A new approach for the evaluation of the maximum specific growth rate in nitrification

~

Per9am0n P11: 50043-1354(96)00031-0

;Vat. Re5. V01.30, N0.7, pp. 1661-1669, 1996 C0pyr19ht • 1996E15ev1er5c1enceLtd Pr1nted 1n 6reat 8r1ta1n.AU r19ht5re5erved 0043-1354/96$15.00+ 0.00

A NEW A P P R 0 A C H F 0 R 7 H E E V A L U A 7 1 0 N 0 F 7 H E MAX1MUM 5PEC1F1C 6 R 0 W 7 H R A 7 E 1N N17R1F1CA710N 5. 5 ~ 2 E N ~ , D. 0 R H 0 N ~ * and H. A. 5AN Env1r0nmenta1 En91neer1n9 Department, 15tan6u1 7echn1ca1 Un1ver51ty, 1.7.0. 1n~aat Fak111te51, 80626 Ma51ak, 15ta6u1, 7urkey (F1r5t rece1ved Au9u5t 95; accepted 1n rev15edf0rm January 1996)

A65tract--M0n1t0r1n9 the 9enerat10n 0f 0x1d12ed n1tr09en c0ncentrat10n 1n 6atch react0r515 the preferred appr0ach f0r the a55e55ment0f the max1mum 5pec1f1c9r0wth rate f0r aut0tr0ph1c 610ma55.7he 51mp11fy1n9 a55umpt10n5 a550c1ated w1th the current1y ava11a61emeth0d5 are n0t a1way5 ju5t1f1a61e and may 1ead t0 m151ead1n9re5u1t5. 7h15 paper pr0v1de5 a cr1t1ca1 appra15a1 0f the re1evant c0nceptua1 6a515and pr0p05e5 a new appr0ach f0r the exper1menta1 determ1nat10n 0f the max1mum 5pec1f1c9r0wth rate 1n n1tr1f1cat10n. 7he pr0p05ed meth0d 15 5ucce55fu11yte5ted 0n d0me5t1c 5ewa9e. 1t 15 a150 te5ted w1th 5ynthet1c 5u65trate, a meat pr0ce551n9 p1ant eff1uent 1nd1v1dua11yand 1n d1fferent m1xture5 w1th d0me5t1c 5ewa9e. C0pyr19ht • 1996 E15ev1er 5c1ence Ltd Key w0rd5--act1vated 51ud9e, n1tr1f1cat10n,aut0tr0ph1c 9r0wth, wa5tewater treatment, d0me5t1c 5ewa9e, meat pr0ce551n9 eff1uent

N0MENCLA7URE 5pec1f1c decay rate 0f aut0tr0ph1c 610ma55 (d-1) ha1f 5aturat10n c0eff1c1ent f0r amm0n1a (m91- t) amm0n1a c0ncentrat10n (m91- t) 0x1d12ed N c0ncentrat10n (m91-1 ) 1n1t1a1c0ncentrat10n 0f 0x1d12ed N (m9 1- t ) c0ncentrat10n 0f 0x1d12ed N exper1menta11ydeterm1ned (m9 1-1) t = t1me (d) XA = c0ncentrat10n 0f aut0tr0ph1c 610ma55 (m91- t ) XA0=1n1t1a1 c0ncentrat10n 0f aut0tr0ph1c 610ma55 (m91-1) YA= 0vera11 y1e1d c0eff1c1ent 0f aut0tr0ph1c 610ma55 (9 ce11 C0D per 9 0x1d12ed N) /1A= max1mum 5pec1f1c 9r0wth rate f0r aut0tr0ph1c 610ma55 (d- 1) 6A =

KNn = 5Nn = 5N0 = 5N00= 5N0~ =

1N7R0DUC710N 7he max1mum 5pec1f1c 9r0wth rate f0r aut0tr0ph1c 610ma55, /1A 15 the m05t cr1t1ca1 parameter 1n the m0de111n9 and de519n 0f n1tr1f1cat10n 5y5tem5, a5 1t p1ay5 a d0m1nant r01e 1n the ma9n1tude 0f the wa5h0ut 51ud9e a9e f0r n1tr1f1er5. 7he va1ue 0f th15 k1net1c c0eff1c1ent 15 very much dependent 0n wa5tewater character15t1c5; theref0re, 1t 5h0u1d 6e determ1ned 5pec1f1ca11y f0r the wa5tewater 0f 1ntere5t. Act1vated 51ud9e react0r5 de519ned f0r n1tr1f1cat10n 5u5ta1n a m1xed cu1ture 0f heter0tr0ph1c and aut0tr0ph1c 610ma55. F0r th15 rea50n, exper1menta1 techn14ue5 deve10ped f0r pure cu1ture5 and re1y1n9 0n the eva1uat10n 0f aut0tr0ph1c 9r0wth 6y d1rect mea5ure*Auth0r t0 wh0m a11 c0rre5p0ndence 5h0u1d 6e addre55ed [Fax: (90) 212 286 6550].

ment5 0f n1tr1f1er5 cann0t 6e u5ed f0r 5uch 5y5tem5. C0n5e4uent1y, a num6er 0f d1fferent pr0cedure5 have 6een 5u99e5ted t0 e5t1mate the va1ue 0f/1A 1n act1vated 51ud9e; they 1nv01ve e1ther act1v1ty mea5urement5 5uch a5 0xY9en uptake rate ( 0 U R ) , 0r m0n1t0r1n9 re1ated m0de1 c0mp0nent5 5uch a5 amm0n1a n1tr09en (NH3-N) 0r 0x1d12ed n1tr09en f0rm5 ( N 0 2 -N + N03--N). 1n the pr0cedure 1nv01v1n9 aut0tr0ph1c act1v1ty, the 0 U R 15 mea5ured 1n a react0r 5u5ta1n1n9 60th heter0tr0ph1c and aut0tr0ph1c 610ma55, 6ef0re and after the 1nh161t10n 0f n1tr1f1er5 (N0wak and 5varda1, 1993); the d1fference 6etween the tw0 mea5urement5 15 1nterpreted a5 a d1rect 1nd1cat10n 0f the 0 U R a550c1ated w1th n1tr1f1cat10n. 7he u5e 0f NH3-N f0r eva1uat1n9 the va1ue 0f/1A 1n act1vated 51ud9e 15 11m1ted 51nce amm0n1a n1tr09en a150 5erve5 a5 the 6a51c n1tr09en 50urce and 1nc0rp0rated 1nt0 610ma55 at the 5ame t1me a5 1t 15 0x1d12ed t0 N03- -N. C0n5e4uent1y, the c0ncentrat10n 0f the 0x1d12ed n1tr09en, 5N0, 15 a much m0re c0nven1ent parameter f0r th15 purp05e, ma1n1y 6ecau5e 5N0 15 the 0n1y m0de1 c0mp0nent 501e1y re1ated t0 aut0tr0ph1c 9r0wth. 8atch 5y5tem5 are 9enera11y preferred a5 they 0ffer a 51mp1er and m0re c0nven1ent 1nterpretat10n 0f the react10n k1net1c5, av01d1n9 p055161e 1nterference 0f react0r hydrau11c5. 7h15 paper pr0v1de5 a cr1t1ca1 appra15a1 0f the current pr0cedure f0r the a55e55ment 0f/1A, 6a5ed up0n the 065ervat10n 0f 0x1d12ed n1tr09en 9enerat10n 1n 6atch react0r5 and pr0p05e5 a new meth0d f0r 1t5 eva1uat10n. 1t rep0rt5 the re5u1t5 0f exper1menta1 5tud1e5 c0nducted f0r the a55e55ment 0f the 5pec1f1c max1mum 9r0wth rate, /1A, character121n9

1661

1662

5. 562en et a1.

n1tr1f1cat10n 1n 15tan6u1 d0me5t1c wa5tewater5. 7he re5u1t5 a150 c0n5t1tute a pract1ca1 app11cat10n 0f a pr0cedure recent1y 1ntr0duced f0r the a55e55ment 0f ~A w1th the re4u1red accuracy and re11a6111ty at d1fferent temperature5. 1t a150 5ummar12e5 51m11ar exper1ment5 carr1ed 0ut 0n a 5ynthet1c wa5te t0 a110w c0mparat1ve eva1uat10n, empha5121n9 p055161e 1nh161t0ry effect5 0ften a550c1ated w1th 5ewa9e n1tr1f1cat10n. 5tud1e5 dev0ted t0 the eva1uat10n 0f the n1tr1f1cat10n p0tent1a1 0f a meat pr0ce551n9 eff1uent, a10ne and 1n c0m61nat10n w1th d0me5t1c wa5tewater a5 1t 15 0ften the ca5e 1n j01nt wa5tewater treatment fac111t1e5 are a150 rep0rted and eva1uated.

