Study On Modified A~2/O Process For Low-strength Domestic Wastewater Treatment

In this paper, the urban sewage as raw water, investigated a point of nitrogen andphosphorus removal of the water the modified A2/O process. The process used rawwater into the same out anaerobic tank and anoxic tank, an increase of anoxic carbonsource, add a filler in hypoxic pool, then into the aerobic tank to improve nitrogenremoval.The results showed that when the influent flow144L/d, the hydraulic retentiontime of11h, sludge reflux ratio of50%MLSS for3000±400mg/L, dissolved oxygenin the aerobic tanks DO is maintained at1to3mg/L, the anaerobic tank dissolvedoxygen DO pool and hypoxia were less than0.2mg/L and0.5mg/L, the raw waterinto the anoxic and anaerobic tank in accordance with the ratio of4:6,during July andAugust, COD, ammonia nitrogen, TN, TP removal effect was relatively stable,effluent concentrations lower than50mg/L,5mg/L,15mg/L,0.50mg/L.In the type nitrification liquid reflux ratio (150%,200%,250%) under theconditions of the system for the removal of COD, ammonia nitrogen, total phosphorus,almost no influence, the system effluent concentrations were33.80mg/L and0.16mg/L,1.00mg/L, the removal rates were82.33%,99.43%,63.44%. The system effluentTN concentration average of14.83mg/L, the removal rate of TN average of64.02%,taken together,200%condition was more appropriate.Different ratio of water conditions, the anaerobic tank flow into the anoxic tankflow ratios of5:5(operation1#)4:6(operation2#) under the conditions of the workingconditions, the system of COD, TP to in addition to the more stable conditionsoperation1#under the conditions of the treatment effect in operation2#.Optimal C/Nratio of4.61~5.01;optimal C/P ratio of35~50.The modified A2/O system to handle low-carbon source sewage effluent qualitywas good and stable, with theoretical and technical reference for the development andimprovement of the water treatment process.