污泥回流比对A2N反硝化除磷工艺脱氮除磷的影响

Study on Influence of Sludge Recycle Ratio on Removal of Nitrogen and Phosphorous in A_2N Denitrifying Phosphorus Removal Process

以城市生活污水为研究对象,探讨了不同的超越污泥和回流污泥回流比对A2N工艺脱氮除磷的影响。在超越污泥回流比与回流污泥回流比相同且分别为0.3、0.4和0.6的条件下,A2N工艺对COD的平均去除率分别为92.5%、90.3%、91.6%,相应的出水COD为20.3、28.4、25.3mg/L;对总氮的平均去除率分别为87.1%、90%、84.9%,出水总氮分别为6.75、5.43、6.95mg/L;对磷的平均去除率分别为99.5%、99.6%和99.0%,出水磷浓度分别为0.02、0.02、0.05mg/L。当回流比为0.4时,A2N系统的除污效果最好。研究还发现,超越污泥流量直接决定了未经硝化而直接进入缺氧池的氨氮量,进而影响出水氨氮浓度。因此,在保证缺氧池有足够污泥的前提下,应尽可能减小超越污泥流量,以降低出水氨氮浓度。

The influence of different sludge ratios from middle sedimentation tank to anoxic reactor （exceeding sludge ratio） and from final sedimentation tank to anaerobic reactor （recycled sludge ratio） on denitrifying phosphorus removal in A2N system was investigated using municipal domestic sewage. When the ratios of two kinds of sludge are 0.3,0.4 and 0.6 respectively, the resulting average COD removal rates are 92.5% , 90. 3% and 91.6% , total nitrogen removal rates are 87. 1% , 90% and 84.9% , and phosphorus removal rates are 99.5% , 99.6% and 99.0% , respectively. The effluent COD concentrations are 20.3 mg/L, 28.4 mg/L and 25.3mg/L, total nitrogen concentrations are 6.75 mg/L, 5.43 mg/L and 6.95 mg/L, and phosphorus concentrations are 0.02 mg/L, 0.02 mg/L and 0.05 mg/L, respectively. When the ratios of two kinds of sludge are 0.4, A2 N system has best pollutant removal efficiency. Moreover, the exceeding sludge flow rate determines the amount of ammonia nitrogen flowing into the anoxic reactor and the effluent ammonia nitrogen concentration. In order to decrease the effluent ammonia nitrogen concentration, the exceeding sludge flow rate should be minimized on the basis that there is adequate sludge in the anoxic reactor.