Brune 1982 Aquacultural-Engineering

7/28/2019 Brune 1982 Aquacultural-Engineering

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Aquacultural Engineering 1 (1982) 63-70

D E S I G N A N D D E V E L O P M E N T O F A F L O W I N G B E D R E A C T O RF O R B R I N E S H R I M P C U L T U R E

D. E. BRUNEDe par tme nt o f Agricultural E ngineering, University o f Cali fornia, Davis 95616, USA

A B S T R A C TA n au tom a t i c s e l f- c leans ing h igh den s i t y b r ine sh r imp reac to r has been de s igned andte s t ed , and t he c on cep t appears succe s s fu l I n i t i a l e xp er im en t s sugges t t ha t e x t ra -ord inari ly h igh dens it i e s o f b r ine sh r imp ma y be ma in ta ined i n such a s y s t em . The con -cep t o f a f l ow ing f i lm o f glas s beads appears t o be a ve ry u se fu l t e chn ique in s cour ingwas t e ma te r ia l f ro m an ima l cu l t u re t anks . The c on cep t i s par t i cu la r l y u se fu l f o r cu l t u reo f sm a l l mar ine he rb i vore s i n con t inu ous cu l tu re . The bead f l o w rap id l y r em oves was t ema te r ia l wh i l e a ll owing f o r wa te r passage, y e t com p le t e l y con ta in ing t he an ima ls .

F u r t h e r d e s ig n i m p r o v e m e n t a n d d e v e l o p m e n t s h o u l d r e s u l t i n a h ig h d e n s i t y b r in eshr imp cu l t u re s y s t em wh ich i s bo th s imp le and i nexpens i ve t o bu i ld , a s we l l a s r e li ab leand c os t e f f e c t i v e t o opera t e , and capab le o f e f f i c i en t a lga l c e l l r emova l f ro m cu l tu rewater .

INTRODUCTIONT h e t r e m e n d o u s p h o t o s y n t h e t i c p r o d u c t i v i t y o f m a s s a lg al c u l tu r e h a s f o r y e a r se x c i t e d b o t h s c ie n ti s ts a n d e n t r e p r e n e u r s a li ke . Y e t a f t e r 3 0 y e a r s o f e x p e r i m e n t a t i o n ,c o n s t r u c t i o n a n d o p e r a t i o n o f l a b o r a t o r y p r o t o t y p e s a n d p i lo t p la n t s , f u n d a m e n t a lp rob l em s r ema in t o be so lved be fo r e a lgal cu l t u r e can be s een a s a v i ab l e and cos te f f e ct iv e m e a n s o f p r o t e i n p r o d u c t i o n .

Three m a jo r p ro b l em s have p r even t e d t he w idesp read u t i l i z a t ion o f a lgal cu l t u r e asa p ro t e in sou rce . F i r s t , l a rge s ca l e a l ga l cu l t u r e s a r e o f t en s een t o become domina t edby un des i r ab l e ' w eed ' a lgae . Second ly , even i f a de s ir ed a lga l spec ie s c an be m a in t a ined ,m an y o f t he f a s t g rowing un i ce l l u l a r a lgae a re poo r ly d ige s ti b l e by mon ogas t r i c an ima l s.An d f ina l ly , un i ce l l u la r a lgal cu l t u r e h a s p roved t o b e d i f f i cu l t t o ha rv es t e conom ica l l y .

63Aquac ultural Engineering 0144-8609/82[0 001-0063]$ 02.75 Applied Science Publishers Ltd,England, 1982Printed in Great Britain


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6 4 D . E . B R U N EA v a r i e t y o f r e c e n t s t u d ie s h av e a t t e m p t e d t o c o m e t o g r ip s w i t h t h e s e p r o b l e m s .

