N2O production in a single stage nitritation/anammox MBBR process
N2O production in a single stage nitritation/anammox MBBR process
N2O production in a single stage nitritation/anammox MBBR process
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found that when the added quantities of carbon source only allowed between 66-88%<br />
denitrification, <strong>N2O</strong> emissions from the system were <strong>in</strong>creased from an average of 0.2%<br />
up to 1.3% of reduced nitrate. Long residence times for <strong>N2O</strong> <strong>in</strong> denitrify<strong>in</strong>g sludge have<br />
been shown to result <strong>in</strong> smaller amounts of emitted <strong>N2O</strong>. S<strong>in</strong>ce <strong>N2O</strong> is an <strong>in</strong>termediate <strong>in</strong><br />
the denitrification <strong>process</strong> dissolved <strong>N2O</strong> <strong>in</strong> the water phase can be turned over by the<br />
denitrifiers and a long residence time for <strong>N2O</strong> <strong>in</strong>creases the possibility that the gas is<br />
converted <strong>in</strong>to d<strong>in</strong>itrogen gas. The experiments show<strong>in</strong>g these results were performed<br />
<strong>in</strong> 100 ml bottles with different sludge volumes which also <strong>in</strong>dicates that <strong>N2O</strong> emission<br />
is greater from wastewater treatment bas<strong>in</strong>s with large surface to volume ratio<br />
(Gejlsbjerg et al., 1997).<br />
2.5.3 Chemical <strong>production</strong> of <strong>N2O</strong><br />
<strong>N2O</strong> can be produced by chemical denitrification <strong>in</strong> a wastewater treatment plant, the<br />
reduction follows the same pathway as dur<strong>in</strong>g biologic denitrification shown <strong>in</strong> eq.<br />
(2.5.3). The difference is that chemical reductants are reduc<strong>in</strong>g the nitrogen compounds<br />
<strong>in</strong>stead of microbial enzymes (Debruyn et al., 1994).<br />
Figures of <strong>N2O</strong> emissions from microbial nitrogen conversion found dur<strong>in</strong>g the literature<br />
study are summarised <strong>in</strong> Table 3.<br />
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