Biofilters
Zero order reaction
For the zero order reaction we have a much simpler expression
rvf= kovf
(5.10)
i Svf kovf L 2
~=ISS
(5.11)
The complete integral is:
For the limiting condition at the surface we get:
~ = 0 , svf = 1 --. K2 = 1
If the observed substance can fully penetrate the film, we get the following limiting
conditions:
as
~=1, a~=o
kovf L 2 2 kovf L 2
SVf = 2 DS ~ -ISS~ + 1
~2
~
Svf=--2-+1
~2
~2
~=.._j 2DS
kovf L2
(5.12)
(5.13)
The concentration distribution in the biofilm is shown in Fig 5.3. For the total
transport through the surface of the film we get
corresponding to the biofilm being fully efficient, which means that the removal is
taking place according to the zero order reaction throughout the full length of the
film. This requires, however, that there is something to remove in the very heart of
the film, which means that the concentration has to be greater than zero for t; = 1.
The result is the following condition:
~>1
If this condition is not complied with, the limiting conditions must be changed:
~ = ~~ , Svf= 0
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