P e r h a p s t h e m o s t p r o m i s i n g a p p r o a c h i s t h a t a d v o c a t e d b y R y t h e r e t a l . ( 1 9 7 5 ) i nwh ich va r i ous f 'd t e r fe ed ing o rgan i sms a r e u sed t o g l ean a lga l c e ll s f r om the cu l t u r em e d i u m a n d c o n v e r t t h e m i n t o a d es ir a b le a n d r e a d il y h a rv e s t e d a n im a l p r o t e i ns o u r c e . R y t h e r e t a l . ( 1 9 7 5 ) a n d G o l d m a n a n d R y t h e r ( 1 9 7 5 ) h a ve d e m o n s t r a t e d th euse o f s econda ry e f f l uen t f r om an ac t i va t ed s l udge was t e wa t e r p l an t a s a f e r t i l i z e r f o rc u l tu r e o f m a r i n e p h y t o p l a n k t o n . W i t h t h e a d d i t io n o f f r o m 2 0 % t o 5 0 % s ew a ge t om a r i n e p o n d s , i t w a s f o u n d t h a t a c o n t i n u o u s h i gh r a te p r o d u c t i o n o f m a r i n e d i a to m scou ld be m a in t a ined . The d i a tom s we re i n t u rn t o be u sed a s a f e ed fo r va r i ous she ll fi sh.T h e c o n c e p t o f u s in g m a r i n e h e r b i v o r e s a p p a r e n t l y s o lv e s t h e p r o b l e m o f a lg al h a rv e s t ,w i th t he a lga l cu l t u r e be ing conve r t ed i n to a u se fu l end p roduc t .

T h e m a j o r d i s a p p o i n t m e n t o f f ie l d c u l t u re s tu d i es h a s b e e n t h e i n a b i li t y t o m a i n t a i ncu l t u r e s o f de s i r ab l e a l ga l spec i e s . The mar ine cu l t u r e s a r e o f t en obse rved t o becomed o m i n a t e d b y c e r t a i n ' w e e d ' ( in m o s t o f t h e m a r i n e w o r k t h e d i a t o m P h a e o d a c t y l u m )a lgae . Unfo r tuna t e ly P h a e o d a c t y l u m as wel l as the o ther weeds a re not u t i l i zab le bym an y o f t he de s i r ed ma r ine f i l t e r fe ed ing o rgan i sms (i .e . c l ams , oys t e r s ) .

The so lu t i on t o t h i s p rob l e m l ie s i n t he s e l ec t ion o f a f i lt e r f e ed ing an ima l c apab l eo f g r o w t h o n t h es e c o m m o n l y o c c u r r in g ' w e e d s ' . O n e s u c h a n im a l , th e b r i n e s h ri m pA r t e m i a s a l i n a , has r ecen t l y r ece ived m uch a t t en t i on . T h i s an im a l s eems i dea l ly su i tedfo r a l ga l b io log i ca l conve r s ion sys t ems . The ab i l i t y o f t h i s an ima l t o u t i l i z e many o ft he f a s t g rowing domina t i ng (Takuno , 1967 ) a lgae combined w i th i t s r ap id g rowth r a t e(Reev e , 1963 ) , h igh p ro t e in co n t en t , and h igh t o l e r ance o f env i ronm en ta l s t re s s , sug -ges ts t ha t t h i s an ima l may be t he key t o f i na ll y ha rnes s ing t he po t en t i a l p rod uc t i v i t yof a lgal cu l ture .

I t i s t he i n t en t o f t h i s p r e sen t a t i on t o de sc ri be r ecen t r e sea r ch wh ich was unde r -t aken i n an e f fo r t to deve lop fu r t he r t he t e chn o logy o f h igh dens i t y b ri ne sh r impcu l t u r e .

D E S I G N M E T H O D S A N D M A T E R I A L S

P r e v i ou s c u lt u r e m e t h o d sA rec i r cu l a ti ng sh r imp cu l t u r e sy s t em was de sc r i bed by M ock et a l . ( 1973 ) . Th i s

sys t em cons i s t s p r imar i l y o f a conc re t e ha t che ry r aceway wi th a c en t e r d r a in . Was t er e m o v a l in t h i s s y s t e m w a s a c c o m p l i s h e d v i a t h e c e n t e r o u t l e t w h i c h w a s e q u i p p e dwi th e i t he r a s l o t t ed p ipe o r p l a s t i c f i l t e r s c reen t o p r eve n t an ima l lo s s . W a te r c i rcu l a -t i o n w a s m a i n t a i n e d b y t h e u s e o f m u l t i p l e a ir li f t p u m p s .

