dryden 1987 aquacultural-engineering 1

7/28/2019 Dryden 1987 Aquacultural-Engineering 1

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Aq uacu l tura l Eng ineer ing 6 ( 1 9 8 7 ) 3 9 - 5 0

A q u a c u l t u r e W a te r T r e a tm e n t b y I o n -E x c h a n g e :I . C a p a c it y o f H e c t o r C l in o p t i l o li te a t 0 - 0 1 - 0 . 0 5 NH . T . D r y d e n t a n d L . R . W e a t h e r l e y

Departm ent o f C hem ica l and Process Eng ineer ing , Herio t -W at t Universi ty ,Ch am bers Street , Edinburgh E H 1 1 H X , U K

A B S T R A C TT h e c a p a c i t y o f t h e n a t u r a l l y o c c u r r i n g z e o l i te c l i n o p t il o l it e h as beend e t e r m i n e d f o r t h e i o n s N H ~ , K * , C a "-+ an d M g 2+ i n t he range o f o ta lc o n c e n t r a t i o n s 0 . 0 1 u - 0 . 0 5 U . T h e r e s u l t s sho w tha t h e ef fect i ve c a p a c i t yo f t he zeo l i t e v a r i e s a c c o r d i n g t o t he i o n i c s p e c i e s i n v o l v e d i n th eexchange. M ax im u m ion u p take was ach i eved f o r t he exchangesN a / N H +4 a n d N a * / K a n d th e measur ed capaci t ies f o r N i l +4 a n d K +were s i g n i fi c a n t l y g r e a t e r t h a n t h o se measu r ed o r Ca 2* an d M g 2+ . T hed a t a p r o v i d e a u s e f u l p o i n t e r t o t h e u s e o f c l i n o p t il o l it e a s a watert r e a t m e n t m e d i u m i n re c i rc u l a ti n g a q u a c u l tu r e s y s te m s .

1 . I N T R O D U C T I O NT h e s te a d i ly i n c r e a s i n g g r o w t h o f f is h fa r m i n g a n d a q u a c u l t u r e in t h e U Ka n d o v e r p ar ts o f W e st e rn E u r o p e s i n c e 1 9 7 0 h a s b e e n a c c o m p a n i e d b ya c o r r e s p o n d i n g i n c r e a s e i n t h e a p p l i c a t i o n o f n e w a n d e x i s t i n g t e c h -n o l o g y t o t h e d e s i g n a n d o p e r a t i o n o f f is h r ea r in g sy s te m s .O n e o f t h e s ig n i f ic a n t d e v e l o p m e n t s , is a g r o w i n g d e s i r e f o r a c o m p r e -h e n s i v e w a t e r t r e a t m e n t s t r a t e g y w h i c h g i v e s t h e f i s h f a r m o p e r a t o r ah i g h d e g r e e o f c o n t r o l o v e r t h e e n v i r o n m e n t a l c o n d i t i o n s i n w h i c h h i ss t o c k g r o w s . T h i s i s r e f l e c t e d i n t h e r e c e n t d e v e l o p m e n t o f i n t e n s i v ec l o s e d r e c i rc u l a t in g sy s te m s w h i c h a l l o w a l m o s t t o t a l r e u s e o f w a t e ri n v e n t o r y b y t h e e m p l o y m e n t o f e f f i c i e n t a n d r a p i d l y r e s p o n d i n g w a t e rt r e a t m e n t s y s te m s w h i c h m a i n ta i n w a t e r q u a l it y a t a n o p t i m u m l e ve l .T h e i n i t i a l w a t e r q u a l i t y c r i t e r i a i n t h i s c o n t e x t a r e m e t a b o l i t e l e v e l s ,i n c l u d i n g a m m o n i a , t e m p e r a t u r e , o x y g e n c o n c e n t r a t i o n , u n d i s s o l v e d+ P r e s e n t a d d r e s s : D r y d e n A q u a c u l t u r e L t d , Abbeymount Techbase , 2 Easter R o a d ,E d i n b ur g h E H 7 5 A N . U K .

3 9Aquacuhura l Eng ineer ing 0 1 4 4 - 8 6 0 9 / 8 7 / S 0 3 . 5 0 - Elsevier Appl ied ScienceP ub l i she rs L td , Eng la nd , 1987 . Printed in G re at Brita in


