控制低溶解氧实现亚硝化的稳定性

以A/O除磷工艺的二级出水为进水,通过低溶解氧控制,实现了亚硝酸盐的稳定积累.为研究系统的稳定性,从3个方面分别研究了总氮损失、水力停留时间(HRT)和回流比(R)对稳定亚硝化的影响.结果表明,系统的表观亚硝化率受COD浓度影响,COD≤50mg/L时,表观亚硝化率降低,COD50mg/L时,表观亚硝化率会增加;延长和缩短HRT都对稳定亚硝化存在正反两方面影响,应根据实际情况进行动态控制;提高回流比会增加破坏稳定亚硝化的风险,以较低回流比0.5为宜.另外,低溶解氧浓度不会降低系统的亚硝化效率,在HRT=6h,R=0.5,t为22～24℃条件下,平均氨氮去除率达83%,氨氮去除负荷为0.28kg/(kg·d),亚硝酸盐积累率接近100%.

Achieving the Stability of Nitrosation Under Low DO Concentration

With A/O phosphorus removal process of secondary effluent as raw water, the stable accumulation of nitrite was achieved under low DO. Total nitrogen loss, hydraulic retention time (HRT) and sludge recycle ratio(R) was separately studied on the effects of stable nitrosation. According the result, apparent nitrosation rate was affected by the concentration of COD influence, when COD < or = 50 mg/L, apparent nitrosation rate was reduced; when COD > 50 mg/L, it was increased. Extension and shortening of HRT has positive and negative effects on nitrosation efficiency, dynamic controlling was an effective method. The system stability would be undermined leading to the risk of nitrification by elevating sludge recycle ration. In addition, low DO concentration did not reduce nitrosation rate. Under the condition of HRT = 6 h, R = 0.5, T = 22-24 degrees C, the average ammonia nitrogen removal rate reached 83%, the ammonia nitrogen removal load reached 0.28 kg/(kg x d), the nitrite accumulation ratio was close to 100%.