[Non-filamentous activated sludge bulking caused by the deficiency of nitrogen]

The effect of nitrogen deficiency on activated sludge bulking was studied specially in some experiments carried on a sequencing batch reactor fed with beer wastewater in this paper. The experimental results showed that the sludge settled properly at a influent BOD/N value of 100/4. When the value of BOD/N was 100/3 and 100/2 respectively, non-filamentous activated sludge bulking caused by an excessive growth of viscous Zoogloea with high moisture content occurred. When the value of influent BOD/N was 100/0.94, more serious non-filamentous bulking occurred. Furthermore, the effect of nitrogen deficiency on the nitrogen sources and phosphorus sources utilization rate and the COD removal rate was studied in the experiments.