EL5EV1ER P 1 1 : 5 0 9 6 0 - 8 5 2 4 ( 9 7 ) 0 0 1 4 8 - 4

810re50urce 7echn0109y 61 (1997) 239-245 • 1997 E 1 ~ 56ence ~m 1 ~d

Pr1med 1n 6 ~ 8r1t~m A11 r19h~ ~ e d 096~852~97 $17.00

D 0 M E 5 7 1 C W A 5 7 E W A 7 E R 7 R E A 7 M E N 7 U 5 1 N 6 A U A 5 8 R E A C 7 0 R

E. 8 e h 1 1 n ~ ~ A. D1a2, a 6 . C 0 f 1 n ~ a M. H e r r e r ~ ~ E. 6 u f 1 e ~ e ~ ~ E. C h a d ~ a N. F e r n a n d e 2 a • C. F. F 0 r ~ e r 6*

(Rece~ed 3 J U ~ 1996; rev15ed ver~0n receNed 30 0ct06er 1996; accepted 1 N0vem6er 1996)

7he p e ~ 0 r m ~ ~ a ~ ~ ~ 0 upf10w ~1ud9e 6~nk~ (UA58) ~acWr ~at1n9 m u n ~ ~wa9e ~ u t a ~ 5upp1em~ta~ h~t1n9 wa5 e x a m ~ ~ a ~ d a y t~aL 7he f10w ~ ~ the d19e5ter wa5 kept c0n5~n~ ~v1n9 a hyd~u~c ~ n ~ n t1me ~ 26 h. A~0u9h ~ e ~ we~ 50me v a ~ a ~ ~ ~e 5tren9th ~ ~e ~wa9e, after ~e 1n1~a~ 18 day5 ~e ~ad1n9 ~ wa5 m ~ n ~ e d at a60ut 1.21 ~ C0D/m~day. A p~- ~anu~ted ~ud9e wa5 u5ed a5 ~e ~ u ~ 6ut ~e 5 t a ~ pe~0d wa5 5 ~ ~n9; a60ut 90 day5. 7he ~m1 ~ ~ a c ~ a ~ a ~ m~0 w~ ~ a ~ h19h, ~ ~ an e~mem ~ ~5m~f1~ • ~e d19e5~ H0weve~ ~ m0~ a~a~n~ wa5 added ~ ~e ~c0m1n9 ~wa9e, ~e m ~ ~ 9 ~ w ~e cff~a1 ~ 0 n ~ ~ had ~ a ~ ~e d19e5t10n p~ce55 5ta61115~ ~ d a ~ d a C0D ~m0~1 e f f 1 ~ a~ra91n9 ~ % and a ~ c ~ 5 ~eM ~ ~ m ~ metha~/k9 C0D ~ m 0 ~ • 1 ~ 7 E15ev1~ ~ n ~ L ~

Key w0rd5: A n a ~ 0 6 ~ d ~ t ~ m u ~ d p ~ ~ w ~ UA58, p ~ r m a n ~ , ~ 0 p ~ ~ 0 ~ .

1 N 7 R 0 D U C 7 1 0 N

Aer0~c 6~-0~d~10n 15 very w1de~ u5ed f0r the ~eatment 0f car60nace0u5 p0Hutan~. H0weve~ the pr0ce55e5 wh1ch fa11 1nt0 th15 cate90ry can he 5a1d t0 have tw0 d~t1nct d~advanta9e~ they u5e ener9y and they 9ener~e app reda~e 4uanf1t~5 0f exce55 610- ma55 wh1ch re4u1re5 d~p05a1. Anaer06~ pr0ce55e~ 1n c0n~a~, 9enerate ener9y ~ the f0rm 0f a meth- ane-r1ch 6109a5. 1n add1t10~ the am0unt 0f 610ma55 wh1ch 15 pr0duced 15 a60ut a 5~th 0f that re5u1t1n9 fr0m aer06~ pr0ce55e5. 7he dev~0pment 0f anaer0- 61c pr0ce55e5 wh1ch 5eparate the 50~d9 retent10n t1me ff0m the hydrau11c retent10n t1me, 50 that there 15 an effe~1ve 1mm061115at10n 0f the 6 ~ m a ~ , ha5 1ed t0 the1r acceptance a5 effe~1ve ~chn0109~5 f0r the ~eatment 0f wa~ewa1e~. H0wever, the app11cat10n

