Colt 1984 Aquacultural-Engineering

7/28/2019 Colt 1984 Aquacultural-Engineering

1/23

..31-_ ~quaculmral Engineering 3 (1984) ~- -,-r~

D e s i g n o f P a c k e d C o l u m n s f o r D e g a s s in g

John C o l tTeufel and Associates, 1303 Lake Boulevard. Davis. California 95616, USA

and

Gerald BouckDivision of Fish and Wildlife (PJS), Bonneville Power Administration.

PO Box 3621, Portland. Oregon 97208. USA

A BSTRA CT

The packed cohtmn can be used to degas large JTows o f water. For a givenhtfluent Ap, temperature, and dissolved oxygen, the e/fluent Ap willdepend on the media size arm the height of the column. Cohtmn heights#t the range 1-3 m are required to meet criteria o f Ap = 20 mm Hg anddissolved oxygen concentration (DOC) >I 90% o f saturation. Selection o fmedia size will depend on consideration o f column height, loadingcapacity, attd media costs. Gas composition within the column has asecondarv effect on the eff luent Ap. Generally, the mole fraction o foxygen bzside the eolttmn cannot be reduced more than 10% and stillsatisfy the dissoh, ed oxygen criteria. For waters high in dissolved oxygen,the use of a vacuum column can reduce the required column height.

NOMENCLATURE

BPCCi.Co~tC*F

Aquacultural Engineering 0144-8609/84/$03.00 Elsevier AppliedPublishers Ltd, England, 1984. Printed in Great Britain

B a r o m e t r i c p r e ss u r e (r a m H g = T o r r )C o n c e n t r a t i o n o f a g a s in w a t e r ( m g l it er - 1)l n f l u e n t c o n c e n t r a t i o n o f a g a s t o t h e c o l u m n (n ag l it er - 1 )E f f l u e n t c o n c e n t r a t i o n o f a g a s t o t h e c o l u m n ( ra g li te r - ~)S a t u r a t i o n c o n c e n t r a t i o n o f a g a s in l i q u i d ( m g l i te r - ~)Infinite series in terms of nKd + K Z

251Science


2/23

2 5 2 J . C o l t , G . B o u c kG

K

P H ,.0AP&Piz2kPin~ o u tAPtn (i)~ k e o u t ( /)TVacXX'Z(I)

Overall system constant for packed column and distributionsystem (dimensionless)Aeration coefficient o f media (m -~)Aeration coefficient of screen or distribution plate (dimen-sionless)The number of screens or distribution platesVapor pressure of water (mm Hg)Difference between total gas pressure and the barometric pres-sure measured by the membrane diffusion method (ram Hg)Differential partial pressure between the liquid and gas phase(mm Hg) for the ith gaslnf luent ~ to the column (mm Hg)Effluent zSd~ from the column (mm Hg)Influent APi for the ith gas (mm Hg)Effluent z5.',- for the ith gas (ram Hg)Water temperature (C)Applied vacuum to column (ram Hg)Mole traction of a gas in atmosphereMole fraction of a gas inside the columnHeight of column (m)Bunsen coeff icient (liters liter - l a tm -~)(KLa)gaJ(KLa)oxygen where KL is the mass transfer coefficient

INTRODUCTIONSupersaturated dissolved gases (both individually and collectively) arecommon in water from wells, springs, streams and lakes and may varyconsiderably between seasons and operations. Chronic exposure ofhatchery fish (especially eggs and larvae) to supersaturated gases mayresult in developmental problems (Peterson, 1971), increased incidenceof infectious diseases, and mortality (summarized by Weitkamp andKatz, 1980). One remedy is a 'packed column' which is a fihn-flowaerator that can be used simultaneously both for oxygen transfer andfor removal of gas supersaturation. Packed columns are inexpensive andreliable, and are used widely at Pacific salmon hatcheries (Owsley,1981), but general design procedures are not readily available. There-fore, we developed a multicomponent transfer model in terms of APbased on a single-component gas transfer model described by Hackney


3/23

Design of packed columns for degassing 25 3a n d C o l t ( 1 9 8 2 ) ; w e n o w p r e s e n t e x p e r i m e n t a l v e r if i c at io n o f t hi sm o d e l a n d d e s i g n c h a r a c t e r i s t i c s f o r i t s u s e i n h a t c h e r i e s . S p e c i a le m p h a s i s is p l ac e d o n t h e r e d u c t i o n o f c o l u m n h e i g h t a n d t h e us e o fv a c u u m a p p l i c a t i o n s .

G A S T R A N S F E R IN T H E P A C K E D C O L U M NT r a n s f e r o f a s in g le g as , s u c h a s o x y g e n , a r g o n , n i t r o g e n o r c a r b o nd i o x i d e , in t h e p a c k e d c o l u m n ( H a c k n e y a n d C o l t . 1 9 8 2) c a n b ew r i t t e n a s:

C * t = do[nKa +KZI (1 )1I n C - ~ - - C o u t JT h i s e q u a t i o n is b a s e d o n a t w o - f i h n m a s s - t ra n s f e r m o d e l .

G a s t r a n s fe r w i th i n t h e p a c k e d c o l u m n t a k e s p l ac e d u e t o b o t h t h ed i s t r i b u t io n s y s t e m a n d t h e m e d ia . T h e p e r f o r m a n c e o f t h e p a c k e dc o h m m d e p e n d s s t ro n g l y o n e v en d i s t r i b u t io n o f t h e w a t e r o v e r t h em e d i a . E x p a n d e d m e t a l s c re e n s, p e r f o r a t e d o r s lo t t e d a l u m i n u m s c re e n s,a n d d r i l l e d o r i f i c e p l a t e s h a v e c o m m o n l y b e e n u s e d a s d i s t r i b u t i o ns y s t e m s in d e g a s si n g s y s t e m s ( M c L e a n a n d B o r e h a m , 1 9 8 0 ; H a c k n e ya n d C o l t . 1 9 8 2 ) .

