Recently,the technique of biologically removing Mn has become well
known. In this technique, the soluble Mn is oxidized to insoluble
metallic Mn oxides by microorganisms
The carbon sources in drinking water are usually insufficient for the
conversion of NH4 + -N to nitrogen gas by the conventional nitrification–denitrification process.
Therefore, NH4 + -N is believed to be
converted to nitrate by nitrification
In such an instance, the nitrogen
in the form of nitrate will continue to exist in the water. However,
for the simultaneous Mn and NH4 + -N removal potable water treatment
biofilter, the operational results in the laboratory showed a
significant nitrogen imbalance between the influent and the effluent
of the biofilter. Although nitrogen could be used as a nutrient
for bacterial growth (Yu et al., 2007), it could not cause such a
remarkable loss of nitrogen. Therefore, in addition to the nitrification
process, there had to be other nitrogen transformation paths
in the biofilter, and it seems likely that the nitrogen loss was
autotrophic.