| Cyclic Activated Sludge System was a kind of improvement on SBR。It had the merits of simple process,small area, easy control,low operating costs,flexible operation, easy to adapt the water quantitative and water quality,high removal results of nitrogen and phosphorus etc。Nowadays,the CASS Process had applied extensively in various industrial wastewater and city sewage in china,it had broad market prospects。The municipal wastewater treatment plant was designed and constructed with pump station,screen unit,aeration grit chamber,CASS tanks,blower house,sludge thickener and sludge dryer unit in Economic and Technological Development Zone of Tongliao city,where 3.11 hectares land was available。The cyclic activated sludge system was utilized to treat 50,000 m3 wastewater per day。The cultivation of activated sludge began in April 2008,and considered as trial-operation, which lasted about ten months。During this period,several kinds of physical and chemical pollutants including pH,BOD5,CODcr,SS,TN,NH3-N and TN, and the characteristics of microorganisms were detected to determine the system's treatment efficiency and regulate the operation's parameters。In addition,Causes and countermeasures of sludge bulking and floating occurred in activated sludge culture were discussed in the paper。According to the design parameters and influent water quality,after ten months of debugging running experiments,the study selected a reasonable operating parameters: entering the water and aeration 3 hours, precipitation 1.5 hours,decanter 60 minutes,idle 30 minutes;MLSS controlled in the 2500 to 3500 mg/L;at the end of the aeration control of dissolved oxygen in the aeration tank 2 to 3 mg/L;controlled Sludge age in 15 to 20 days。In this cycle of operation BOD5,CODcr,SS,NH3-N and other indicators of water achieved in standard of《Discharge standard of pollutants for municipal wastewater treatment plant》(GB18918-2002)。The results complied with design requirements。...
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