51mp11f1ed a5 the f0110W1n911near f0rm: 1n 5N0 = 1n YA f

6A XA°+(fA-6A)1"

(7)

7he 510pe 0f th15 11near funct10n y1e1d5 the va1ue 0f f A - 6A, fA 15 then e5t1mated w1th a rea50na61e a55umpt10n f0r 6A. A carefu1 eva1uat10n 5h0w5 that the 51mp11fy1n9 a55umpt10n5 nece55ary f0r the a60ve pr0cedure may n0t a1way5 6e mathemat1ca11y ju5t1f1a61e. 1n fact, the mathemat1ca1 1nterpretat10n 0f the5e a55umpt10n5 1mp11e5 that 1

fA

CR171CAL APPRA15AL0F CURREN7 PRAC71CE

5N0° ~ YA fA -- 6A XA°"

7he chan9e 1n the c0ncentrat10n 0f 0x1d12ed amm0n1a f0rm5, 5N0 15 c0mm0n1y re1ated t0 the 9r0wth 0f aut0tr0ph5 6y the f0110w1n9 rate expre5510n:

7he r19ht-hand-51de term 1n th15 e4Uat10n may r0U9h1y 6e C0nCe1Veda5 4.2 XA0 f0r f A / f A -- 6A) = 1.0 and YA= 0.24 9 ce11 C0D/9 N. 1t 15 p055161e t0 5tart the exper1ment W1th a Very 10W 1eVe10f 1n1t1a10X1d12ed n1tr09en C0nCentrat10n and a 5ma11 610ma55 5eed1n9, 6Ut ne91ect1n9 the C0rre5p0nd1n9 term5 may 1ndUCea mathemat1Ca1 err0r 1n the 9raph1Ca1 501Ut10n 51nCe 5N00 15 Very Un11ke1yt0 6e 0f the 5ame ma9n1tude a5 4.2 XA0. FUrtherm0re, ne91ect1n9 5N00 1n the 501Ut10n 0f e4Uat10n (6) 1neV1ta61y 1nV01Ve5 d15re9ard1n9 th15 parameter 1n the 9raph1Ca1 11near12at10npr0Ce55; th15 appr0ach 15 11ke1y t0 y1e1d Very C105e Va1Ue5 f0r the 510pe 0f the 11near expre5510n at d1fferent temperature5, def1ned 6y mean5 0f the 1ea5t 54uare meth0d, w1th0ut rec09n1t10n 0f 5N00 a5 an 1n1t1a1 c0nd1t10n. 7he pr061em5 a550c1ated w1th th15 type 0f eva1uat10n are 111u5trated 6y u51n9 the exper1menta1 re5u1t5 f0r a 5ett1ed d0me5t1c 5ewa9e 5amp1e (5amp1e n0. 6 1n 7a61e 6), 06ta1ned at 20 and 15°C a5 0ut11ned 1n 7a61e 1. 7he 9raph1ca1 eva1uat10n 0f the exper1menta1 data, d15re9ard1n9 the 1n1t1a1 0x1d12ed n1tr09en c0ncentrat10n 5N00 1n acc0rdance w1th e4uat10n (7) wh1ch ref1ect5 the 51mp11f1ed11near appr0x1mat10n pr0p05ed 6y Ant0n10u et a1. (1990), 155h0wn 1n F19. 1: a1th0u9h each react0r 15 5tarted w1th the 5ame am0unt 0f 610ma55 5eed1n9 and theref0re the 5ame 5N00va1ue f0r a 91ven wa5tewater 5amp1e, the 11near re1at10n5h1p 06ta1ned 6etween 5N0 and t1me, 6y mean5 0f the 1ea5t 54uare meth0d y1e1d5 a1m05t the 5ame 510pe5 w1th d1fferent 1ntercept5 c0rre5p0nd1n9 t0 519n1f1cant1y

d5N0 dt

fA 5Nr1 xA, YA KNH + 5NH

(1)

where, YA 15 the 0vera11 y1e1d c0eff1c1ent ref1ect1n9 60th the 9r0wth 0f N1tr050m0na5 and N1tr06acter 5pec1e5. 1n the ca5e where 5Nn 15 h19h en0u9h n0t t0 6e rate 11m1t1n9, e4uat10n (1) may 6e 51mp11f1ed a5: d5N0 ~YA f A X A. dt

(2)

F0r th15 c0nd1t10n, the 9r0wth rate 0f n1tr1fy1n9 610ma55 15 appr0x1mated 6y the f0110w1n9expre5510n:

dxA dt

= (fA -- 6A)Xa •

(3)

1n a 6atch react0r, the c0ncentrat10n 0f n1tr1f1er5 can 6e c0mputed 6y the 1nte9rat10n 0f the a60ve rate expre5510n: 2A = XA° e(,A 6A),.

(4)

U51n9 the va1ue 0f XA expre55ed a60ve, e4uat10n (2) 15 rearran9ed a5: d5N0 • fA XA0e(#A 6A),. dt YA

(5)

1nte9rat10n 0f the a60ve e4uat10n y1e1d5: 8N0 -- 5N0 0 --

fA~eVA0

YA(fA -- 6A)

e(~A

6A)t

•

fAXA0

YA(fA

- 6A),

(6)

where 5N00 15 the 1n1t1a1 N0x c0ncentrat10n 1n the 6atch react0r at the 6e91nn1n9 0f the te5t. An exper1menta1 5cheme 1n a 6atch react0r ha5 t0 6e 6a5ed up0n the a60ve expre5510n f0r the determ1nat10n 0f f1A. 51nce XA0, YA and 6A cann0t 6e 5eparate1y determ1ned dur1n9 the exper1ment, the current1y ad0pted appr0ach 15 t0 arran9e an exper1menta1 5etup w1th 5uff1c1ent1y10w va1ue5 0f 5N00 and XA0 50 that the re1ated term5 may 6e ne91ected (Ant0n10u et a1., 1990). 1n th15 ca5e, e4uat10n (6) 15

7a61e 1. 8atch n1tr1f1cat10ndata f0r 5ett1ed d0me5t1c5ewa9e 0x1d12ed n1tr09en, 5N0 (m9/1) 71me (day5) 20°C 15~C 0 0.2 0.2 1 0.7 0.3 2 1.7 1.2 3 3.3 2.4 4 5.6 3.8 5 8.8 4.8 6 13 6.8 7 20 9.5

(8)

