kruner 1987 aquacultural-engineering

7/28/2019 Kruner 1987 Aquacultural-Engineering

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A quacultural Engineering 6 ( 1987) 79-9 6

C i r ca d ia n P e r i o d i c i ty o f B i o l o g ic a l O x i d a t i o n U n d e rT h r e e D i f f e r e n t O p e r a t i o n a l C o n d i t i o n sG . Kri iner and H . R osenthal

Biologische Anstalt Helgoland, Zentrale Ham burg, Notkestr. 31, 20 00 Ham burg 52,F R G

A B S T R A C TD a i l y c y c le s o f b i o l o g i ca l o x i d a t i o n e f fi c ie n c y w e r e s t u d i e d i n t h r e ed i f fe r e n t b io f ih e r s : h i g h - l o a d t r ic k l in g f i lt e r A , 6 4 k g f i s h m - s , B I O . N E T ~m a t e r i a l ( N o r d d e u t s c h e S e e k a b e l w e r k e ) , 2 6 0 m 2 a c t iv e s u r fa c e a r ea p e rm 3 v o l u m e ; l o w - l o a d t r ic k l in g fi l te r B , 1 "2 k g f i s h m - s , l o w e r s e c ti o nH y d r o p a k * - f o i l (F r ie dr ic h U h d e G m b H ) , 2 0 0 m 2 m - 3 , u p p e r s e c t io nB I O - N E T m a te ria l, 2 6 0 m 2 m -S ; a n d l o w - l o a d s u b m e r g e d r o t a t i n gc o n t a c t o r ( S R C ) , B I O - N E T m a t e ri al , 3 8 0 m 2 m -3 .

T h e d i s so l v ed B O D 5 r e m o v a l e ff ic ie n c y o f tr ic k li n g f l t e r A w a sd e p e n d e n t o n t h e p H a n d o n t h e s p a c e - l o a d o f o r g a n ic m a t te r . T h e to t a la m m o n i a - n i t r o g e n o x i d a t i o n e f fi c ie n c y d e c r e a s e d d ir e c tl y a f te r f e e d i n gf r o m 6 0 % t o j u s t o v e r 2 0 % a n d r e t u r n e d 4 h l a t er t o th e e a r li er o x i d a t i o n -r ate o f 6 0 % f l u c t u a t i n g b e t w e e n 6 0 % a n d 3 0 % ( in i ti a l t o t a la m m o n i a - n i t r o g e n c o n c e n t ra t io n s r a n g e d b e t w e e n 0 "7 8 a n d 2" 89 m g Nl i tre - 1 8 h a f t e r f e ed ing) . Th i s dec reas ing e f f i c iency w as cause d by ani n c re a s in g i n it ia l c a r b o n a c e o u s ( B O D ) l e v e l f r o m 4 to 2 0 m g 0 2 l i tr e - 1. I nt h e l o w - l o a d t r ic k l in g f i lt e r B t h e t o ta l a m m o n i a o x i d a t i o n e f fi c ie n c yr a n g e d b e t w e e n 3 5 % e a rly i n t h e m o r n i n g t o 6 0 % , 1 0 h a f te r t h e f i rs tf e e d in g . T h e r e m o v a l e f fi c ie n c y in t h e S R C i n c r e a s e d c o n s ta n t l y f r o mn e a r ly 2 % t o m o r e t h a n 4 0 % 7 h a f te r t h e f i r s t f e e d i n g a n d d e c r e a s e dd u r i n g n i g h t t im e t o v a l u e s o f a b o u t 4 % .

Th e degrad at ion e f f ic i ency o f t o ta l n i t rogen in b o th t r i c k ling f il t e r s f e l ld r as tic ally a f te r f e e d i n g ( fr o m 7 5 t o 2 3 % a n d f r o m 8 8 t o 42 % ) . T h e S R Cs h o w e d a r ela tiv ely c o n s t a n t i n c r e a s e f r o m 2 8 % d i r e ct ly a f te r f e e d i n g t o58% 7 h la ter .

I N T R O D U C T I O NT h e r e m o v a l o f d i ss o l v e d o r g a n ic s u b s t a n c e s a n d s i m u l t a n e o u s n i t ri f ic a -t io n a r e i m p o r t a n t p r o c e s s e s i n t h e p u r i f i c a t i o n o f r e c i r c u l a t e d f is h

79.Aquacul tural Engineer ing 0144-8609/87/S03.50-- El sev ier Appl i ed Sc iencePublishers Ltd . England. 19 87 . Printed in Great Britain


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80 G. Kr iiner , H . Rose n tha lcu l tu r e sy s t ems u s in g b io f i l t e r s a s t r ea tmen t u n i t s ( Mead e , 1 9 7 4 : L i aoa n d M a y o , 1 9 7 4 ; K r i i n e r a n d R o s e n t h a l , 1 9 8 3 ; R o s e n t h a l e t a l . , 1 9 8 4 ;K lem et so n an d Co h en , 1 9 8 4 ) . I n r ecen t y ea r s a t l es t f iv e t y p es o f b io f ilmr e a c t o r h a v e b e e n u s e d f o r b i o l o g ic a l w a s t e w a t e r t r e a t m e n t ( R i t tm a n n ,1982) .T h er e a r e s ev e r a l ad v an tag es i n u s in g b io f i l t e r s t h a t a r e f i l l ed w i thp l as ti c me d ia i n a f i sh cu l tu r e r ec i r cu l a t in g sy st em:

(a) C l o g g in g p r o b l e m s w i th i n t h e m e d i u m a r e m i n i m a l b e c a u s e o f t h esh ea r in g an d h y d r au l i c f o r ces.(b ) A er a t i o n i s eas i ly an d in d e p e n d en t ly co n t r o l l ed b y s ep a r a t e . ae ra -t ion .(c ) M o s t o f t h e o r g an i sms a r e a t t ac h ed to t h e f il te r ma t r ix as b io mass ;t h ey a r e n o t eas i ly w a sh ed o u t o f t h e sy s t em d u r in g a h y d r au l i csurge.

T h r e e p o t e n t i a l m e t a b o l i c s o u r c e s o f a m m o n i a e x i s t i n b i o l o g i c a lt r e a t m e n t s y s te m s : (1 ) d e a m i n a t i o n o f o r g a n i c n i t ro g e n c o m p o u n d s , (2 )f o r m a t i o n o f a m m o n i a f r o m e n d o g e n o u s r e s p i r a t i o n a n d ( 3 ) r e l e a s e o fam m o n ia b y ce ll l y si s ( Pa in t e r, 1 9 7 5 ) . T h e ad s o r b e d o r g an ic su b s t an cessu ch a s ca r b o h y d r a t e s , f a ts an d p r o t e in s a r e en zy m at i ca l ly sp ri t i n tosma l l mo ie ti e s . T h e y a r e o x id i zed an d acces s ib l e t o t h e g r o w th o f n ew lyf o r m e d b a c t e r i a l c ells . I n t e r m e d i a t e p r o d u c t s a r e c o n v e r t e d t o a m m o n i aa n d a c id s t h r o u g h p r o t e i n h y d r o ly s i s. T h e m i c r o b i o l o g ic a l r e a c t io n sr e s u l t i n a d d i t i o n a l m i c r o b i a l b i o m a s s , o x i d a t i o n p r o d u c t s c o n t a i n i n gs m a l l e r c a r b o n c h a i n s , a n d c a r b o n d i o x i d e . A d a m s a n d E c k e n f e l d e r( 1 9 7 7 ) p o in t ed o u t t h a t t h e r a t e - l im i t i n g s t ep i n t h e n i t r if i ca t io n r eac t io ni s t h e c o n v e r s i o n o f a m m o n i a t o n i t r i t e b y b a c t e r i a b e l o n g i n g t o t h eN i t r o s o m o n a s g r o u p .I t is w e ll e s tab l i sh ed th a t w a te r q u a l i t y p a r am ete r s f l u c tu a t e co n s id e r -ab ly d u r in g d ay t ime in f i sh cu l tu r e sy s t ems . T h ese f l u c tu a t io n s mayr e a c h a m p l i t u d e s a s h i g h a s 2 0 0 - 4 0 0 % a b o v e t h e b a s e l i n e c o n c e n t r a -t i o n s d e t e r m i n e d i n m o r n i n g s a m p l e s . M a x i m u m p e a k s m a y r e a c hc r i ti ca l l ev el s f o r a m m o n ia an d n i t r i te s ev e r a l times a d ay ( Ro se n th a l e ta l . , 1 9 8 0 , 1 9 8 2 , 1 9 8 4 ; H 6 n er , 1 9 8 4 ) . D e ta i l ed k n o w led g e o f t h e sh o r t -t e r m v a r i ab i l it y o f th e m o s t im p o r t an t w a te r q u a l i ty p a r am ete r s i sr e q u i r e d i n o r d e r t o o p t i m i z e o p e r a t i o n a l p r o c e d u r e s f o r f i s h c u l t u r erecyc l ing sys tems .B io - t ech n o lo g ica l p r o c ed u r es w h ich a r e ab l e t o s tab i li ze t h e p e r f o r m -an ce o f a b io f i l te r can o n ly b e p r o p e r ly d es ig n ed i f: (a ) t h e r ea c t io n s o fsu ch f i lt e rs t o v a r i a t i o n s i n w a te r q u a l i ty p a r am ete r s a r e k n o w n , an d (b ) i tis p o s s ib l e t o p r ed i c t t h e f r eq u en cy an d am p l i t u d e o f t h ese f l u c tu a t io n su n d er g iv en cu l tu r e co n d i t i o n s ( i.e . d e f in ed b io ma ss ; sy s t em v o lu me) .


