14.3 Anaerobic digesters for BOD removal and sludge stabilisation 14.4 Microbial removal of nitrogen from waste water 14.4.1 The nitrogen cycle N2 Denitri/fication Nitrogen fixation NO Nitrate assimilation R-NH2 Nitrification Ammonia assimilation Ammoni ficationNH Deamination,etc The nitrogen cycle.See text above for further explanation.14.4.1 The nitrogen cycle 14.3 Anaerobic digesters for BOD removal and sludge stabilisation 14.4 Microbial removal of nitrogen from waste water