Study On Effects Of Carbon Source And Electron Acceptor On Denitrifying Phosphorus Removal System

In order to investigation the mechanism of denitrifying phosphorus removal, in this paper anaerobic/anoxic(aerobic) SBR reactor and microbial molecular ecology were studied with synthetic wastewater to study the efficiency of phosphorus removal systems with different electron acceptors and denitrifying phosphorus removal systems with different carbon sources. Besides anaerobic phosphorus release and anoxic phosphorus uptake in different mixed carbon sources were also investigated macroscopically in this paper.The results show that the effect of phosphorus uptake was good when oxygen and nitrate acted as electron acceptor. However, the phosphorus removal rate in anoxic condition was much lower than that in aerobic condition. The ratio of maximal phosphorus removal rate in anoxic condition to that in aerobic condition was 1:1.85. Nitrite in aerobic phosphorus removal system possessed great inhibiting effect. While it made no difference to denitrifying process in denitrifying phosphorus removal system(nitrate), and nitrite was able to act as electron acceptor without toxic effect when its concentration was low. As nitrite was the sole electron acceptor in denitrifying phosphorus system, the higher the concentration of nitrite was, the less the amount of phosphorus uptake per unit sludge was.When the system operated steadily after long time domestication, the effect of denitrifying phosphorus removal system with sodium acetate and sodium propionate as sole carbon source was prominent. And the removal efficiency of PO₄^3--P in the two systems was 86% and 82% respectively. The phosphorus removal effect of glucose as carbon source was the worst. The removal efficiency of PO₄^3--P in this system was only 31%. Phosphate-Accumulating Organism took a lot of time to utilize glucose, and this process was complex. Consequently prolonging anaerobic reaction could improve the effect of phosphorus removal in the system.Anaerobic phosphorus release and anoxic phosphorus uptake in mixed carbon sources of sodium acetate and sodium propionate were both better than in mixed carbon sources of sodium acetate and glucose. When sodium acetate and sodium propionate were mixed in the ratio of 1:1, the phosphorus uptake efficiency which was 4.353mg/mgNO₃^- was the greatest. And the phosphorus release efficiency which was 15.178mg/gMLSS·h was the greatest as the ratio was 3:1. Anaerobic phosphorus release and anoxic phosphorus uptake were both the worst in the system of sodium acetate and glucose mixed in the ratio of 1:3. In mixed carbon sources, sodium acetate could be used best by Phosphorus-Accumulating Organisms, while sodium propionate worse and glucose worst. But as a whole, the effect of anaerobic phosphorus release in mix carbon sources were all worse than that in systems of sodium acetate and sodium propionate as sole carbon source.16SrDNA of denitrifying-phosphorus-removal sludges from the systems of different electron acceptors and different carbon sources were respectively analysed and compared elementarily. It could be found in experiments that microbial community structure and amount of population were related with electron acceptor and carbon source. The type of carbon source influenced sludges which had the capability of denitrifying phosphorus removal greater. Especially the system with glucose as sole carbon source was different greatly from the system with sodium acetate or sodium propionate as sole carbon source.