S o r g e l o o s e t a l . ( 1 9 7 9 ) u s e d a m o d i f i e d v e r s i o n o f M o c k ' s r a c e w a y s y s t e m f o rc u l t u r i n g b r i n e s h r i m p . E x p e r i m e n t s w e r e c o n d u c t e d i n w h i c h b r i n e s h r i m p w e r eg r o w n f o r p e r i o d s o f t w o w e e k s o r m o r e b y o p e r a t i n g t h e r a c e w a y s a s r e c ir c u la t in gba t c h sys t ems . The f eed u sed co ns i s t ed o f ad d i t i ons o f va r ious f i ne ly d iv ided pa r t i-c u l at e o r g an i cs . I n e a r ly e x p e r i m e n t s , n o a t t e m p t w a s m a d e t o r e m o v e p a r t ic u l a tew a s t e p r o d u c t i o n f r o m t h e c u l t u r es . I n m o r e r e c e n t w o r k s , s u c h a t t e m p t s w e r e m a d e


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F L O W I N G B E D R E A C T O R F O R B R I N E S H R IM P C U L T U R E 6 5

i n h o p e s o f i m p r o v i n g a n d m a i n t a i n i n g c u l t u r e w a t e r q u a l i ty . T o d a t e t h e m o s t s u c c es s -f u l r e s u l ts h a v e b e e n o b t a i n e d b y t h e u se o f c r o s s f l o w s c r e en s t o s e p a r a t e a n i m a lb i o m a s s f r o m p a r t i c u l a t e w a s t e m a t e r i a l .

On a la rge r sca le , Mi l l igan e t a L ( 1 9 7 9 ) r e p o r t o n t h e u s e o f a d u a l t a n k s y s t e mw h i c h u t i f iz e s a c e n t r a l ' h i g h ' d e n s i t y b r i n e s h r i m p t a n k , l o c a t e d w i t h i n a l o w e r d e n s i t yl a r g er v o lu m e t a n k . T h e a lg a l f e e d s o u r c e e n t e r s i n to t h e s m a l l e r c e n t r a l t a n k . A t th eo u t l i n e o f t h e s m a l le r t a n k a n ai r- li ft p u m p r e t u r n s t h e m a j o r i t y o f t h e b r in e s h r i m p t ot h e s m a l l c e n t r a l t a n k . H o w e v e r , a c e r t a in p o r t i o n o f t h e a n i m a l s a re a l w a y s e s c a p i n gt o t h e l a r g e r o u t e r t a n k ; t h u s , t h is s y s t e m d o e s n o t e f f e c t a t r u e s e p a r a t io n , b u t r a t h e ra c t s a s a c o n c e n t r a to r o f b r i n e s h r im p . A s a r e s u l t , t h e i n t e r n a l t a n k is l im i t e d t o ar a t h e r lo w t o t a l a n i m a l d e n s i t y o f o n l y 3 0 0 - 4 0 0 a n i m a l s /l i te r .

T o b i a s e t a l . ( 1 9 7 9 ) d e s c r i b e d t h e u s e o f m o d i f i e d p l a st ic a q u a r i a f o r c u l t u r i n g b r i n es h r i m p o n a l g a e. I n t h e i r s y s t e m t h e b r i n e s h r i m p w e r e s e p a ra t e d f r o m t h e o u t f l o w b yu s e o f f i n e m e s h n i t e x s c r e e n s . F in e m e s h s c r e e n s w e r e a ls o u s e d o n 1 9 0 l i t e r r a c e w a yc u l t u r e s , t h e s i z e o f t h e s c r e e n s b e in g m a n u a l l y c h a n g e d a s t h e b r i n e s h r i m p g r ew .C lo g g in g o f t h e s c r e e n s b y p a r t i c u l a t e w a s t e w a s a p r o b l e m r e s u l t i n g i n a n im a l s b e in gl o s t f r o m t h e c u l t u r e s w h e n t h e y o v e r f l o w e d .

T h e p r e v i o u s m e t h o d s u s e d t o r e t ai n s m a l l h e r b i v o r e s s u c h a s b ri n e s h ri m p i nc u l t u r e v e ss el s f a ll in t o t w o t y p e s : t h e c o n c e n t r a t o r s y s t e m s u c h a s t h e D O W s y s t e m ,a n d t h e u s e o f f i ne m e s h s c r ee n s . B o t h m e t h o d s h a v e d i sa d v a n ta g e s . T h e c o n c e n t r a t i n gm e t h o d a p p e a r s l i m i t e d t o l o w b i o m a s s le v el s, t h e r e b y r e q u i r in g v e r y la rg e c u l tu r ev o lu m e s , w h ic h i n t u r n im p l i e s a l a rg e c a p i t a l i n v e s tm e n t . T h e u s e o f f i n e m e s h s c r ee n sa l lo w s f o r a m u c h h i g h e r a n i m a l b i o m a s s , b u t c l o g g in g p r o b l e m s a n d t h e n e e d t oc h a n g e s c r e e n s i z e as th e a n im a l s g r o w m a k e s t h i s a n a w k w a r d d e s ig n f o r p o t e n t i a lu s e in la rg e s ca le a u t o m a t i c c u l t u re s . F u r t h e r m o r e , i t m a y b e d e s i ra b le t h a t s u c h as y s t e m b e c a p a b l e o f o p e r a t i n g w i t h a r a n d o m d i s t r i b u t i o n o f a n i m a l siz es . T h e u s e o fs c re e n s d o e s n o t m e e t t h i s r e q u i r e m e n t . A s y s t e m is n e e d e d t h a t c a n :