A t 2 0 C , v a l u e s o f Kd r an g e f r o m 0 . 0 8 t o 0 .6 8 ( M c L e a n a n d B o r e h a m ,1 9 8 0; H a c k n e y a n d C o l t , 1 9 8 2) . F o r t h e o r if ic e d i s t r i b u t i o n s y s t e m ,K a i n c r e a s e s s l i g h t l y a s t h e s u r f a c e l o a d i n g r a t e i s i n c r e a s e d ( H a c k n e ya n d C o l t, 1 9 82 ). K a v a lu e s a t o t h e r t e m p e r a t u r e s c a n b e c o m p u t e df r o m :

K a( r ) = Ka(2oc) 1-0 24 (7- - 20~ (2)T h e v a lu e o f K d e p e n d s o n l o ad i n g ra te a n d t h e m e d i a siz e t H a c k n e y

a n d C o l t , 1 9 8 2 ) . F o r p a l l r in g s , t y p i c a l v a l u e s o f K a t 2 0 C , ra n g e f r o m1-0 t o 2 -5 m - I a n d c a n b e a d j u s t e d t o o t h e r t e m p e r a t u r e s b y e q n ( 2 ) .F o r a p a r t ic u l a r m e d i u m , t h e v a lu e o f K is c o n s t a n t u n t i l t h e c o l u m ns t a rt s t o t lo o d . F l o o d i n g in a p a c k e d c o l u m n is d e f i n e d as a n in v e r s io no f p h a se s so th a t t h e l iq u id p h a s e b e c o m e s c o n t i n u o u s w i t h i n t h e v o i ds p a c e b e t w e e n t h e m e d i a ( N o r t o n C o ., 1 97 7 ). F l o o d i n g i s c a u s e d b ye x c e s s i v e h y d r a u l i c l o a d i n g a n d r e s u l t s i n a s i g n i f i c a n t c h a n g e i n t h em a s s t r an s f e r c h a r a c te r is t ic s o f th e c o l u m n . F l o o d i n g p r o d u c e s t h r e ec o n d i t i o n s t h a t o p p o s e d e g a ss in g : ( 1 ) a ir f l o w t h r o u g h th e c o l u m n is


4/23

254 J . C o l t , G . B o u c k

reduced; (2) the pressure within the column is increased; and (3 ) theair-water surface area is reduced. The elevated pressure inside thecolumn increases the effective C* value above the atmospheric value.Therefore, the water leaving a flooded column will be supersaturatedregardless of the column design. Maximum loading rates for packedcolumns are presented by Hackney and Colt (1982).

The transfer of different gases in a given system depends on thediffusivity of the individual gases. The ratio of the mass transfer coef-ficient of the ith gas divided by the mass transfer coefficient of oxygenis represented by q5 and can be used to adjust the transfer rates of thedifferent gases. For packed columns, a value of 0-85 and 1.00 shouldbe used for qSN~+Ar and ~co~, respectively (Speece and Humenick,1973; McLean and Boreham, 1980).

The Co,,t concentration for an individual gas can be computed fromeqn (1). However, the risk to aquatic animals depends primarily on thezXP (Bouck, 1980; D'Aoust e t a l . , 1980). zXP is the differential hyper-baric gas pressure and is equal to the difference between the totaldissolved gas pressure and the local barometric pressure. The ,..YP can bemeasured directly by instruments described by D'Aoust e t a l . (1980)and Bouck (1982) and is reported typically in millimeters of mercury(ram Hg). Given this relationship, degassing columns should be designedbased on z2ff', rather than on the concentrat ion of a single gas. Thecriterion for z2xP depends on the tolerance of the species, its develop-ment stage and the depth of the culture system. Chronic exposure to

values of 30 mm Hg can increase the mor tali ty of tish (Bouck,1976). In shallow rearing systems, clinical signs of gas bubble diseasecan be produced in larval striped b a s s M o r o n e s a . v a t i l i s at ZXP = 22 mm Hg(Cornacchia and Colt, 1984). Growing evidence indicates that ext remelysensitive organisms should not be exposed in hatcheries to z3a >~ 0, i.e.Atlantic salmon S a l m o s a l a r , brown trout S a l m o t r u t t a .

Another requirement is that the dissolved oxygen in the effluent of apacked column must be or exceed 90% of air saturation. Higher dis-solved oxygen allows support of a greater mass of fish, given the sameflow of water. As the dissolved oxygen approaches the saturation level,the transfer efficiency of aerators decreases (Colt and Tchobanoglous,1981). A criterion of 90% of oxygen saturation is based on trade-offsbetween carrying capacity and costs. Therefore, the design of packedcolumns must consider both the z2~P and the dissolved oxygen criteria.


5/23

Design o f packed columns for degassing 255T h e d i f f e r e n c e b e t w e e n t h e p r e s su r e o f a g as i n a l i q u i d a n d t h e

a tm osphe r e f o r t he i t h ga s i s r e f e r r e d to a s z ~ ,. For the major gases(Co l t , 19 83) th e v a lues of- -APi a re equ a l to :

C o : ( 0 .5 3 1 8 ) - - X o : (B P - - P H : o ) ( 3)6 / ' 0 : - ; 30 , .Cco.A P c : /3co. ( 0 . 3 8 4 5 ) - - X c o : ( B P - - P H ~ o ) ( 4)

Co Cco~Z2UN,.Ar = BP +~2x_P-- v: (0 .53 1 8) . . . . . . (0- 38 45 )~o: &o:- - X N : A r (B P - -PH20) (5)

A d d i t i o n o f e q n s ( 3 ) - ( 5 ) s h ow s th a t:- -~ '~LPo: { - ~ k P N ~ . + A t + ~ 1 9 C 0 ~ (6)

S u b s t i t u t i o n o f e q n s ( 3 ) - ( 5 ) i n t o e q n ( 1 ), re s u lt s i n t h e f o l lo w i n ge q u a t i o n s :O x y g e n : In [ z3aPin('---------~) = 1 .00 (n K a + K Z ) (7 )~&Pout(O,)aN itro ge n + a rgo n: In [ zS,P i n t N ~ ~ ) ] = 0 . 8 5 ( n K a + K Z ) (8 )[ ~ k P o u t ( N : + A r ) -I

[ z ~ k P i n ( C O : ) ] =C a rb o n d io x id e : In [ ~ ) j 1 .00 (n K a + K Z ) (9 )o r :

Sinc e :~Pout~Pout

Z ~ D o u t ( O : ) = g ~ D i n ( O 2 ) e-(nKd+KZ) ( 10 )z ~ , D o u t ( N , A r ) = z ~ k P i n ( N : + A r ) e -'85(nKd+Kz) ( 1 1 )Z ] k P o u t ( C O ~ ) = Z ~ D i n ( C O : ) e - ( n K d +KZ) ( 1 2)

= xPout(O:) + &Pout(N:+~) + -- /~out(co o= Z ~ i n ( O , ) C (nKd+KZ) + ~ i n ( N ~ + A r ) e-O'85(nKd+KZ)

q - z ~ k P i n ( C O : ) e-(nKd +KZ) (13)


6/23

2 5 6 J . C o l t , G . B o u c kEquation (13) can be used to predict the performance of a packedcolumn used for degassing.

In most surface waters, the partial pressure of carbon dioxide is smalland typically in analysis its pressure is included with nitrogen + argon.Equations (5) and (6) can be written as:

~ N +At+CO, = BP -- z iP-- Co;: 13o= (0-5318) -- PH=o- - X N : +~ r+ C O : ( B P - - P H : O ) ( 1 4 )

AP = APo~ + APN, + ~ + c o . (15)Since the contribution o f carbon dioxide to APN~+Ar+CO: s small, theerror due to assuming that CI,co: = CbN,+Ar is also small, and APout isequal to:

Z~/Oout = Z~ in (O =) e - ( " K d + K Z ) + ~ k P i n ( N = + A r + C O 2 ) e -O ' 8 5 ( n K d + K z )(16)

If APincco= is above 5 mm Hg, eqn (13) should be used. Some springor well waters may contain excessive amounts of carbon dioxide (Mrsic,1933). Removal of carbon dioxide may be slower than predicted byeqn (13) because detention time in the packed column can be less thanthe time required for all the carbonate species to approach equilibrium.