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Circadian periodicity o f biological oxidation 81I n d u s t r i al , d o m e s t i c a n d f ish c u l t u r e wa s t e w a t e r s a r e c o m p l e x i n th e i r

c o m p o s i t i o n , c o n t a i n i n g p a r t i c u l a t e o r g a n i c m a t t e r , d i s so l v e d o r g a n i c sa n d i n o r g a n i c so l u b l e c o m p o n e n t s . I n f ish c u l tu r e r e c y c l in g sy s t em s , t h eo r g a n i c wa s t e c o m p o n e n t s i n c l u d e m a i n l y d i s so lv e d , c o ll o i d a l a n ds u s p e n d e d m a t te r , a n d t h e i r re m o v a l d e p e n d s t h e r e fo r e n o t o n l y o n t h ee f f i c i ency o f the b io log ica l t r ea tm ent p roc ess bu t a l so on the e f fec t ivem e c h a n i c a l s e p a r a t io n o f t h e s u s p e n d e d m a t t e r ( H i lg e a n d R a k e l m a n n ,1 9 8 4) . S i n c e d i s so l v e d su b s t a n c e s a r e m a i n l y t r a n sp o r t e d b y d i f fu s i o nin to the b io log ica l ly ac t ive bac te r i a l f i lm cove t ing the b io f i l te r subs t ra t e ,t h e su s p e n d e d m a t t e r w i ll b e p a r t i a l ly a d h e r e d t o t h e su r f a c e o f t h e fi lm ,d e g r a d e d t h e r e o r b e i n g o v e r g r o w n b y b a c te r ia . C o m m e r c i a ll y av a il ab l ep l a s t i c m e d i a , wh i c h a r e d e p l o y e d a s c o n v e n t i o n a l su b s t r a t e s i n b i o -f i l t e r s , p rov ide a su i t ab le su r face fo r bac te r i a l a t t achment whi l e thewas tewa te r f lows ove r i t i n a t h in f i lm . The su r face a rea o f s l ime va r i e swi th the type , d i s t r ibu t ion and pack ing cha rac te r i s t i c s o f t he f i l t e rm e d i u m a n d t h e r e f o r e t h e a v a i l a b l e s l i m e su r f a c e i s c o n s i d e r e d t o b ep r o p o r t i o n a l t o t h e sp e c i f i c su r f a c e o f t h e m e d i u m ( Gr o m i e c e t a l . ,1972) .

R e m o v a l r a te s m e a su r e d o n s a m p l e s t a k e n f r o m t h e b i o fi lt e r i n le t a n do u t l e t m u s t b e c a r r i e d o u t o n a sy s t e m wh e r e c o m p l e t e c o n t r o l o f a l lp a r a m e t e r s t h a t in f l u e n c e t h e p r o c e s s is p o s s i b le .In the p resen t s tudy , two t r i ck l ing f i lt e r s and a subm erge d ro t a t ingc o n t a c t o r ( SR C ), t h e la t t e r b e i n g a p r i m e e x a m p l e o f a c o m p l e t e l y m i x e db i o f i l m r e a c t o r , we r e u se d t o g e n e r a t e e m p i r i c a l d a t a o n t h e e f f e c t o ff l u c t u a t i n g l o a d o n b i o f i l t e r p e r f o r m a n c e i n t wo d i f f e r e n t r e c y c l i n gsys t ems .

M A T E R IA L S A N D M E T H O D ST wo t r ic k l in g f il te r s e q u i p p e d wi t h d if f e r e n t su b s t r a t e c o m b i n a t i o n s a n da su b m e r g e d r o t a t i n g c o n t a c t o r ( SR C ) s e r v e d a s th e t e c h n i c a l u n i t s o f t h eexp e r im ent s (Tab le 1 ).T r ic k li n g f il te r A w a s e q u i p p e d w i th B I O - N E T ~ m a t e r i al( N o r d d e u t s c h e S e e k a b e l w e r k e A G , N o r d e n h a m m ) . T r ic k li n g f il te r B w a sf i l l e d ( l o we r s e c t i o n ) w i t h Hy d r o p a k * - f o i l ( F r i e d r i c h Uh d e Gm b H,D o r t m u n d ) a n d w i th t h e B I O - N E T m a t e r ia l ( u p p e r s ec tio n ). W a s te w a t e rsu p p l i e s t o t r i c k l i n g f i l t e r s A a n d B we r e p r o v i d e d b y a r o t a r y m o t o r -d r i v e n sp r i n k l e r sy s te m , o p e r a t i n g a t c o n s t a n t t u r n i n g sp e e d .T h e H y d r o p a k m a t e r i a l co n s is ts o f a la r ge n u m b e r o f c lo s e d, s m o o t hc h a n n e l s ; B I O - N E T h a s a u n i q u e c y l i n d r ic a l n e t st r u c tu r e .Biof i l t e r A was con ne c ted to a ' quas i-c losed" recyc l ing f i sh cu l tu re


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82 G. Kriiner, H. Rosenthals y s t e m o f a b o u t 1 4 m 3 t o ta l w a t e r v o l u m e . T h e t e m p e r a t u r e w a s m a i n -t a in e d a t a b o u t 2 5 C a n d t h e s a l in i ty w a s k e p t b e t w e e n 1 4 a n d 1 6 % o .Th e wa t e r f l o w r a t e t h r o u g h t r i ck l i n g f i l t e r A was m a i n t a i n ed a t a co n -s t an t 8 m 3 h - 1 (Tab le 1 ).

T h e B O D s - l o a d i n t h e c u lt u re s y s t e m v a ri e d b e t w e e n 0 .4 a n d 4 . 0 k gO 2 d a y - ~ c o r r e s p o n d i n g t o a l e v e l b e t w e e n 2 a n d 2 0 m g 0 2 l i t re - J i n th ein - f low of the b io f i l t e r . To ta l ammonia- . -n i t rogen load ranged be tween0 . 0 31 an d 0 . 0 7 8 k g N- NH ~ - d ay -~ d u r i n g t h e en t i r e ex p e r i m en t a lp e r io d . T h e f is h s t o c k e d w e r e T i l a p i a ( m a i n ly S e r a t h e r o d o n m o s s a m b i c a ,S . a u r e a a n d S . n i l o t ic a ) a n d e e l ( A n g u i l l a a n g u i l la ). Du r i n g t h e ex p e r i -m e n t a l p e r i o d t h e s t o c k i n g d e n s i t y r e a c h e d 6 4 k g f is h m - 3 c o r r e s p o n d -i n g t o a m a x i m u m f is h l o a d o f 8 9 6 k g. F i s h w e r e f e d o n c e p e r d a y( fe e d in g t i m e - - 0 8 . 0 0 h ; f e e d in g r a t e = 1 - 2 % b o d y w e i g ht, d r y to w e tw eigh t bas i s ).

T A B L E lCharacteristics of Two Trickling Filters and the Submerged Rotating Co ntactor (SRC)with Different PackingM aterials Du ring Ou r ExperimentsOperational data Trickling Trickl ing SR Cf il ter A f il ter B B IO -N E TB I O - N E T B I O - N E T /Hydropak

Specific surface a r e a (m2 m-3) 260 260/200 380Total vo lume (rna) 4.42 2.21/2.38 0.0076Total su rface (m2) 1 150 575 /477 29.0Hy draulic load (m3day -l m-~) 43.4 20.1 20.8Flow rate (m3 h -t ) 8.0 3.85 0.066Flow rate (m3da y- t m - z) 0.167 0.088 0.055

D e t a i l e d i n f o r m a t i o n r e g a r d i n g t h e h i g h - l o a d c u l tu r e s y s t e m a n d t h ech a r ac t e r i s ti c s o f t r i ck li n g f i lt e r A h as b een g i v en r ecen t l y e ls ew h er e( R e n n h a c k , 1 9 8 2 ; K r i in e r a n d R o s e n t h a l , 1 9 8 3).T h e r o t a t i n g p l a s t i c p a c k a g e o f t h e S R C e x h i b i t e d a p o r o u s n e t -s t r u c t u r e a n d w a s c o m p l e t e l y s u b m e r g e d w h i l e i n o p e r a t i o n ( S e k o u l o van d He i n r i ch , 1 9 8 1 ; He i n r i ch , 1 9 8 4 ; P l i i m k e , 1 9 8 5 ) . Th e u n i t r ece i v edi t s was t ewa t e r an d i t s a i r su p p l y t h r o u g h t h e cen t r a l ax i s . C o n t ac t m ad eb e t w een t h e was t ewa t e r , a i r an d su b s t r a t e co u l d b e l a r g e ly co n t r o l l edt h r o u g h a d j u s t m e n t o f t h e r o t a t i o n s p e e d a n d w a s t e w a t e r f l o w r a t e ,t h e r e b y p r o v i d i n g a c o n t i n u o u s f l o w t o w a r d s t h e p e r i p h e r a l r e g i o n s o ft h e fi lt er . T h e r o t a t i o n sp eed a f fec t s o x y g en tr an s f e r an d m a i n t a i n s th e


