Effect of nitrate recycle ratio on the performance of combined ylindrical anoxicaerobic moving bed biofilm reactor for domestic wastewater treatment

Abstract EN

continuous up-flow moving bed biofilm reactor (MBBR) were used to treat 4m3/d of domestic wastewater in Chongqing city at Southwest China .Both the anoxic and aerobic reactors were filled to 50 %( v/v) with Kaldnes (K1) biofilm carriers.

After developing the biofilm on the carriers,the effect of nitrate recycle ratio on biological nutrients removal from domestic wastewater was investigated by operation of reactors under 3 different nitrate recycle ratios ranging from 50% to 150% (50%, 100%, and 150%) through changing the value of this parameter every one week.

During this operation mode, the MBBRs was operated under the optimal value of gas/water ratio which equal to 7/1 and hydraulic retention time (HRT) equal to 6.2 hours.

The experiment results showed that optimum value of the nitrate recycle ratio for simultaneous organic carbon and nutrients removal was equal to 100%.

In this nitrate recycle ratio, the average removal efficiencies were 92.16 %, 98.84 %,71.23 % and 91 % for COD, NH4+-N,TN and TP respectively, while the average dissolved oxygen concentration (DO) in aerobic and anoxic MBBRs were 4.35 mg./L and 0.19 mg./L respectively .