*Amh0r t0 wh0m c0rre5p0ndence 5h0~d 6e addre~ed. 239

0f th~ ~chn~09Y ha5 tended t0 6e re~r1cted t0 5tr0n9 ~du~r1~ eff1uen~. 1ndeed, a recent 5urvey 0f anaer06~ react0r5 w1th1n Eur0pean C 0 m m u ~ c0untr1e5 ha5 5h0wn th~, ~n0f1n9 51ud9e d ~ e ~ n and 1andf111 51te5, 50% 0f the d ~ e ~ e ~ are t r e ~ 9 farm ~urr1e5 and the rem~nder are 6e1n9 u5ed f0r the ~ e ~ m e n t cf ~du~r1~ eff1uent5 (Nyn~ 1994).

7he 5ucce55 0f anaer06~ pr0ce55e5 a5 a ~ e ~ m e n t ~chn0~9y f0r h ~ h ~ e n p ~ 1ndu~r1a1 eff1uent5 ha5 meant th~, 0ver the 1a~ decade, the p0tent1~ 0f the5e pr0ce55e5 f0r the ~ e ~ m e n t 0f 10w ~ren9th ( < 1 0 0 0 m 9 C 0 D / 1 ) eff1uent5 ha5 6een e v ~ u ~ e ~ 7hu5, data have 6een rep0~ed f0r m05t 0f the h~h- rate anaer061c pr0ce55e5 at 5~e5 ran~n9 ff0m h60ra t0ry~c~e t0 f u ~ c ~ e ~ 1 ~ n 5 (R0ckey • F0r~eL 1985; Le~1n9a ~ a1., 1993; V1e1ra et a1., 1994). De5p~e th15, anaer061c 5ewa9e ~ e~me n t ~ n0t accepted a5 a pr0ven ~chn~09y (5w1t2en6aum, 1995). 0 n e area 0f c0ncern ~ the ~ m p e r ~ u r e 0f 0 p e r ~ n . W1th ~9h-~ren9th wa~e~ 5uff1~ent ener9y 1n the f0rm 0f 6109a5 can 6e 9ener~ed t0 5u5~1n me50p~1~ 0perat10n. WRh mun1c1p~ 5ew- a9e5 th15 cann0t 6e 9uaranteed and there 15, theref0re, c0ncern a60ut the ener9y 6~ance and the c05t~ffect1vene55 0f anaer061c 5ewa9e ~e~ment . 7h~ 15 0f p a ~ u h r c0ncern 1n ~ m p e r a ~ c0untr1e5 where am~ent ~mperature5 ate 10we~ Vene2ue1a, p a ~ a d y Maraca~0, mu~ 6e th0u9ht 0f a5 6e1n9 ~ 0 p ~ , w1th medhn ~mper~ure5 1n the 5ummer 0 u n e - 0 ~ 0 6 e ~ 0f ar0und 32°C. D ~ e ~ e r h e ~ 9 15, theref0re, n0t a re1evant c0ncern. 7hu5, th15 paper rep0~5 the re5uR5 0f an ekam~af10n 0f a pf10t~c~e upf10w 51ud9e 61anket (UA58) rea~0r 0per~ed w1th0ut 5upp1emenmry h e ~ 9 at am61ent ~mpera- ture 0ver an extended (200 day) per10d.

M E 7 H 0 D 5

7 h e U A 5 8 ~ a ~ 0 r 7he 1ay0ut 0f the U A 5 8 react0~ wh~h had a w0rk- ~ 9 v~ume ~ 55.51, ~ ~ 0 w n 1n N9. 1. 7he

240 E. 8eh11n9 et a1.

feed~0ck wa5 taken fr0m the mun~1pa1 5ewa9e 5y5- tem wh~h ran acr055 the Un1ver51ty 0f 2u11a campu5. 1n the 1n~1a1 5ta9e5 0f the w0rk, the 5ewa9e wa5 pumped d1rect1y t0 the react0~ H0weve~ th15 9ave an appre~a61e var1at10n 1n the 10ad1n9 rate (0.5-3.9 k9 C0D/m3day) and, theref0re, fr0m day 18 5ewa9e wa5 pumped t0 an e4ua1~at10n tank and then fed 6y 9rav1ty t0 the UA58. 7h~ ena61ed a

m0re 0r 1e55 c0n5tant 10ad1n9 rate t0 6e ma1nt~ned; the avera9e va1ue 6e1n9 1.21 k9 C0D/m3da~ 7he feed f10w rate wa5 7.2 ~h. 7yp1ca1 an~yt~a1 data f0r the wa~ewater are 91ven 1n 7a61e 1 .7he react0r wa5 5eeded w1th a 9ranu1ar ~ud9e fr0m the anaer061c react0r at a 10ca1 6rewery. 7he ~ud9e had a t0ta1 50f1d~ c0ncentrat10n 0f 34000 m9/1 (84% v01at~e5) and the ~2e 0f the 1n0cu1um wa5 10% 0f the react0r