1 . C o m p le t e ly r e t a in t h e b r i n e s h r im p a t all s ta g e s o f g r o w th a t h ig h d e n s i t y .2 . A l l o w f o r r ap i d a n d c o m p l e t e p a r t i c u l a t e w a s t e r e m o v a l .3 . A l lo w f o r a h ig h r a t e o f w a t e r p a s s a g e t o d e l iv e r t h e n e e d e d a lg a l s u s p e n s io n .T w o d e s ig n c o n c e p t s a r e o f p a r t i c u l a r v a lu e i n m e e t i n g t h e s e r e q u i r e m e n t s . F i r s t t h e

c o n c e p t o f t h e s i m p l e a q u a r i u m s u b g ra v e l fi lt e r, a c o n c e p t u t i l iz e d b y F a r r a r ( 1 9 7 7 ) f o rc u l t u r e o f o y s t e r l a rv a e ; a l t h o u g h e f f e c ti v e i n r e m o v i n g w a s te s , t h e s y s t e m a s p r e s e n t l yu t i l iz e d c a n n o t h a n d l e h e a v y w a s t e l oa d s . H o w e v e r , th e s e c o n d c o n c e p t d e s c r i b e d b yS a n d i f i e r e t a l . ( 1 9 7 4 ) , t h e u s e o f a t a n k w i t h a n in c l in e d f l o o r t o a c h ie v e m o v e m e n t o fw a s t e m a t e r i a l t o a n o u t l i n e , p r o v i d e s t h e a n s w e r t o t h e l o a d in g p r o b l e m . T h e s e t w oc o n c e p t s w e r e u s e d a s t h e b a s is o f a n e w s y s t e m ; t h e d e s i g n w a s f o r m u l a t e d a n d a s m a llp r o t o t y p e r e a c t o r w a s b u i l t a n d t e s t e d .T r i a l r u n s w i t h a d u l t b r i n e s h r i m p

T h e f i r st e x p e r im e n ta l u n i t ( F ig . 1 ) c o n s i s t e d o f a 1 2 x 1 2 x 8 i n ( 3 0 x 3 0 x 2 0 c m )p l ex i g la s t a n k w i t h b a f f le s 1 i n ( 2 . 5 c m ) f r o m t h e e n d s , a n d o p e n ~ i n ( 1 . 9 0 5 c m ) a t


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6 6 D . E . B R U N EOverflow to settlingAnimal ~ tankconpar e n ~

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t h e b o t t o m . T h e f l o o r o f t h i s v e s se l w a s f il le d w i t h F e r r o m i c r o b e a d s i n t h e s iz e r a n g eo f 5 0 0 - 7 1 0 # m . T h i s s iz e g r o u p i n g w a s f o u n d t o b e m o s t e f f e c t iv e in c o n t a i n i n g t h ea d u l t Artemia, y e t p r o v i d i n g h i g h p o r o s i t y f o r w a t e r p a s s a g e.