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Circadian periodicity o f biological oxidation 8 3e n t i r e a tt a c h e d b a c t e r i a l b i o m a s s i n a n a e r o b i c c o n d i t i o n . T h e r o t a t i o n o ft h e d r u m a l so p r o v i d e s a m e c h a n i c a l m e a n s t o r e m o v e t h e a c c u m u l a ti n gso l id p a r t i c l e s ad h e r e d to t h e m a te r ia l . T i ff s is ach i ev e d ma in ly b y th esh ea f in g f o r ces . I t a l so ma in t a in s t h e s lo u g h ed so l id s in su sp en s io n .B o t h t r ic k l in g f il te r B a n d t h e S R C w e r e c o n n e c t e d t o a ' q u a si - c lo s e d 'r ec i r cu l a t i n g cu l tu r e sy s t em w i th a l o w b io m ass l o ad in g . Sy s tem in t eg r a -t i o n w as r eac h ed v i a a b y - p as s c o n n e c t io n ( ' mu l t i- cy c l e ' sy s tem: to t a lv o l u m e i n c l u d in g t ri c k li n g f il te r, o z o n a t i o n u n i t a n d a n a e r o b i c d e -n i t r i f i ca t i o n = 1 8 m3; s a l in i t y = 2 0 - 2 3 % o ; t e m p e r a t u r e = 2 3 - 2 5 C ; p Hv a l u e s -- - 7 .8 - 8 . 4 ; t o t a l a m m o n i a - n i t r o g e n = 0 . 0 0 8 - 0 . 0 7 8 m g N l it r e -1 ;B O D s = 1 - 0 -5 . 4 m g 0 2 l it r e -1 ; c o r r e s p o n d i n g t o 0.1 a n d 0 .5 k g d a y -1B O D 5 l o a d ; a l l d a t a b a s e d o n d a i ly o b s e r v a t i o n s d u r i n g m o r n i n g h o u rs ).F i s h s p e ci e s s t o c k e d w e r e T i l a p i a ( m a i n ly S e ra t h e ro d o n mo ssa mb i c a ,S. aurea a n d S. galilaea), ee l (Angui l la angu iUa) a n d m u l l e t ( M u g i lcephalus). S t o c k i n g d e n s i ty d u r i n g t h e e x p e r i m e n t a l p e r i o d r e a c h e d 1 .2k g m - 3 c o r r e s p o n d i n g t o a m a x i m u m b i o m a s s f is h l o a d o f a p p r o x i m a t e ly2 8 k g. F i sh w er e f ed tw ice p e r d ay ( f eed in g t ime = 0 9 .0 0 h an d 1 7 .0 0 h ;f eed in g r a t e = 1 - 2 % b o d y w e ig h t, d r y t o w e t w e ig h t b asi s) .A l l t a n k s o f t h e s y s te m s w e r e m a d e o f p o l y e s t e r -g l a s s f ib r e . A l l p l u m b -in g w as o f PV C.C o m p o s i t e s a m p l e s f o r w a t e r q u a l i t y a n a l y s i s w e r e t a k e n s i m u l -t an eo u s ly a t t h e i n l et s an d o u t l e t s o f t h e b io f i lt e r s. Sam p les w er e t ak e n o na n h o u r l y b a s is d u r i n g n i g h t ti m e a n d a t h a l f - h o u r in t e rv a l s d u r i n g d a yt ime.W a t e r q u a l i t y a n a l y s i s i n c l u d e d d e t e r m i n a t i o n s o f t o t a l a m m o n i a( N H 3 + N H ~ - ) a n d n i tr it e , p H - v a l u e s a n d b i o l o g ic a l o x y g e n d e m a n d( B O D s) . D e t e r m i n e d t o t a l a m m o n i a - a n d n i t r i te - c o n c e n t r a t i o n s w e r ec a l c u la t e d a n d p r e s e n t e d a s t o t a l a m m o n i a - n i t r o g e n ( N -N H ~ - ) a n dn i t r i t e - n i t r o g e n ( N - N O ~-). A n a l y t i c a l m e t h o d s u s e d w e r e s li gh tl y m o d i -f i e d f r o m G r a s s h o f f et al. ( 1 98 3 ). B O D 5 w a s d e t e r m i n e d a s t h e o x y g e nc o n s u m p t i o n d u r i n g 5 d a y s o f i n c u b a t i o n a t 2 0 C i n f i l t e r e d s a m p l e s .I n h ib i t i o n o f n i tr i f ie r s w as ach i ev e d b y ad d in g 2 mg l i t r e - 1 a l l y l th io u r ea .T h e t o t a l r e m o v a l o f o r g a n i c p o l l u t a n t s w a s m e a s u r e d o n f i l t e r e dsamp les i n an a t t em p t t o d esc r ib e t h e r em o v a l e f f i c ien cy f o r d i s so lv edBO D . S in ce co l lo id s can b e o f a .s ize t h a t i s sma l l e r t h an th e p o r e s ize o ft h e f l t e r p a p e r s , c o l l o id s c o n t r i b u t e t o a c e r t a i n d e g r e e t o t h e m e a s u r e dd i s so l v e d B O D .N o a t t e m p t w a s m a d e t o i so l a te o r i d e n t if y t h e m i x e d b a c t e r i a l p o p u -l a t io n s t h a t d e v e lo p ed o n th e b io f i l t e r su b s t ra t e s .I t i s im p o r t an t to n o t e t h a t t h e b io f i lt e r s w er e o p e r a t e d a t a co n s t an th y d r au l i c fl o w r a t e d u r in g eac h o f t h e s tu d y p e r io d s ( see T ab le 1 ).


6/18

84 G . K r i in e r , t l . R o s e n t h a l

R E S U L T SD i u r n a l v a r i a t i o n s o f w a t e r q u a l i t y in v a r i o u s b i o f i l t e r sH i g h - l o a d t r ic k l in g f i lt e r A ( 64 k g f i s h m - 3)T h e d i u r n a l v a r i a t i o n s o f p H , t o t a l a m m o n i a , n i t r i t e a n d B O Dco n ce n t r a t i o n s a t t h e i n l e t an d o u t l e t o f t r i ck lin g f i lt e r A a r e g iv en in F ig .1. T h e c u r v e s a r e b a s e d o n h a l f - h o u r l y c o m p o s i t e s a m p le s .T h e p H v a lu es v a r i ed b e tw een 6 .0 an d 6 .3 a t th e f i lt e r i n le t . T h e p H o fth e w a te r w as co n s i s t en t ly l o w e r ed in t h e b io f i l te r so t h a t t h e o u t l e tv a lu e s w e r e o n a v e r a g e r e d u c e d b y a b o u t 0 . 0 3 u n it . T h e v a r i a ti o n s o fp H a n d o f to t a l a m m o n i a c o n c e n t r a t io n at t he i n le t d e p e n d e d o n t h o s e o ft h e e n t i r e r e c y c li n g s y st em . M a x i m u m p H v a lu e s o c c u r r e d a t t h e s am et ime a s t h e m ax im u m to t a l am m o n ia v a lu es , u su a l ly w i th in 4 h a f t e r f eed -ing the f i sh .T o t a l a m m o n i a - n i t r o g e n c o n c e n t r a t i o n s i n t h e b i o f i l t e r i n l e t v a r i e dc o n s i d e r a b l y o v e r a 1 2 - h o b s e r v a t i o n p e r i o d , b e g i n n i n g d i r e c t l y a f t e rfeed ing . Values r ang ed f ro m 0 .78 to 2 .89 mg N l i tr e -~ 8 h a f te r f eed ing .T h e o u t l e t c o n c e n t r a t i o n s r a n g e d b e t w e e n 0 . 19 a n d 1 .3 3 m g N l i t r e -T h e e f fi ci en c y o f t o ta l a m m o n i a - n i t r o g e n o x i d a ti o n d e c r ea s e dd i r e c t ly a f t e r f e e d i n g f r o m 6 0 % t o j u s t o v e r 2 0 % a n d r e t u r n e d 4 h l a t e rt o t h e e a r l i e r o x i d a t i o n - r a t e o f 6 0 % , f l u c t u a ti n g b e t w e e n 6 0 % a n d 3 0 % .D u r in g n ig h t time th e d e g r a d a t io n e f f i c ien cy w as q u i t e co n s t an t a t lev e lsa r o u n d 6 0 % .T h e n i t r i t e - n i t r o g e n c o n c e n t r a t i o n s t a r te d a t a r e la t iv e ly l ow v a l u edu r ing m orn ing ho urs ( in le t 0"33 m g N l i t r e -~ , ou t le t 0 .21 mg N l i tr e -~ )b u t i n c r e ased co n s t an t ly d u r in g th e d ay , r each in g a p ea k ab o u t 1 3 h a f te rf eed in g (i n le t 0 .8 5 m g N l i tr e - ~ , o u t l e t 0 .7 6 mg N l it re - ~ ) . T h e d ec l in eb eg a n th e r ea f t e r. A f t e r f eed in g , t h e r ed u c t io n e f f i c ien cy o f n i t ri t ed ec r eased to a lm o s t ze ro , b u t i n c r eased s t ead ily 4 h l a te r , r each in g th ein i ti a l e f f i c ien cy ab o u t 1 8 h a f t e r co m m en ce m en t o f f eed in g .C a r b o n a c e o u s ( B O D ) l e v e l s d u r i n g t h e e x p e r i m e n t a l p e r i o d r a n g e df r o m 2 0 m g O ~ l it r e -~ d i r ec t l y a f t e r f eed in g to ab o u t 4 m g O , l i t r e -d u r in g n ig h t t ime ( b io f il t e r i n le t) . T h e cu r v e f o r B O D 5 d eg r ad a t io n e ff i-c i e n c y s h o w e d its m i n i m u m a b o u t 6 h a f t e r f e e d in g a n d d e c l i n e d f r o m6 0 % to 1 0 %, i n d i ca t i n g t h a t th e n i t r i f i ca t io n p r o ces s b e cam e in c r eas in g lyim p o r t an t ab o u t 1 .5 h a f te r f eed in g .F ig u r e 2 sh o w s a t tw o d i f f e r en t p H r an g es ( p H 6 "1 .-6 .3 an d 6 .5 - 6 .6 )th a t t h e n i t r i f i ca t i o n p r o ces s i s h ig h ly d e p e n d en t o n t h e l o ad o f o r g an icm a t t e r, a n d t h a t t o t a l a m m o n i a - n i t r o g e n c o n v e r s i o n e f f ic i e n cy is a l m o s tneg l ig ib le a t h ig h o rgan ic load ings .