28cm 8109a5 Cham6er [= 1 =[

••,1 1 13cm • 2 ~

~m ~ ~

~ 1 ~ ~ 1 ~ 1 ~

85cm

17cm

~(~(~(~(~(~(~(~~" ~" ~" ~ " ~" ~ " ~" ~" ~::.~3~5~3~3~3~3~3~:.~5~:. - . - .~1~

1.3cm d1a ~ ~ 8109a5

~ ~ ~1ue~

~ ~ . ~ m ~

5 ~ e n t ~ 0 n C0ne ~ 1~erme~e C0ne f0r 8109a5

/

~ 7em~ratum mea5umme~

~.~em ~

~ -D1ffu5er c0ne

6mve1

1nf1uent ~ 1.5chemat1c ~a9ram 0f ~e UA58 react0~

5am~e p01nt f0r ~ud9e

7a61e 1.7yp1ca1 c0mp05~10n 0f the untreated wa5tewater

Parameter C0ncemrat~n (m~1)

Ma~mum M~1mum Mean C0D 1206 200 423 Amm0n1aca1-N 63 1.1 21.3 0r9an1c N 10.6 3.6 7.3 70ta1 P 30 7 • 0.9 70ta1 5u5pended 5011d 462 76 162 V01at11e 5u5pended 5011d5 350 58 123

5ewa9e treatment 6y UA58 241

v01ume (5.5 1). 0nce the 5eed had 6een added, the react0r wa5 f111ed w1th wa~ewater and 0perated a5 a 6atch 5y5tem f0r 48 h. After th15 1n1t1a1 per10d, a c0nt1nu0u5 f10w re~me wa5 ad0pted. A 1 k ~ 1 ~ wa5 c0ntr01~d 6y the add~10n 0f 50d1um 6~ar60nate, w1th the c0ntr01 1eveL a~er day 8~ 6e1n9 1620 m9/1. 6a5 wa5 c0Hected 6y the d0wnward d~p1acement 0f w~e~ 7he 9a5 c0mp051t10n, t09ether w1th the c h e m ~ c h a r a ~ e r 1 ~ 5 0f the 1nf1uent and ~eated eff1uent were mea5ured every 0ther day f0r the f1r~ 3 week5 0f 0perat10n and then 1e~ ~e4uent~ a5 the react0r perf0rmance ~a61115e~

Ana1yt1ea1 ~chn14ue5 7he c0ncentrat10n5 0f C0D, 5u5pended 5011d5 and ~ k ~ 1 ~ were mea5u~d 6y ~andard m~h0d5 ( 6 ~ e n 6 e r 9 et aL, 1992). 7he c0mp0f1t10n 0f the 6~9a5 wa5 mea5u~d w1th a p0~a61e 9a5 meter (6a5ran9er 736R, Cr0wc0n 1n~rument5 Ltd) the c ~ t 1 0 n 0f wh~h wa5 checked w1th kn0wn m~- ture5 0f m e ~ a n e and car60n ~0f1de. 7he v01af11e h ~ y ac1d5 (VFA) c0ncentrat10n5 ( ~ 1 , acetate and F r0~0n~e) w e ~ m e ~ u ~ d 6y 9 ~ 4 ~ d chr0m~ ~9raphy (Perk~-E1mer A u t 0 ~ e m ) u51n9 a FFAP Quadrex c a ~ 1 h ~ c~umn (15 m ×0.25 mm 1D).

0xY9en-f1ee n~r09en wa5 u5ed a5 the carr1er 9a5 at a f10w rate 0f 29 m1/m1n and the e1uted fa t~ a~d5 were detected 6y f1ame ~n15at10n. 7he1r c0ncentra- t10n5 were mea5ured 6y an 1nte9rat0r (PE Ed50n 1022) wh~h had 6een p re~N~ra ted w~h a ~andard mNture 0f fa t~ ac1d~ Pr10r t0 ana~515, the 5amp1e5 were f1Rered thr0u9h a mem6rane f11ter (0.45 ~m p0~e 5~e) and m~ed w1th f0rm1c add (1 pa~ acN t0 10 pa~5 f1Rrate). 7he 5amp1e v01ume wa5 1 ~1.

