Study On Biological Phosphorus Removal By Single-stage Oxic Process In Sequencing Batch Reactor

In recent years, the economy and the industry develop speedily. it is serious increasingly that the nitrogen, phosphorus compound causes the phenomenon of water pollution. Therefore, the wastewater not only needs to remove COD, but also needs to take off nitrogen and phosphorus. It had become the most important question of the water pollution research.Wang Dongbo et al discoverd a phenomenon by the anteriorly research, that is in the course of nitrogen and phosphorus removal of municipal wastewater with inner-loop SBR, wastewater enterd the aeration phase directly, without anaerobic phase, the anaerobic phase was conventionally considered as a key phase for phosphorus removal, but a predominant phosphorus removal were still achieved.The research based on Wang Dongbo's research. Set two reactors, pH was 8.0(R1)and 7.0(R2). After two reactors operate smoothly, the R1's influent of phosphorus was 20mg/L and effluent was under 3mg/L, the removal rate was 90%. In the same way, the R2's influent was 20mg/L, but the effluent was 4-6mg/L, the removal rate was 75%-85%. In the same time, two reactors's COD removal rate were above 95%. So, we consider the condition which pH was 8.0 is better than the pH was 7.0 to sustain the operate of phosphorus removal.After confirm the best condition of SBR, the researcher studied the effect of VFAs on the performance of phosphorus removal, and the path of biochemistry were also studied. Two reactor's pH was in the rang of 7.5~8.5. Two typical substrates of acetate and propionate were, respectively, fed to R1 and R2 qua the sole carbon source. Two reactors operate by the mode that aerobic(4h), deposit(0.5h), settling(7.5h). After two reactors operate smoothly, the R1's influent of phosphorus was 20mg/L and effluent was under 6-7mg/L, the removal rate was 65%-75%. After the settling phase, phosphorus release was 0.5mg/L. the R2's influent of phosphorus was 20mg/L and effluent was under 2-3mg/L, the removal rate was above 85%. After the settling phase, phosphorus release was 3mg/L. Two reactors's effect of COD removal were high, the removal rate was above 95%.The energy storage in R1 was PHA, but in R2 was glycogen, they were accumulated when external carbon source was comsumed and the phosphorus's decrease was not obvious. The phosphorus decrease fleetly when the endogenous carbon source was comsumed. Because the biochemistry processes of the microorganisms were different, the system of R2 need more energy than R1. That's the reason why the polyphosphate plays a very important role in the biochemistry processes. The microorganisms need energy to maintain in the long-time settling phase.