Applied Research On A~2/O Combined MBR Process For Municipal Wastewater

Based on the drawback problem of existing treatment facilities that can not satisfy the full load capacity in a northwest town and the water resources shortage, this paper presented the combination process of A~2/O and MBR to fulfill the handling ability of waster from 2500m3/d to 5000m3/d under the limited area, meanwhile achieved wastewater recycling. The project can provide an example for reusing of wastewater and advancing of sewage treatment plant in northwest area.Based on wastewater quality characteristics, the A~2/O biological treatment process was chosen, and the effective water depth of the anaerobic tank, anoxic, aerobic tank was increased to 10.5m. This achieved the purpose of degradation of pollutants completely within a limited area under an enough long hydraulic retention time. Depending on the proportion of organic matter and nutrients of nitrogen and phosphorus, the hydraulic retention time of aerobic tank, anaerobic tank and anoxic tank was 1.5h, 4h, 4.5h respectively. The hydraulic retention time of subsequent membrane bioreactor (MBR) adopted a built-submerged configuration was 1h. The influence factors and the long-term operation effect of A~2/O-MBR showed that the finished water quality achieved the requirements of "urban wastewater reuse for urban reclaimed water quality" (GB/T18920-2002). This paper analyzed the mechanism of the membrane fouling and constructured a membrane fouling control model, Combining with the actual operation management features and process design.Comparing with conventional activated sludge treatment and advanced sencordary effulent, this study assessed economic indicator of the process, and implied the numerous advantage of the A~2/O-MBR process that can obtain higher water quality with a small covering area and lower energy consumption.