回流量对生活污水净化槽处理效果的影响

Influence of Recirculation Flow Rate on Domestic Sewage Treatment in Purifying Tank

使用家庭生活污水净化槽,将沉淀区不同流量污水回流至厌氧一区,考察了回流量对净化槽各区处理家庭生活污水以及去除氮、磷营养物的影响。结果表明,随着回流量的增大,各区的净化效果都明显提高,当回流量为22.5 L/d时,净化槽出水COD、BOD5、氨氮、总氮和总磷值分别为38、8.1、6.5、19.1和3.32 mg/L,除总磷外,其他各指标都达到了《城镇污水处理厂污染物排放标准》(GB 18918—2002)的一级排放标准;当回流量继续增大为30 L/d时,对各污染物的去除率增加不明显,而且厌氧一区的生物膜有脱落现象,影响了净化槽厌氧区功能的发挥,增加了处理成本。因此,最终确定净化槽最佳回流量为22.5 L/d。

The influence of recirculation flow rate on domestic sewage treatment in diflerent zones of purifying tank was investigated through an experiment of circulating different volumes of sewage from the settling zone to the first anaerobic zone. It is found that the removal effect is improved with increasing the recirculation flow rate. When the recirculation flow rate is 22.5 L/d, the effluent COD, BOD5 , ammonia nitrogen, TN and TP are 38 mg/L, 8.1 mg/L, 6.5 mg/L, 19. 1 mg/L and 3.32 mg/L respectively. Except TP, all the other indexes meet first class criteria specified in the Discharge Standard of PoUutantsfor Municipal Wastewater Treatment Plant （ GB 18918 - 2002 ）. When the recirculation flow rate is increased up to 30 L/d, the removal efficiency of pollutants is not evidently increased, and the biofilm detachment occurs in the first anaerobic zone, which affects the function of the anaerobic zone in purifying tank and increases the cost of sewage treatment. It is concluded that 22.5 L/d is the optimal recirculation flow rate of purifying tank.