RE5UL75 AND D15CU5510N

An e x a m ~ n cf the ~mperature f 1 u ~ u ~ n 5 1n the react0r 0ver the tr1M per10d 5h0wed that, Mth0u9h there were 50me f 1 u ~ u ~ n 5 6etween 29 and 30°C ~1t1a11~ ~am6~nt h e m ~ pr0duced a m0re 0r 1e55 c0n~ant d ~ e ~ n ~mpermure 0f 30°C. 7h15 15 10wer than the n0rmM m e 5 0 p h ~ d ~ e ~ n ~ m p e r ~ u r e 6ut 1t 15 n0t 10w en0u9h t0 cau5e any rea1 1mpa~ 0n the perf0rmance (Hen2e • Harre- m0e5, 1983).

7he var1at10n5 1n the Mad~9 rate, wh~h are #ven 1n F19. 2, 5h0w 4u~e deaf1y the ~f1uence 0f the e 4 u M ~ n tank M 5m00th~9 the pe~ur6m~n5 1n the feed. 7he data M50 5h0w th~, 0nce the MadM9

v ~ • ~ ~

2 5 ~

1 e

,

.

0 11. . : :1 , ~ . , .2 11-5 ~ ~ . : ~ 0 :: ~ : .~ .•" ~ 1 ~ : ~: : , • .............. ~

, : ~ . . . . 11 " 5 1

: e e , , ;: • ~ : .

- ; ~ •

1 ~ ~ • • • •

0 5 0 1 0 0 1 5 0 2 0 0 2 5 0

71me (day5) ~ 2. Vaf1~n5 ~ the a p ~ d 10ad1n9 rate (e) and the 9a5 pr0duct10n (.).

242 E. 8eh11n9 et ~.

had 6een 5m00the~ the 9a5 p r 0 d u ~ n 1ncrea5ed ~ead1~ unt11 1t reached a p1amau va1ue 0f a60ut 28 ~d. 7h~ t00k 60-70 day5. A ~m11ar 5kuat10n can 6e 5een ff0m F19. 3, wh~h 5h0w5 the eff1uent C 0 D data 9 r a d u ~ decrea51n9 w~h t1me t0 a p1ateau v~ue 0f 56 m9/1. 1n th~ ca5e, h0weve~ the effect 0f the e 4 u ~ a t 1 0 n tank wa5 n0t r e ~ n0t1cea61e and the p01nt wh~h mu5t 6e h~h1~hted 15 the 6uffer1n9 effect 0f the UA58, 6ear1n9 1n m ~ d the f1uctuat10n5 1n 10ad wh~h 0ccurred 6ef0re day 20.

7he 4ue5t10n5 0f ~a~-up and 5teady-5ta~ c0nd1- t~n5 are 0f 50me ~9n1f1cance. E a d ~ r w0rk (600dw1n et a1., 1992) ha5 5h0wn that the p r a ~ e 0f u~n9 a pre-9ranu1ated 5eed w1f1 ena61e a m0re rap1d ~a~-up t0 6e ach1eved. 7he data 1n F195 2 and 3 1mp1y that even u51n9 a 9ranu1ar 51ud9e a5 the 5eed, an appreda6~ t1me (c. 90 day5) wa5 needed 6ef0re the d~e5ter c0u1d 6e deemed t0 6e at ~eady-~ate w1th c0mp1ete ~ar~up ach1eved. 7h~ wa5 u ~ d y t0 6e a temperature effect. 7he u5e 0f a pre-9ranu1ated 5eed may we11 ~v0Ne 5u~ect1n9 the 610ma55 t0 a chan9e 1n the nature 0f the car60nace0u5 mater1~ ~ 15 6e1n9 re4~red t0 de9rade. 1n 50me ca5e5, th~ ~pe 0f chan9e ha5 6een 5h0wn t0 have an adver5e effect 0n the perf0rmance (M0r9an et a1., 1990). 1n

th15 pre5ent ca5e, the car60n 5u65trate wa5 6e1n9 chan9ed fr0m a 6rewery wa5te t0 d0me5t~ 5ewa9e.