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40 14. T. Dryden, L. R. Weatherleys o li d s c o n t e n t a n d p H . I t is t h e r e m o v a l o f a m m o n i a a s a m m o n i u m i o n sb y i o n - e x c h a n g e t o w h i c h th e p r e s e n t w o r k w a s d i r e c te d a n d i t is a p p r o -p r i a t e b r i e f ly to p u t t h e u s e o f io n - e x c h a n g e i n t o c o n t e x t.T ra d i t i ona l l y , b io log i c a l f i l t r a t i on i s t he p roc e s s u s e d f o r t he r e m ov a lo f a m m o n i a f r o m f is h f a r m w a s t e w a te r ; th e p r o c e s s is e c o n o m i c t oi n s ta l l a n d t h e o p e r a t i n g a n d m a i n t e n a n c e c o s t s a re m i n i m a l . T h ec a p a c i t y o f t h e f i lt e r t o r e m o v e a m m o n i a a t th e d e s i r e d r a t e i s a c h i e v e db y c o n d i t i o n i n g o f th e f i lt e r o v e r a p e r i o d o f s e v er a l w e e k s. D u r i n g t h i sp e r i o d c o l o n i e s o f s u i t a b l e b i o m a s s a r e c u l t i v a t e d o n t h e f i l t e r s u p p o r tun t i l the r e qu i r e d l e v e l o f a c ti v i t y i s a c h i e v e d . T h e l ong bu i l d -up t ode s ign c a p a c i t y m e a ns t ha t b io log i c a l f i l t e r s e x h ib i t a r e l a t i v e ly s l owr e s p o n s e t o c h a n g e s i n a m m o n i a c o n c e n t r a t i o n a n d o v e r a l l l o a d i n g .T h u s b i o f i l tr a t i o n le n d s i ts e l f t o s t e a d y - s t a t e e n v i r o n m e n t s .B y c on t r a s t , i on -e x c ha nge o f f e r s a r a the r m ore f l e x ib l e s y s t e m , a lbe i tc o n f i n e d t o f re s h w a t e r s y s te m s , w h i c h c a n r e s p o n d r a p i d l y to c h a n g e s i nf e e d w a t e r c o n c e n t r a t i o n , f lo w r a t e a n d o v e r a l l l o a d in g .I t o f fe r s a t u r n - k e y p r o c e s s w h i c h m a y b e b r o u g h t o n - l in e a t v e r y s h o r tn o t i c e a n d o f fe r s a s i g n i fi c a n tl y g r e a t e r t u r n d o w n f le x i b il it y c o m p a r e dw i t h b i o fi lt ra t io n . W a t e r t r e a tm e n t p e r f o r m a n c e c a n b e m a i n t a i n e d o v e ra w i d e r r a n g e o f t e m p e r a t u r e s a n d c o n c e n t r a ti o n s a n d i o n - ex c h a n g e isl ik e l y t o s h o w t h e m o s t u s e fu l a p p l i c a t io n t o a q u a c u l t u r e s y s t e m s fo rw a t e r t r e a t m e n t d u r i n g f is h t r a n s p o r t a t i o n a n d a s a b a c k - u p s y s t e m tob io log i c a l f i l t r a t i on i n l a rge s ys t e m s .

T h e i o n - e x c h a n g e r s e le c t e d fo r s t u d y h e r e w a s th e n a t u r a l l y o c c u r r i n gze o l i t e c l inop t i l o l i te . T h i s m a te r i a l i s h igh ly s e l e c t iv e fo r a m m on ium ionsa n d h a s b e e n u s e d w i t h c o n s i d e r a b l e s u c c e s s i n s e c o n d a r y s e w a g ee f fl u e n t t r e a t m e n t ( P o lt a a n d d e F o r e , 1 9 7 8 ) a n d o t h e r l a rg e - s c al e w a t e rt r e a tm e n t s y s t em s (S h e r m a n , 1 9 7 8) . T h e a m m o n i a c o n c e n t r a t io n sc o n s i d e r e d t o b e a m a x i m u m f o r f is h c u l t u r e w a t e r s a re v e r y m u c h l o w e rt h a n t h o s e e n c o u n t e r e d i n s e w a g e w a t e r s a n d t h u s t h e i o n - e x c h a n g ec a p a c i t y o f c l i n o p t i lo l i te a t c o n c e n t r a t i o n s o f t h e o r d e r o f 0 .0 1 N w e r es t u d ie d . T h i s v a l u e r e p r e s e n t s a n u p p e r l im i t o f c a ti o n c o n c e n t r a t i o n sn o r m a l l y e n c o u n t e r e d i n f is h f a r m w a te r s.T y p i c a l f is h f a r m w a t e r a l so c o n t a i n s s i g n if ic a n t c o n c e n t r a t i o n s o fs o d i u m , p o t a s s i u m , c a l c i u m a n d m a g n e s i u m i o n s . T h e s o d i u m i o np r e s e n c e c a n b e a p p r e c i a b l y e n h a n c e d d u e t o t h e u s e o f s o d i u m i o ns o lu t i ons f o r t he r e ge ne ra t i on o f i on e x c ha nge r s . T hus f i v e c a t i ons we re

- t- " ~ + " ~ +c ho s e n f o r c a p a c i t y s t ud i e s , i.e . N H 4 , Na + , K + , Ca - , M g- .2 . C A P A C I T Y

I n t h e d e s i g n o f c y c li c i o n - e x c h a n g e s y s te m s o p t i m a l s iz i n g o f t h ec o l u m n s r e q u i r e s a n a c c u r a t e k n o w l e d g e o f t h e s p e c i f i c c a p a c i t y o f t h e


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A q u a c u l t u r e wa t e r rea tmen t b y i o n - e x c h a n g e - - 1 4 1e x c h a n g e r f o r p a r t i c u l a r i o n s . T h i s i s i n a d d i t i o n t o t h e s e l e c t i v i t y f o rt h o s e i o n s p r e s e n t . I n t h e c a s e o f c li n o p t i l o l it e t h e r e is c l e a r e v i d e n c e t h a tc a p a c i t y i s v a r i a b l e ; s e e J o r g e n s e n e t a l . ( 1 9 7 9 ) , A m e s ( 1 9 6 7 ) , C r i d l a n d( 1 9 7 9 ) a n d K l i e v e a n d S e m m e n s ( 1 9 8 0 ) . Q u a l i t a t i v e i n t e r p r e t a t i o n o fo b e r v e d d a t a in d i c a t e s t h a t t o t a l s in g l e i o n c a p a c i t y c a n b e i n f l u e n c e d b yi o n i c s t r e n g t h o f t h e c o n t a c t s o l u t i o n , z e o l i t e h i s t o r y , r e g e n e r a t i o n m o d ea n d p r e t r e a t m e n t c o n d i t io n s .A c o m p a r i s o n o f t o t a l e x c h a n g e c a p a c i t i e s f o r H e c t o r c l i n o p t i l o l i t em e a s u r e d b y a n u m b e r o f i n v e s t i g a t o r s i s s h o w n i n T a b l e 1 . M e a s u r e dc o m p o s i t i o n s o f c l i n o p t i l o l i t e a r e l e s s v a r i a b l e t h a n i n d i c a t e d b y t h ev a ri a ti on s i n h o m o - i o n i c c a p a c it y a n d t h e m o d e o f p r e t r e a tm e n t p r i o r t oc a p a c i t y d e t e r m i n a t i o n m a y b e a m a j o r f a c t o r a f f e c t i n g t h e o b s e r v e dvariabi l i ty.

