Biological Nitrogen And Phosphorus Removal By An Alternating Anaerobic-Anoxic-Aerobic Sequencing Batch Reactor

The research of this thesis emphasized on the process paramenters and the mechanism of biological nutrient removal (BNR) in a sequencing batch reactor under alternationg anaerobic-anoxic-aerobic conditions, which was fed with synthetic wastewater and municipal wastewater respectively.Firstly, the process parameters of SBR was investigated through acitivate sludge culture and the process adjusting. And the final operating cycle of SBR was: 1.5h anaerobic period, 1h aerobic period, 1h anoxic period, 20min aerobic period, 1h anoxic period and 20min aerobic period. Comparing with the original anaerobic/aerobic mode, the oxygen supply could be decreased about 44% in theory. Removal efficiency of COD, total nitrogen and phosphorus of the reactor A fed with synthetic wastewater was 88%, 89%, 100%, respectively. While Removal efficiency of COD, total nitrogen and phosphorus of the reactor B fed with municipal wastewater was 85%, 78%, 99.5%. Through the research on the effect of influent quaility fluctuating on removal efficiency, it was found that the influent COD fluctuating gave little impact on removal efficiency, the increasing TN content of influent would increasing the TN, TP content of effluent a little which still could meet the standard, and the increasing TP content of influent would reduce the phosphorous removal efficiency to 60%. When the influent pH value was 7.5, the nutrient removal efficiency was the best.It was found that in reactor A, the TP removal was carried out by PAOs in aerobic stage which responsible for 90% TP removal and DPAOs in anoxic stage, while the TN removal was carried out by denitration which responsible for 70% TN removal and microorganism growth requirement. And in reactor B, the TP removal was carried out by PAOs in aerobic stage which responsible for 88% TP removal and DPAOs in anoxic stage, while the TN removal was carried out by denitration which responsible for 79% TN removal and microorganism growth requirement.Though there were much differences of Polyhydroxyalkanoates (PHAs) accumulated and phosphorous release in anaerobic stage between the SBR systems fed with synthetic wastewater and municipal wastewater, the amount of anaerobic phosphorus release...