T w o a i r - w a t e r l if t p u m p s r a n a l o n g t h e b o t t o m o f t h e t a n k u n d e r t h e b e d f l o o r .T h e s e p u m p s c o n s i s t e d o f t w o ~ i n ( 1 .9 0 5 c m ) p l e x i g l as tu b e s w i t h a 9 0 b e n d a t th er e ar b a f f le . T h e t a n k w a s p o s i t i o n e d o n a w o o d e n s u p p o r t w i t h a p r o v i s i o n f o r c h a ng -i n g t h e a n g l e o f i n c l i n e . T o b e g i n o p e r a t i o n , t h e t a n k w a s f il l e d w i t h a s y n t h e t i c s e aw a t e r m i x t u r e ( ' I n s t a n t O c e a n ' ) a n d e n o u g h b e a d s w e r e a d d e d t o a c h ie v e t h e ~ i n( 1 . 9 0 5 . c m ) b e a d d e p t h . N e x t t h e t a n k w a s i n c l i n e d u n t i l t h e a ng le o f r e p o s e o f s u b-m e r g e d b e a d s w a s a c h i e v e d ( i .e . th e p o i n t a t w h i c h t h e y b e g i n to f l o w ) . T h is a n g le w a sf o u n d t o b e 3 0 f o r t h e 5 0 0 - 7 1 0 / J m s iz e g ro u p . A i r f lo w t o t h e a i r - w a t e r l i ft w a ss t a r t e d a t t h i s p o i n t . T h e a n i m a l c o m p a r t m e n t ( t h e c e n t e r v o l u m e ) w a s t h e n l o a d e dw i t h 8 0 0 0 a d u l t Artemia p e r l i t e r . F o r t h e a d u l t Artemia r u n s , a s u s p e n s i o n o f w h o l ew h e a t f l o u r w a s f e d i n a t a r a te w h i c h g a ve a h y d r a u l i c r e t e n t i o n t i m e o f a b o u t 8 h .

T h e o p e r a t i o n o f t h e s y s t e m w a s as f o l lo w s : i n th e f r o n t c o m p a r t m e n t , t h e a ir -w a t e r l i f t p u m p s w o u l d c o n t i n u a l l y l if t a s l u rr y o f b e a d s a n d p a r t i c u l a t e w a s t e t o th e


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F L O W I N G B E D R E A C T O R F O R B R I N E S H R I M P C U L T U R E 6 7r e a r c o m p a r t m e n t . I n t h is c o m p a r t m e n t t h e l ig h t er w a s t e p a rt i c ul a t es w o u l d s e p ar a tef r o m t h e b e a d s a s t h e h e a v y b e a d s s e t t l e d r a p i d l y t o t h e b o t t o m w i t h th e w a s tem a t e r i a l r e m a i n i n g i n t h e w a t e r c o l u m n a s a r e s u lt o f t h e b u b b l i n g a c t i o n o f t h e a ir -w a t e r l if t s. A s t h e b e a d s t r a v e l a c r o s s t h e f l o o r o f t h e t a n k , p a r t i c u l a t e w a s t e s s e t tl eo n a n d i n t o t h e b e d . A t t h e f r o n t b a f f le , th e w a s t e - lo a d e d b e d s l u m p s u n d e r t h e p l a t et o b e r e m o v e d o n c e a g a i n b y t h e a i r -w a t e r l if t. T h e a n i m a l s ; h o w e v e r , r e s p o n d t o t h ef l o w in g f l o o r a s i f i t w e r e a s o l i d s u r f a c e a n d r e m a in b e h in d . T h e c l e a n s e d b e a d sc o n t i n u a l l y r e - e n t e r u n d e r t h e r e a r b a f f l e .

I n t h e se i n it ia l e x p e r i m e n t s , t h e t a n k w a s o p e r a t e d o v e r a p e r i o d o f 7 2 h . W i t h ab e d t r a v e l t i m e a c r o s s t h e b o t t o m o f a p p r o x i m a t e l y 3 0 r a in , t h e c l e a n s in g a c t i o n w a sf o u n d t o b e m o r e t h a n s u f f i c ie n t . T h e f lo w i n g b e d ra p i d l y r e m o v e d w a s t es f r o m t h et a n k , w h i l e c o n f i n e m e n t o f t h e a d u l t b r i n e s h r i m p w a s c o m p l e t e . T h e o n l y a n im a l sc a r r ie d t h r o u g h t h e b e d ( a n d t o t h e s e tt l in g t a n k ) w e r e t h o s e w h i c h w e r e a p p a r e n t l yd a m a g e d i n h a n d l i n g a n d t r an s f er . T h e s e d e a d a n d d y i n g a n i m a l s w e r e e f f e c t i v e l yr e m o v e d f r o m t h e c u l t u r e b y t h e f l o w i n g b e d a c t i o n .

