溶解氧浓度对硝化速率的影响
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60 ε0
Initiot NHi-N =20^s/t C o n t o c tT i m e 9 4 s e c , p H 7 . 4 , T e m p e r o t u r2 3 C e
o
o
`,0
2.o ε 。 D5/Γ K″
5.0 ∶ ⒎ 丿泅 T`C,
4,9
5.9
3ˉ 26
o。'C,
0。 05
‰
: 冫 。` 9 ‰ C 1r 丿
o
0.5
',o D0,D`ss0LVε
`。 D0X丫
5
2.0 CEⅣ , mg/`
2.5
3.0
While the generaleffect of DO on kineticsis firmly established, there needsto be further study to determinethe factors affectingthe valuesof Kg2. All of the variousestimates are is and no measurefrom systemswhere combinedcarbonoxidation-nitrification practiced for stage mentshavebeenmadeon separate nitrificationsystems.K62 values separate stage nitrification systems may very well be different than those for combined carbon oxidation-nitrification systems. Further refinement Kg2 valuescan be expected.For of illustrative use in this manual,a valueof Kg2 of 1.3mg/l hasbeenassumed. valuefalls This in the middle of the rangeof Kg2 observations(0.15 2.0 melD and is of a magnitude to such that if the operatingDO is 2-0 m{l or less, nitrification (or nitrifier) growthirateis the 60.6 percent(or less)of the peakrate.This orderof reductionin rate could account for most of the differencein growth rate observed Downing,et al. (seeSection3i2.5.4) by between river watervalues high DO levels activated at and sludge operating dataat DQ levels of 2.0 mg/l of less. 3.2.5.6 Effect of pH on Kinetics
i
The hydpogen ion concentration (pH) has been generallyfound to have.a strong effect on the rate of ritrification. Figure 3-5-presentstypical pH relationships from a number of -The results of other investigations investigations. have been summ arized in the litera,44 Th"r" is a wide rangein reportedpH optima;the almost universal ture.l finding is that as the pH moves to the acid range, the rate of ammonia oxidation declines. This has been found to be true for both unacclimatedand acclimatedcultur,es, although acclimation tends
FIGURE3砰 EFFECT OF DIsSOLVED OXYGEN ON NITRIFICATION RATE
o。`5
u 卜 < ∝ 之 0 ` 卜< Q 一x 0 之凵 0 ° ∝ 卜 ` 之 < 一之 0 亠 泛 <
> 嚣 \ o B Σ 骂 \ 千 甘 之 巴
D忄 o oo NglodHwrh(e,3) f oe n oot Rf 6
l
FIGURE3ˉ
9 NITRIFICAⅡ ON
EFFECT OF BOD5/TKN RATIo oN RATEˉ EXPERIMENTAL ATTACHED
GROWTH|SYsTEM
源自文库
`oo ` \ ° E ハ " 。 Q ハ 臼 卜 ` 〓 卜 ` ℃ ι 0 卜 〓 0 吐 ⒋ 〓 之
20 40
13 3ˉ
1 t
the design,the BOD5/TKN ratio can be alteredby increasing organiccarbon removalahead unit. of the nitrification It must be emphasizedthat the nitrification rates developedin this section are only estimated relationshipsbased on theoretical considerations. Actual measuredvaluesare I presented Section4.6.3. in As a practicalexampleof the effect of the BODs/TKN ratio on nitrification rates,rate data for an attachedgrowth system44are plotted agai-nst BOD5/TKN ratio in Figure3-9.The the effect of BOD5 in the syntheticwastewas to displace nitrifien with heterotrophicbacteria in the bacterial film, thereby reducing the nitrifier fraction. and the nitrification rare. I n t e r e s t i n g l ya s m a l la m o u n t o f B O D 5 . - 1 0 m g / l ) w a s f o u n d t o e n h a n c e h e n i t r j f i c a t i o n , t rate.
Initiot NHi-N =20^s/t C o n t o c tT i m e 9 4 s e c , p H 7 . 4 , T e m p e r o t u r2 3 C e
o
o
`,0
2.o ε 。 D5/Γ K″
5.0 ∶ ⒎ 丿泅 T`C,
4,9
5.9
3ˉ 26
o。'C,
0。 05
‰
: 冫 。` 9 ‰ C 1r 丿
o
0.5
',o D0,D`ss0LVε
`。 D0X丫
5
2.0 CEⅣ , mg/`
2.5
3.0
While the generaleffect of DO on kineticsis firmly established, there needsto be further study to determinethe factors affectingthe valuesof Kg2. All of the variousestimates are is and no measurefrom systemswhere combinedcarbonoxidation-nitrification practiced for stage mentshavebeenmadeon separate nitrificationsystems.K62 values separate stage nitrification systems may very well be different than those for combined carbon oxidation-nitrification systems. Further refinement Kg2 valuescan be expected.For of illustrative use in this manual,a valueof Kg2 of 1.3mg/l hasbeenassumed. valuefalls This in the middle of the rangeof Kg2 observations(0.15 2.0 melD and is of a magnitude to such that if the operatingDO is 2-0 m{l or less, nitrification (or nitrifier) growthirateis the 60.6 percent(or less)of the peakrate.This orderof reductionin rate could account for most of the differencein growth rate observed Downing,et al. (seeSection3i2.5.4) by between river watervalues high DO levels activated at and sludge operating dataat DQ levels of 2.0 mg/l of less. 3.2.5.6 Effect of pH on Kinetics
i
The hydpogen ion concentration (pH) has been generallyfound to have.a strong effect on the rate of ritrification. Figure 3-5-presentstypical pH relationships from a number of -The results of other investigations investigations. have been summ arized in the litera,44 Th"r" is a wide rangein reportedpH optima;the almost universal ture.l finding is that as the pH moves to the acid range, the rate of ammonia oxidation declines. This has been found to be true for both unacclimatedand acclimatedcultur,es, although acclimation tends
FIGURE3砰 EFFECT OF DIsSOLVED OXYGEN ON NITRIFICATION RATE
o。`5
u 卜 < ∝ 之 0 ` 卜< Q 一x 0 之凵 0 ° ∝ 卜 ` 之 < 一之 0 亠 泛 <
> 嚣 \ o B Σ 骂 \ 千 甘 之 巴
D忄 o oo NglodHwrh(e,3) f oe n oot Rf 6
l
FIGURE3ˉ
9 NITRIFICAⅡ ON
EFFECT OF BOD5/TKN RATIo oN RATEˉ EXPERIMENTAL ATTACHED
GROWTH|SYsTEM
源自文库
`oo ` \ ° E ハ " 。 Q ハ 臼 卜 ` 〓 卜 ` ℃ ι 0 卜 〓 0 吐 ⒋ 〓 之
20 40
13 3ˉ
1 t
the design,the BOD5/TKN ratio can be alteredby increasing organiccarbon removalahead unit. of the nitrification It must be emphasizedthat the nitrification rates developedin this section are only estimated relationshipsbased on theoretical considerations. Actual measuredvaluesare I presented Section4.6.3. in As a practicalexampleof the effect of the BODs/TKN ratio on nitrification rates,rate data for an attachedgrowth system44are plotted agai-nst BOD5/TKN ratio in Figure3-9.The the effect of BOD5 in the syntheticwastewas to displace nitrifien with heterotrophicbacteria in the bacterial film, thereby reducing the nitrifier fraction. and the nitrification rare. I n t e r e s t i n g l ya s m a l la m o u n t o f B O D 5 . - 1 0 m g / l ) w a s f o u n d t o e n h a n c e h e n i t r j f i c a t i o n , t rate.