Nitrogen removal efficiency of an A2/O bio-reactor treating domestic sewage mixed with landfill leachate and fecal sewage

A set of anaerobic-anoxic-aerobic (A2/O) bio-reactor system was used to treat domestic sewage
mixed with landfill leachate and fecal sewage in Datansha Sewage Treatment Plant in Guangzhou
China. The experiment investigated the optimal mixing proportion of treating landfill leachate, fecal
sewage mixed with domestic sewage synchronously and the optimal running conditions for the
removal efficiency of nitrogen by an orthogonal array test. A confirmatory experiment was also
carried out to verify the optimal parameters obtained by the orthogonal array test. The results showed
that: the optimal volume ratio of landfill leachate, fecal sewage and urban wastewater in the A2/O
process was 1:3.75:1000. The average removal efficiency of NH3-N, TN and COD can reach 96%,
61% and 85% respectively under the conditions of hydraulic retention time (HRT) of 11h, dissolved
oxygen (DO) of 3 mg L-1 the mixed-liquid return ratio (r) of 200% and sludge return ratio (R) of 80%.