A l th o u g h t h i s b e d s i z e r a n g e w a s q u i t e s u c c e s s f u l i n m a in t a in in g a h ig h d e n s i t y o fa d u l t b r in e s h r i m p , i t d i d n o t c o n t a i n t h e n a u p l i i w h i c h w e r e b e i n g r e le a s e d b y t h ea d u l t p o p u l a t i o n . A t t h e e n d o f th i s e x p e r i m e n t a l r u n , a h i g h d e n s i t y o f n a u p l ii w e r ef o u n d s w a r m in g i n t h e s e t t l in g t a n k . T h i s r e s u l t w a s c a r e f u l l y n o t e d , a s i t s u g g e s ts t h ep o s s i b i li t y o f a n a u t o m a t i c c o n t i n u o u s m e a n s t o s e p a r a t e n a u p l i i f r o m a b r i n e s h r i m pb r o o d s t o c k .

Trials runs with A r t e m i a naupliiA s e c o n d , l a rg e r c u l t u r e v e ss e l ( 1 1 4 l it e rs ) w a s c o n s t r u c t e d ( F i g . 2 ) i n c o r p o r a t i n g

th e s a m e b a s i c p r i n c ip l e s u s e d i n t h e f i rs t r e a c to r . T h e p u r p o s e o f t h i s s e c o n d s e ri e s o fe x p e r i m e n t s w a s t w o f o l d . F i r st , i t w a s n e c e s s a r y t o e v a l u a te a se ri es o f b e a d d i a m e t e r sw i t h r e g ar d t o n a u p l i i r e t e n t i o n a n d p o r o s i t y t o w a t e r f lo w . I n a d d i t i o n , a m o r e r u g g e da p p a r a t u s w a s n e e d e d s o t h a t t h e p e r f o r m a n c e o f t h e f l o w i n g b e d c o u l d b e e v a l u a t e do n a l o n g e r t e r m b a s i s .

I n o r d e r t o s t u d y t h e c h a r a c t e r i s t i c s o f th e v e r y s m a l l d i a m e te r g la ss b e a d s , it w a sn e c e s s a r y t o m o d i f y t h e t a n k d e si gn t o i n cl u d e t h e u se o f a s u p p o r t e d n i t e x s c r e e n.T h i s s c r e e n w a s i n c l u d e d p u r e l y a s a r e s e ar c h t o o l t o a l lo w f o r a n e v a lu a t i o n o f th eb e a d f l o w r a te a t b e a d d i a m e t e r s ( 1 0 5 - 1 4 9 / 3 m ) g i vi n g v e r y l o w p o r o s i t y .

T h e a n g le o f i n c l i n a t i o n i n t h e s e e x p e r i m e n t a l r u n s w a s i n c r e a se d t o 4 5 A t t h isa n g le , t h e b e d d e p t h w a s d e c r e a s e d t o l es s t h a n ~ i n ( 7 9 . 4 m m ) . T h e o p e r a t i o nr e m a in e d b a s i c a l l y t h e s a m e a s w i th t h e o r i g in a l c u l t u r e d e v i c e , e x c e p t t h a t t h e f l o w in gb e d w a s m o r e o f a t h i n s c o u r i n g f i lm a n d t h e b u l k o f t h e w a t e r n o w w o u l d e x i tt h r o u g h t h e f l o w i n g f i l m a n d a c r o s s t h e s u p p o r t i n g s c r e e n , r a t h e r t h a n e x i t in g as ab e a d - w a t e r s l u r r y a t t h e o u t l e t s u m p .

T h e r e a c t o r w a s s e t i n t o o p e r a t i o n w i t h t h e a i r- w a t e r li f t p u m p s a d j u s te d t o p u m pa to t a l v o l u m e o f 3 l i t e rs / h e a c h . O f t hi s v o l u m e , a p p r o x i m a t e l y 6 0 % w a s b e a d s . T h eto t a l b e a d v o lu m e in t h e 3 0 g a l l o n ( 1 3 6 .5 l i t e rs ) t a n k w a s s e t a t 1 .6 l i te r s , w h ic h g a v e ab e d d e t e n t i o n t im e o f 4 5 m i n w i t h a f l o o r v e l o c i t y o f 0 - 5 i n ( 1 .2 7 c m ) / s . A e r a t i o n f o r


6/8

6 8 D . E . B R U N E

. . i o " , o : o , . . . . .

~ l o n k

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6 ? ( 2 Ioo,,.,

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F i g . 2 . M o d i f i e d f l o w i n g b e d r e a c t o r .

t h e c u l t u r e w a s s u p p l i e d p r im a r i l y f r o m t h e a c t i o n o f t h e a ir - w a te r l if t p u m p . A na d d i t i o n a l a e r a t i o n t u b e w a s u s e d i n th e t a n k i t s e lf f o r t h e p u r p o s e o f m i x i n g t h ec u l t u r e i n a g e n t le f a s h i o n .

