A2/O氧化沟工艺中NO3-对生物除磷影响

为研究NO3-对生物除磷的影响,采用A2/O氧化沟中试对城市污水进行4个月的研究,并结合静态试验和实际A2/O氧化沟污水处理厂运行结果,研究NO3-对厌氧释磷影响,首次全面研究NO3-对二沉池释磷的影响.中试试验反应器总有效容积为375 L.结果表明,氧化沟出水ρ(NO3-)>5.0 mg/L时,回流污泥带入的NO3-较多,不利于磷的释放,TP去除率随出水NO3-的升高而降低;氧化沟出水ρ(NO3-)<5.0 mg/L时,NO3-较低导致在二沉池中进行了内碳源释磷反应,TP去除率随NO3-的降低而降低;静态试验结果证明当ρ(NO3-)>0.5 mg/L时,NO3-抑制磷的内碳源释放.NO3-降低至0.5 mg/L以下时,发生内碳源释磷,比内碳源释磷速率为0.18~0.47 mg/(gVSS.h);某污水处理厂运行结果也证明,二沉池污泥停留时间过长,发生内碳源释磷致使出水TP升高.

Effect of nitrate on biological phosphorus removal with anaerobic-anoxic-aerobic oxidation ditch process

In order to study the effect of nitrate on the biological phosphorus removal,the anaerobic-anoxic-aerobic(A2/O) oxidation ditch(OD) process was adopted to treat the municipal wastewater combined with the captive test for 4 months,meanwhile the operation data of an A2/O oxidation ditch wastewater treatment plant were analyzed.The effect of nitrate on phosphorus release in the anaerobic zone and in the secondary clarifier was studied.The volume of the whole reactor was 375 L.The result indicated that with the effluent NO3-of the OD more than 5.0 mg/L,the phosphorus release was restrained by NO3-carried by the returned activated sludge,resulting in the decrease of TP removal rate with the increase of NO3-in the effluent.When NO3-in the effluent was less than 5.0 mg/L,the TP removal rate was decreased with the decrease of NO3-in the effluent due to the phosphorus release happened in the low NO3-condition with inner carbon resource acting as an electronic acceptor.The captive test indicated that the phosphorus release with inner carbon resource acting as the electronic acceptor was restrained when NO3-was more than 0.5 mg/L in the secondary clarifier,while phosphorus was released with the inner carbon being the electronic acceptor when NO3-was less than 0.5 mg/L,and the specific phosphorus release rate was 0.18-0.47 mg/(gVSS·h).The operation result of the wastewater treatment plant indicated that retention time of the activated sludge in the secondary clarifier was so long that it would increase the effluent TP due to the phosphorus release with inner carbon resource.