Basic Biological Processes
matter or other nutrients) or is subject to strong dynamic influences, the release of
intermediate products can be increased.
3.5.1 Reactions by denitrification
The energy yielding process for denitrifying bacteria which uses organic matter in
wastewater as an energy and carbon source can be written as a combination of the
two half-expressions
;O C18H1909N + ~~ H20 ---+ ¥oco2 + ;O HC03 + ;O Nlf! + H+ + e~G0(W) = -32 kJ/e-eqv
and
1 No- 6 H+ -
3++e
5
5
~G 0 (W) = + 71 kJ / e-eqv
By combination we find:
~G 0 (W) = -103 kJ/e-eqv
(3.29)
The energy developed, -103 kJ I e-eqv, ends up as heat or in the form of biological
growth.
3.5.2 Yield constant by denitrification
Provided that all the energy is used for growth, the maximum yield constant of the
process can be calculated at 0.47 kg biomass/kg organic matter which proves to be
close to that of aerobic heterotrophic conversion (0.50 kg biomass/kg organic
matter). The corresponding equation of reaction, provided that the organism assimilates ammonium, is
(3.30)
The equation of reaction, provided that nitrate is assimilated, does not differ much
from (3.30)
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