Equation (16) can be rewritten as:z ~ P o u t = ~ i n e - O '85 ( nK d+K Z ) " q - z ~ P i n ( O , . ) F (17)

If the second tenn is neglected, then:APout = APi, e -~Ss("'rd+Kz) (18)Equation (18) should not be used for design, but the essential char-

acteristics of the packed column can be shown by examinat ion of thisequation. After passing through the distribution system, AP willdecrease exponentially as the water passes through the media. For agiven system at constant temperature and flow,

~ou t- - - constant (19)APinAs APi. changes, APou t will change in a linear manner.


7/23

Design oF packed colum ns br degassing 2 5 7T h e d e s ig n o f a p a c k e d c o l u m n f o r d e g a s si n g w i ll r e q u i r e m e a s u r e -

m e n t o f ~_YP, t e m p e r a t u r e , b a r o m e t r i c p r e s s u r e , d i s s o lv e d o x y g e n , w a t e rt e m p e r a t u r e a n d s a l in it y . T h e v a lu e s o f ~ f o r t h e c o m p o n e n t g a s a ret h e n c o m p u t e d f r o m e q n s ( 3 ) - ( 5 ) o r e q n s 13) a n d (1 4 ). T h e n t h e - - ~ o . tv a l u e c a n b e c o m p u t e d f r o m e i t h e r e q n ( 1 3} o r e q n ( 1 6 ) . F o r a g iv e nd i s t r i b u t i o n s y s t e m , m e d i a a n d ~-YPin v a l u e s , th e h e i g h t o f t h e c o l u m n ist h e m a j o r e n g i n e e r i n g p a r a m e t e r . T h e h e i g h t r e q u i r e d t o s a t i s fy a g iv e n/-Y Pout c r i t e r i o n w i l l i n g e n e r a l r e q u i r e a tr i a l a n d e r r o r s o l u t i o n .

L i m i t e d i n f o r m a t i o n is a v a i l a b le o n t il e v a l u e s o f K d a n d K . T h eo v e ra ll s y s t e m c o n s t a n t G c a n b e d e f i n e d a s:

G = nKa + KZ ( 2 0 )F o r o x y g e n , t he v a lu e o f G ca n b e c o m p u t e d b y s u b s t i t u t i o n o f e q n( 2 0 ) i n t o e q n I 1 ):

[ c ' : _ - < , , ] t2 )G =In kC*--Co ut ]T h e r e f o r e , e v e n i f th e v a l u es o f K d a n d K a re u n k n o w n , t h e v a lu e o fG f o r a g iv en s y s t e m c a n b e c o m p u t e d f ro m m e a s u r e m e n t o f Cin a n dC o~t. S u b s t i t u t i o n o f G i n t o e q n s ( 1 3 ) o r ( 1 6 ) c a n b e u s e d t o e s t i m a t et h e p e r f o r m a n c e o f t h e s y s t e m u n d e r d i f f e r e n t z X Pi. v a lu e s .

O n c e a d i s t r i b u t i o n s y s t e m a n d m e d i a h a v e b e e n s e l e c t e d , t h e p e r-f o r m a n c e o f a d eg a ss in g c o l u m n w ill d e p e n d p r i m a r il y o n t h e c o l u m nh e i g h t ( e q n ( 11 8 )) , L o w A P v a l ue s r e q u i r e h ig h c o l u m n h e i g h t s a n dr e d u c t i o n o f & P o ut to z e r o t h e o r e t i c a l l y r e q u i r e s a n i n f in i t e ly h ig hc o l u m n . A v a c u u n l s y s t e m h a s b e e n s u g g e s t e d to r e d u c e t h e c o l u m nh e ig h t ( F u s s , 1 9 8 3 ) , a n d a v a c u u m - s i p h o n s y s t e m h as b e e n s u g g es te dt o r e d u c e p u m p i n g c o s t s ( M o n k et al., 1 9 8 0 ). V a c u u m s y s t e m s re d u c et h e e f f e c t i v e b a r o m e t r i c p r e s s u r e , h e n c e i n c r e a s e t h e 2 t/- ' a n d t h e r e f o r ei n c re a s e t h e g as t r a n s f e r r at e. T h e d e s ig n o f v a c u u m p a c k e d c o l u m n sc a n b e a p p r o a c h e d f r o m t h e f o l l o w i n g . T h e '.X P i, v a l u es a re c o m p u t e df r o m e q n s (3) - (5) o r e q n s ( 3 ) a n d ( .1 4 ) u s i n g a v a l u e o f B P e q u a l t oB P - - V a c . T h e ~-XPo~t is t h e n c o m p u t e d f r o m e i t h e r e q n s ( 1 3 ) o r ( 1 6 ) .T h i s v a lu e is t h e ~ o f th e w a t e r a t t h e b o t t o m o f t h e c o l u m n . T h ef in a l & P o~ t a f t e r t h e w a t e r l e a v e s t h e c o l u m n is e q u a l t o / - k P o u t - V a c .H o w e v e r , s o m e p r e c a u t i o n s a r e w a r r a n t e d in th e u s e o f v a c u u n l d e ga s s-i n g a s d e s c r i b e d by M a r k i n g et al. ( 1 9 8 3 ) ( s e e t h i s p a p e r , ' D e s i g n o fVacuulm Columns').


8/23

2 5 8 J . Colt, G. Bouck

M O D E L V E R I F I C A T I O N

M o d e l v e r i f ic a t i o n w il l b e b a s e d o n t h e w o r k r e p o r t e d b y B o u c k e t a l .( 1 9 8 4 ) . T h e p e r f o r m a n c e o f a n u m b e r o f d i f f e re n t m e d i a w as e v a l u a t e da s a f u n c t i o n o f i n f lu e n t & P a n d c o l u m n h e ig h t . S i n ce th e se w o r k e r sd i d n o t u s e a d i s t r i b u t i o n p l a t e a n d n = 0, e q n ( 7 ) s h o u l d b e r e w r i t t e n a s

o r

h i r ~ k P i n ( ; ' ] = KZ {~)LZXPout(o:)l - "

[ ~ r ~ in O ~ ] Kl o g - ( 2 3 ). . ' O U OA P o u t( o :) ] "~ -, ,-,.,l e t t i n g K ' = K / 2 . 3 0 3 a n d r e a r r a n g i n g e q n ( 2 3 - ) r e s u l t s i n :

log [LkPou t (o :) ] = log [APin (O : ) ] - - K ' Z ( 2 4 )T h i s e q u a t i o n h a s t h e f o r m :

l o g ( y ) = b + m Z ( 2 5 )w h e r e b = I o g [ L k P i n ( o : ) l a n d m = - - K ' .