F o r e x a m p l e , p r e t r e a t m e n t w i t h m i n e r a l a c i d , s o m e t i m e s p r a c t i s e d t or e m o v e c a r b o n a t e a n d c la y im p u r i t ie s , m a y r e s u l t i n d e a l u m i n a t i o n ( s e eM u m i n o v e t a l . , 1 9 7 7 ; B a r r e r a n d M a k k i , 1 9 6 4 ) , w i t h a c o n s e q u e n tr e d u c t i o n i n ca p a c it y .I n t h e c a s e o f a l k a l i p r e t r e a t m e n t , i n c r e a s e s i n c a p a c i t y h a v e b e e no b s e r v e d ( Y o k o t a , 1 9 7 5 ; Y o s h i d a et a l . , 1 9 7 6 ; K l i e v e a n d S e m m e n s ,1980; Jorgen sen e t a l . , 1979).H e a t t reatment and t h e c o n c e n t r a t i o n o f c o n d i t i o n i n g s o l u t i o n s a r ea l s o l i k e l y t o i n f l u e n c e o p e r a t i n g c a p a c i t y o f c l i n o p t i l o l i t e ( s e e S a l e k eta l . . 1 9 7 9 ; G a l a b o v a , 1 9 7 9 ; C h e l i sh c h e v a n d V o l o d i n , 1 9 7 6 ) .

T A B L E 1Ion-E xch an ge Capac i ties o f He ctor C l inopt ilo li teIn ve s ti ga tor C a t i on C a pac i t y

( m e q . c a t io n g - 9A m e s ( 1 9 6 3 )A m e s ( 1 9 6 7 )B a r r e r a n d T o w n s e n d ( 1 9 7 6 )B a r r e r et al . ( 1 9 6 7 )S k u d d e r i 1 9 7 6 )K o o n a n d K a u f m a n ( 1 9 7 5)H o w e r y a n d T h o m a s ( 1 9 65 )"

C r i d l a n d ~1 9 7 9 )L a p o r t e

( p e rs o n a l c o m m u n i c a t i o n . 1 9 8 2

Cs + 1"7N H ~ 1 "8 1N H ] 2 . 1 4N H ; 1 . 8 3N H ] 1 . 9- 2 .1 ( 2 -0 4 ) hN a + 1 -9N a * 2 " 0 4 6 + 0 " 0 1 7 7C s 2 " 0 3 9 + 0 " 0 1 1N H ~ 1 .9 7N H ~ 1 - 9 - 2 . 1 ( 2 . 0 4 ) bN H ] 1 . 8 4

L' G e o l o g i c a l s o u r c e o f m i n e r a l w a s n o t s p e c if i ed ."M ea n .,r iven in pa ren th ese s .


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42 H . T. Dryden, L . R . W eather ley3 . E X P E R I M E N T A L