T h e t a n k w a s l o a d e d w i t h 1 4 5 0 0 0 A r t e m i a n a u p l i i p e r l i t e r , a n d a f l o w r a t e o f1 8 l i t e r /h o f a lg a l s u s p e n s i o n w a s f e d i n t o t h e t a n k . T h e a l ga u s e d i n t h i s e x p e r i m e n tw a s Phaeodac t y l um sp . p r o d u c e d f r o m a 1 1 4 l it e r c o n t i n u o u s c u l tu r e . I n f l u e n t c e l ld e n s i t i e s a v e r a g in g 8 . 5 x 1 0 s c e l l /l it e r w e r e m a i n t a i n e d . T h e r e a c t o r p e r f o r m a n c e w a sm o n i t o r e d f o r a p e r i o d o f 1 6 d a y s , p r i m a r i l y t o e v a l u a t e t h e e f f e c t i v e n e s s o f t h e r e t e n -t i o n o f t h e n a u p l i i. D u r i n g t h i s p e r i o d m e a s u r e m e n t s o f t h e b r i n e sh r i m p b i o m a s s , a lg a lc e l l c o u n t s a n d d i s s o l v e d o x y g e n l e v e l s w e r e m a d e o n c e e a c h d a y .

D I S C U S S I O NCu l t u r e behav i o r

T h e p r o d u c t i v e c a p a c i t y o f t h e c o n t i n u o u s a lg al c u l tu r e w a s q u i te l i m i t e d c o m p a r e dt o t h e e x t r a o r d i n a r y b r i n e s h r i m p d e n s i t y b e i n g m a i n t a i n e d . T h e b r in e s h ri m p b i o m a s s


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FLOWING BED REACTOR FOR BRINE SHRIM P CULTURE 69

ou tg rew the a lgal cu l t u r e b y t he fo u r th day . Ho wev e r , du r ing t h i s sho r t pe r iod t hesucces s o f f l owing bed i n r e t a in ing t he naup l i i was comple t e and r ead i l y appa ren t .

I t i s i n t e r e s t ing t o exam ine t he da t a du r ing t he f ir s t f ew days o f ope ra t i o n (F ig . 3) .The g rowth o f t he b r ine sh r imp b iomass i s r e f l e c t ed i n t he dec l i ne i n t he d i s so lvedoxygen leve ls . This growth i s a l so re f lec ted in the rap id dec l ine in e f f luent a lga l ce l ldens i t y w i th in t he i n i t ia l 72 h o f ope ra t i on . By day fou r t he cu l t u r e was a l r eadyseve re ly food l imi t ed a s s een i n t he ce l l coun t s ; t h i s i s f u r the r shown in t he up tu rn i ncul ture D.O. on day f ive , as a resu l t o f fa l l ing resp i ra t ion ra tes .

I00 I0o_8 0 ~ 8-J 5

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~ 40 - 4 az~3d goo~2 0 - 2 7 ~

0 I 2 3 4 5 6 7 8DAYSFig. 3. Culture algal cell counts and dissolved oxyg en levels during first eight days of operation.

Beg inn ing on day f i ve , a su spens ion o f r i ce b r an was f ed i n to t he cu l t u r e ove r a48 h p e r iod . The r e su l t ing d rop i n t he D .O . was d r am a t i c , v iv id ly i l lu s t r a ti ng t he p r i cetha t mus t be pa id when a t t emp t ing t o u se pa r t i cu l a t e o rgan i c s i n such sys t ems . I n sp i t eo f s h o r t d e t e n t i o n t i m e s a n d r a p i d p a r t i c u la t e u p t a k e r a te s , o rg a n ic l o a d i n g ca n b ee x p e c t e d t o i m p o s e a h e a v y o x y g e n d e m a n d o n s u c h a sy s t e m . T h is o b s e r v a t io n isi m p o r t a n t t o n o t e i n v i e w o f t h e v a r i o u s s y s t e m s p r o p o s e d f o r t h e u t i l i z a t i o n o fpa r t i cu l a t e o rgan i c s by b r ine sh r imp (So rge loos , 1979 ) .