A s im i l a r e x p r e s s i o n c a n b e d e v e l o p e d f o r N 2 + A r + C O : . U s in g t h ed a t a p r e s e n t e d in t a b l e 3 o f B o u c k e t a l . ( 1 9 8 4 ) , l o g [ z XP ou t] w a s p l o t t e da g a i n s t Z in F i g . l . E x c e p t f o r l o w v a l u e s o f_ .A .P o: a n d ~ t P x : + A r c o 2 ,w h e r e m e a s u r e m e n t e r r o r s b e c o m e m o r e s e r i o u s , t h e p e r f o m l a n c e o ft h e c o l u m n c a n b e d e s c r i b e d b y e q n ( 2 5 ) . T h e o v e r al l r e m o v a l o f 2xPc a n b e d e s c r i b e d a s a n e g a t iv e e x p o n e n t i a l d e c r e a s e w i th c o l u m n h e i g h t( e q n ( 1 8 ) ) . T h e z SP ou t d e p e n d s in a l i n e a r m a n n e r o n z X P i, t F i g. 2 ) a s isp r e d i c t e d b y e q n ( 1 9 ).

U s i n g i n d e p e n d e n t l y c o l l e c t e d d a t a , th e e s s e n ti a l f e a tu r e s o f t h ep r o p o s e d m a s s t r an s f e r m o d e l a re c o n f i r m e d . T h i s m o d e l w ill n o w b eu s e d t o i n v e st ig a te t h e e f f e c t s o f v a ri o u s p a r a m e t e r s o n t h e p e r f o r m a n c eo f t h e p a c k e d c o l u m n f o r d e g as si n g a p p li c a ti o n s .

D E S IG N O F P A C K E D C O L U M N S F O R D E G A S S IN GT il e p e r f o r m a n c e o f p a c k e d c o l u m n s w a s c o m p u t e d f ro m e q n ( 1 6 ) a sa f u n c t i o n o f t e m p e r a t u r e , d i s s o l v e d o x y g e n a n d _4.P . T h e s y s t e m


9/23

Design of packed columns for degassing 259

1 0 0 0

I 0 0

A

1 (

Fig . 1 .

10.00

0 ~ ' ~ ,

- - APN . . . . CO, - - ~ P o ,

I I I J ~0.30 O.GO 0.90 1 "~0Column Height (m)

Performa nce of the packed col umn as a functi on of col umn height (cf.Table 3 of Bouck e t a l . , 1984) .


10/23

2 6 0 J . Colt, G. Bouck

n -t L I 1 2 0

O. a1 1 3

z

Fig. 2.

AI

II

III

II

II

II' /

!/ g/

B Co /

///

.XP~ , S a t . ' ( m r . P i g )

1 3 3 ! S O

1 2 6 I 0 0

0 0 -

1 0 6 5 0 -

1 0 0 0 i I i l ] t r I I I I I t , ] I I I0 2 5 5 0 7 5

. 1P ( m m H O )I [ I I0 1 0 3 1 0 7 1 1 0

a t 7 6 0 m m H g % S a l u t a t i o n IO U T - F L O W W A T E R

&Pout v e r s u s ~ P i n for the packed column.

m o d e l e d h a d a si n g le d i s t r i b u t i o n p l a t e (K d = 0 . 4 0 a t 2 0 C ) . T i l e Kv a l u e s t e s t e d w e r e 1 .0 5 , 1 .5 8 , t . 7 1 a n d 2 . 5 0 m -1 , a n d c o r r e s p o n d t o8 . 8 9 , 5 . 0 3 , 3 . 81 a n d 2 . 5 4 c m d i a m e t e r p l a st ic p a ll r in g s ( N o r t o n C o . ,A k r o n , O h i o ). T h e s a t u r a t i o n c o n c e n t r a t i o n s f o r th e f o u r g as es w e r ec o m p u t e d f r o m W e is s ( 1 9 7 0 , 1 9 7 4 ). T h e b a r o m e t r i c p r e s su r e w a sa s s u m e d e q u a l t o 7 6 0 . 0 m m H g . E x c e p t w h e n s t a t e d to th e c o n t r a r y ,t h e c r it er ia f o r A P a n d d i s so l v e d o x y g e n w e r e 2 0 m m H g a n d 0 . 9 0 C * ,r e s p e c ti v e ly . T h e c o l u m n h e i g h t i n c l u d e s a n a d d i t i o n a l t o t a l o f 0 . 2 0 mf o r t h e d i s t r i b u t i o n s y s t e m a n d d r a in s y s t e m . I f b o t h c r i te r i a w e r e m e ta f t e r p as s in g t h r o u g h t h e d i s t r i b u t i o n p l a t e ( n o c o l u m n r e q u i r e d ) , t h eh e ig h t o f t h e s y s t e m w a s a ss u m e d t o b e 0 .1 5 m .

G a s - t o - li q u i d r a t io ( G / L ) is t h e v o l u m e o f g a s t h a t p a s s e s t h r o u g h t h ec o l u m n p e r u n i t v o l u m e o f l iq u i d a n d is e x p r e s s e d a s a d i m e n s i o n l e s s


11/23

Design o/ packed columns ] ' b r degassing 261r a ti o . T h e G / L r a t i o w a s b a s e d o n t h e c ri t e r i o n t h a t t h e m o l e f r a c t i o no f o x y g e n i n t h e g as l ea v in g t h e c o l u m n w a s e q u a l t o 9 9 ~ o f th e n o r m a lm o l e f r a c t io n in th e a t m o s p h e r e . G a s f l o w s w e r e c o m p u t e d in t e rm s

= o 6 : , c ) ( Y u n t .f s t a n d a r d c o n d i t i o n s (2 0 C , I a t m , r e la t iv e h u m i d i t y ' ~1 9 7 9 ) .E f f e c t o f K o n c o l u m n h e ig h tT h e r e q u i r e d c o l u m n h e i g h t d e p e n d s o n t h e m e d i a s e l e c t e d a n d ._AP( F ig . 3 ). A t 1 5C a n d a d i s s o l v e d o x y g e n c o n c e n t r a t i o n ( D O C ) = 5 . 0m g li t e r -~ ira t h e i n f l u e n t , t h e c o l u m n h e i g h t r a n g e s f r o m 0 - 9 t o 3 . 4 m .A t a g iv e n in f l u e n t D O C , m e d i a s iz e a n d t e m p e r a t u r e , t h e c o l u m nh e i g h t r e q u i r e d t o s a t i sf y t h e d i s s o l v e d o x y g e n c r i te r i o n i s a c o n s t a n ta n d d o e s n o t d e p e n d o n z2LP. T h e c o l u m n h e i g h t r e q u i r e d t o m e e t t h e,.,kP c r i te r io n is z er o fo r z2~Pi, = 0 , an d inc rea se s as - -APi, is inc rea se d .S i n c e t h e c o l u m n is r e q u i r e d t o m e e t b o t h c r it e r ia s i m u l t a n e o u s l y ,t h e r e q u i r e d c o l u m n h e i g h ts ar e c o m p u t e d f o r b o t h c ri te r ia a n d t h el a rge r o f t he tw o va lue s i s u s ed fo r d es ign . A t l ow ,.X_, va lue s , t hec o l u m n h e i g h t is c o n t r o l l e d b y t h e d i s s o h ' e d o x y g e n c r i te r i o n . A b o v e

1 0Ea =

1 0

Fig. 3.