7/18

O r c a d i a n periodicity of biological oxidation 85pH

6 3 1 = * - - , m e t ~ . , . . & , , ~ , - - o u t l e t

N-NH~ I( r a g L t )O3-

/ ~ i o - - inlet" : . . : " / i . ~ i *--outle~0 2 , ; , / i ~ ,

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,O O o o. . . . J " _ o , . ,""

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5 0 - " ~ . " ' , , " ~ ' ~ " ~ , . ., ,. " - '% , . .. .~ . . . . . . . ..- ~ - - ~ . . .. . . .

t~ e g r a d a t , o n e f f i c i e n c y

6 0 !

i 6 . / ' ~ " 80D 52 0 i ~ i . , a . 9 ' / = N - N H ~

1 ; ' p , . - " . - N O :O ( 3 0 ! ~ 2 0 0 1 6 ' 0 0 2 0 ' C0 2 & ' O 0 4 ' 0 0 t l m e o f d a y

F i g . 1 . W a t e r t r e a t m e n t i n a h i g h - l o a d f i s h c u l t u r e s y s t e m u s i n g tr i c k l in g f il te r s: t i m ec u r v e s fo r p H , t o t a l a m m o n i a - n i t r o g e n , n i t r i t e - n i tr o g e n , B O D s a n d t h e r e la t ed r e l a ti v e

d e g r a d a t i o n e f f i c ie n c i e s ( b a s e d o n i n it ia l c o n c e n t r a t i o n ) . A r r o w = fe e d i n g t i m e .


8/18

86 G. Kr i iner , H. Rosen tha ld e g r a d a t i o n e f f i c i e n c y N -N H ~ , { * / ,}100

\~o y = 27 7-3 71 n xo \ r = - 0 . 9 4 8 n = 3 6p H = 6 . S - 6 . 6

o o o o

y : 156 - 19 In x o~R.r = - 0 . 8 2 0 n = 3 6 k; )H= 6.1 - 6.3 I I

O

0 I 0100 500 1000f l O D s - s p a c e l o a d {g .m ~3,d " I )Fig. 2. T ota lamm onia-nitrogen rem oval in a trickling filter at tw o d ifferent pH rangesin relation to the B aD :s p ac e load. n = number of observations; r--coefficient o fcorrelation; dots ---pH range 6.1-6.3; circles - p H range 6.5-6.6.

T h e d i ss o lv e d B a D r e m o v a l a s a f u n c t io n o f t he B a D : s p a c e l oa d in ga t t w o d i ff e r e n t p H r a n g e s ( p H 6 . 1 - 6 . 3 a n d 6 - 5 - 6 .6 ) w a s d e m o n s t r a t e d( F ig . 3 ) f o r o n e o f t h e t e s t e d b i o f il te r s . F r o m t h e s e d a t a it is o b v i o u s t h a tt h e r e m o v a l o f B a D is h i gh ly d e p e n d e n t o n p H l ev e l a n d t ha t th e p e r-c e n t a g e r e m o v a l i n c re a s e s a s B a D : s P a c e l o a d i nc r ea s es .L ow - lo ad tr ick ling f i lt e r B (1 .2 kg f i sh m -~)F i g u r e 4 s h o w s t h e d a il y f lu c t u a ti o n s o f p H , a m m o n i a , n i tr i t e a n d B a Dc o n c e n t r a t i o n s a t t h e i n l e t a n d o u t l e t o f t r i c k l in g fi lt e r B ( fl o w r a te 4 m 3h - ~ c o n s ta n t ly ) . T h e p H v a r i e d b e t w e e n 8 .0 a n d 8 .1 a t t h e in l e t a n d w a sa l w a y s h i g h e r ( o n l y o n e t i m e lo w e r ) i n t h e o u t l e t ( a b o u t 0 . 0 7 u n i t) .P r io r t o f e e d in g , t h e t o ta l a m m o n i a - n i t r o g e n c o n c e n t r a t io n i n th eb i o f il te r in l e t v a r i e d b e t w e e n 0 - 0 7 8 a n d 0 . 0 3 9 m g N l i t r e - ~ d u r i n g 11 ha f te r t h e f ir st fe e d i n g . A t t h e s a m e t i m e t h e o u t l e t c o n c e n t r a t i o n s r a n g e db e t w e e n 0 . 0 1 6 a n d 0 -0 3 1 m g N l it re -~ . T h e o x i d a t i o n e f f ic i en c yi n c r e a s e d f r o m 3 5 0 d u r i n g t h e e a rl y m o r n i n g to a b o u t 6 0 % w i th i n 1 0 ha f t e r t h e f ir s t f e e d i n g .


9/18

Circadian periodicity o f biological oxidation 8 7

Fig. 3 .

80-

50

d e g r a d a t i o n e f f i c i e n c y B OD s P /= )Yr

pH

o

% o o

0 0

/ : O oo

= - 1 0 5 + 2 5 l n x= 0 8Z .1 n = 2 7= 6 5 - 6 . 6

y = - 6 * 9 I n xr = 0 5 0 9 n = 3 6p H = 6 . 1 - 6 . 3

0 I i100 500 1000

B O D s - s p a c e l o a d ( g m ' 3 . d -1)D i s s o l ve d BO D ~ r e m ova l e f f i c i e nc y i n a t r i c k l i ng f i l t e r a t t w o d i f f e r e n t pH

r a nge s i n r e l a t ion t o t he BO D s - s pa c e l oa d .

T h e i n le t n i t r i t e - n i t r o g e n l ev e l i n c r e a s ed c o n s t a n t l y a n d c o n s i d e r a b l yo v e r d a y t i m e ( 0 - 0 3 - 1 - 0 7 m g N l i t r e - ' ) ; m a x i m u m n i t r i t e c o n c e n t r a t i o n so c c u r r e d s i m u l t a n e o u s l y w i t h t h e m a x i m u m t o ta l a m m o n i a - n i t r o g e nv a lu e s . T h i s t r e n d is d u e t o t h e d r a s t i c a ll y d e c r e a s e d d e g r a d a t i o n e ff i-c i e n c y o f t h e s e c o n d s t e p o f n i t r i f i c a t i o n r a n g i n g b e t we e n 8 0 a n d 3 0 %i m m e d i a t e l y a f te r f e e d in g b u t r e c o v e r i n g t o m o r e s t a b le v a lu e s o f a b o u t60 % 2 h l at e r.L o w - l o a d s u b m e r g e d r o t a ti n g c o n t a c t o r ( S R C ) ( 1.2 k g f i s h m --~)T h e d i u r n a l v a r i a t i o n s o f p H , t o t a l a m m o n i a a n d n i t r i t e a t t h e i n l e t a n do u t l e t o f t h e SR C a n d t h e a s so c i a t e d e f f i c i e n c i e s o b t a i n e d f o r t h e sefac to r s a re d ep ic t e d in F ig . 5.T h e i n l e t v a l u e s fo r t h e S R C a r e a l m o s t i d e n t ic a l to t h o se f o r t r i c k li n gf il te r B ( p H - - 8 . 0 - 8 . 1 ; N - N H ~ - = 0 - 0 4 - 0 . 0 8 m g N l it re -~ ; N - N O ; - =0 . 0 6 1 - 0 - 1 0 7 m g N l i t r e - ~) s i n c e b o t h u n i ts we r e o p e r a t e d i n p a r a l le l b y -p a s se s o f th e s a m e r e c y c l i n g sy s te m .T h e o u t l e t v a l u e s o f p H we r e c o n s t a n t a t 8 .3 , w h i c h m e a n s a n i n c r e a seo f a b o u t 0 .2 u n i t. T h e o u t le t c o n c e n t r a t io n s o f t o ta l a m m o n i a - n i t r o g e ni n t h e SR C r a n g e d f r o m 0 "0 3 9 t o 0 - 0 3 1 m g N l i t r e - ' . T h e r e m o v a l e f f i -c i en c y i n c r e as e d c o n s t a n t l y f r o m n e a r ly 2 % t o m o r e t h a n 4 0 % 7 h a ft e rt h e fi rs t f e e d i n g a n d d e c r e a s e d d u r i n g n i g h t ti m e t o v a l u e s o f a b o u t 4 % .


