Experimental Study on Treatment of Sewage with Low Carbon/Nitrogen(C/N) Ratio

A combined treatment technology was used to filter and treat low carbon/nitrogen （C/N） rural domestic wastewater,which consisted of a combination of aerobic/anoxic （A/O）/denitrification/coagulation and sedimentation/fibre.In addition,improved operating parameters,enhanced sludge reflux and the addition of an additional carbon source were used with a view to achieving deeper treatment of low C/N rural domestic wastewater.The results showed that when the control conditions that dissolved oxygen concentration in the aerobic zone was 1.5～2.5 mg/L,dissolved oxygen concentration in the anoxic zone was 0.2～0.5 mg/L,C/N was10:1,the ratio of influent and external return and internal return was 1:1:2.5,the discharge water had a chemical oxygen demand （COD） concentration of approximately 13 mg/L,ammonia nitrogen （NH₃-N） concentration of approximately 0.4 mg/L,the treatment efflciency of TP was 97%,TN was 94%,COD was 97%and NH₃-N was99%,and the discharge water reached the requirements of "quasi-IV water".It was further proved that under this control condition,the deep and efflcient treatment of rural domestic wastewater would be achieved.