JJJJK . I O 5

K o : ~ ,

I / I I '

. .~ P . ( r a m H g )E f f e c t o f K o n c o l u m n h e i g h t ( 1 5C , i n f l u e n t D O C = 5 . 0 m # li~ e r - z ),


12/23

262 J. Colt, G. Bouck'i!

F i g . 4 .

IJ

l o .g

i1 .G

f

/ i ~ I I I I

aP. (mm Hg)Effect of temperature o n column height (K = 1.71 m -1 at _0 C, influentDOC = 5 . 0 mg liter -z ),

a ~ k P i n of approx imat ely 60 mm Hg, the colum n height is controlledby the zXP criterion.Effect of temperature on column heightFor a given &P, tile required column height decreases at higher tem-peratures (Fig. 4), This is a direct result of the effect of temperature onKa and K. An increase in temperature from 5 to 30C will increase theK value threefold. If the dissolved oxygen criterion was based on anabsolute con cen tra tion in nag liter -1, a di ffere nt response would beproduced. The increase in the K values will be counteracted by thedecrease in the C : : " value (eqn (1)).Effect of dissolved oxygen on colu mn heightAt a given APi, value, increasing DOC in the influen t, reduces tilecolumn height slightly {Fig. 5). This results because the mass transferrate of oxygen is larger than N2 + Ar + CO.,. Increasing DOC at acons tant _4J' increases the Afio: value. At ~ = 0, the column height


13/23

Des(gn of packed columns for degassing 2 63

I 0

: . P . l O 0

~ p . - o

o o ~ o . . . . . . ~ ~ , , , ~ I* 2 , I s i ~ I g ~o 11

Fig . 5 . ..) oE f f e c t o f d i s s o lv e d o x y g e n o n c o l u m n h e i g h t ( K = 1 - 7 1 m -1 a t . ,0 C ,T = 15C) .

i ' , c o

o

!

[

!F ig . 6 .

/I r i $ o

l o o ~ sa~ P . { r a m H g !

2O 0

, i ,200 2SO

E f f e c t o f d i s s o l v e d o x y g e n a n d A B o n c o l u m n h e i g h t ( K = 1 .7 1 m "1 a t2 0 C . T = 1 5 C ) .


14/23

264 3". C o l t . G . B o u c kis c o n t r o l l e d s o l e l y b y t h e o x y g e n c r i te r i o n . F o r i n f l u e n t D O C a b o v e0 . 9 0 C * o r 9 - 0 7 m g l it e r -1 a t 1 5 C , a c o l u m n is n o t n e e d e d ( F ig . 5 ) .

E f f e c t o f d i ss o lv e d o x y g e n a n d A P o n c o l u m n h e ig h tA t 1 5 C a n d t h e 3 . 8 1 c m m e d i a , t h e r e q u i r e d c o l u m n h e i g h t ra n g e sf r o m 0 t o 2 . 2 m ( F ig . 6) . A t l o w A P v a l u e s, t h e r e q u i r e d c o l u m n h e i g h td e p e n d s s t r o n g l y o n t h e i n f l u e n t D O C . A t h ig h e r A P v a l u e s , d i s s o l v e do x y g e n h a s a s e c o n d a r y e f f e c t o n c o l u m n h e i g h t .

E f f e c t o f A P a n d d i s s o lv e d o x y g e n c r i te r ia o n c o l u m n h e i g h tA s t h e A / ' c r i t e ri o n a p p r o a c h e s 0 , t h e c o l u m n h e i g h t i n c re a s e s in a ne x p o n e n t i a l m a n n e r ( F ig . 7 ). R e d u c t i o n o f th e A P c ri te r io n f r o m 5 0t o 5 m m H g in c r e a s e s t h e r e q u i r e d h e i g h t b y a f a c t o r o f 2 - 3 .

A t l o w v a l u e s o f z X P i,, t h e c o l u m n h e i g h t is c o n t r o l l e d b y t h e dis -s o l v e d o x y g e n c r i t e r i o n a n d is t h e r e f o r e i n d e p e n d e n t o f t h e A P c r i t e r i o n .A t 1 5 C , D O C = 5 - 0 m g l i t e r -~ a n d K = 1 -7 1 m - 1 a t 2 0 C , a c o k m m

3 . O

2 1 1

O O o ;

F i g . 7 .

I I i I I Js o 1~ Iso ~oo 2so 3Qo

. ' ,P . ( r a m H g }oEffect o f A P criterion on colum n height (K = 1.71 m -l at 20 C. T = 15C,inf luent DOC = 5 -O m gli ter- ' ) .


15/23

Design of'packed co lum ns /or degassing 265height of 1.03 m is required to satisfy the dissolved oxygen criterion.If the dissolved oxygen criterion was reduced to 85% (rather than90%) the column height needed to meet the dissolved oxygen criterionwould be reduced to 0-76 m. The required column height would onlybe decreased in the zone bound ed by the co lumn heights equal to1.03 and 0.76 m.Effect of the mole fraction of oxygen on column heightTile co mposit ion of gas within the c olu mn has little effect on /_kPoubut has a critical effect on effluent dissolved oxygen. The C* concen-tration for oxyg en is propo rtio nal to the partial pressure of oxygenwithin the column:

C* c~ Xo :(BP --P H:o) (28)As the value of Xo. decreases, the required colum n height significant lyincreases, especially in the dissolved oxygen limited area (Fig. 8). At an

2 Og.1=

Fig . 8 .

x , a ~ o i g ~

i I ! , ~ t !so voo 1so ~so Joo

.~P~ (ram Hg)

Effect of the mole fraction of mole oxygen on column height (T= 15C,K = 1.71 m -1 at 20~C).


16/23

266 J . Col t , G. BouckX~), of 0- 195 O0 or less, the column height is controlled totally by thedissolved oxygen criterion

For influent dissolved oxygen levels less than the criterion, thepartial pressure of oxygen in the column must be greater than or equalto 90% of the atmospheric value:

X ' o . ( B P - - P H : o ) > f 0"90Xo:(BP--PH:o) (29)In columns at atmospheric pressure, then

X~: > 0.1885 130)If X'< 0-1885, then the C* value within the column is less than thecriteria, and the dissolved oxygen criterion cannot be satisfied underany conditions.