10/18

8 8 G. K r i i ner , H . Rosen th a lp H

8 3 1 * - - i n l e te - - o u t l e te 2 . . . . . _ :

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N ' N H Z( r a g L I )

0 0 8 -

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d e g r Q d a t l o n e f f i c i e n c yiO/o) /

' ; ) 9 , d '~1 \

8 0 0 ~ 1 2 O 0 1 6 0 0 ~ 2 0 0 0 2 / -0 0 ~ . 0 0 h m e o f d a y

F i g . 4 . W a t e r t r e a t m e n t in a l o w - l o a d f is h c u l t u r e s y s t e m u s i n g tr i c k l in g fi lt e r B p a r a l le lt o a s u b m e r g e d r o t a t i n g c o n t a c t o r : t i m e c u r v e s f o r p H , t o t a l a m m o n i a - n i t r o g e n ,n i t r i t e - n i t r o g e n a n d t h e r e l a t e d r e l a t i v e d e g r a d a t i o n e f f i c i e n c i e s ( b a s e d o n i n i t i a l

c o n c e n t r a t io n ) . A r r o w = f e e d i n g t i m e .


11/18

Ci r cadian per i od ic i ty o f b io log ical ox ida t ion 8 9

pHf

8 2 7 * - i n l e t/B t - . - o u t l e t

i

L , i , , ,

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0 0 / . -ft., ~ P ' K o . . ~ r '~ " ~

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t ~

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u= '='e'~'o----o*...~.~x0 0 8 . ~ " * ' , .,w \= p "r \;= = ~ = . . \ \

I a , f l , ,, a . . o , p ,. u ~ A P " q r 4 " ~ a ~ x x \ x xL " ~ P " ~ / ~ " ,0 0 / . , ! " - , , , . , ~ " " ~ '~ '~ ' . . . . l e t " . ~ "

* - o u t l e t ~ " . x0 J " ' 8

0egrodot ion efh oency

" ! 1 1 / " , , ~ , , , . . . ~ Y ' - - - - , . " : ~ , , - - . . .I - , 1 t " , ~ ~" . : " = ~ . ,~ ' . . P ' ~ ' " . - , . ' . . " : ~4 " v " V ' / " . , ' ~ " i : - " T " " .| - - A ' ~ : " , ~ .2 0 ~ , ,d = N - N I "I ~ _ " ~

, , ,? = N-NO~ " '- -- . "~O I= ! ""8 0 0 t 1 2 ' 0 0 1 6 ' 0 0 ~ 2 0 ' 0 0 2 L ' 0 0 & ' 0 0 t , m e o f d o y

F i g . 5 . W a t e r t r e a t m e n t m a l o w - l o a d f i s h c u l t u r e s y s t e m u s i n g a s u b m e r g e d r o t a t i n gc o n t a c t o r p a r a l l e l t o t r i c k l i n g f i l t e r B : t i m e c u r v e s f o r p H , t o t a l a m m o n i a - n i t r o g e n ,n i t r i t e - n i t r o g e n a n d t h e r e l a te d r e l a t iv e d e g r a d a t i o n e f f i c i e n c i e s ( b a s e d o n i n it ia l

c o n c e n t r a t io n ) . A r r o w = f ee d i n g t i m e .


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9 0 G. Kr i iner, H. Ros en tha l

T h e o u t le t c o n c e n t ra t io n s o f n i t ri te - n i tr o g e n d e c r e a s e d f r o m 0 . 0 4 3 t o0 . 0 0 7 m g N l i t re - ~ 1 5 h a f t e r t h e fi r st f e e d i n g . T h e d e g r a d a t i o n e f fi -c i e n c y v a r i e d b e t w e e n 3 0 % a n d 4 5 % 6 h a f t e r t h e f i r s t f e e d i n g a n dd e c r e a s e d c o n s t a n t l y f r o m t h is le v e l t o 1 0 % e a r l y i n t h e m o r n i n g .D e g r a d a t i o n e f f ic i e n c y o f t o ta l n i t r i te - n i t r o g e nT h e n i t r i t e v a l u e s h a v e t o b e c o n s i d e r e d i n r e l a t i o n t o t h e t o t a l n i t r i t ed e r i v e d f r o m t h e i n l e t t o t a l a m m o n i a . S i n c e t h e t o t a l a m m o n i a o x i d i z e df r o m t h e m e d i u m h a s t o p a s s t h e n i t r it e s t e p , n i t r if i c a ti o n o f n i t ri te c a n b ed e s c r i b e d b y c a l c u l a t i n g t h e d i f f e r e n c e b e t w e e n t h e n i t r i t e - n i t r o g e no u t l e t v a l u e s a n d t h e t o t a l n i t r i t e - n i t r o g e n p r o d u c e d i n t h e u n i t ( i n l e tm i n u s o u t l e t t o ta l a m m o n i a - n i t r o g e n c a l c u la t e d a s n i t r i te - n i t r o g e n p l usi n le t n i t r i t e - n i t r o g e n ) .F i g u r e 6 s h o w s t h e n i t r i f i c a t i o n e f f i c i e n c y o f t h e t o t a l n i t r i t e - n i t r o g e no f t h e t h r e e b i o f i lt e rs . T h e d e g r a d a t i o n e f f ic i e n c y i n b o t h t ri c k li n g f il te r sf e l l d r a s t i c a l l y a f t e r f e e d i n g t h e f i s h . T h e d e g r a d a t i o n e f f i c i e n c y i nt ri ck li ng f il te r A ( N - N O 2 : 0 - 0 2 - 0 . 2 m g N d a y -1 m -2 ) d e c r e a s e d f r o m

d e g r a d a t i o n e f f , c i e n c y N - N O ~(%)

8 0

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? r ' V +++~'+ ./ \ .? + . + / x , . . .. / . ,+ t r i c k l i n g f i l t e r A " - . .~J~, . t r i c k l t n g f t l t e r B

s u b m e r g e d r o t a t i n g c o n t o c t o r

0 8 / 0 0 , 2 1 0 0 , 6 ' 0 o 2 0 ' 0 0 2 ~ ' 0 0 ~ b o t i m e of dayF i g . 6 . C o m p a r i s o n o f s e c o n d - s t e p n i t r i f i c a t i o n e f f i c i e n c y in b i o l o g i c a l f i l t e r s d u r i n go n e d a i l y c y c le : t r i a n g l e = t r i c k l i n g f i l t e r A c o n n e c t e d t o h i g h - d e n s i t y f i s h c u l t u r er e c i r c u l a t i n g s y s t e m ; c i r c l e s = t r i c k l i n g f i l t e r B ; d o t s = S R C j o i n t ly c o n n e c t e d t o a l o w -

d e n s i t y c u l t u r e s y s te m . A r r o w = f e e d i n g t im e .


13/18

Circadian periodicity o f biological oxidation 917 5 % t o 2 3 % , a n d t r ic k l in g f i lt e r B ( N - N O f : 0 . 0 2 - 0 . 0 1 nag N d a y - 1 m - 2)f r o m 8 8 % t o 4 2 % . A 7 0 % d e g r a d a t i o n p la t e a u w as r e a c h e d b y t ri c kl in gf i l t e r B af te r 2 h a nd af te r 4 h in t r i ck l ing f i l t e r A . F i l t e r A was , inco n t r a s t t o f i lt e r B , v e r y u n s t ab l e an d th e e f f i c ien cy v a r i ed g r ea tl y , w i th4 5 % o f v a lu e s f a ll in g b e t w e e n 4 5 % a n d 8 0 % r e m o v a l.T h e S R C ( N - N O f : 0 . 0 3 - 0 -1 m g N d a y -1 m - z ) h a d a r e la t iv e l y c o n -s t an t i n c r eas e i n n i t r i f ica t i o n e f f i c ien cy f r o m 2 8 % d i r ec t l y a f t e r f eed in gth e f ish t o 5 8 % 7 h l a t er , f o l l o w e d b y a d e c r eas in g r a t e d u r in g n ig h t t imet o r e a c h 1 5 % e a r l y i n t h e m o r n i n g .

