Activity of Nitrifiers and Metabolized Products in a Membrane Bioreactor MBR Under the Condition of Non-Sludge Discharge
无排泥运行下膜生物反应器的硝化代谢产物及细菌活性

A membrane bioreactor fed with synthetic ammonium bearing inorganic wastewater was operated under the following conditions: HRT, from 30h to 7h; influent NH4+-N, 500mg/L; non-discharge of sludge. Formation of extra-cellular polymers (ECP) and their influence on the activity of nitrifiers in the membrane bioreactor was investigated. Over the whole experimental period of 200 d, the activity of nitrifiers in terms of overall ammonium-oxidizing rate decreased from 2.1kg/(L·d) to 1.5kg/(L·d), and the nitrifier number using INTF absorbency measurement decreased from 0.023×10-3 to 0.01×10-3, although the MLSS increased from 4 500mg/L to 10 500mg/L. The ECP content increased from the initial 300 mg/L to 600mg/L. Batch tests using the extracted ECP also indicated that the activity of nitrifiers could be inhibited by the existence of ECP.