For influent dissolved oxygen greater than the criterion, the criticalX~: will depend on the influent DOC and APi~. The maintenance ofadequate air flow through the column will generally require installationof low pressure blowers (Hackney and Colt, 1982). Self-ventilating

" r

F i g . 9 .

o ,o

woi~ ao

"3o2.a

Jf , r o10C"

Jf o

~P (ram HO)Effect of temperature on t i l e nlaxinmm G/L ratio (intluent DOC = 0 mg

l i t e r - x , K = 1 . 7 1 m - ~ a t 2 0 C ) .


17/23

Design of packed co lure ns fo r degassing 2 6 7c o l u m n s c a n b e d e s i g n ed u sin g l a g e m e d i a a n d lo w su r f a ce lo a d in gr at es . D e t a i l e d i n f o r m a t i o n o n t h e d e s ig n o f th is t y p e o f c o l u m n is n o ta v a il a b le a t t h is t i m e . T h e a d e q u a c y o f c o l u m n a i r f l o w c a n b e c h e c k e db y d i r e c t m e a s u r e m e n t o f X ~ : w i t h a d i s so l v e d o x y g e n p r o b e . T h e c o s to f m a i n t a i n i n g a d e q u a t e a ir fl o w t h r o u g h t h e c o l u m n is l o w in c o m -p a r is o n t o a d d i n g a d d i t i o n a l c o l u m n h e i g h t to c o m p e n s a t e f o r ar e d u c e d v a l u e o f X'o .

E f f e c t o f t e m p e r a t u r e a n d d i s s o l v e d o x y g e n o n t h e G / L r a t i oT h e a ir f l o w r e q u i r e d t o m a i n t a i n X ~ ): = 0 . 9 9 X o , is d e v e l o p e d in t e r m so f t h e G / L r a ti o . T h i s r a ti o d e p e n d s o n t h e d i s s o lv e d o x y g e n le v el , & P ,t e m p e r a t u r e a n d c r it e ri a f o r d i ss o lv e d o x y g e n a n d & P. T h e m a x i m u mG / L r a t io ( D O C = 0 . 0 m g l it e r -1 ) r a n g e s f r o m 3 t o 6 o v e r t h e n o r m a lt e m p e r a t u r e a n d & P i , v a l u e s ( F ig . 9 ) . T h e G / L r a t i o is l a rg e r a t l o wt e m p e r a t u r e b e c a u s e a g iv e n L2kP in r e p r e s e n t s m o r e g a s o n a m a s s b a s i s .

~ 4 a

I~* f J"o. _ ~ o o . 5 o -~ 2 0 J

k o o . r $ -!

Fig . 10 .",P (ram Hg)

Effect of dissolved ox ygen on the G IL ratio at 15 C (K = 1-7 1m -1at 20C).


18/23

268 J. Colt, G. BouckT h e r e f o r e , a la rg e r a ir f l o w i s n e e d e d t o a c h i e v e t h e e f f l u e n t m o l ef r a c t i o n c r i t e r io n . A t 1 5a C. th e G / L r a t io f o r t y p i c a l d is s o l v e d o x y g e na n d A _ Pin v a l u e s r a n g e s f r o m 2 t o 3 (F i g . I 0 ) . F o r t y p i c a l d e s i g n ,G / L = 5 s h o u l d b e a d e q u a t e , T h e s e g as f l o w ra te s a re c o m p u t e d int e r m s o f s t a n d a r d c o n d i t i o n s (1 a t m , 2 0 "C , 3 6,,G r e la t iv e h u m i d i t y ) :a c t u a l f l o w r a t e w i ll d e p e n d o n lo c a l t e m p e r a t u r e , p r e s s u r e a n d r e la ti v eh u m i d i t y (Y u n t , 1 9 7 9) .D e s i g n o f v a c u u m c o l u m n sI n c r e a s i n g t h e v a c u u m a p p l i e d t o t h e c o l u n m r e d u c e s t h e r e q u i r e dc o l u m n h e i g h t f o r th e A P c r it e r io n , b u t i n c r ea s es th e c o l u m n h e ig h tn e e d e d f o r th e d i ss o l v ed o x y g e n c r i te r io n . T h e r e q u i r e d h e ig h t f o r b o t hc r i te r ia d e c r e a s e s a t lo w v a c u u m s , t h e n s t a rt s t o i n c re a s e a t in t e r m e d i a t ev a c u u m s ( F ig . 1 I ). A t h i g h e r v a c u u m s , t h e r e q u i r e d c o l u m n h e i g h t isla rg e r t h a n f o r th e a t m o s p h e r i c c o l u m n s . T h e d i s s o lv e d o x y g e n c r it e r i o nis t h e l im i t in g p a r a m e t e r u n d e r m o s t c o n d i t i o n s .

3 .C

2 . 0g

!t o

o , o

Fig. 11.

/

I I I [ I I Ilo 2o 3a ~ so so 7o aoVac uum { ram H g)

Effect o f vacuum and dissolved oxygen on column height I T = 15C,AP in = 150 mm Hg, K = 1.71 m-~ at 20C).


19/23

Design of packed columns ]or degassing 269

Uio

oo o , io - - t o ~ i , 'l s ~ o ~ o , ~ oVacuum (ram Hgl

al

Fig. 12. EtTect of vacuum and mole fraction on column height (T= 15C,~'Pin = 150 mm Hg. dissolved oxygen = 5.0 mg liter -1, K = 1.71 m -1 at 20C).

For inlluent dissolved oxygen levels less than the criterion, thepartial pressure of oxygen inside the column must be equal to or exceed90% of the atmospheric value:

X~): (BP- -Vac --PH:o) ~> 0.90Xo~(BP--PH:o) (31)If the mole fraction of oxygen in tile column is equal to the atmo-spheric value (X~). = Xo,), then the ma xi mu m vacuum inust be ~


20/23

270 J . C o l t . G . B o u c k

required column heiglat is 0.60 m. If a 0.80 m column is used, DOC willbe reduced below the criterion of 9.07 mgl iter -~ and the system fails.

A single design value of the G/L ratio = 5.0 is recommended for theatmospheric column because the cost of the tow pressure fans is low.For waters containing high dissolved oxygen levels, this design value ofthe G/L ratio may be overly expensive to maintain in vacuum systems.Continuous monitoring of the partial pressure of oxygen within thecolumn can allow control of the air flow rate to maintain the required

svalue of Xo=.The use of vacuum columns is seriously limited by the necessity of

meeting both the dissolved oxygen and zXP criteria (Marking e t a l . ,1983). The use of a vacuum column for waters low in dissolved oxygenis not recommended without pret rea tment by a packed column. Airentrainment, heating and photosynthesi s can produce oxygen super-saturation as welt as total dissolved gas supersaturation (Weitkamp andKatz, 1980). Under these conditions, the use of a vacuum column canresult in a significant reduction in colunm height and pumping costs.

