Biofilters
Expression (5.20) gives:
2
(k%,HAc)
kwt,HAc = kovt,HAciKs,HAc = 2 DHAc · Ks,HAc
kwt,HAc =
2·0.7·10-4·2
As the biofilm is considered to be very thick, we have from Expresssion (5.9):
%
k1A,HAc = -.fDHAc · kwt,HAc = ( 0.7 · 10- 4 · 3.9 · 10 4 ) = 1.7 m/d
Balance:
0 81- k1A · A2 · 83 = 0 83
960 g HAc/d = ( 1.7 · 500 + 1 OO) 83
83 = 1 g HActm 3
5.10. Technical conditions concerning
biofilters
A number of important conditions will be briefly discussed below. The conditions
are important for the functioning of biofilter plants and include
-aeration
- growth and sloughing off of the biofilm
5.10.1 Aeration in biofilters
As it appears from the above, the supply of oxygen to bioffiters is of greater importance
than for other biological plants because the oxygen supply is not just stoichiometrically
decisive, but frequently it is also governing for the reaction rate. The following types of
aeration can be used:
Separate aeration of the flow of recycle
This type of aeration is not different from the aeration which is required in activated
sludge plants. The theories gained from the activated sludge plants can be used
directly /15/.
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