5pec1f1c 9r0wth rate 1n n1tr1f1cat10n

1663

4

3

• 20°C • • 0.82 / d a y

• 2006 • - 0.54 / d a y a 1506 • " 0.52 / d a y

•,

~2 •

0

~

71 0 °1 -2

1

1

a 1

1

1

2

1 3

1

1

4

5

•,

1

0

6

Q t 1

1 2

1 3

t 4

71me (day5)

d1fferent 1n1t1a1 0x1d12ed n1tr09en 1eve15 f0r the tw0 te5t temperature5; c0n5e4uent1y, the re5u1t1n9/1A- 6A va1ue5 at 15°C appear t0 6e appr0x1mate1y the 5ame a5 the 0ne5 at 20°C a5 0ut11ned 1n 7a61e 2. 7he 1nc1u510n 0f the 1n1t1a10x1d12ed n1tr09en c0ncentrat10n, 5N00 1n the 9raph1ca1 eva1uat10n d0e5 n0t apprec1a61y c0rrect the err0r 1n the 1nterpretat10n 0f exper1menta1 re5u1t5; a5 1nd1cated 1n F19. 2, the /1A - 6A va1ue5 are 5t111very c105e t0 0ne an0ther at 20 and 15°C, and the 1ntercept5 c0rre5p0nd1n9 t0 1n1t1a1 5N0 1eve15 are marked1y d1fferent than the va1ue5 exper1menta11y a55e55ed at the 6e91nn1n9 0f the exper1ment5. Furtherm0re, 5N00 15 n0ted t0 1nf11ct an 1ncrea5e 0n /1A and there 15 n0 way t0 1dent1fy the va1ue 0f/1A wh1ch rea11y character12e5 the wa5tewater. A C105e 1n5pect10n 0f the 9raph1ca1 eva1uat10n 1nd1cate5 that the rea1 pr061em 15 the 1nterpretat10n 0f the exper1menta1 data a5 a 11near funct10n. 1n fact, the re5u1t5 111u5trated 1n the f19ure5 c1ear1y 5h0w a hyper6011c trend, m0v1n9 away fr0m a 11near funct10n a5 the 5u65trate c0ncentrat10n 6ec0me5 11m1t1n9dur1n9 the 1ater 5ta9e5 0f the exper1ment. An attempt can 6e made t0 1n515t 0n 11near 1nterpretat10n 6y d15re9ard1n9 the data pre5uma61y a550c1ated w1th 5u65trate 11m1ted 9r0wth. 7h15 appr0ach 15 te5ted w1th the ava11a61e data f0r the 5ame 5amp1e; 1t 91ve5, a5 5h0wn 1n F19. 3, /AA--6A va1ue5 0f 0.57d -1 at 20°C and 0.58d -1 at 15°C, 0n the 6a515 0f the exper1menta1 re5u1t5 f0r the f1r5t 51x day5 (0m1tt1n9 day 7). A 51m11ar eva1uat10n 0f the data c0rre5p0nd1n9 t0 the f1r5t f1ve day5 (0m1tt1n9 day5 6 and 7), y1e1d1n9 0.67 d -1 f0r /2A- 6A at 15°C, a h19her va1ue than 0.63 d -1 51m11ar1y 06ta1ned f0r 20°C. 1t 15 n0ted that the/1A - 6A va1ue5 06ta1ned are h19h1y var1a61e depend1n9 0n h0w the data 15 1nterpreted; the 1mp0rtant p01nt 15 that the meth0d d0e5 n0t pr0v1de any 1nf0rmat10n re9ard1n9

the 519n1f1cantp0rt10n 0f the data and the fract10n t0 6e d15carded, a5 marked1y d1fferent/1A -- 6A va1ue5 f0r a 91ven wa5tewater 5amp1e are ca1cu1ated w1th an a1m05t e4ua11y h19h and re11a61e re9re5510n c0eff1c1ent a5 1nd1cated 1n 7a61e 2. C0NCEP7UAL 8A515 0F 7HE PR0P05ED

Re9re5510n c0ef. (r)

0.54 0.62 0.57 0.63

0.988 0.975 0.988 0.991

6A (day -1)

Re9re5510n c0ef. (r)

0.52 0.56 0.58 0.67

0.948 0.964 0.946 0.949

/1A --

APPR0ACH

7he0ret1ca1framew0rk 7he 6a51c expre5510n def1n1n9 the 5N0 pr0f11e 1n a 6atch react0r 15 n0n-11near a5 dep1cted 6y e4uat10n (6). C0n5e4uent1y, a ••curve f1tt1n9•• appr0ach appear5 t0 6e a much m0re re11a61e and 5en51t1ve t001 f0r the a55e55ment 0f the c0rre5p0nd1n9 /1A- 6 A va1ue. 1f k

YA(/~A -- 6A)

~AX.0

(9)

15def1ned f0r a 91ven exper1menta1 5etup, e4uat10n (6) may 6e expre55ed a5: 1

5N0 = 5N00+ ;- [e a~- 1],

(10)

where a =/1A - 6A. 7h15 e4uat10n 91ve5 the the0ret1ca1 5N0 pr0f11e; 1t 5h0u1d 6e n0ted that even 1f exact va1ue5 0f c0eff1c1ent5 k and a were kn0wn, the e5t1mated 5N0 after a react10n t1me, t, w0u1d 6e d1fferent t0 50me extent fr0m the c0rre5p0nd1n9 exper1menta11y mea5ured 0x1d12ed n1tr09en c0ncentrat10n, 5N0E, due t0 rand0m err0r5 a550c1ated w1th exper1menta1 pr0cedure5. 1n 0ther w0rd5, f0r each t, there 15 a d1fference (5N0-5N0E) and the 5um 0f the 54uare5 0f

15°C

6A (day 1)

7

F19. 2. A55e55ment 0f a =/~A- 6A f0r 5ett1ed d0me5t1c 5ewa9e u51n9 the 51mp11f1ed11near12ed appr0ach 1nc1ud1n9 the 1n1t1a10x1d12ed n1tr09en c0ncentrat10n.

7a61e 2. Re5u1t5 06ta1ned f0r 5ett1ed d0me5t1c 5ewa9e w1th 11near appr0x1mat10n

/1A --

1 0

71me (day5)

F19. 1. A55e55ment 0f a =/1 A - - 6 A f0r 5ett1ed d0me5t1c 5ewa9e u51n9 the 51mp11f1ed11near12edappr0ach.

20°C

t 5

C0mment5 A11 data (d15re9ard1n9 5Nc~) A11 data (1nc1ud1n9 5N00) Data f0r the f1r5t 6 day5 (d15re9ard1n9 5r~00) Data f0r the f1r5t 5 day5 (d15re9ard1n9 5N00)

1664

5. 562en

et a1.

d1fference5 (5N0-5N0E) f0r a 5et 0 f exper1menta1 data can 6e determ1ned a5 f0110w5: 4 ~ ( a , k ) = ~ (5N01-5N0E,) 2.

(11)

25

0 80 m0 5511 • 1 0 0 m 9 85/1 0 150 m0 55/1 $ 200 m0 551t

20 ~

15

•

•

$

,

1

c 0

/=1

1

51nce 5N00 15 mea5ured at the 6e91nn1n9 0f the exper1ment, e4uat10n (10) may 6e rearran9ed 1nt0 a m0re u5efu1 f0rm f0r the eva1uat10n 0f the exper1menta1 data:

•

6 • 5

0

0

1

1

y = at,

(12)

0

D~J

-+~-

1

2

3

71me (day5) F19. 4. Effect 0f 1n1t1a1 610ma55 c0ncentrat10n XA0 0n 5N0 pr0f11e5.

where y = 1n[k(5N0E -- 5N00) + 1].

(13)

F0r a 91ven k c0eff1c1ent, the va1ue 0f a = f 1 A - 6A c0u1d ea511y 6e ca1cu1ated fr0m e4uat10n (12), 6y mean5 0f 1ea5t 54uare5 a5:

~ = 1 (Y1t1) a --

1

(14) 1=1

7heref0re, 4~(a, k) 1n e4uat10n (11), can 6e re9arded a5 a funct10n 0f k 0n1y: 4~(k) = ~" ( 5 N 0 , - 5N0E+)2.