D I S C U S S I O NT h e r e su lt s o f o u r i n v e s t i g a t io n i n d i ca t e t h a t h ig h lo ad in g w i thsu sp e n d e d an d co l lo id a l p a r t i c l e s s ig n i f ican t ly l o w er s t h e n i t r i f ica t i o nr a te . A d ec r ease d n i t r i f i ca t io n r a t e , w h en co l lo id a l p a r t i c le s a r e p r esen t ,w i ll n eces sa r i l y a ff ec t t h e d es ig n o f t h e p r e t r ea tm en t p r o ces ses . A l a r g ep a r t o f t h e n o r m a l B O D w i ll h a v e to b e r e m o v e d i m m e d i a t e l y a f t er th ew a te r l eav es th e f i sh t an k ( o u tl e t) an d p r io r t o en t r y o f w as t ew a te r s t o t h en i t r i f i ca t i o n u n i t.D a t a f r o m b o t h s tu d ie s d e s c r ib i ng B O D 5 r e m o v a l a n d t h e c o m b i n e dr e m o v a l o f B O D 5 a n d n i tr o g e n -s p e c ie s d e m o n s t r a t e d t h a t s h o c k l o a d sp r o d u c e a d r a m a t i c a n d r a p i d d e t e r i o r a t i o n in e f fl u e n t q u a li ty .I t was f e l t tha t a r ea l i s ti c appra i sa l o f n i t r i f i ca t ion k ine t ics in them a r i n e c u l t u r e e n v i r o n m e n t w o u l d b e o b t a i n e d i f l a rg e m i x ed p o p u l a -t io n s o f n i t ri f y in g b a c t e r i a w e r e m a i n t a i n e d u n d e r a d e f i n e d s e t o f c o n d i-t i o n s f o r r e l a t i v e ly l o n g p e r io d s o f t ime ( i n t h is s t u d y 8 m o n th s ) .

L o n g - c h a i n e d o r g a n ic c o m p o u n d s c o n t a in i n g a s tr o ng l y p o l a r g r o u pw i ll f o r m o r i e n t ed l ay e r s a t t h e w a te r su r f ace . It s eems p o s s ib l e t h a t t h esel ay e r s co u ld ac t a s a d i f f u s io n b a r r i e r f o r o x y g en th r o u g h su r f aces. Su chb ar r i e r s w o u ld a l so a l t e r su r f ace d y n am ics an d a f f ec t t h e t r an s f e r co e f f i-c i e n t o f o x y g e n a n d o t h e r g as es .T h e p e r f o r m a n c e o f b io l o g i ca l f il te r s i n r e m o v i n g o r g a n i c m a t e r ia la n d n i tr i fy i n g its n i t r o g e n c o m p o n e n t s is a f fe c t ed b y m a n y d e s ig n f a c to r ssu ch a s t h e d ep th o f th e f i lt e r, h y d r au l i c lo ad an d s ize an d sh ap e o f th em e d i a . F u r t h e r m o r e , t h e p h y s i c o - c h e m i c a l c h a r a c te r i st ic s o f t h e w a s te -w a te r , an d th e am p l i t u d e o f d a i l y f l u c tu a t io n s o f v a r io u s w a te r q u a l i t yp a r a m ete r s p l ay a d ec i s iv e r o l e in t r ea tm en t e f f i c ien cy ( M eh ta e t a l . ,1 9 7 2 ; S t en q u i s t e t a l . , 1 9 7 4 ; Po r t e r an d Smi th , 1 9 7 9 ; K f i i n e r an dR o s e n t h a l , 1 9 8 3 ; H i l g e a n d R a k e l m a n n , 1 9 8 4) . I n a n a e r o b i c b io l o g i c a ls y st em , t h e B O D r e d u c t i o n r e su l ts f r o m b i o c h e m i c a l a c ti v it y o f h e t e r o -t r o p h ic b ac t e r i a . Po r t e r an d Sm i th ( 1 9 7 9 ) sh o w ed th a t t h e e ff i c ien cy o f


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92 G . K r i i n e r , H . R o s e n t h a lB O D r e m o v a l i n a b i o f il t e r o f a g iv e n t o t a l v o l u m e is d e t e r m i n e d m a i n lyb y t h e s u r fa c e a r e a a v a i la b l e f o r b a c t e r i a l a t t a c h m e n t p e r u n i t v o l u m e o fp l a s t ic m ed ia .O x id a t io n o f t o t a l am m o n ia t o n i t r a t e i n aq u a t i c so lu t i o n s ut il ize s d i s-so lv ed o x y g en a n d w i ll o cc u r o n ly i f t h e o x y g en is ma in t a in ed a t l ev e lst h a t p r e v e n t t h e d e v e l o p m e n t o f a n a e r o b i c c o n d i t i o n s . O x y g e nc o n c e n t r a t i o n s i n t h is s t u d y w e r e s t o i c h io m e t r ic a l l y g r e a t e r t h a n t h a tr e q u i r e d f o r c o m p l e t e o x i d a t i o n . T h e r e q u i r e m e n t s f o r n i t r if i c a ti o n a r eth e p r e sen c e o f am m o n ia , o x y g en , t r ace n u t r i en t s , an d a r e l a t iv e ly l o wlev e l o f o r g an ic ca r b o n in t h e b io lo g i ca l f il te r . L i t tl e i n f o r m a t io n ex is ts o nt h e o p t i m u m c o n d i t i o n s fo r n i t r if i c a t io n i n a c o m b i n e d c a r b o n o x i d a -t i o n - n i t r i f i c a t i o n s y s te m i n v o lv i n g p l a st ic m e d i a. T h e r e a r e f e w d a t a o nth e m ax im u m sp ec i fi c g r o w th r a t e f o r n i t r if y in g o r g an i sm s a t 2 0 C , i n d i-c a t in g t h a t s u c h v a lu e s a r e m u c h l o w e r t h a n t h o s e f o r h e t e r o t r o p h i c b a c -t e r i a ( Pa in te r , 1 9 7 5 ; W ick in s , 1 9 8 3 ) , an d th a t n i t r i f i ca t io n i s g en e r a l l yd e p e n d e n t o n t h e o r g a n i c l o a d i n g a n d o n t e m p e r a t u r e ( S t e n q u i s t e t a l . ,1974) .U n d e r t h e p h y s i c o - c h e m i c a l c o n d i t io n s c o m m o n l y f o u n d i n w ell-ae r a t ed w as t ew a te r s , o x id a t io n p r o ces ses o cc u r a t a d e t ec t ab l e r a t e o n lyi n th e p r e s e n c e o f c e r ta i n c h e m o - a u t o t r o p h i c a n d h e t e r o t r o p h i c b a c te r i a( Fo ch t an d V er s t r ae te , 1 9 7 7 ) . T ab le 2 p r o v id es t h e d a t a o b t a in ed d u r in go u r e x p e r i m e n t s. T h e r a te o f o x i d a t i o n o f c a r b o n a c e o u s m a t t e r is a ls od e p e n d e n t o n t h e m u l t ip l i c a t io n r a t e o f b a c te r ia . M o s t b a c t e r ia o b t a i nt h e i r f o o d a n d e n e r g y r e q u i r e m e n t s f r o m o r g a n i c m a tt er . T h e o x i d a t i o no f ca r b o n aceo u s ma te r i a l i s ca r r i ed o u t i n t h e f i r s t s t ag e BO D r eac t io n .I n g e n e r a l it w a s f o u n d t h a t t h e u p p e r h a l f o f t h e b i o f il te r r e m o v e s m o r e

T A B L E 2Typical Range s of Phys ico -chem ical Var iab les in We l l -aera tedRec i rcu l a t i on F i sh C u l tu re U n i tsV a r i a b l e S y s t e m I S y s t e m 11

64 kg m - "~ 1 .2 kg m - "~Te m pera ture (C) 25 .8 21 .5Salinity (%o) 12"9 20.0pH 6 . 05 -6 -27 7 . 97 -8 ' 07N H 3 (mg l i t re- ~) 0 .000 4-0 .003 0-001 -0 .004N-N Hj" (nag l i t re- ~) 0 .47-2 .81 0 .03-0 .08N -N O r (mg l i t re- ~ 0"21-0"88 0 .04-0-10N-N O~ (mg l i t re-J ) 36 .1-39"7 22 .6-2 3 .2D O (mg l i tre-~) 5-9-7.7 7-1-8"5BOD 5 (mg l i t re- ~) 3.4-20 "0 1.0-5"4