3 . 1 . C a p a c i t y a t 0 . 0 5 NT w o t y p e s o f c li n o p t i lo l i te f r o m t h e H e c t o r d e p o s i t w e r e S e le c te d f o rs t u d y . T h e s e a r e d e s i g n a t e d A a n d B , b e i n g d i s t i n g u i s h e d b y d i f f e r e n tc o l o u r a t i o n s .T he c l i nop t i l o l i t e wa s d ry - s i e v e d t o a p a r t i c le s ize r a nge be tw e e n 0 . 60a n d 0 "8 5 m m , a n d w a s h e d i n d i s ti ll e d w a t e r t o r e m o v e t h e f in e s .S inc e t he i on -e x c ha nge f i l t r a t i on i s a c yc l i c p roc e s s , t he c ond i t i on ingp r o c e d u r e p r i o r t o c a p a c i t y d e t e r m i n a t i o n w a s b a s e d o n a s i m i l a rp r e t r e a t m e n t s tr a te g y . T h e c l i n o p t i lo l i te w a s c o n v e r t e d t o th e a m m o -n iu m f o rm by r e p e a t e d c on t a c t w i th 0 . 05 r~ -Na +C1 - , a t p H 11.5 t o 12 .0( p H r e g u l a t i o n w i t h N a + O H - ) f o l lo w e d b y 0 . 0 5 N - N H a C I so l u t i o n a t at e m p e r a t u r e b e t w e e n 1 8 a n d 2 1 C . T h e c l in o p t i lo l i te ( 3 0 g ) w a ss u p p o r t e d b y a p e r f o r a t e d p l a s t i c p l a t e i n a g l a s s c o l u m n 2 5 0 m m i nl e n g t h , a n d 2 6 m m i n t e r n a l d ia m e t e r . D u r i n g e a c h c y c l e o f t h e c o n d i t i o n -i n g p r o c e d u r e , 2 4 l i tr e s o f c o n t a c t s o l u t i o n w e r e p a s s e d u p - fl o w t h r o u g ht h e z e o l i t e b e d a t a c o n s t a n t f l o w r a t e o f 5 0 0 m l h - 1 , m a i n t a i n e d b y ap e r is ta l ti c p u m p ( W a t so n M a r l o w t y p e M H R E 2 0 0) . T h e c y c le w a sr e p e a t e d f o u r t i m e s , b u t f o r t h e l a s t t r e a t m e n t 6 0 l i t r e s o f a m m o n i u mc h l o r i d e s o l u t io n w e r e p a s s e d t h r o u g h t h e z e o l i te b e d . F i n a l ly , t h e z e o l i tew a s t h o r o u g h l y w a s h e d w i t h d e - i o n i s e d w a t e r a t a f l o w r a t e o f 1 0 0 0 m lh -1 un t i l t he e f f l ue n t ga v e a ne ga t i v e c h lo r ide i on r e a c t i on w i th s i l v e rn i t r a te s o l u t i o n , a n d a z e r o r e a d i n g w i t h N e s s l e r ' s r e a g e n t f o r a m m o n i a .T h e z e o l i t e g e n e r a l l y r e q u i r e d a p p r o x i m a t e l y 6 0 l i t r e s o f d e - i o n i s e dw a te r t o g ive a n i on - f l e e e f f lue n t .T h e c o n d i t i o n e d c l i n o p t il o l it e w a s r e m o v e d f r o m t h e c o l u m n s a n d l e ftt o d r y o n a t r a y a t r o o m t e m p e r a t u r e f o r a p e r i o d o f o n e m o n t h , a f t e rw h i c h t i m e i t w a s s t o r e d i n a c o n s t a n t - h u m i d i t y b o t t le a b o v e 1 .0 y -a m m o n i u m c h l o r id e f o r a n a d d i t io n a l p e r i o d o f o n e m o n t h . T h i s l e n g th yp r o c e d u r e w a s r e q u i r e d t o a v o i d h e a t tr e a t m e n t , t o e l u te a ll s o r b e ds o lu t e i ons , a nd t o e ns u re a c on s t a n t wa t e r c on t e n t p r i o r t o we igh ing .T h e c a p a c i t y o f c l in o p t i lo l i te f o r th e a m m o n i u m i o n w a s d e t e r m i n e db y a s m a l l c o l u m n e l u t i o n t e c h n i q u e s i m i la r t o t h e m e t h o d d e s c r i b e d b yH o w e r y a n d T h o m a s ( 19 6 5 ). A s m a ll g la ss c o l u m n m e a s u r i n g 8 0 m m i nl e n g t h a n d 5 . 0 m m i n t e r n a l d i a m e t e r w a s f i l l e d w i t h 0 . 5 0 0 g o f a m m o -n i u m - b a s e d h y d r a t e d c l i n o p t il o li te . T h e z e o l it e w a s c o n t a c t e d w i th 1l i t r e o f 1 . 0 N-s od ium c h lo r ide s o lu t i on a t a f l owra t e o f 50 m l h - i . T hee l u a n t w a s c o l l e c te d a n d a n a l y s e d f o r a m m o n i a ; th u s t h e a m m o n i u m i o nc a p a c i t y w a s d e t e r m i n e d a n d t h e s o d i u m i o n c a p a c it y b y in f e r e n c e, si n c et h e e x c h a n g e r e a c t i o n i s s t o i c h i o m e t r i c . S o l i d - p h a s e a m m o n i u m i o n


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Aquacul ture water treatment by ion-exchange -- 1 43a n a l y si s g a v e a z e r o r e a d i n g , i n d i c a t in g t h a t a l l o f t h e a m m o n i u m i o n sh a d e x c h a n g e d o f f th e c l in o p t i lo l it e . T h i s a n a l y s i s in v o l v e d w a t e r -w a s h i n g a c r u s h e d s a m p l e o f t h e z e o l i te f o ll o w e d b y a d d i t i o n o f N e s s l e r 'sr e a g e n t. A n e g a t iv e r e a c t io n c o n f i r m e d t h e s a m p l e t o b e a m m o n i a - f r e e .A s i m i l a r p r o c e d u r e u s i n g p o t a s s i u m c h l o r i d e i n p l a c e o f s o d i u mc h l o r i d e e n a b l e d t h e p o t a s s i u m i o n c a p a c i t y o f t h e z e o l i t e t o b ed e t e r m i n e d .C a l c i u m a n d m a g n e s i u m i o n c a p a c i ti e s w e r e m e a s u r e d b y a m o d i f i c a -t io n o f t h e d e s c r i b e d p r o c e d u r e . S ix l it re s o f 0 . 0 5 N c a l c iu m a n d m a g n e -s i u m c h l o r i d e s o l u t i o n s w e r e p a s s e d t h r o u g h s m a l l c o l u m n s c o n t a i n i n g0 .500 g o f c l i nop t i l o l i te , f o l l ow e d b y a w a s h w i t h 1 li tr e o f de - i on i s e dw a t e r ( f l ow ra t e 50 ml h -~ ) . O ne l i t r e o f 1 .0 N - s od i um c h l o r i de s o l u t i onw a s n e x t p a s s e d t h r o u g h e a c h c o l u m n a n d t h e e l u a n t w a s a n a l y s e d f o ra m m o n i a . T h e c a l c iu m a n d m a g n e s i u m i o n c a p a c it ie s w e r e c a l c u la t e d b ys u b t r a c t in g t h e m i ll ie q u i v a l e n ts o f a m m o n i u m e l u t ed b y s o d i u m f r o m t h et o ta l a m m o n i u m i o n c a p a c i ty o f t h e ze o li te . T h i s p r o c e d u r e w a s a d o p t e db e c a u s e o f t h e d i f fi c u lt y i n a n a l y s in g f o r a m m o n i a i n th e p r e s e n c e o f1 .0 N - ca lc iu m o r m a g n e s i u m c h l o r i d e , d u e t o t h e p r e c i p i t a t io n o f t h e s ei o n s a t th e h i g h p H r e q u i r e d f o r a m m o n i a a n a l y si s.T h e s m a l l - c o l u m n e l u t i o n t e c h n i q u e a n d l i q u i d - p h a s e a n a l y s i s w a sc hos e n i n p r e f e r e nc e t o d i r e c t s o l i d -p ha s e a na l ys i s by K je l da h l d i s t i l l a -t i o n ( B r e m n e r , 1 9 6 0 ; S k u d d e r , 1 9 7 6 ; C r i d l a n d , 1 9 7 9 ; F le t c h e r , 1 9 7 9 )b e c a u s e o f th e s i m p l ic i ty a n d a c c u r a c y o f t h e m e t h o d . R e a g e n t - g r a d ec h e m i c a ls w e r e u s e d t h r o u g h o u t t h e c o n d i t i o n i n g a n d c a p a c i ty d e t e r m i -na t i ons .3 . 2 . C a p a c i t y a t 0 " 0 1 NI t w a s s h o w n in th e p r e v i o u s s e c ti o n t h a t h o m o - i o n i c a m m o n i u m - f o r mc l i n o p t il o l it e w h i c h w a s c o n d i t i o n e d w i t h 0 .0 5 N s o l u ti o n s c o u l d b et o t a l ly . de p l e t e d o f t he r e s i de n t c ou n t e r - i on by e l u t i on w i th 1"0 Ns o l u t io n s o f s o d i u m o r p o t a s s iu m c h l o r id e s .I t w a s d e c i d e d t o r e p e a t t h e e l u t i o n p r o c e d u r e u s i n g s o l u t i o n s a t at o t a l c on c e n t r a t i on o f 0 "01 N i n o rd e r t o e s t a b l i s h t he a v a i l a b l e e f f e c ti v ee x c h a n g e c a p a c i t y a t t h is l o w e r c o n c e n t r a t io n .