(15)

1=1

51nce 60th e4uat10n5(12) and (13) are n0n-11near w1th re5pect t0 k, a 0ne-d1men510na1 5earch techn14ue w1th a 91ven 1nterva1, c0nta1n1n9 the m1n1mum va1ue 0 f the 5um 0 f the 54uare5 0 f d1fference5 ~6(k), 15 needed f0r 1t5 501ut10n. A n 1nterva1 f0r k 15 1n1t1a11y 5e1ected c0nta1n1n9 the 0pt1mum va1ue 0 f th15 c0eff1c1ent, c0rre5p0nd1n9 t0 the m1n1mum va1ue 0f 4~(k). 1n v1ew 0 f the 0perat1n9 c0nd1t10n5 9enera11y ad0pted f0r the aerated 6atch te5t, th15 1n1t1a1 1nterva1 may 6e 5e1ected a5 0 < k < 2 . 7 h e n , an 1terat1ve 0pt1m12at10n m e t h 0 d kn0wn a5 the F160nacc1 5earch 15 u5ed t0 reduce the 1en9th 0f the 1nterva1 1n each 1terat10n 6y keep1n9 45(k) 1n the reduced 1nterva1 (W11de, 1964). MA7ER1AL5 AND ME7H0D5

Exper1ment5 f0r the mea5urement 0f the 5pec1f1c 9r0wth rate f0r n1tr1f1er5 were c0nducted 1n 11 aerated 6atch

20°C • - 057 /d11y 0 15°6 " " 0 58 1d•Y

•

2 ~~--, 0~ 1

J

~

•

-1

0

-2

1

1

1

2

0

1

3

1

1

4

5

1

6

71me (day5) F19. 3. A55e55ment 0f a =/1A- 6A f0r 5ett1ed d0me5t1c 5ewa9e u51n9 the 51mp11f1ed11near12ed appr0ach 0m1tt1n9 the day 7 data.

react0r5 5eeded w1th n1tr1fy1n9 51ud9e fr0m a f111and draw un1t 0perated at a 51ud9e a9e 0f 10 day5. 7he k1net1c ana1y515 0n each 5amp1e repre5ent1n9 d1fferent type 0f wa5tewater5, 1.e. d0me5t1c 5ewa9e, 5ynthet1c wa5te, meat pr0ce551n9 wa5te 0r c0m61ned d0me5t1c-meat pr0ce551n9 wa5te wa5 made, u51n9 a 5et 0f f0ur para11e1 6atch react0r5 0perated under the 5ame c0nd1t10n5 and the c0rre5p0nd1n9 re5u1t wa5 expre55ed a5 the avera9e va1ue 0f the 1nd1v1dua1 eva1uat10n5 0f the exper1menta1 data 06ta1ned fr0m each react0r. Exper1ment5 were c0nducted at d1fferent temperature5, 1n a pH ran9e 0f 7.5-8.5 and w1th n0 a1ka11n1ty 11m1tat10n. C 0 2 wa5 6u661ed thr0u9h the react0r f0r pH c0ntr01. 1n th15 5tudy, the effect 0f 1n1t1a1 n1tr1f1er5 610ma55 15 1nve5t19ated 6y runn1n9 f0ur para11e1 6atch react0r5 fed w1th d0me5t1c 5ewa9e at 20°C. Each react0r wa5 1n1t1a11y 5eeded w1th a d1fferent 610ma55 c0ncentrat10n 0f 50, 100, 150 and 200 m9 1-1 55, taken fr0m a n1tr1fy1n9 m1xed cu1ture c0nt1nu0u51y ma1nta1ned w1th the 5ame d0me5t1c 5ewa9e at a 51ud9e a9e 0f a60ve 10 day5. 7he chan9e 1n N0x c0ncentrat10n 1n the react0r5 wa5 m0n1t0red f0r f0ur day5, 0n the 6a515 0f e19ht rand0m1y 5e1ected 5amp1e5 a5 1nd1cated 1n F19.4. 7he eva1uat10n 0f the N0x pr0f11e5 0n the 6a515 0f the pr0p05ed meth0d c1ear1y 1nd1cate5 that the 1n1t1a1 610ma55 519n1f1cant1y affect5 the re11a6111ty 0f the exper1ment5. C0n515tent and re11a61e re5u1t5 are 06ta1ned 1n the react0r 5tarted w1th an 1n1t1a1n1tr1fy1n9610ma55 0f 50 m9 1-~ 55.1n fact, f0r th15 exper1menta1 5etup an a va1ue 0f 0.424).45 d-~ 15 ca1cu1ated a5 5h0wn 1n 7a61e 3 re9ard1e55 0f the 5et 0f data c0n51dered f0r eva1uat10n, 0n1y exc1ud1n9 the 1a5t 5amp1e wh1ch 15 pre5uma61y affected 6y 5u65trate 11m1tat10n. 1t 15 w0rth n0t1n9 that the k parameter def1ned 1n th15 pr0cedure ha5 an 1mp0rtant phy51ca1 mean1n9 a550c1ated w1th XA0, a5 def1ned 6y e4uat10n (9), and the pr0cedure 1ndependent1y 5e1ect5 the va1ue 0f k wh1ch 6e5t 5u1t5 the data 0f each 1nd1v1dua1 exper1menta1 5etup. 7hen, 1t may 6e 5tat15t1ca11y accepta61e 6ut phy51ca11y 1rre1evant t0 have d1fferent k va1ue5 f0r exper1ment5 5tarted w1th the 5ame c0nd1t10n5. 1n th15 framew0rk, k va1ue5 a11 1n the ran9e 0f 0.24-0.27 (m91-~) -t and 1ndependent1y 5e1ected f0r d1fferent 5et5 0f data 06ta1ned w1th an 1n1t1a1 610ma55 c0ncentrat10n 0f 50 m9 1- m55, pr0v1de further 5upp0rt t0 the re11a6111ty 0f the pr0p05ed pr0cedure. 7he data c011ected fr0m the react0r 5tarted w1th an 1n1t1a1 610ma55 c0ncentrat10n 0f 100 m9 1-~ 55 exh161t 519n1f1cant 5u65trate 11m1tat10n after 2 day5, appr0x1mate1y c0rre5p0nd1n9 t0 the 5th 5amp1e. 7he rema1n1n9 f0ur data p01nt5 appear t0 6e t00 few t0 draw a 7a61e 3. Eva1uat10n 0f ,f1A-6A w1th 1n1t1a1 610ma55 c0ncentrat10n 0f 50 m9 1 t 55 N0. 0f 5amp1e5 a = ,f1A- 6A k 0-8 0.10 0.04 0.291 0-7 0.42 0.24 0,076 0-6 0.45 0.27 0.073 0-5 0.45 0.27 0.087

1665

5peC1f1C 9r0Wth rate 1n n1tr1f1Cat10n 7a61e 4. 8uffer and m1nera1501ut10n5f0r the 5ynthet1cwa5te 501ut10n 5u65tance C0ncentrat10n(9 1-~) 501ut10n A 501ut10n 8

K2HP04 KH2P04 M95047H20 Fe504 7H20 2n504 7H20 Mn504 3H20 CaC12

320 160 15 0.5 0.5 0.5 2.0

7a61e 5. character12at10n 0f 15tan6u1 d0me5t1c 5ewa9e Parameter C0D. (m91 ~) 80D 5 (m91- ] )