GENERAL DESIGN CONSIDERATIONSOptimum design of a degassing system will depend on a knowledge ofthe seasonal variation in zkPi,(S:+Ar+CO=), Z ~ k e in (O 2 ) a n d temperature.Gas supersaturation may typically peak in the spring and summer(Lindroth, 1957; Harvey, 1967; Bouck, 1976). In rivers, dissolved gasconcentrations may depend strongly on the water flow, hydroelectricor other operation conditions (Harvey and Cooper, 1962; D'Aoust andClark, 1980) and therefore may vary significantly on a daily basis.Under these conditions, continuous dissolved gas monitoring (D'Aoustand Clark, 1980; Bouck, 1982) may be required. The chronic effectsof gas supersaturation may require prolonged exposure before mor-tality results. This delay in response coupled with the seasonal variationin zkP require that dissolved gas data be collected in a systematicmanner. Degassing columns should be designed with at least 1 year'sdata (collected once or twice a week). Since column height depends onboth zXP and temperature, the maximum column height may notcorrespond to the maximum ZM . Therefore, the design of the columnshould be based on the maximum required column height plus a safetyfactor. Collection of adequate data for design is expensive, but canprevent overdesign or system failure. Continuous monitoring of zkP


21/23

Design of packed columns tbr deggssing 271( D ' A o u s t a n d C l ar k . 1 9 8 0 : B o u c k , 1 9 8 2 ) an d d is s ol v ed o x y g e n m a ya l lo w a u t o m a t i c c o n t r o l o f t h e de g as si ng s y s t e m a n d r e d u c e p o w e rc o s t s .

T h e u s e o f v a c u t tm s y s t e m s r e q u i r e s sp e c ia l d es ig n c o n s i d e r a t i o n s .C o n s e r v a t i v e d e s ig n o f c o l u m n h e i g h t ( e x c e ss i v e c o l u m n h e i g h t ) in t h ea t m o s p h e r i c c o l u m n s o n l y i n c r e a se s t h e p u m p i n g c o s ts . In ti l e v a c u u mc o l u m n , t h is p r o c e d u r e c a n r e s u lt in s y s t e m f a il u re i f t h e e x c e s s h e i g h tr e d u c e s t h e d i s s o l v e d o x y g e n b e l o w t h e c r i t e r i o n .

P o o r d i s t r i b u t i o n o f t h e l iq u i d o v e r th e m e d i a a n d f l o w d o w n t h es id e w a ll d e g r a d e t i le p e r f o r m a n c e o f th e p a c k e d c o l u m n . T h e s ep r o b l e m s m a y b e c r i t ic a l t o t h e p r o d u c t i o n o f ,'_kP v a l u e s le ss t h a n2 0 r a m H g . F o r th e s e a p p l ic a t io n s , t he m i n i m u m n u m b e r o f p o i n t sa t w h i c h t il e w a t e r s h o u l d b e a p p l i e d t o t h e s u r f a c e is u n k n o w n . T h em i n i m u m n u m b e r in t h e c h e m i c a l i n d u s t r 3 is 4 5 p o i n t s m -2 , w h i leH a c k n e y a n d C o l t ( 1 9 8 2 ) u s e d 8 0 0 p o i n t s m - : . T h e e f f e c t s o f w all f lo wc a n b e r e d u c e d b y t h e u s e o f la rg e c o t u n m s a n d r e d i s t r i b u t i o n p l a te s .T h e w o r k r e p o r t e d b y H a c k n e y a nd C o l t / 1 9 8 2 ) is b a s e d o n a I mh ig h c o l u m n . T h e p l a c e m e n t o f a r e d i s t r i b u t i o n p l a t e e v e r y I m m a yb e a d v i sa b l e . W h il e s e v er a l t y p e s o f m a n u f a c t u r e d r e d i s t r i b u t i o n p l a te sa re a v a il a b le ( N o r t o n C o . , 1 9 7 8 ) , a s i m p l e a n n u l u s f o r m e d o u t o fs h e e t p l a st ic m a y b e a d e q u a t e . T h e w i d t h o f t h e a n n u l u s s h o u l d b e~ - ~ o f t h e c o l u m n d i a m e t e r .

A s a fe & P i s n o t a w e l l - d e f i n e d c r i te r i o n f o r c h r o n i c e x p o s u r e o fm o s t fis h, c r u s t a c e a n s a n d m o l l u sc s . T y p i c a l w o r k o n g a s b u b b l e d is e a seh a s b e e n c o n d u c t e d o n P a c i f ic s a l m o n i d f is h es , u s u a l l y e x p o s e d t oa c u t e l y l e th a l ~ v a l u e s ( W e i t k a m p a n d K a t z , 1 9 8 0 ) . E g gs a n d la rv a lf is h a p p e a r m o r e s e n s it iv e t o d i ss o l v e d g a s s u p e r s a t u r a t i o n t h a n j u v e n i l eo r a d u l t f is h b u t t h is v a ri es b e t w e e n s p e ci es . P a c k e d c o l u m n s c a np r o d u c e g a s le v els w h i c h h a v e p r o v e d s af e f o r r a i n b o w t r o u t Salmogairdneri. H o w e v e r , p r e l i m i n a r y b u t s t r o n g e v i d e n c e s u g g e st s t h a tr a i n b o w t r o u t a re c o n s i d e r a b l y m o r e t o le r a n t t h a n b r o w n t r o u t Salmotrutta a n d A t l a n t i c s a l m o n t o A ~P l ev e ls in t h e r a n ge 0 - 2 5 m m H g .T h e r e f o r e , a d d i t i o n a l r e s e a r c h is n e e d e d t o a s su r e m a x i m u m s a f e t y f o rt h e f i s h a t m i n i m u m c o s t s t o o p e r a t o r s .

A C K N O W L E D G E M E N T ST h e a u t h o r s w o u l d l ik e t o t h a n k K r is O r w i c z f o r h e l p in t h e c o m p u t e rm o d e l i n g a n d f o r a c r i ti c a l r e v i e w o f th i s a r ti c le .


22/23

272 J . Colt, G. BouckR E F E R E N C E S

B o u c k , G . R . ( 1976 ) . Sup er sa tu ra t ion and f i she ry obse rva t ions in se lec ted a lp ineOregon s t r eams . In : Gas Bubble Disease, eds D. H. F ickeisen and M. H. Scheider ,CO NF -7410 33 . Techn ica l In fo rm at ion Cen te r , Energy Resea rch and Deve lop-m e n t A d m i n i s tr a t io n , O a k R i dg e , Te n n e s se e , p p . 3 7 - 4 0 .

