h n s o n and K a r a s i e w i c z Company, C o l u m b i a , SC Davis, W i l l i a m , Sepratech RECEIVED

I n c . , Rock H i l l ,

SC

February 18, 1981.


Multiyear Experience with Oily and Organic ... - ACS Publications

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