t0ta1 5ett1ed f11tered

Mean 540 396 185

5.D. 167 103 43

Ran9e 250-840 250-585 105-265

t0ta1 5ett1ed f11tered

328 190 75

83 10 5

245-410 180-200 70-80

350

117

141)-530

61 56 51

20 10 11

35-118 35-73 33~8

40

11

24-53

55 (m91 1) 5tat15t1ca11y va11d c0nc1u510n 0n the ma9n1tude 0f the k1net1c parameter5. 1n1t1a1 c0ncentrat10n5 0f 150 and 200 m9 1-~ 55 are 065erved t0 y1e1d n0 mean1n9fu1 re5u1t5 f0r k1net1c 1nterpretat10n. 7e5t5 c0nducted w1th 1n1t1a1 610ma55 1eve15 10wer than 50 m9 1-~ a150 91ve errat1c re5u1t5 519n1f1cant1y affected 6y exper1menta1 err0r5. C0n5e4uent1y, eva1uat10n5 0ut11ned a60ve 1nd1cate that an exper1menta1 5etup w1th an 1n1t1a1 n1tr1fy1n9610ma55 c0ncentrat10n 0f ar0und 50 m9 1-t , 0perated f0r appr0x1mate1y 4 d w1th a 5amp11n9 fre4uency 0f tw0 5amp1e5/day, a m1n1mum 0f 3-4 h apart, may 6e rec0mmended f0r the a55e55ment 0f/1A 1n d0me5t1c 5ewa9e (562en, 1995). 1t 5h0u1d 6e n0ted that the 1a5t data p01nt repre5ent1n9 the ran9e 0f 5u65trate 11m1tat10n 15 aut0mat1ca11y 1eft 0ut 6y mean5 0f the r0ut1ne 5tat15t1ca1 pr0cedure 6u11t 1n the pr0p05ed meth0d due t0 the fact that 1t y1e1d5 the much h19her ~6 va1ue. 1n the exper1ment5 c0nducted w1th 5ynthet1c wa5te, react0r5 were 1n0cu1ated w1th 610ma55 prev10u51y acc11mated t0 d0me5t1c 5ewa9e. 7he 5ynthet1c wa5te wa5 prepared a5 de5cr16ed 6y 0•C0nn0r (1972), t0 5u5ta1n n1tr1f1cat10n 0n1y; 1t c0nta1ned 10 m1 1-t each 0f the 6a51c 6uffer and m1nera15 501ut10n5 de5cr16ed 1n 7a61e 4, w1th n0 0r9an1c car60n 50urce. 7he n1tr09en c0ntent 0f the 5ynthet1c wa5te wa5 r0u9h1y ma1nta1ned at 50 na9 1-1, a 1eve1 c0mpat161e w1th d0me5t1c 5ewa9e 6y add1n9 an appr0pr1ate am0unt 0f NH4C1. A 51m11ar a1ka11n1ty adju5tment wa5 made 6y mean5 0f NaHC0 3. 7he react0r5 0perated w1th the meat pr0ce551n9 wa5te a10ne and m1xed w1th d0me5t1c 5ewa9e were a11 5eeded w1th m1xed cu1ture a114u0t5 prev10u51y acc11mated t0 the meat pr0ce551n9 eff1uent 1n a f111and draw un1t, a5 th15 eff1uent c0nta1n5 a 519n1f1cant p0rt10n 0f d0me5t1c-type wa5tewater 9enerated 6y the w0rker5/per50nne1 1n the p1ant. A11 ana1y5e5 were perf0rmed 1n acc0rdance w1th 5tandard Meth0d5 (APHA, 1989). 5ett1ed 5ewa9e wa5 06ta1ned a5 the 5upernatant 0f a cy11ndr1ca1 5ett11n9 c01umn after a h01d1n9 t1me 0f 2 h. 7he 501u61e (f11tered) C 0 D wa5 def1ned a5 the f11trate thr0u9h Whatman 6 F / C 91a55 f16er f11ter5. N0x mea5urement5 were perf0rmed 6y a Chem La6 aut0ana1y2er u51n9 the hydra21ne reduct10n meth0d.

EXPER1MEN7AL EVALUA710N

7KN (m91 ~)

t0ta1 5ett1ed f11tered

NH3--N (m91-t) 70ta1 P (m91 ~)

t0ta1 5ett1ed f11tered

12 9.5 7.8

A1ka11n1ty (m91- • cac03 )

1.8 3 1.5

343

97

10-15 5-14.5 5-10 9ff495

F19ure 5 5h0w5 the reeva1uat10n 0 f the 5ame data prev10u51y u5ed f0r the cr1t1ca1 appra15a1 0 f the 51mp11f1ed 11near12ed appr0ach. 1t y1e1d5/1A -- 6 A va1ue5 0 f 0.42 d - ] at 20°C and 0.27 d - t at 15°C, t0ta11y d1fferent fr0m the 0ne5 115ted 1n 7a61e 2. F19ure 6 91ve5 the 1nterpretat10n 0 f an0ther exper1ment c0nducted 1n acc0rdance w1th the pr0cedure def1ned 1n th15 5tudy. 7 h e 1ncrea51n9 trend 0 f the •C0x pr0f11e5 1n the5e f19ure5 may 6e 1nterpreted a5 an 1nd1cat10n that the ent1re 5et 0 f exper1menta1 data wa5 n0t affected 6y 5u65trate 11m1tat10n, and theref0re 1nc1uded 1n the k1net1c ana1y515. 7 h e k1A- 6 A 1eve15 0f 0.38 d -] and 0.13 d - 1 at 20 and 10°C re5pect1ve1y, a550c1ated w1th th15 5ewa9e 5amp1e are very c105e t0 avera9e va1ue5 character121n9 15tan6u1 d0me5t1c 5ewa9e. A5 111u5trated 1n the5e f19ure5, ref1ect1n9 60th exper1menta1 data and the c0rre5p0nd1n9 the0ret1ca1 N0x pr0f11e5 c 0 m p u t e d 0n the 6a515 0 f e4uat10n (13), n0ne 0f the exper1menta1 065ervat10n5 were 5u1ta61e f0r 1nterpretat10n 6y mean5 0 f the 51mp11f1ed a p p r 0 a c h prev10u51y pr0p05ed f0r 5uch eva1uat10n5 (Ant0n10u et a1., 1990). 7 h e re5u1t5, a5 5ummar12ed 1n 7a61e 6, 5h0w that/1 A - h A 1eve15 at 20°C were h19h1Y var1a61e w1th1n

A55e55ment 0 f ft~ f0r d0me5t1c 5ewa9e 7 h e exper1menta1 eva1uat10n 0f/1 A wa5 undertaken 1n c0njunct10n w1th a c0mprehen51ve character12at10n p r 0 9 r a m carr1ed 0ut 0ver a per10d 0f 18 m0nth5, a150 1nv01v1n9 a deta11ed C 0 D fract10nat10n and the a55e55ment 0 f maj0r k1net1c c0eff1c1ent5 u n d e r aer061c and an0x1c c0nd1t10n5 ( 0 r h 0 n et a1., 1994). Ana1y5e5 were carr1ed 0ut 0n raw, 5ett1ed and f11tered 5amp1e5 and the re5u1t5 06ta1ned f0r re1evant parameter5 are 5ummar12ed 1n 7a61e 5. 7 h e max1mum 5pec1f1c 9r0wth rate 0f n1tr1f1er5 wa5 exper1menta11y determ1ned f0r 12 d0me5t1c 5ewa9e 5amp1e5 5e1ected t0 repre5ent d1fferent wa5tewater pr0pert1e5 u51n9 the new eva1uat10n pr0cedure.

25 • 20°(3 • • 0.42 1d1y 0 150C • • 0.27 1dLy

20

9

0

0

~ 1

~ 2

3

~ 4

• 5

• 6

7

71me (day5)

F19. 5. Reeva1uat10n 0f the exper1menta1 data f0r 5ett1ed 5ewa9e f0r the a55e55ment 0f a =/1A - 6A.

1666

5. 562en et a1. 7a61e 7. C0mpar150n 0f /1A- 6 A va1ue5 f0r d0me5t1c 5ewa9e and 5ynthet1c wa5te ~A- 6A (day •)

25 20

0

• 20°C • • 0.38 /day 010°C a • 0.13 /day

~,/,~J~.

5amp1e n0. 2 3 5 10

10

7emperature (°c) 20 20 20 20 10

0 0

1

D0me5t1c 5ynthet1c 5ewa9e wa5te 0.37 0.41 0.24 0.33 0.52 0.45 0.36 0.38 0.10 0.13

3

2

71me (day5) F19. 6. Exper1menta1 data and the c0rre5p0nd1n9 N0x 9enerat10n curve5 f0r a 5ewa9e 5amp1e u51n9 the pr0p05ed pr0cedure.

a ran9e 0f 0.24--0.52 d -~, w1th an avera9e Va1Ue 0f 0.38d -1. N 0 C0rre1at10n Wa5 p055161e 0r jU5t1f1a61e 6etWeen /1A- 6A Va1Ue5 and any 0f the C0nVent10na1 parameter5 character121n9 d0me5t1c 5ewa9e 5amp1e5. At 10°C wh1ch 15 the cr1t1ca1 wa5tewater temperature 1n w1nter f0r the de519n 0f treatment 5y5tem5, the avera9e va1ue 0f /1A-6A wa5 065erved t0 dr0p t0 0.14 d -1, 0ne th1rd the 1eve1 a550c1ated w1th 20°C and 1t5 var1at10n f0r d1fferent 5ewa9e 5amp1e5 5tayed w1th1n a narr0wer ran9e 0f 0.10-0.17d -~. 51m11ar exper1menta1 065ervat10n5 1n the 11terature 5u99e5t that the effect 0f temperature 0n/1A may 6e expre55ed 6y an Arrhen1u5 type 0f an e4uat10n, 1n the ran9e 0f 7-30°C: ~A,7 = ~A,20 0 7 - 20