Bou ck . G . R . (19 80) . E t io logy o f gas bubb le d isease , Trans. Am. Fish. Soc.. 1 9 0 ,7 0 3 - 7 .

B o u c k , G . R . ( 1 9 8 2 ) . G a so m e t e r : a n i n e x p e n s i v e d e v i ce f o r c o n t i n u o u s m o n i t o ri n gof d i sso lved gasses and supe r sa tu ra t ion . Trans. Am. Fish. Soc., 1 1 I , 5 0 5 - 1 6 .

Bo uck . G . R ., K ing , R . E . & B ouc k- se hm id t , G . L . (1984 ) . Com para t ive r en tova lo f gas super sa tu ra t ion by p lunges , sc r eens , and packed co lumns . AquaeulturalEizgbleerbzg, 3 , 1 5 9 - 7 6 .

Co l t , J . E . {1983) . T he com pu ta t ion and r epor t ing o f d isso lved gas r evels , lear.Res., 1 7, 8 4 l - 9 .

Co l t , J . & Tch oba nog lous . G . (1981) . Design o f ae ra t ion sys t ems fo r aqua cu l tu re .lu : Proceedhzgs of the Bio-Engineering Symposium for Fish Culture. eds. L. J.Al len and E. C. Kinney, F ish Cul ture Sect ions, Amer ican Fisher ies Socie ty ,Be thesda , Mary land , pp . 138-48 .

Cornacc t t ia . J . W. & C ol t, J . E . (19 84) . The e f f e c t s o f d i sso lved gas super sa tu ra t iono f larval s t r iped bass Morone saxatilis (Walbaum ) . J. Fish Dis., 7 , 1 5 - 2 7 .D 'Aous t . B . G . & Cla rk , M. J . R . (1980) . Ana lys i s o f super sa tu ra t ed a i r i n na tu ra lwaters and reservoi rs . Trans. Am. Fish. Soc., 1 0 9 , 7 0 8 - 2 4 .

D 'Aou s t , B . G . . S tay ton . L . & Sm i th , S . S . (1980 ) . S epara t ion o f bas ic pa ramete r so f dcco .n press ion using f inger ling sahno n . Undersea Biomed. Res., 7 , 1 9 9 - 2 0 9 .

Fuss , J . T. (198 3) . Ef l'ec tive f low - throu gh vac uum degasser for f ish hatche r ies .Aquaculmral Engineerilzg, 2 , 3 0 1 - 7 .

Hac kney , G . E . & Col t, J. E . (198 2) . T he pe r fo rm anc e and des ign o f packed co lum naera to r s fo r aquacu l tu re . Aquaculutral Enghleering, 1 , 2 7 5 - 9 5 .Harvey , H . H . (196 7) . Sup er sa tu ra t ion o f l ake w a te r wi th a p recau t ion to ha tc heryusage. Trans. Am. Fish. Soc., 9 6 , 1 9 4 - 2 0 1 .

Harvey , H . H . & C oop er , A . C . (1962 ) . Or ig in and t r ea tm en t o f a super sa tu ra t edr iver water . Progress Report No. 9, In te rna t iona l Pac i f i c Sa lmon F i sher i es Com-miss ion , New W estmins te r , Br i ti sh Co lumbia .

Lin dro th , A . (195 7) . A b iogen ic gas supe r sa tu ra t ion o f r ive r wa te r . Arch. Hydrobiol.,5 3 , 5 8 9 - 9 7 .

Marking. g. L., Daw son , V . K . & Crow ther , ,I. R . (1983) . Com par i son o f co lum naerators and a vacuum degasser for t rea t ing supersa tura ted cul ture v . 'a ter . Prog.Fish-Cull., 4 5 , 8 1 - 3 .

M cLean , W. E . & Boreh am, A. L . (1980 ) . T he design and assessmen t o f ae ra t iontowers . F i she ri es and Oceans , V ancou ver , Br itish Co lum bia , Canada (unpub-l i shed) .


23/23

Design of packed columns/or degassing 273M onk. B. E. , Long , C. W. & Dawiey, E. M. (19 80) . Feasib i l i ty of s iphons for degass-

ing w ater . Trans. Am. Fish. Soc., 1 0 9 , 7 6 5 - 8 .Mrsic . W. (1933) . Die Gasblasendrankhei t der F ische. Ursachen, Begle i terschein-

umgen und Abhi l f e . Zeitschri/t ffir Fisherei. 3 1 . 2 9 - 6 7 . ( Q u o t e d i n W e i t k a m p& Katz , 1980 . )Nor ton Co , (1977) . Des ign in fo rmat ion fo r packed tower s . Bullet#z DC-ll , A k r o n ,

Ohio .Nor ton Co . (1978) . Packed tower in t e rna l s . Bulletin TA-80. A k r o n , O h i o .Owsley . D. E, (1981 ) . Ni t rog en gas remo val using pac ked colum ns. In : Proceedings

of the Bio-engbteering Symposium for Fish Culntre, eds L. J. Allen and E. C.Kinney , F i sh Cu l tu re Sec t ion . Amer ican F i she r i es Soc ie ty . Be thesda , Mary land .p p . 7 1 - 8 2 .

Pe te r son . H . (197 1) . Sm ol t r ea ring metho ds , equ ipm ent , and t echn iques usedsuccessfuUy in Sweden. In: Atlantic Salmon Workshop, Unipress Co., Frederic-ton , New Brunswick , pp . 32 -62 .

Speece , R . E . & H um enick , M. J . ( 19 73) . C arbon d iox ide s t r ipp ing f rom oxy genac t iva ted s ludge sys t ems . J . War. Poll Cont. Fed.. 4 5 , 4 1 2 - 2 3 .

Weiss , R . F . (1970 ) . The soh tb i l it y o f n i t rogen , ox ygen , and a rgon in wa te r andseawate r . Deep-Sea Res., 1 7 , 7 2 1 - 3 5 .

Weiss , R . F . (1974 ) . Carbon d iox ide in wa te r and seawater : t he so lub i l i ty o f a non-ideal gas. Mar. Chem.. 2 , 2 0 3 - 1 5 .W ei tkamp , D. E. & K atz , M . (19 80 ) . A review of d issolved gas sup ersa tu ra t ionl i t e r a tu re . Trans. Ant. Fish. Soc., 1 0 9 , 6 5 9 - 7 0 2 .

Yu nt , F . W. (1979 ) . Gas f low and pow er m easurem ent . I n: Proceedings: WorkshopToward an Oxygen Transfer Standard, EPA-600/9-78-021, ed . W, C. Boyle ,US Env i ronmenta l P ro tec t ion Agency . Cinc inna t i . Oh io , pp . 105-27 .

Date post:	03-Apr-2018
Category:	Documents
Upload:	jorge-rodriguez
View:	216 times
Download:	0 times

Colt 1984 Aquacultural-Engineering

Documents