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Circadian periodicity o f biological oxidation 93organic m at ter tha n the lower hal f and that n i tr if ica t ion n orma l ly occursin the deeper zones of the f i l t e r (Balakr i shnan and Eckenfelder , 1969;Re nnh ack, 1982; Kr i iner and Ro senthal , 1983) . Th e n i t ri fy ing bacter iaare not able to compete eff icient ly with the organo-heterotrophicbacteria unless they have plenty of substrate. The ni t r i f iers also-dependon the re lease of inorganic n i t rogen com pou nds f rom the organic m at terwhich i s usual ly degra ded by the he tero t rophs .Normally, ni t r i f icat ion rates are s t rongly influenced by pH becauseni t r i f i ca t ion produces two mole hydrogen ions for each mole ofammonia oxid ized , which leads to pH lower ing dur ing the process . Thedec reas e o f pH value causes , in turn, the lowering of the ni tr i ficat ion rate.Apar t f rom that , the change of pH may a l so inf luence the react ion ra teindirectly.S rna and Bagga ley (1975) showed tha t the op t imum p H fo r comple teni t r if icat ion is aro un d pH 7.45 in a sub gravel f il ter and effective ni t ri f ica-t ion i s achieved between pH values of about 7"0-8 .2 ( tempera-tu re = 2 0-24 C ; sa l in i t y= 26 + 2%0). Wi ld e t a l . (1971) showed a pHopt imum for n i t r i f i ca t ion in f reshwater a t pH 8 .4 . Haug and McCarty(1972) repo r ted the ada pta t ion of n i tr if iers on a subm erged f i l te r to pHlevels between 6.0 and 5.5 within about 10 days. Ni t r i f icat ion ceasedcom plete ly below pH values of 5-5 ( tem pe ratu re= 25C; f reshwater) .McHamess and McCar ty (1973) ob ta ined ev idence tha t n i t r i fy ingbacter ia cou ld be cond i t ioned to opera te a t m axim um effic iency ev en a trelatively low pH values i f they w ere held at low p H levels fo r a sufficientlength of t ime ( tem per ature = 20C; freshwater) .The pH range inves t igated in our s tudies was between 6 .05 and 6 .27in system I (64 kg f ish m -3) and betw een 7.97 an d 8.07 in system II (1.2kg f ish m-3). The reduct ion in pH values from 8"3 to 8"0 in the SRC (intr ickl ing fi l ter B the pH dr op pe d only 0.1 unit ) is a conse quen ce of lesseff icient s t r ipping of carbon dioxide from the mixed l iquor by the rela-t ively smal l volume of gas discharged to the atmosphere via aerat ion.Very lit tle wo rk h as been carr ied out o n the effect of high con cen trat ionsof oxygen and ca rbon d iox ide on the g rowth and metabo l i sm of t hemajor bacter ia l groups involved in water t rea tment . Jones and Paskins(1982) repor ted that carbon d ioxide concent ra t ions in the aera t ion gasranging between 0 .03 and 2% of the to ta l gas content do not af fec t thegrowth cons tants of N i t r o s o r n o n a s ( t e m p e r a t u r e = 2 0 C ; p H = 7 . 8 ) ,whereas high concentrat ions of oxygen are ini t ial ly inhibi tory to N i t r o -s o m o n a s and m ay a l so be inhib itory to the growth of N i t r o b a c t e r .The ser ies of vary ing peaks super imposed on the genera l ly cons tantto ta l ammonia-n i t rogen degradat ion ef f ic iency observed 5 h af ter feed-ing in t r ickl ing f i l ter A probably represents a real phenomenon, because


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94 G. Kriiner, H. Rosenthalt h e d a t a p o in t s f a l l w e l l o u t s id e t h e r a n g e o f an a ly t i ca l e r r o r . A lm o s t t h es a m e b e h a v i o u r i n to t a l a m m o n i a - n i t r o g e n o x i d a ti o n h a s b e e n o b s e r v e din t h e o th e r tw o b io f i lt e r s.T w o h o u r s a f t e r f e e d in g , t h e t o t a l a m m o n i a - n i t r o g e n o x i d a t i o n r a t e inb o th b io f i l t e r s w i th a l o w b io m ass l o a d ( t ri ck lin g f i lt e r B an d SRC ) w asa l m o s t u n i f o r m d u r i n g t h e e n t i r e e x p e r im e n t . T h i s o b s e r v a t i o n i n d ic a t e sth a t t h e n i t r i fi e r s w o r k ed n e a r t h e i r max im u m e f f i c ien cy a t a l l t imes , an dw e r e , t h e r e f o r e , l a r g e l y i n d e p e n d e n t o f t h e r e s i d u a l o f t o t a la m m o n i a - n i t r o g e n c o n c e n t r a t i o n o cc u r r in g d u r in g t h e e a r l y m o r n i n gh o u r s . B o t h N i t r o s o m o n a s sp . an d N i t r o b a c t e r sp . a re usua l ly sens i t ive int h e i r m e t a b o l i c a c ti v it y t o c h a n g e s i n n i t r o g e n o u s s u b s tr a te c o n c e n t r a -t i o n s , w h ich a r e t h e i r e s sen t i a l su b s t ra t e s . A d d i t i o n a l ly , t h ese n i tr i f y in gs p e ci e s a r e a l s o i n f l u e n c e d b y t h e c o n c e n t r a t i o n o f o r g a n ic l o a d w h i c hu s u a ll y s u p p o r t s o t h e r b a c t e r i a l g r o u p s s u c h a s t h e h e t e r o t r o p h s ( P a i nt er ,1 9 70 ). T o t a l a m m o n i a - n i t r o g e n a n d n i t r i te - n i t r o g e n c o n c e n t ra t io n s i nw a s t ew a te r f r o m f i sh cu l tu r e d o n o t u su a l ly r eac h l ev e ls t h a t i n h ib i t t h eac t iv i ty o f n i t r if i e r s .R e c e n t l y W i l d e t a l . ( 1 9 7 1 ) f o u n d , a m o n g o t h e r f a c t o r s , t h a t t o t a la m m o n i a - n i t r o g e n a t a c o n c e n t r a t i o n o f a b o u t 4 6 . 8 8 m g N l i tr e - ~ n t h ee f f lu en t d id n o t h av e an y in h ib i to r y e f f ec t o n t h e r a t e o f n i t r if i ca t i o n a tp H v a lu es o f 8 "5 . T h i s i s an o th e r i n d i ca t i o n t h a t t h e ac t iv i ty o f n i tr i f y in gb a c t e r i a i s n o t s ig n i fi c an t ly a f f ec t e d b y t o t a l a m m o n i a - n i t r o g e n c o n -cen t r a t i o n s n o r ma l ly en co u n te r ed i n f i sh cu l tu r e sy s t ems ( T ab le 2 ) .D u r i n g n i g h t t im e i t s e e m s t h a t t h e t o t a l a m m o n i a - n i t r o g e n c o n c e n t r a -t i o n s w er e b e lo w th e c r i t i ca l l ev el s n e ed e d to m a in t a in an ac t i v e n it r if y -i ng p o p u l a t i o n . K n o w l e s e t a l . ( 1 9 6 5 ) s h o w e d t h a t b e t w e e n 3 0 a n d 6 0 %o f a p o p u l a t i o n o f N i t r o s o m o n a s b ac t e r i a su r v iv ed w i th o u t n u t r i en t s f o rl o n g e r t h a n a 5 - d a y p e ri o d . B e t w e e n 8 0 a n d 9 0 % o f a N i t r o b a c t e r p o p u -l a t i o n su r v iv ed f o r 0 .8 d a y w i th o u t n u t r i en t su p p ly .N i t r i f i ca t i o n e f f i c ien cy h as n o t b e en f o u n d to i n c r ease s ig n i f ican t lyw i t h a d e c r e a s e i n c a r b o n : n i t r o g e n r a ti o (B a l a k r i s h n a n a n d E c k e n f e l d e r ,1 9 6 9 ) . Wi th o th e r p a r amete r s ( t emp er a tu r e , p H , D O , e t c . ) h e ld co n - "s t an t, t h e d eg r ee o f n i t r i f i ca t i o n d ec r eases s ig n if i can tly w i th an i n c r easeo f t h e o r g a n i c l o a d ( P r a k a s a m a n d L o e h r , 1 9 7 2 ) . T h e r e m o v a l o f t o t a la m m o n i a - n i t r o g e n i n r e la t io n to t he a p p l i e d B O D s - sp a c e l o a d i nt r ick l in g f i lt e r A is sh o w n in F ig . 2 . T h e r em o v a l w as g en e r a l l y b e tw e en1 0 a n d 1 0 0 % a t a p H r a n g e o f 6 . 5 -6 - 6 ( o r 1 0 - 6 5 % a t a p H r a n g e o f6 - 1 -6 - 3 ). T h e r e i s u su a l ly so m e s t r a t if i ca t i o n o f t h e h e t e r o t r o p h ic an dau to t r o p h ic m ic r o - o r g an i sms in a b io lo g i ca l f il te r , t h e h e t e r o t r o p h s t en d -i ng to o c c u p y t h e u p p e r l a y e r s w h e r e t h e c o n c e n t r a t i o n o f o rg a n i c m a t t e rin t h e f eed l i q u o r is g rea t e s t, w h i l e th e a u to t r o p h s f l o u r i sh i n t h e l o w e rr eg io n s w h er e t h e i r su b s t r a t e s a r e m o r e ab u n d a n t . I n h ig h - r a t e f i l t ra t i o n


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Circadian periodicity o f biological oxidation 95t e c h n i q u e s , h e t e r o t r o p h i c g r o w t h o c c u r s t h r o u g h o u t t h e d e p t h o f t h ef il te r, s u p p r e s s i n g t h e a u t o t r o p h i c o r g a n i s m s . H i g h B O D l o a d i n g s i n s u c hf i l t e r s w o u l d e v e n t u a l l y c a u s e n i t r i f i c a t i o n t o c e a s e b e c a u s e o f t h ew a s h i n g - o u t e f f e c t o f s l u d g e , w h i c h w o u l d a l s o a f f e c t n it ri fi e rs .