(16)

7he re5u1t5 06ta1ned a150 c0nf1rm the va11d1ty 0f th15 expre5510n y1e1d1n9 an avera9e va1ue 0f 1.098 f0r the temperature c0eff1c1ent, 0, 4u1te 1n acc0rdance w1th the ran9e 0f 1.08-1.123 rep0rted f0r th15 c0eff1c1ent 0n the 6a515 0f 51m11ar 5tud1e5 (Ekama and Mara15, 1984; 86hnke, 1989; N0wak and 5varda1, 1990; A131, 1991; 6 u j e r et a1., 1995). 0 n e 0f the m05t de6ated 155ue51n n1tr1f1cat10n 15 t0 c1ar1fy whether the exper1menta11y determ1ned va1ue f0r ~A 15 1ntr1n51c t0 the wa5tewater 0f 1ntere5t 0r affected 6y 1nh161t10n. A wa5tewater 5uch a5 d0me5t1c

5ewa9e 1nC0rp0rate5 a 1ar9e 5peCtrUm 0f d1fferent C0mp0nent5, 50me exh161t1n9 1nh161t0ry 0r t0x1c effect5 t0 6101091Ca1 pr0Ce55e5. A m 0 n 9 the k1net1C C0eff1C1ent5, the max1mUm 5peC1f1C 9r0wth rate 15 h19h1Y 5en51t1ve t0 5uCh effect5 1n wa5tewater n1tr1f1cat10n. A 9reat dea1 0f eff0rt 15 needed t0 1dent1fy and e11m1nate c0mp0und5 11ke1y t0 create 5uch effect5 f0r the 0pt1mum de519n and 0perat10n 0f treatment p1ant5 capa61e 0f 6101091ca1 n1tr09en rem0va1 (51nkjaer et a1., 1994). Recent1y, meth0d5 have 6een 5u99e5ted t0 4uant1fy the extent 0f 1nh161t10n under 0perat10na1 c0nd1t10n5 (N0wak et a1., 1994). 1n th15 5tudy, 6atch react0r5 have 6een 0perated w1th 5ynthet1c wa5te dev01d 0f 1nh161t0r5, para11e1 t0 d0me5t1c 5ewa9e react0r5 t0 eva1uate the ex15tence and the extent 0f 1nh161t0r5. Exper1ment5 have 6een carr1ed 0ut f0r f0ur d1fferent 5ewa9e 5amp1e5 hav1n9 d1fferent character15t1c5 and a550c1ated w1th /~A- 6A 1eve15 1n the ran9e 0f 0.24-0.52 d -1, ma1n1y t0 exp10re 1f 10w va1ue5 f0r the k1net1c c0eff1c1ent5 c0u1d 6e exp1a1ned 0n the 6a515 0f 1nh161t0ry effect5. 7he re5u1t5, a5 5ummar12ed 1n 7a61e 7, d0 n0t 1nd1cate an apprec1a61e d1fference 0f pract1ca1 519n1f1cance 6etween d0me5t1c 5ewa9e and 5ynthet1c wa5te. 7he 065erved d15crepancy 0f ar0und 10% 15 n0t 5y5temat1c and we11 w1th1n the accuracy 11m1t5 0f exper1menta1 eva1uat10n. 7h15 065ervat10n rema1n5 a150 va11d f0r exper1ment5 carr1ed 0ut at d1fferent temperature5. 1n fact, exper1ment n0. 10 wa5 perf0rmed at 20 and 10°C 60th w1th d0me5t1c 5ewa9e and 5ynthet1c wa5te, y1e1d1n9 pract1ca11y the 5ame re5u1t5 a5 5h0wn 1n F19. 7: the/1A -- 6A va1ue 0f 0.36d ] a550c1ated w1th the d0m-

5°F

7a61e 6. A55e55ment0f/1A- 6Af0r d0me5t1c 5ewa9e a = ~A - 6A (day ~)

40

5amp1e n0.

20~:C

30t

1 2 3 4 5 6 7 8 9 10 11 12

0.47 0.37 0.24 0.51 0.52 0.42 0.25 0.30 0.39 0.36 0.39 0.38

*At 1YC.

• 20*6 c10me*t10*ew~* n 10*Cc10m~1k~mew~pe d1,~0~0C~yn1h1t10 w • 4 t • 10Q1~*yn1h41¢1c3 waete 0at0u/4te41~0~.a

j/

- -

10~C

0 -

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

0.27* 0.12 0.14 0,17 0.10 0.15 0.13

1.092 1.076 1.079 1.087 1.136 1.100 1.113

0 0

1

2

3

4

5

6

71me (day5)

F19. 7. Exper1menta1 and the0ret1ca1 5N0 va1ue5 f0r d0me5t1c 5ewa9e and 5ynthet1c wa5te.

5pec1f1c 9r0wth rate 1n n1tr1f1cat10n 7a61e 8. Character12at10n 0 f meat pr0ce551n9 p1ant eff1uent Parameter C0D (m91 - ~)

t0ta1 5ett1ed f11tered

55 (m91 1) 7KN (m91-1 )

t0ta1 5ett1ed f11tered

NH3--N (m91-1 ) 70ta1 P (m91-1 ) A1ka11n1ty ( m 9 1 - ~C a C 0 3 )

t0ta1

Mean

5.D.

2122 1326 742

942 553 327

608-3534 550-1800 315-1110

1063

408

785-1766

163 140 109

66 28 24

72-280 112-168 85-132

81

35

52-150

9.3

485

1.5

76

Ran9e

7.8-10.8

395-620

e5t1c 5ewa9e 5amp1e at 20°C 15 a1m05t the 5ame a5 0.38 d-1 character121n9 the 5ame k1net1cc0eff1c1ent f0r 5ynthet1c wa5te. 7he 5ame pattern a150 h01d5 true at 10°C, w1th a 5119ht1y h19her va1ue 0f th15 parameter f0r the 5ynthet1c wa5te a5 c0mpared t0 d0me5t1c 5ewa9e. 7he5e 065ervat10n5 1ead t0 c0nc1ude that 1nh161t10n, 1f pre5ent, 150f n0 pract1ca11mp0rtance f0r the 15tan6u1 d0me5t1c wa5tewater5. 1n5pect10n 0f F19. 7 5h0w5 that the 5N0 curve5 6reak 0ver fr0m an 1ncrea51n9 t0 a decrea51n9 510pe after cr1t1ca1 5N0 c0ncentrat10n5 1nd1cat1n9 thre5h01d5 0f 5u65trate 11m1tat10n re910n. 7h15 re910n 15 aut0mat1ca11y detected and exc1uded fr0m the k1net1c ana1y515 6y the pr0p05ed appr0ach.

