The phosphorus balance of The A/A/O process for a municipal sewage plant of Beijing in China

According to the determining results of total phosphorus for the A/A/O all-process of a wastewater treatment plant of Beijing in China, it were analyzed for the phosphorus balance of the system and the denitrifying phosphorus removal of the anoxic phase. And it was discussed for the correlation between the phosphorus removal and process operating parameters. Then the optimal parameters of A/A/O process control were proposed based on the phosphorus removal. The main conclusions were as follows: The phosphorus removal of anoxic phase and oxic phase were 4.97mg/L and 5.5mg/L separately, which there was the obvious denitrifying phosphorus removal in anoxic phase. On the whole, the phosphorus load of the influent and effluent in the process was balance, the total phosphorus removal rate of sewage was about 78~94%. There was a negative correlation relation between phosphorus removal rate and sludge retention time. The larger excess activated sludge discharge, the lower phosphorus accumulation in the A/A/O process system. The appropriate sludge discharge of the process should be remained at 4000~5000m³ per day. The phosphorus load proportion of influent accounted for 98 percent of entering into the process system, the rest came from the waste liquor of sludge treatment process in the wastewater treatment plant. In the discharge phosphorus load of the treatment plant, dewatered sludge cake had taken out 84 percent, effluent accounted for 14 percent, and the waste liquor of sludge treatment process was only 2 percent.