7he we11-6e1n9 0f a react0r can 0~en 6e jud9ed 6y the eff1uent pH and an exam1nat10n 0f the pH v~ue5 0f the 1nf1uent and the treated eff1uent (F~. 4) 5h0w5 that a dr0p 1n pH v~ue d1d 0ccur acr055 the d19e~e~ 7he add09en~ e~ment 0f the 0ver~1 d19e5t10n pr0ce55 w111 9enerate add5, 6ut under n0r- ma1 drcum~ance5 th15 w0u1d 6e 6uffered 6y the a1k~1n1ty 1n the react0~ 7a61e 2 5h0w5 the ~k~1nhy (expre55ed a5 c ~ d u m car60nate) 6e1n9 fed t0 the react0~ Acc0rd1n9 t0 W1~0x et a1. (1995), an anae- r061c d19e5ter re4uke5 a 6~ar60nate a1k~1nky 0f 6etween 1000 and 3000 m9 CaC03/1 f0r 5ta61e 0per- at10n, wh115t Jenk1n5 et aL (1991) 5tated that v~ue5 6e10w 1200 m9/1 (6a5ed 0n a f1~at10n t0 pH 5.75) were 1nd~atNe 0f d19e~er tr0u61e. 7he re5uR5 1n 7a61e 2 deaf1y 1nd~ate that 6y th15 cr1ter10n, pr10r t0 day 8~ the ~k~1n1ty v~ue5 were t00 10w. H0w- eveL data pre5ented 6y van Haand~ and Le~1n9a (1994) f0r the U A 5 8 6e1n9 0perated at Pedre9~ 5h0w an avera9e 1nf1uent a1k~1n1ty 0ver a 30-week per10d 0f 303 m9/1, whh a ran9e 0f 220-390 m9/1. 0 n th15 6a51~ 5uff1dent ~k~1n1ty wa5 ava11a61e 1n the pre5ent d19e5ter.

160

140

120

---, 100

....E

0 0 80 ~¢ ~--

m 60

,;

20

0

~ ~ ¢ ¢ ¢ ¢ ¢ ¢ ¢ ¢ ¢ ¢

40

1 0 0 250

v ~ - ~ - - ~ . . . . . . . . . . . . • • 1 • 1

50 100 150 200 ~ m e ~ a y ~

~ 8

0.6

~ 4

~ 2

~ 3. v a f 1 ~ n 1n the eff1uem c 0 D (.) and the v F A : a 1 k ~ rat~ (0).

m m

< •

5ewa9etreatment6yUA58 243

1n ~ 1 ~ , the pH 15 90verned 6y the 1nteract10n5 6etween the car60nate and ~ 0 ~ n - ~ d 6 u ~ r ~ 6 ~ . 8ecau5e 0f th15, 1t ha5 6een 5u9- 9e~ed that a m0re 5enf1t~e m e ~ u ~ 0f the 5tate 0f a d ~ e ~ e r c0u1d 6e the t0 t~ V ~ : ~ y rat10 and that there are three cf1t1c~ va1ue5 0f th15 rat10 ( ~ c k ~ e • Hay~ , 1976; 5w~2en6aum et a1., 1990):

<0.4 the d ~ e ~ e r 5h0u1d acc0m0d~e m1n0r f1uctuat10n5 ~ 0 m any m~0r chan9e 1n pH;

7a~e ~ 1nf1uent ~ k a ~

71me A 1 k ~ 1 ~ (day5) (m9 CaC03/1) 0-8 115.2 8-14 246.2

14-21 450 21-32 320 32-44 430 44-56 500 56-68 700 68-80 750 80-200 1628

0 A - 0 ~ 50me 1n~a611~y can 6e expe~ed; 0.8 the d ~ e ~ e r ~11 expedence 5~n~cam

~ ~ 7he v a f 1 ~ n 5 1n th15 rat10 are p ~ n ~ d 1n F19. 3

and 5h0w that, a~er the ~R1~ 2week~ ~ wa5 1e55 than the c f 1 t ~ va1ue 0f 0.4.