A55e55ment 0f ft A f0r meat pr0ce551n9 eff7uent Meat pr0ce551n9 15 0ne 0f a few 1ndu5tr1a1act1v1t1e5 9enerat1n9 wa5tewater5 w1th a 519n1f1cant p0tent1a1 f0r n1tr09en p011ut10n. C0n5e4uent1y, wa5tewater character12at10n 1n th15 1ndu5tr1a1 cate90ry may pr0v1de va1ua61e 1nf0rmat10n f0r the 5e1ect10n 0f the appr0pr1ate treatment 5cheme f0r n1tr09en rem0va1 t0 6e 1mp1emented 1nd1v1dua11y 0r 1n c0m61nat10n w1th d0me5t1c 5ewa9e. 7he 5e1eCted p1ant 1n th15 5tudy 15 a fu11y1nte9rated 51au9hter and meat pr0ce551n9 c0mp1ex 10cated w1th1n the 15tan6u1 Metr0p011tan Area, w1th an annua1 capac1ty 0f 500,000 5heep and 80,000 head5 0f catt1e. 7he p1ant 15 current1y 0perated at ha1f the capac1ty and emp10y5 ar0und 250 w0rker5 and per50nne1. 1t ha5 a wa5tewater treatment p1ant 1n 0perat10n, de519ned f0r a wa5tewater f10w rate 0f 1000 m3d 1, 1nc1ud1n9 d15501ved a1r f10tat10n and extended aerat10n type 0f a 6101091ca1 treatment 5cheme. Exper1menta1 a55e55ment 0f/1A f0r th15 1ndu5tr1a1 wa5tewater wa5 a150 c0up1ed w1th a m0n1t0r1n9 pr09ram extended 0ver three m0nth5. 5amp1e5 were taken fr0m the 0ut1et 0f the d15501ved a1r f10tat10n un1t t0 character12e the 1nf1uent t0 the 6101091ca1 treatment un1t and ana1y2ed f0r 6a51c p011ut1n9 parameter5. 7he re5u1t5 06ta1ned, a5 5ummar12ed 1n

1667

7a61e 8, 1nd1cate a 5tr0n9 wa5te 0f a h19h1y var1a61e nature and c0mp051t10n, ref1ect1n9 the w1de 5pectrum 0f t1me 5e4uence5 a550c1ated w1th d1fferent act1v1t1e5 w1th1n the p1ant. 7hree 5et5 0f exper1ment5 were c0nducted at tw0 d1fferent temperature5, f0r the c0mparat1ve a55e55ment 0f/1A f0r the meat pr0ce551n9 eff1uent, d0me5t1c 5ewa9e and d1fferent c0m61nat10n5 0f the tw0 wa5tewater5. Eva1uat10n 0f the exper1menta1 data 15 5ummar12ed 1n 7a61e 9. 7he num6er5 1n th15 ta61e refer t0 d0me5t1c 5ewa9e 5amp1e5 prev10u51y def1ned 1n 7a61e 6, u5ed f0r the preparat10n 0f 5ewa9e-meat pr0ce551n9 wa5te m1xture5. A p01nt 0f 1ntere5t 1n c0nnect10n w1th th15 eva1uat10n 15 the 065ervat10n that the meat pr0ce551n9 wa5tewater y1e1d5 marked1y h19her /1A-6 A va1ue5 a5 c0mpared t0 d0me5t1c 5ewa9e. F0r the three 5amp1e5 1nve5t19ated the avera9e / J A - 6A 1eve1 f0r the meat pr0ce551n9 eff1uent 15 0.58 d-1 at 20°C, 80% h19her than 0.32 d-1 ca1cu1ated a5 the avera9e va1ue 0f th15 parameter f0r d0me5t1c 5ewa9e at the 5ame temperature. 7he 5ame 065ervat10n rema1n5 a150 va11d f0r the exper1ment5 at 10wer temperature5: At 10°C f0r examp1e, avera9e va1ue5 0f 0.27 and 0.13 d - ~have 6een f0und t0 character12e th15 c0eff1c1ent f0r the meat pr0ce551n9 wa5te and d0me5t1c 5ewa9e, re5pect1ve1y. An0ther 519n1f1cant 065ervat10n re1ate5 t0 the exper1ment5 c0nducted 0n m1xture5 0f 5ewa9e and meat pr0ce551n9 wa5te5. 1n tw0 d1fferent 5et5, there 15 exper1menta1 ev1dence t0 5h0w that the rate 0f n1tr1f1cat10nat 20°C 15 6a51ca11y c0ntr011ed w1th meat pr0ce551n9 wa5te w1th a h19her act1v1ty: 1n exper1ment n0.6, the 50: 50 m1xture y1e1d5 a /1A- 6 A 0f 0.58 d - 1 , pract1ca11y the 5ame a5 the va1ue 0f 0.57 d-~ a550c1ated w1th the meat pr0ce551n9 wa5te a10ne. 51m11ar1y, the re5u1t5 0f exper1ment n0. 8 at 20°C are eva1uated t0 c0rre5p0nd very c105e1y t0 /1A- 6• va1ue5 0f 0.58 and 0.63 d -1 f0r 50:50 m1xture and meat pr0ce551n9 wa5te, re5pect1ve1y. 1n th15 exper1ment, the va1ue 0f th15 c0eff1c1ent exh161t5 a 9radua1 decrea5e fr0m 0.58 t0 0.43 d -1 when the re1at1ve pr0p0rt10n 0f 5ewa9e 1n the 5amp1e 5tud1ed 15 1ncrea5ed fr0m 50 t0 75%, 5t11150mewhat h19her than 0.30 d-t character121n9 5ewa9e 5amp1e a10ne f0r the 5ame exper1menta1 5et-up a5 111u5trated 1n F19. 8.7he 5ame trend, a1th0u9h pre5ent, 15 1e55 apparent and

7a61e 9. A55e55ment 0f/1A - 6 A 1n d0me5t1c 5ewa9e-meat pr0ce551n9 wa5te m1xture5 ~A -- 6A (day 1)

5ewa9e/meat wa5te m1xture5 5amp1e n0.

D0me5t1c 5ewa9e

M e a t pr0ce551n9 wa5te

50: 50

25 : 75

75 : 25

6 20°C 15°C 7 20°C 10°C 8 20°C 10°C

0.42 0.27 0.25 0.12 0.30 0.14

0.57 0.30 0.56 0.33 0.63 0.22

0.58 0.42 -0.12 0.58 0.22

-----0.24

----0.43 0.20

1668

5. 562en et a1.

50 40 ~

r•1 ~) ~* • ~

t

d0meJt10 e0wa00 m e t p r0~N11n 0

%60 d0¢~4)Qt1~*%601ned11pr000n01n(1 %76 d0re.ee11¢*%26meat pr00ee81n9 0•10u11t8d pr0f11e

A ~1 /

,

0

1

2

3

4

5

6

71me (day5) F19.8. Exper1menta1 and the0ret1ca1 5N0 va1ue5 f0r d0me5t1c 5ewa9e and meat pr0ce551n9 wa5te m1xture5 at 20°C. c0nc1u51ve at 10°C, 0n the 6a515 0f the 11m1ted data ava11a61e f0r eva1uat10n. C0NCLU510N5 7he pr0p05ed appr0ach 1n th15 5tudy 15 n0t a m0re 50ph15t1cated meth0d 0f ana1y21n9 the k1net1c5 0f n1tr1f1cat10n, 6ut a u5efu1 pr0cedure f0r a re11a61e a55e55ment 0f/1A f0r 1mpr0v1n9 the n1tr1f1cat10n de519n and ana1y515.1n th15 c0ntext, the f0110w1n9 155ue5 0f 5c1ent1f1c and pract1ca1 519n1f1cance are empha512ed a5 the c0nc1u510n5 0f th15 5tudy. 7he a55e55ment 0f the max1mum 5pec1f1c aut0tr0ph1c 9r0wth rate due t0 11near12ed m0d1f1cat10n 0f the k1net1c expre5510n 15 n0t 9enera11y 5u1ta61e f0r k1net1c eva1uat10n a5 dem0n5trated 0n the 6a515 0f the0ret1ca1 and exper1menta1 ev1dence, 6ecau5e 1t 15 n0t a1way5 p055161e mathemat1ca11y t0 ju5t1fy the 51mp11fy1n9 a55umpt10n5 re1ated t0 th15 pr0cedure and ma1n1y 6ecau5e the exper1menta1 re5u1t5 d0 n0t 5h0w the expected 11near trend. 7h15 6ec0me5 cruc1a11y 1mp0rtant and m151ead1n9 when try1n9 t0 a55e55/~A at d1fferent temperature5, a5 the 51mp11f1ed expre5510n ha5 an 1nherent def1c1ency 1n 1dent1fy1n9 /~A under d1fferent 0perat1n9 c0nd1t10n5, w1th an accepta61e accuracy. 7he meth0d f0r the a55e55ment 0f PA put f0rward 1n th15 paper, make u5e 0f the 6a51c e4uat10n wh1ch de5cr16e5 the rate 0f N0x 9enerat10n 1n a 6atch react0r, w1th n0 51mp11f1cat10n5. 1t def1ne5 a k parameter re1ated t0 the 1n1t1a1 c0ncentrat10n 0f n1tr1fy1n9 610ma55 1n the exper1ment, and 1ntr0duce5 a 5earch techn14ue y1e1d1n9 the m05t appr0pr1ate k va1ue fr0m a 5tat15t1ca1 framew0rk. 7h15 va1ue 15 u5ed t0 ca1cu1ate ~ A - 6 A . 7he 1n1t1a1 610ma55 c0ncentrat10n, XA0 15 5h0wn 519n1f1cant1y t0 affect the exper1menta1 re5u1t5. 0pt1mum re5u1t5 f0r d0me5t1c 5ewa9e are 06ta1ned w1th an 1n1t1a1 610ma55 5eed1n9 0f 50 m9 1- ~55 fr0m a n1tr1fy1n9 m1xed cu1ture. 7he pr0p05ed meth0d 15 5ucce55fu11y te5ted 0n 5amp1e5 fr0m d0me5t1c 5ewa9e and meat pr0ce551n9 wa5te5, y1e1d1n9 c0n515tent and re11a61e f1A - 6A va1ue5 60th at 20 ° and 10°C, re9ard1e55 0f the 5et 0f exper1menta1 data c0n51dered f0r eva1uat10n.

