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ACWa builds leachate treatment plant
ISSN
An International Newsletter
1993/7
0958-2118
N u m b e r 39
Membrane Technology i
7
9 •
of roses
• • •
membrane Ant/. ~ater
s0ftene~
ELSEVIER ADVANCED
ACWa b u i l d s leachate treatment plant A n i n t e r n a t i o n a l l y - e x p e r i e n c e d w a t e r a n d effluent t r e a t m e n t s p e c i a l i s t ACWa S y s t e m s Ltd, b a s e d i n S k i p t o n , UK, h a s w o n a £ 5 2 0 0 0 0 c o n t r a c t to d e s i g n a n d b u i l d a n e w l e a c h a t e t r e a t m e n t p l a n t for site r e m e d i a t i o n . The c o n t r a c t w a s a w a r d e d for the c o m p a n y ' s i n n o v a t i v e a n d cost-effective d e s i g n of a five-stage s y s t e m u t f l i s i n g a c o m b i n a t i o n of t e c h n o l o g i e s i n c l u d i n g u l t r a f l l t r a t i o n , two r e v e r s e osmosis processes, a n d traditional chemical treatment. The site, formerly u s e d for t h e p r o d u c t i o n of v a r i o u s c h e m i c a l p r o d u c t s , h a s over a p e r i o d of y e a r s b e c o m e heavily c o n t a m i n a t e d . Rainfall c a u s e s l e a c h i n g of c o n t a m i n a n t s , w h i c h a r e t h e n c a r r i e d into local w a t e r c o u r s e s . The b r i e f r e q u i r e d a t r e a t m e n t p l a n t to m e e t the r e q u i r e m e n t s a n d d i s c h a r g e c o n s e n t s set d o w n b y the N a t i o n a l Rivers A u t h o r i t y , while m a i n t a i n i n g m i n i m u m r u n n i n g costs. A l t h o u g h the flow from the site is b a l a n c e d i n a large lagoon, t h e v o l u m e to b e t r e a t e d still r e q u i r e d m a j o r c a p i t a l e x p e n d i t u r e o n large t r e a t m e n t vessels, a n d excessive r u n n i n g costs. The first stage of the ACWa s y s t e m f e a t u r e s a n u l t r a f f i t r a t i o n p l a n t (10 m 3 / h r o u t p u t ) to r e m o v e p a r t i c u l a t e a n d colloidal m a t t e r w h i c h m i g h t foul the later p r o c e s s e s . The s e c o n d a n d t h i r d s t a g e s (reverse o s m o s i s p l a n t s ) a r e u s e d to c o n c e n t r a t e all t h e p r o b l e m c o n t a m i n a n t s i n t o o n l y 15% of t h e i r o r i g i n a l v o l u m e - a six-fold c o n c e n t r a t i o n factor. The p e r m e a t e from the RO stage (8.5 m 3 / h r ) h a s a TDS level of a r o u n d 5 m g / l i t r e from a 6 0 0 0 m g / l l t r e feed. C o n c e n t r a t e from t h e RO s t a g e s (1.5 m 3 / h l ") c o n t a i n s all t h e o r i g i n a l c o n t a m i n a t i o n , c o n c e n t r a t e d six times. The r e d u c e d v o l u m e e n a b l e s t h e following t r e a t m e n t p r o c e s s e s to be economically-sized a n d efficiently operated. In the c o n c e n t r a t e t r e a t m e n t , pH a d j u s t m e n t is u s e d i n c o n j u n c t i o n with f e r r i c - s u l p h a t e d o s i n g to r e d u c e c e r t a i n c o n t a m i n a n t s to a n a c c e p t a b l e form. p H a d j u s t m e n t u s i n g NaOH is t h e n u s e d to p r e c i p i t a t e m e t a l oxides.
TECtlNOLOGY © 1 9 9 3 E l s e v i e r S c i e n c e P u b l i s h e r s Ltd., E n g l a n d . / 9 3 / $ 6 . 0 0
per i t e m
No part of this publication may be reproduced, stored in a retrieval system, or transmitted by any form or by any means, electronic, mechanical, photocopying, reeordlngor otherwise, without the prior permission of the publishers. (Readers in the U.S.A. - - please see special regulations listed on back cover.)