7he c 0 n c e ~ t ~ n 5 0f acetate and p r 0 p ~ n ~ e 1n the treated eff1uem are p ~ n ~ d 1n ~ 9 . 5 and 5h0w a c1ear dem~kaf10n 6etween the re5uR5 wh1ch were 06 t~ned when the ~ k ~ 1 ~ wa5 1e55 than 1628 m ~ and th05e when 1twa5 9 ~ . 7he W ~ 0 m ~ 0f p ~ p ~ n a ~ under c0n~f10n5 0f d ~ e ~ e r 5tre55 15 we11 kn0wn. F0n9a~ku1 et a1. (1994), ~ r exam~e, have rep0~ed that th15 0ccurred when the h y d ~ ~ m ~ n t1me wa5 decrea5ed t0 t00 10w a va1ue. 7hey a150 ~ p 0 ~ e d that a5 th15 happened, the t0ta1 V F A : ~ k ~ 1 ~ ra t~ 1ncrea5ed t0 a va1ue 9reater than 0.6. 1n th15 current w0rk, the 5tre55 ~ m ~ n wa5 a ~ ed~ 0ck wh~h wa5 un6~anced 1n ~ t ~ n t0 a ~ 1 ~ . H19h p r 0 p ~ n ~ e c 0 n c e ~ t ~ n 5 0ccur when there 15 an 1ncrea5e 1n the pa~1~ pre55ure 0f hydr09en and, 1ndeed, m e ~ u ~ m e ~ 5 0f hydr09en 1n the 6109a5 have 6een 5u99e~ed a5 a p~em1~ c0n- tr01 m e ~ u ~ ( M ~ e ~ 1982). H0weve~ H~key • 5 ~ e n ~ u m (1991) have 5h0wn that a d ~ r can

•5

8.3

8.1

~9

~ 7

= ~ 5

~3

~ 1

~9

6,7

6.5 0

~1 ,,, *~Q

• ~ . . ~ . . . . •

• • • •

50 100 150 200 71me(day5)

F1~ 4. Vaf1at10n5 1n the pH0f the 1nf1uent (0) and the eff1uent(e).

244 E. 8eh11n9 et ~.

140

120 ::

100

N e ~ *

, ~ 1

~ 0 ~ ~ 1 °

~ : 1

1•

>

0 50 100 150 200 71me (day5)

~ 5. Var1at10n 1n the acetate (~) and pr0~0na~ (*) c0ncentrat10n5 1n the treated eff1uem.

6e 1n an un5ta61e c0nd1t10n, a5 5h0wn 6y h19her V F A accumu1at10n and a h19h VFA:~k~1n1ty rat10, w1th0ut there 6e1n9 h ~ h c0ncentrat10n5 0f hydr09en 1n the 9a5. 1n the pre5ent w0rk, au t0mated c0ntr01 mea5ure5 were n0t app1~d. Ra theL c0ntr01 wa5 exerc15ed 6y the m a n u ~ add1t10n 0f ~k~1n1ty and the u5e 0f the t0ta1 VFA:a1ka11n1ty rat10.

C 0 ~ 0 ~

D0me5t~ 5ewa9e can 6e t rea ted 5ucce55fu11y 1n ~ 0 p ~ N reN0n5 w1th0ut the need f0r 5upp1ementary heat1n~ H0weveL a U A 5 8 5y~em w111 take a f1n1~ t1me t0 reach ~eady -~a t e c0nd1t10n~ even when a pre-9ranu1ated Nud9e 15 u5ed a5 the 6ed 1n0cu1um. 1n th15 5tudy, the ~ a ~ - u p t1me wa5 a60ut 90 day5. 7 h e w0rk a150 d e m 0 n ~ r a t e d the 1mp0~ance 0f ma1nta~1n9 an ade4uate Nka11n1ty 1n the 5y~em.

R E F E R E N C E 5

F0n9a5t1tku1, R., Mav1n1c, D. 5. • L0, D. V. (1994). A tw0-pha5ed anaer061c d19e~10n pr0ce5~ c0ncepL pr0- ce55 fa11ure and max1mum 5y5tem 10ad1n9 rate. Water Env1r0~ Re5., 66, 243-254.

600dw~, J. A. 5., Wa5e, D. A. J. • F0r~e~ C. F. (1992). P r e ~ r a n ~ e d 5eed5 f0r UA58 rea~0~: h0w nece~ary are they• 810re5. 7echn01., 41, 71-79.

6reen6er9, A. E., C1e5cer1, L 5. • E~0n, A. D. (ed5) (1992). 5mndard Me~0d5 f0r ~ e Exam~at10n 0f Wa~r and Wa5tewater, 18th edn. APHA, AWWA, WEF, Wa5h1n~0~ DC.