7he avera9e va1ue 0f the rate c0eff1c1ent, /~A - 6A character121n9 n1tr1f1cat10n at 20°C, wa5 f0und t0 6e 0.38d -1 f0r 15tan6u1 d0me5t1c 5ewa9e. 7h15 va1ue dr0pped t0 0.14d -1 at 10°C, the cr1t1ca1 5ewa9e temperature f0r 15tan6u1, w1th a c0rre5p0nd1n9 avera9e temperature c0eff1c1ent, 0, 0f 1.098.7he pr0p05ed pr0cedure f0r the exper1menta1 a55e55ment pr0ved t0 6e 4u1te 5en51t1ve and re11a61e 1n a11 the eva1uat10n5 w1th d1fferent wa5tewater 5amp1e5 and under d1fferent c0nd1t10n5. 7he va1ue 0f the rate c0eff1c1ent/~A - 6A f0r 5ewa9e, wa5 065erved t0 f1uctuate 1n the ran9e 0f 0 . 2 4 ~ . 5 2 d -t at 20°C, and 0.10-0.17d t at 10°C. 7h15 var1at10n c0nf1rm5 the c0mm0n under5tand1n9 that 9r0wth character15t1c 0f aut0tr0ph1c 610ma55 are very much wa5tewater-5pec1f1ed and 5h0u1d 6e 5eparate1y determ1ned f0r each ca5e. Para11e1 5tud1e5 run w1th d0me5t1c 5ewa9e and 5ynthet1c wa5te w1th n0 1nh161t0ry 0r t0x1c c0mp0nent5, re5u1ted 1n very c105e va1ue5 f0r the k1net1c parameter5 0f aut0tr0ph1c 9r0wth, 1ead1n9 t0 the c0nc1u510n that 1nh161t10n 15 0f n0 pract1ca1 519n1f1cance f0r d0me5t1c 5ewa9e 1n 15tan6u1. 51m11ar 5tud1e5 c0nducted w1th meat pr0ce551n9 eff1uent, a 5tr0n9 wa5tewater w1th a t0ta11y d1fferent character, wa5 065erved t0 y1e1d 519n1f1cant1y h19her ~A - - 6A va1ue5 c0mpared t0 5ewa9e at d1fferent temperature5.7h15 trend wa5 n0ted t0 per515t f0r d1fferent d0me5t1c 5ewa9e/meat pr0ce551n9 wa5te m1xture5, where the meat pr0ce551n9 wa5te w1th a h19her aut0tr0ph1c act1v1ty appeared t0 c0ntr01 the rate 0f n1tr1f1cat10n.

REFERENCE5

A131 (1991) 8eme55un9 v0n e1n5tuf19en 8e1e6un95an1a9en a6 5000 E1nw0hnerwerten. A7V A6wa55ertechn15che Vere1n19un9, 5t. Au9u5t1n. APHA (1989) 5tandard Meth0d5 f0r the Exam1nat10n 0f Water and Wa5tewater, 17th Ed1t10n. Amer1can Pu611c Hea1th A550c1at10n, Wa5h1n9t0n, DC. Ant0n10u P., Ham11t0n J., K00pman 8., Ja1n R., H0110way 8., Ly6erat05 6. and 5v0r0n05 5. A. (1990) Effect 0f temperature and pH 0n the effect1ve max1mum 5pec1f1c 9r0wth rate 0f n1tr1fy1n9 6acter1a. Wat. Re5. 24, 97. 86hnke 8. (1989) 8eme55un9 der 5t1ck5t0ffe11m1nat10n 1n der A6wa55erre1n19un9-Er9e6n155e e1ne5 Erfahrun95au5tau5che5 der H0ch5chu1en. K0rre5p0ndent A6wa55er, 36, 1046-1061. Ekama 6. A. and Mara15 6. v. R. (1984) 8r1ef de5cr1pt10n 0f the determ1nat10n 0f the max1mum 5pec1f1c9r0wth rate 0f n1tr1f1er5. 1n 7he0ry, De519n and 0perat10n 0f Nutr1ent Rem0va1 Act1vated 51ud9e Pr0ce55e5. Water Re5earch C0mm15510n, Pret0r1a. 6ujer W., Hen2e M., M1n0 7., Mat5u0 7., Went2e1 M. C. and Mara15 6. v. R. (1995) 7he act1vated 51ud9e m0de1 n0.2:6101091ca1 ph05ph0ru5 rem0va1. 1/Vat.5c1. 7echn01., 31(2), 1-11. N0wak 0. and 5varda1 K. (1990) N1tr1f1kat10n und Den1tr1f1kat10n. F0rt11dun95kur5--81010915che A6wa55erre1n19un9, W1ener M1tte11un9en, 8and 81(6), 1-55. N0wak 0. and 5varda1 K. (1993) 065ervat10n5 0n the k1net1c5 0f n1tr1f1cat10n under 1nh161t1n9 c0nd1t10n5 cau5ed 6y 1ndu5tr1a1 wa5tewater c0mp0und5. Wat. 5c1. 7echn01. 28(2), 115.

5pec1f1c 9r0wth rate 1n n1tr1f1cat10n N0wak 0., 5chwe19h0fer P. and 5varda1 K. (1994) N1tr1f1cat10n 1nh161t10n--a meth0d f0r the e5t1mat10n 0f actua1 max1mum 9r0wth rate5 1n act1vated 51ud9e 5y5tem5. Wat. 5c1. 7echn01. 30(6), 9-119. 0•C0nn0r J. 7. (1972) Env1r0nmenta1 En91neer1n9 Un1t 0perat10n5 and Un1t Pr0ce55e5 La60rat0ry Manua1. A550c1at10n 0f Env1r0nmenta1 En91neer1n9 Pr0fe550r5. 0 r h 0 n D., 562en 5. and U6ay, E. (1994) A55e55ment 0f n1tr1f1cat10n---den1tr1f1cat10n p0tent1a1 0f 15tan6u1 d0me5t1c wa5tewater5. Wat. 5c1. 7echn01. 30(6), 21-30.

1669

51nkjaer 0., Ynd9aard L., Harrem0e5 P. and Han5en J. L. (1994) Character15at10n 0f the n1tr1f1cat10n pr0ce55 f0r de519n purp05e5. Wat. 5c1. 7echn01. 30(4), 47-56. 562en 5. (1995) Exper1menta1 eva1uat10n 0f n1tr1f1cat10n-den1tr1f1cat10n k1net1c5. Ph.D. 7he515, 15tan6u1 7echn1ca1 Un1ver51ty. W11de D. J. (1964) 0pt1mum 5eek1n9 Meth0d5. Prent1ceHa11, Rahway, N.J.