T h e e x c h a n g e s y s te m s s h o w n in T a b l e 2 w e r e st u d i e d a n d t h e c o l u m nc o n d i t i o n s ar e s u m m a r i s e d i n T a b l e 3. T h e v a r i o u s c a t io n i c f o r m s o fc l in o p t i l o li te B w e r e p r o d u c e d a s p r e v io u s l y d e s c ri b e d a n d w e r ee x c h a n g e d w i th s o l u t i o n s c o n t a i n i n g o n l y t h e e x c h a n g i n g c o u n t e r - i o na n d c h l o r i d e c o - i o n a t 0 " 0 1 N. S a m p l e s o f e l u a n t w e r e t a k e n a t h o u r l yi n t e rv a l s f o r t he f ir s t 2 4 h a nd a t tw o-h ou r l y i n t e rv a ls f o r t he s e c on d 2 4 hinterval .


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4 4 H . T . D r y d e n , L . R . W e a t h e r l e vT A B L E 2Small-Column Binary Cation Exchange System

R u n n o . S o l i d - p h a s e i o n L i q u i d - p h a s e i o n1 N a + M g : +2 Na + Ca :*.3 Na K*4 N H ~ N a "5 NH ~ Ca 2+6 N H ~ M g2+7 N a + N H ~8 Ca 2+ N H9 M g z+ NH ~

T A B L E 3Experimental Co ndit ions of the Binary Ion-Exchange Co lum nR u n sV a r i a b l e V a l u e

0"01 Notal normality of feed solution(chloride-ion salt)Particle size of clinoptiloliteWeight of hydra ted zeoli te inammonium fo rm per co lumnFlowrate (bed volume p er hour)Bed vo lumeDirection of flowTemperatureInternal diam eter o f the glass columnDurat ion o f run

0 '60 -0"85 mm30 g10 BV h - I34"5 mlDownf low19-2 IC26 mm4 8 h

A t t a i n m e n t o f s t e a d y s t a t e w a s c o n f i r m e d b y c e s s a t i o n o f c a t io ne l u ti o n . T h e t o ta l e x c h a n g e a c h i e v e d a t s t e a d y s t a t e w a s c a l c u l a t e d f r o mt h e e l u t i o n c u r v e d a t a b y c u r v e f i t ti n g a n d i n t e g r a ti o n .

4 . E X P E R I M E N T A L R E S U L T ST h e m e a s u r e d c a p a c i t i e s o f b o t h c l i n o p t i l o l i t e 'A? a n d ' B ' f o r th e c a t i o n sN H +, K + , C a 2+ a n d M g 2+ a t 0 . 0 5 N a r e g i v e n i n T a b l e s 4 a n d 5 . T h er e s u l t s a r e p r e s e n t e d a s m i l l i e q u i v a l e n t s ( c a ti o n ) g -~ , w e i g h e d a s 1 g o fa m m o n i u m - b a s e d c l in o p t i lo l i t e . T h e r e f o r e , i n o r d e r t o a r r i v e a t t h e


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A q u a c u l t u r e w a t er t r e a t m e n t by i o n - e xc h a n g e - - 1

T A B L E 4Capacity of Clinoptilolite ~A' for Cations

45

C a p a c i t y ( m e q . c a t i o n g - ~)N + K +4 C a 2+ M g 2+

Number of replicatesMean capaci ty (meq. g-Standard deviationConfidence limits (59%)Low