A C K N O W L E D G E M E N T SW e a r e i n d e b t e d t o M s W i e g e f o r e x p e r t t e c h n ic a l a s si st an c e d u r i n g t h ee x p e r i m e n t s , w a t e r a n a l y s e s a n d d r a w i n g s.

R E F E R E N C E SA dam s, C. E. & Eck enfe lder , W. W. (1977) . Ni tr i fi ca tion des ign appro ach forh igh s t rength ammonia was tewaters . J. W ater Pollut. C on trol Fed., 49 ,4 1 3 - 2 1 .Balakr i shnan, S . & Ec ken fe lder , W. W. (1969) . Ni t rog en re la t ionships in b io-logical t reatment processes . I . Ni t r i f icat ion in the act ivated s ludge process .WaterRes . , 3 , 7 3 - 8 1 .Focht , D. D. & Ve rst raete , W. (1977) . B ioch em ical eco logy of ni t r if icat ion anddeni t r i f icat ion. Adv. Microb. Ecol . , 1 , 1 3 5 - 2 1 4 .Grasshof f , K . , Ehrhardt , M. & Kreml ing , K. (1983) . Methods o f SeawaterAnalysis, Ver lag Chem ie , Weinhe im , FRG .G rom iec , M. J ., M al ina , J . E & Ec kenfe ld er , W. W. (1972) . Per forman ce ofplast ic m ed iu m in t r ickl ing fi lters. W ater Res., 6 , 1 3 2 1 - 3 2 .Hang, R. T. & McCarty, E L. (1972) . Ni t r i f icat ion with submerged f i l ters . J .Water Pollut. Co ntrol Fed. , 4 4 , 2 0 8 6 - 1 0 2 .He inr ich , D. (1984) . Un tersu chu ng en zur Ni t r i fika t ion von A bw i issern in iiber -

s tau ten Fes tbe t t reaktoren . Stuttg. Bet. Siedl.-wass.-wirtsch., 81 , R . O lden-bourg , Mi inchen .Hi lge , V. & Ra kelm ann, U . V. (1984) . Labo ra tory sca le exper im ents on the n i t r i-f icat ion of f ish tank eff luent in a fLxed f i lm be d reactor . EM S special pub l ica-t ion, No. 8, Research on Aqu aculture, eds H. R osen tha l & S. Sarig , pp . 5 5-6 6.H6 ner . G . (1984) . A usw irkung en dichteabh~ingiger Um w el tbed ingu ng en in derIn tens ivha l tung auf Jungf i sche von Sarotherodon galilaeus. Dipl.-Arb. Uni-versit~it M arburg, pp. 1- 12 3.Jon es, G. L. & Paskins, A . R. (1982) . Inf lue nce of high par t ia l pres sure o f carb ondiox ide and oxy gen on ni tr if ication. J . Ch em . Tec h. Biotechnol., 3 2 , 2 1 3 - 2 3 .Klem etson, S . L . & C oh en, D . (1984) . Sys tem analys is and des ign of b iof il te r sf o r t h e t h r e e c o m p o n e n t s o f Macrobrachium produc t i on . F ina l Repor tB A R D , N o . U S - 6 0 - 8 0 . pp . 1 - 1 1 7 .Know les, G ., Dow ning, A. L. & Bar re t t, M . J. (1965) . D eterm ina t ion of k ine t iccons tants for n i tr ify ing bac te r ia in m ixed cul ture ; wi th the a id of an e lec t roniccom puter . J. Gen. Microbiol., 3 8 , 2 6 3 - 7 8 .Kriiner. G. & R osen thal , H. (1983 ) . Ef ic ie nc y of ni t ri f icat ion in t r ickl ing f i ltersusing diffe ren t substrates. Aquacultural Engineering, 2 , 4 9 - 6 7 .


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96 G. Kri iner , H. RosenthalLiao , P. B. & M ayo, R . D. (1974). In ten s i f ied f ish cu l ture com bining waterr econd i t i on ing wi th po l lu t i on ab a t emen t . A q u a c u l t u re , 3 , 6 1 - 8 5 .M cH arness , D . D . & M cCar ty , E L . (1973). F i e ld s tudy o f n i tr if ica t ion wi th thesubm erged filte r. EP A R ep t . No . R2-73-1 58 , W ash ing ton DC .Meade , T . L . (1974) . The t echno logy o f c lo sed sys t em cu l tu re o f s a lmon ids .A n i m . S c i . / N O A A S e a G r a n t , T e c h n i c a l R e p o r t 3 0 , U n i v e r s i t y o f R h o d eIs land , King s ton .M eh ta , D . S. e t a l. (1972) . O xyg en theo ry in b io logica l t rea tm ent p lan t des ign . J .S a n i t a ry E n g i n e e r i n g D i v i s i o n S A 3 .Pa in te r , H . A . (1970) . A r ev i ew o f l it e r a tu re on ino rgan ic n i trogen m e tabo l i sm inmic ro -o rgan i sm. W a t e r R e s ., 4 , 3 9 3 - 4 5 0 .Pa in te r , H. A . (1975) . M icrobia l t ransform at ions of inorganic n i t rogen . I A W P R

C o n f . o n N i t r o g e n a s a W a t e r P o l l u t a n t , K o p e n h a g e n 1 9 7 5.Pl i imke , E . (1985) . Wasseraufbere i tung in e inem Fischzuchtkre i s lauf :A b b a u l e i s tu n g e i ne s D r e h t r o m m e l r e a k t o r s u n t e r v e r s c h i e d e n e n B e tr ie b s -bed ingungen . D ip l .-Arb . Fach hoch schu le H am burg , pp . 1 -91 .Por te r , K. E . & Smi th , E . (1979) . P las t ic -media b io logica ls . W a t er P o l l u t .C o n t r o l , 7 8 , 3 7 1 - 8 1 .Prakasa m , T . B. S . & Lo ehr , R . C. (1972). M icrobia l n i t r if ica t ion and deni t r if ica-t i on in conce n t r a t ed w as te s . W a t e r R e s ., 6 , 8 5 9 - 6 9 .Re nnh ack , H . (1982) . B io log isch chem ische U n te r suc hun gen f ibe r d i e E ignungd r e i e r v e r s c h i e d e n e r M a t e ri a li e n in e i n e m T r o p f k 6 r p e r z u r A u f b e r e i tu n g y o nFischabw~kssern in e inem geschlossenem Warmwasserkre i s lauf . Dip l . -Arb .Un ive r si ti it H am burg , pp . 1 -70 .R i t tmann , B . E . (1982) . Compara t ive pe r fo rmance o f b io f i lm r eac to r t ypes .B i o t e c h n o l . B i o e n g . , 2 4 , 1 3 4 1 - 7 0 .Ro sentha l , H. , And jus , R . & K r i iner , G. (1980) . D ai ly var ia t ions o f w ater qua l i typa ram e te r s u nd e r i n tens ive cu l tu re con d i t ions i n a r ecyc ling syst em. E I F A C /8 0 / S y m p . : E / 5 9 , p p . 1 - 1 0 .Ro sentha l , H . , Hoffm ann , R. , J6rgen sen , L ., K r i iner , G., Pe te rs , G. , Schlo t fe ld t ,H . - J. & S chom ann , H . (1982) . W a te r manag em en t in c i rcu l a r t anks o f a com -m erc ia l in tens ive cu l ture uni t a nd it s e ffec t s on w ater qua l i ty and f ish cond i -t ion. I C E S C M . 1982/F. '22, pp. 1-13.Ro sentha l , H. , Chiba , K . & K r i iner , G. (1984) . D ai ly f luc tua tions of w ater qua l i tyin a rec i rcu la t ing sys tem and i t s in f luence on the per formance of a ro ta t ingbio net biolog ical fi lter . I C E S C .M . 1984/F. '20, pp. 1-11.Sekoulov , I . & Heinr ich , D. (1981) . P i lo tversuche zur Ni t r i f ika t ion in Fes t -be t t r eak to ren . W a s s er wi r t s ch a f i , 7 1 , 3 3 1 - 3 .Srna , R. E & Baggaley , A. (1975) . Kine t ic respo nse o f per turb ed m ar ine n it ri fi-cat io n system s. J . W a t e r P o l l u t. C o n t r o l F e d ., 4 7 , 4 7 2 - 8 6 .Stenquis t, R . J ., Parker , D. S . & D osh , T . J . (1974) . C arb on oxida t ion-n i t r i f ica-t ion in synthet ic media t r ickl ing f i l ters . J . W a t e r P o l l u t. C o n t r o l F e d ., 46 ,2 3 2 7 - 3 9 .Wickins, J . E (1983) . Studies on marine biological f i l ters . W a t er R es . , 17,1 7 6 9 - 8 0 .W ild, H. E . , Sawy er , C. N . & M cM ah on , T. C. ( 1971 ). Factors affect ing ni tr i f ica-t ion kinet ics . J. W a t er P o l l u t . C o n t r o l F e d . , 4 3 , 1 8 4 5 - 5 4 .

kruner 1987 aquacultural-engineering

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