Hen2e, M. • Harrem0e5, P. (1983). Anaer0~c ~e~ment 0f wa~ew~er 1n f1xed •m react0~--a 1Rerature re•ew. Wa~r 5c1. 7echn01., 15, 1-100.

H~ke~ R. F. • 5w~2en6aum, M. 5. (1991). 7he re5p0n5e and ut~1~ 0f hydr09en and car60n m0n0~de a5 pr0ce55 1 n d ~ 0 ~ cf anaer06~: ~9 e~e~ 5u~e~ t0 0r9an~ and h y d r a ~ 0ver10ad5. Re5. 2 Water P011u~ C0ntr01 Fed., 63, 129-140.

Jen~n~ 5. R., M0r9an, J. M. • 2han~ X1a0. (1991). Mea5ur1n9 the u5a~e car60nate ~ k ~ 1 ~ 0f 0perat1n9 d~e~e~. Re5. ~ Wa~r P011u~ C0ntr01 Fe~, 63, 28-34.

Le~1n9~ 6., de Man, A., van der La5t, A. R. M., W1e- 9ant, W., van Kn~pen6er~ K., Fr~n~ J. • van 8uuren, J. C. L. (1993). Anaer0~c ~e~ment 0f d0me5t1c 5ewa9e and wa~ew~e~ Wa~r 5cL 7echn01., 27, 67-73.

M0r9an, J. W., 600dw~, J. A. 5., Wa5e, D. A. J. • F0r~e~ C. F. (1990). 7he effe~5 0f uf1n9 var10u5 ~pe5 0f car60nace0u5 5u6~rate 0n UA58 9ranu1e5 and 0n rea~0r perf0rmance. 8~L W a ~ , 34, 55-71.

M05e~ F. E. (1982). New dev~0pmen~ 1n the anaer061c ~e~ment cf ~du~f1~ wa~e5. Wa~r P011u~ C0ntr01, 81, 540-552.

Nyn5, E. J. (1994). A 6u1de ~ 5ucce55fu1 1ndu5tr1~ 1mp~- men~t10n 0f 8~me~an~a~0n 7echn01091~. 1n5t1tute

5ewa9e treatment 6y UA58 245

W ~ m Namu~ 8e191um, f0r the Eur0pean C0mm~- 510n D6XV11.

R0cke~ J. 5. • F0r~e~ C. F. (1985). 5tud1e5 w1th an anaer06~ expanded 6ed rea~0r c0mpar1n9 the perf0~ mance5 ac~eved w1th ~n~et1c wa~e and d0m~t~ 5ewa9e. En2ym. M1cr0~ 7echn01., 7, 401-404.

5w~2en6aum, M. 5. (1995). 0 6 ~ a d ~ 1n the 1 m ~ e m e ~ t~n cf anaer061c ~e~mem ~chn0~9y. 810re5. 7echn~., 53, 255-262.

5w~2en6aum, M. 5., 6 ~ d ~ 6 0 m e ~ E. • H~ke~ R. F. (1990). M0n1~f1n9 0f the anaer06~ m~hane ~ r m e ~ t10n pr0ce55. En2ym. M1cr0• 7echn01., 12, 722-730.

van Haandd, A. C. • L~f1n9~ 6. (1994). Anaer0~c 5ewa9e 7reatment. J0hn W11ey and 50n5, Ch~he~e~

U ~ V~1r~ 5. M. M., C a ~ h ~ J. L , 8ar~an, F. P. 0 . •

Rech, C. M. (1994). ~ ~ 0f the UA58 tech- n ~ 0 ~ ~ r ~wa9e ~ e ~ m e m ~ a 5m~1 c 0 m m u ~ ~ 5 u m ~ 5a0 Pau~ 5tate. ~ r 5 ~ ~ n ~ , 3~ 203-210.

~ 5. J., H ~ D. L , H ~ F. R. • 6 ~ , A. J. (1995). A neur~ ~ L 6a5ed 0n 6 ~ a ~ 0 n ~ e m 0 n ~ 0 r ~ t0 c 0 ~ r ~ anaer06~ ~ 9 e ~ n . ~ ~ . , 2~ 1465-147~

~ ~ C. • H~e5, R. 8. J. (1976). A n ~ 6 ~ ~ D ~ : ~ n 5 ~ n u a L EPA 43~%76~01, U5 Naf10n~ 7 e c h n ~ ~ r m a f 1 0 n ~ 5pr1n9f1d~ ~ .