Fig3.8
Maxium specific
growth rate
11m ax
10
~b
d~
20
Basic Biological Processes
Temperature curve for
slow variation
Temperature
30
The effect of rapid and slow temperature changes on the growth rate. Based on /19/.
a = rapid heating (15 --. 25°C)
b =adaptation (slow)
c = rapid cooling (25 -t 15°C)
d =adaptation (slow)
Nitrification can take place in high oxygen concentrations, for example in a pure
oxygen plant. 60 g oxygen/m 3 do not inhibit the process /12/.
pH
The nitrification process is pH dependent with an optimum in the 8-9 range - see Fig
3.9. Because of the influence of the nitrification process on pH, the pH value in floes
and biofilm will be lower than the value which can be observed in the liquid phase.
Nitrification rate compared to rate at pH 7.5
1.6
1.4
6.0
7.0
8 .0
9.0
10.0 pH
Fig 3.9
The overall nitrification rate as a function of pH /21/.
81