High

6 5 3 32"066 2-067 1"905 0"8390"010 0"031 0"008 0"0202'046 2'006 1'890 0'7992"086 2"130 1"920 0"878

T A B L E 5Capacity of Clinoptilolite 'B" for Cations

C a p a c i ty ( m e q . c a t i o n g - ; )N H +~ K + C a 2 + M g 2 +

Number of replicates 6 5 3 3Mean capacity t meq. g-~) 2-159 2" 114 2.004 0.682Standard deviation 0"026 0"010 0"003 0"020Confidence limits (95%)Low 2.106 2.095 1.999 0.642

High 2-211 2.133 2.009 0.722

T A B L E 6Water Content of Clinoptilolite 'B'Form of clinoptilolite Na + K * Ca-" + Mg 2+Mean water content (% wt) 14.7 13.7 15.8 14.5

precise capacity for each respective ion, the different atomic weights ofeach cation and the percentage water content of each cationic form ofthe zeolite required consideration.The water content of clinoptilolite ~B" based on Na , K +, Ca 2- andMg 2- was determined by heating 1 g samples of the zeolite to 850C fora period of 24 h, after which the zeolite was weighed at 200C todetermine weight loss. Most of the weight loss will be attributed to water,but loss of aluminium and carbonates as carbon dioxide may occur. Theresults are presented in Table 6.


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46 H . T. Dryden, L . R . Weather leyx

I

0 I0 20 30 ~0 50 60TIME (HOURS)Fig . 1 . Bina ry cat ion co lum n exhaus t ion prof il es : e , run 1 , Na~_/Mg2+; w, run 2 , Na+ /Ca-'+; x , run 3 , N a+ /K + .

T h e e l u t i o n d a t a o b t a i n e d a t 0 .0 1 N f o r e a c h o f t h e e x c h a n g e s l is te d i nT a b l e 2 a re p lo t t e d i n F igu re s 1 , 2 a n d 3 . T he c a p a c i t y da t a i n f e r r e d f romt h e c u r v e s a r e s h o w n i n T a b l e 7 f o r e a c h i n d i v i d u a l c a se .

5. D I S C U S S I O N O F R E S U L T ST h e r e s u lt s o b t a i n e d i n th i s i n v e s ti g a t io n s h o w t h a t t h e c a t i o n i c e x c h a n g ec a p a c i t y o f c l i nop t i l o l i t e 'X a nd ' B ' a t 0 .05 N a re v e ry s im i l a r f o ra m m o n i u m , s o d i u m , p o t a s s i u m a n d c a l c iu m b u t d i f f er g r e a t ly f o r m a g -ne s ium . T h e r e s u l ts a l s o i nd i c a t e t ha t f u l l e x c ha nge , e x c e p t f o r t ha t o f c a l-c i u m a n d m a g n e s i u m , h a s b e e n a c h i e v e d i n a p e r i o d o f le s s t h a n 2 0 h a tr o o m t e m p e r a t u r e . T h i s r e s u lt is r a th e r s u r p r i s in g i n v ie w o f t h e r e p o r t e df in d i n g s o f S k u d d e r ( 1 9 7 6 ), C r i d l a n d ( 1 9 7 9 ) a n d N o d a ( 1 9 8 0 ) i n w h i c hf u l l e x c h a n g e w a s o n l y a c h i e v e d a f t e r s e v e r a l w e e k s a t r o o m t e m p e r a -tu re .T h e m e a n c a p a c i t y o f c l i nop t i l o l it e 'A? a nd ' B ' ob t a ine d by t hee x c h a n g e o f s o d i u m w i t h s o l i d - p h a s e a m m o n i u m w a s 2 . 0 6 6 a n d 2 . 1 5 9m e q g - t r es p e ct iv e ly . T h e s e r e s u lt s a re a m o n g s t t h e h i g h e s t r e c o r d e d f o rHe c to r c l i nop t i l o l i t e ( s e e T a b l e 1 ) , a nd t a k ing i n to a c c oun t t ha t t he


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Aquaculture water treatment by ion-exchange - - 1 4 7

Fig. 2.

1 0 . 0 ]

80

TIME (HOURS)B i n a r y c a t io n c o l u m n e x h a u s t i o n p r of il e s: o , r u n 4 , N H ~ / N a +, " ; r u n 5 , N H ] /

C a 2 + ; x , r u n 6 , N H ] / M g 2 +.

Fig. 3.

1 0 . 0 . . -

l / /0 10 20 30 ~ 50 60

T I M E ( H O U R S )+ +Bi n a r y ca t i o n co l u m n ex h au s t i o n p r o f i le s : o , r u n 7 , N a / N H ~ ; I , r u n 8 , C a - '+ /

N H .~ : x , run 9 , Mg 2+ / N H ~ .