B e c au s e o f s ev e re f o o d l i m i t a t io n , a h i g h r a t e o f m o r t a l i t y w a s o b s e r v e d f r o m d a ys ix onward . Howeve r , t he r eac to r was a l l owed to ope ra t e t o fu r the r obse rve t he c l eans -ing ac t i on . The sys t em was qu i t e e f f i c i en t i n r emo v ing pa r t i cu l a t e m a t t e r , a l t hou gh thei m p o r t a n c e o f a n u n o b s t r u c t e d b e d w a s n o t e d . A n y ' d e a d s p o t s ' w o u l d i m m e d i a t e l ya c c u m u l a t e w a s t e m a t e r i a l .

T h e r e a c t o r w a s o p e r a t e d c o n t i n u o u s l y f o r a t o t a l o f o n e m o n t h . D u r i n g t h is ti m e ,t h e b e d r e m a i n e d c o m p l e t e l y c le a n . R e t e n t i o n o f t he A r t em i a w a s c o m p l e t e d u r i n gp r o p e r o p e r a t i o n .


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70 D . E . BRUNED e s i g n i m p r o v e m e n t

Two pot enti al problem areas were identified: first, it was found that if air flow tothe air-water lift pump was even momentarily interrupted, the pump would clog withbeads. Secondly, it was fou nd th at design of the bead inl et led to unstable operation.The success of the separation was dependent on a volume of beads being retained inthe rear inlet box. Occasionally this level would fall and an open commun ica tio nwould be established through which brine shrimp were lost to the s ettling tank.

Design modifications are currently being tested to solve these problems. Theapparent solution lies in the development of a low rpm feeding device at the bead inletand outlet. This device will give control of bead velocity and detention time. Withproper selection of blade clearance in the feeder, it has been possible to retain thebeads while allowing for water passage, thus giving independent control over thehydraulic de ten tio n time and the scouring rate. The dev elopment of a feeder also solvesthe clogging problems with the air lift pumps, since bead flow is restricted to a ratewell below the delivery capability of the air lift pumps.

ACKNOWLEDGEMENTSThe author wishes to express his appreciation to Patrick Burke for his assistance indeveloping and c onstru cting the flowing bed models.

REFERENCESFarrar, S. W. (1977). Mortality problems in oyster hatcheries. F i s h F a r m i n g I n t e r n a t i o n a l , March1977.Goldman, J. C. & Ryther, J. H. (1975). Nutrient transformation in mass cultures of marine algae.J. Env. Eng. Div. , June.Milligan, D. J., Quick, J. A., HiU, S. E., Morris, J. A. & Hover, R. J. (1979). Sequential use of bac-teria, algae and brine shrimp to treat industrial wastewater. S y r u p . o n t h e B r in e S h r i m p Artemiasalina, Corpus Christi, Texas.Mock, C. R., Neal, R. A. & Salser, B. R. (1973). A closed raceway for the culture of shrimp. Proc.4 t h A n n u a l W o r k s h o p W o r ld M a r i c u lt u r e S o c ie t y , Monterrey, Mexico, pp. 247-59.Reeve, M. R. (1963). The filter feeding o f A r t e m i a . J . E x p . B i o l . , 40.Ryther, J. H., Goldman, J. C., Gifford, C. E., Huguenin, J. E., Wing, A. S., Clarner, J. P., Williams,L. D. & Lapointe, B. E. (1975). Physical models of integrated waste recycling.A q u a c u l t u r e , 5,163-77.Sandifier, P. A., Zielinski, P. B. & Castro, W. E. (1974). A simple airlift operated tank for closed-system culture of decapod crustacean larvae. H e lgo lande r w i s s M e e re sun te r s , 26, 82-7.Sorgeloos, P. (1979). The culture of Ar te m ia sa l ina on rice bran. l O t h A n n u a l M e e t i n g o f W o r l dM a r i c u l t u r e S o c i e t y , Honolulu.Takuno, Hideaki (1967). Rearing experiments of brine shrimp on diatom diet. Bul l . T o k a i Re g .F i sh Re s . L ab . , No. 52.Tobias, W. J., Sorgeloos, P., Bossuyt, E. & Reels, O. A. (1979). The technical feasibility of massculturing Ar te m ia sa l ina in the St. Croix artificial upwelling mariculture system, l O t h A n n u a lW o r l d M a r i e u l t u r e S o c i e t y M e e t i n g , Honolulu.

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Brune 1982 Aquacultural-Engineering