An International Newsletter
1993/7
0958-2118
N u m b e r 39
Membrane Technology i
7
9 •
of roses
• • •
membrane Ant/. ~ater
s0ftene~
ELSEVIER ADVANCED
ACWa b u i l d s leachate treatment plant A n i n t e r n a t i o n a l l y - e x p e r i e n c e d w a t e r a n d effluent t r e a t m e n t s p e c i a l i s t ACWa S y s t e m s Ltd, b a s e d i n S k i p t o n , UK, h a s w o n a £ 5 2 0 0 0 0 c o n t r a c t to d e s i g n a n d b u i l d a n e w l e a c h a t e t r e a t m e n t p l a n t for site r e m e d i a t i o n . The c o n t r a c t w a s a w a r d e d for the c o m p a n y ' s i n n o v a t i v e a n d cost-effective d e s i g n of a five-stage s y s t e m u t f l i s i n g a c o m b i n a t i o n of t e c h n o l o g i e s i n c l u d i n g u l t r a f l l t r a t i o n , two r e v e r s e osmosis processes, a n d traditional chemical treatment. The site, formerly u s e d for t h e p r o d u c t i o n of v a r i o u s c h e m i c a l p r o d u c t s , h a s over a p e r i o d of y e a r s b e c o m e heavily c o n t a m i n a t e d . Rainfall c a u s e s l e a c h i n g of c o n t a m i n a n t s , w h i c h a r e t h e n c a r r i e d into local w a t e r c o u r s e s . The b r i e f r e q u i r e d a t r e a t m e n t p l a n t to m e e t the r e q u i r e m e n t s a n d d i s c h a r g e c o n s e n t s set d o w n b y the N a t i o n a l Rivers A u t h o r i t y , while m a i n t a i n i n g m i n i m u m r u n n i n g costs. A l t h o u g h the flow from the site is b a l a n c e d i n a large lagoon, t h e v o l u m e to b e t r e a t e d still r e q u i r e d m a j o r c a p i t a l e x p e n d i t u r e o n large t r e a t m e n t vessels, a n d excessive r u n n i n g costs. The first stage of the ACWa s y s t e m f e a t u r e s a n u l t r a f f i t r a t i o n p l a n t (10 m 3 / h r o u t p u t ) to r e m o v e p a r t i c u l a t e a n d colloidal m a t t e r w h i c h m i g h t foul the later p r o c e s s e s . The s e c o n d a n d t h i r d s t a g e s (reverse o s m o s i s p l a n t s ) a r e u s e d to c o n c e n t r a t e all t h e p r o b l e m c o n t a m i n a n t s i n t o o n l y 15% of t h e i r o r i g i n a l v o l u m e - a six-fold c o n c e n t r a t i o n factor. The p e r m e a t e from the RO stage (8.5 m 3 / h r ) h a s a TDS level of a r o u n d 5 m g / l i t r e from a 6 0 0 0 m g / l l t r e feed. C o n c e n t r a t e from t h e RO s t a g e s (1.5 m 3 / h l ") c o n t a i n s all t h e o r i g i n a l c o n t a m i n a t i o n , c o n c e n t r a t e d six times. The r e d u c e d v o l u m e e n a b l e s t h e following t r e a t m e n t p r o c e s s e s to be economically-sized a n d efficiently operated. In the c o n c e n t r a t e t r e a t m e n t , pH a d j u s t m e n t is u s e d i n c o n j u n c t i o n with f e r r i c - s u l p h a t e d o s i n g to r e d u c e c e r t a i n c o n t a m i n a n t s to a n a c c e p t a b l e form. p H a d j u s t m e n t u s i n g NaOH is t h e n u s e d to p r e c i p i t a t e m e t a l oxides.
TECtlNOLOGY © 1 9 9 3 E l s e v i e r S c i e n c e P u b l i s h e r s Ltd., E n g l a n d . / 9 3 / $ 6 . 0 0
per i t e m
No part of this publication may be reproduced, stored in a retrieval system, or transmitted by any form or by any means, electronic, mechanical, photocopying, reeordlngor otherwise, without the prior permission of the publishers. (Readers in the U.S.A. - - please see special regulations listed on back cover.)