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4 8 H . T . Dryden , L . R . Weaiher leyT A B L E 7

T o t a l I o n U p t a k e b y C l i n o p t i lo l i te ' B ' A f t e r 4 8 hR un no . So l id -phase ca t ion L iqu id -ph ase ca t ion Ion up takeOneq. g - i )

1 N a + M g 2+ 0 . 1 1 22 N a + C a 2 0 . 9 7 93 N a K 2 . 2 1 64 N H ] N a + 1 .0 185 N H : C a -'+ 1 . 1 786 N H ~ M g 2+ 0 " 1 1 97 " N a N H 4 2 " 11 78 C a -' N H ~ 1 ' 5 0 89 M g 2+ N H : 0 . 3 4 2

s a m p l e s w e r e f u l ly h y d r a t e d , t h e c a p a c i ti e s m e a s u r e d p r o b a b l y r e p r e -s e n t, o r a r e c l o s e t o , m a x i m u m e x c h a n g e .T h e c a p a c it y v a lu e s m e a s u r e d w i t h t h e c a l ci u m a n d m a g n e s i u m i o n sa r e l o w e r t h a n t h e m a x i m u m c a p a ci ty . T h i s r e s u l t im p l ie s e i t h e r t h a te x c ha nge is v e ry s l ow a nd i n s u f f i c ie n t t i me ( a bou t f iv e da ys ) w a s g i v e n top e rmi t f u l l e x c ha nge , o r t ha t c a t i on e x c ha nge t e rmi na t e s a t a p o i n t l e s st h a n t h e m a x i m u m c a p a c i t y , e s p e c i a l l y i n t h e c a s e o f m a g n e s i u m .K o y a m a a n d T a k e u c h i ( 1 9 7 7 ) r e p o r t e d t h a t th e m a g n e s iu m i o n w a s o n l yf ound a t t he M (4) e x c ha nge s i t e a nd t ha t i t s oc c up a nc y a t t h i s s i t e w a sv e r y l o w . T h i s o b s e r v a t i o n m a y e x p l a i n t h e l o w c a p a c i t y v a l u e d e t e r -m i ne d i n t h is i nv e s t iga t i on .H o w e r y a n d T h o m a s ( 1 9 6 5 ) c o m m e n t e d o n t h e c a p ac i ty o f c l in o p t il o -l it e in t h e b i n a r y s y s te m s o d i u m / c a e s i u m . T o t a l e x c h a n g e c a p a c i t y i n th em i x e d i o n s o l u t i o n w a s a l w a y s l e s s t h a n t h e s u m o f t h e h o m o - i o n i cc a p a c i t i e s f o r e a c h i o n . N o e x p l a n a t i o n c o u l d b e g i v e n f o r t h e r e s u l te x c e p t t ha t i t w a s n o t due t o hys t e r e s is . T he re is v e ry l it tl e i n f o rm a t i on i nt he l i t e r a t u r e r e ga rd i ng p a r t i a l i on - s i e v i ng w i t h c l i nop t i l o l i te , a nd i t is no tk n o w n i f e x c h a n g e a c t u a ll y t e r m i n a t e s o r p r o c e e d s o n l y s lo w l y t o f u lle x c ha nge .T h e u p t a k e d a t a f o r e x c h a n g e o f p o t a s s i u m i o n s at 0 . 0 1 N o n t os o d i u m - b a s e d z e o l i t e a n d f o r a m m o n i u m i o n s o n t o s o d i u m - b a s e dze o l i t e ( se e F i gs 1 a nd 3 ) s how t ha t e x c ha n ge is e s s e n t i a ll y c om p l e t e a f t e r48 h . Th i s i s r e f l e c t e d i n t he c a p a c i t y v a l ue s f o r t he s e e x c ha nge s ( s e eT a b l e 6 ) w h e n c o m p a r e d w i th th e c a p a c it ie s d e t e r m i n e d a t 0 ' 0 5 ~ .I n t h e c a s e o f i n d i v i d u a l u p t a k e o f so d i u m , c a l c iu m a n d m a g n e s i u mi ons a t 0 .01 N on t o a m m on i um -ba s e d ze o l i te (F i g. 2), t he e l u t i on o f the


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Aq uac ul ture water t reamzent by ion-exchange -- 1 49r e s i d e n t i o n a p p e a r s t o b e s t i l l i n p r o g r e s s e v e n a f t e r 4 8 h a n d t h u s n ot r u e f in a l c a p a c i t y f ig u r e w a s o b t a i n e d . T h e e f f e c ti v e u p t a k e c a p a c i t ie sc a l c u l a te d i n th e s e c a s e s a n d p r e s e n t e d i n T a b l e 6 c o n f i r m t h is w h e nc o m p a r i s o n w i t h t h e c a p a c it y v a lu e s o b t a i n e d a t 0 -0 5 N is m a d e .

I n t h e c a s es o f u p t a k e o f a m m o n i u m i o n s a t 0" 01 N o n t o h o m o - i o n i cc a lc iu m , s o d i u m a n d m a g n e s i u m f o r m s o f c l in o p t i lo l it e a m u c h m o r ef a v o u r a b l e u p t a k e w a s o b s e r v e d ( s e e F i g . 3 ) , a n d t h i s i s r e f l e c t e d i nu p t a k e v a l u e s s h o w n i n T a b l e 6 .T h e u p t a k e c a p a c i t y v a l u e s s h o w n i n T a b l e 6 a r e n o t s t r i c t l y t r u ec a p a c i t i e s i n a ll c a s e s a s i t is c l e a r f r o m t h e e l u t i o n d a t a t h a t e x c h a n g e c a np r o c e e d a t a fi n it e b u t v e r y s l o w r a t e t o w a r d s t h e f in a l s ta g e s o f u p ta k e .H o w e v e r , t h e d a t a a r e c o n s i s t e n t w i th t h e i d e a o f p a r ti a l e x c h a n g e w i thc e r t a i n s p e c i e s o f io n s a n d i n s pe c i fi c d i r e c t i o n s o f e x c h a n g e .

L a t e r w o r k o n s e l e c ti v it y o f c l i n o p t i lo l i t e h a s c o n f i r m e d t h is o b s e r v a -t i on ( s ee pa r t II ).

A C K N O W L E D G E M E N TT h e a u t h o r s w i sh to a c k n o w l e d g e t h e s u p p o r t o f t h e S E R C f o r a s tu d e n t -s h i p f o r H . T . D r y d e n .

R E F E R E N C E SA m es , L . L . (1963) . Mass ac t ion re la tionships of some zeol i t es in the reg ion ofh igh com pet ing ca t ion concen t ra t ions . A m . M i n e r a l o g i s t , 4 8 , 8 6 8 - 8 2 .A m es , L . L . (1967) . Zeo l i t e remo val of am m on ium ions f rom agr icu ltura l andother was tewaters . P r o c . 1 3 t h P a c i f i c N o r t h w e s t l n d u s t . W a s t e w a t e r C o n f . ,W a s h i n g t o n S t a t e U n i v e rs it y , P u l l m a n , W A , U S A .Barrer. R. M. & Makki , M. B. (1964) . M olecular s i eve sorbents f rom c l inop t ilo-lite. C a n . J . C h e m . , 4 2 , 1 4 8 1 - 7 .Barrer . R . M. & T ow nsen d, R. P. (1976) . Transi t ion metal ion-exc han ge inzeol i tes. Part 2 - A m ine s of C o 3, C u 2+ and Z n 2 in cl inopt i lol i te ,m or de ni t e and phil lipsite. J . C h e m . S o c . , F a r a d a y T r a n s . I. , 7 2 , 2 6 5 0 - 6 0 .Barter . R. M.. Pa pad opo ulos , R. & Rees, L. V. C. (1967) . Exc han ge of sod ium incl inopt i lol i te by orga nic cat ions. J . l n o r g a n . N u c l . C h e m . , 2 8 , 6 2 9 - 4 3 .Bremner . J . M. (1960) . Determina t ion of n i t rogen in so i l by the Kje ldahlme thod . J. A g r i c . S c i . , 55 , 11 -33 .C hel ishchev . N. F. & V olodin, V. F. (1976) . Io n-ex cha ng e kinet ics of a lkalis a ndalkal ine ear ths in natural c l inopt i lol i te . G e o c h e m . I n t e r n a t . , 13(6) , 127-36.Cr id land. M. (1979) . Ammonia removal f rom was tewaters . Ph .D. Thes i s ,Ca m br idge Universi ty .Fletcher , P. (1979) . T ransi t ion m etal ion-exc han ge in zeol ites . Ph.D. T hesis , C i tyUnivers ity . Lo nd on .


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50 H.. 1". Dr yd en , L. R . WeatherleyGalabova , I . M. (1979) . Rela t ionships be tw een new s t ruc tura l da ta o n c l inop t i lo-l it e and its b ehav iour in ion-ex chan ge in hea t ing . Z. Natur forsch . , 34(9).2 4 8 - 5 0 .How ery , D . E . & Tho m as , H . C . ( 1965). I on -exchange on t he m ine ra l c l inop t il o -lite. J. Ph y s . Ch e m ., 69(2) , 531-7 .Jorgensen, S. , Libor , O. , Barkaes , K. & Kuna, L. (1979) . Equi l ibr ium andcapaci ty da ta o f c l inopt i lol i te . Wa ter Res ., 13 , 159-65 .Kl ieve , J . R. & Sem m ens , M. J . (1980) . A n eva lua t ion of p re t rea ted na tura lzeo l it e s fo r a m m on ium remova l . Wa ter Res ., 14(2) , 161-8.Koon, J . & Kaufman, W. J . (1975) . Ammonia removal f rom munic ipa l was te~waters by ion-exchange . J . W ater Pol lu t ion Co ntrol Fed. , 47(3) , 448-65.K oyam a, K. & Tak euchi , Y. (1977) . C l inopt i lol i te : the dis t r ibut ion of potassiu m

atom s a nd i ts ro le in therm al s tabil ity. Zeit . Kristallographie, 1 4 5 , 2 1 6 - 3 9 .Muminov , S . Z . , Mirsa l imov, A. M. & Aropiv , E . A. (1977) . A compara t ives tudy of the m odi f ica t ion of c l inop t ilo l it e wi th ac id . Z h . F i z . K h i m . , 51(1),168.N oda , S . (1980) . A s imple me tho d for de te rm ining the ca t ion exchange capac ityof natural zeol i tes . N e n d o K a g ak u, 20(3) , 78-82.Polta , R. C. & de Fore , R. W. (1978) . A d em ons t ra t ion of am m onia remo val byion-exchange . P r o c . In d u str ia l W a s t e C o n f . , 9 - 1 1 M a y . P u r d u e U n i v.,Lafayet te , Indiana, USA, 3 3 , 6 0 4 - 1 3 .Salek, H. , Vin cen t , H. & Pat ton, M. (19 79) . X -ray diffract ion s tudies of s tabil i-t ies of zeol it es to t em pera tu re chang es and so lu t ion t rea tme nt . A d v a n . X - r a yA n a l . , 22 , 193-9 .Sherman, J . D. (1978) . Ion-exchange separat ions wi th molecular s ieve zeol i tes .A . I .C h . E . S y m p o s i u m S e rie s, 7 4 ( 17 9 ) , 9 8 - 1 1 6 .Skudder , A. J . (1976) . A m m on ium ion-exch ange on zeolites. Ph .D. T hes i s ,Ca m br idge Univers ity .Yokota , E (1975) . Zeol i t es for advanced was tewater t rea tment . Chem. Abstr . ,82 , 115687 .Yo shida, H. , Kurata , Y. & Sange, K. (1976 ) . Rem ova l of heavy metal ions frompol lu ted w ater w i th zeol i tes . M iz a S h o r i G i fu ts a , 17(3), 219 -26 .

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