低溶氧生物膜反应器对城郊低浓度混合污水进入湿地前的预处理

Treatment of low concentration mixed wastewater in the suburb using low dissolved oxygen biofilm reactor

采用低溶氧生物膜反应器对滇池北岸村镇混合污水进行预处理,旨在去除难以自然沉淀的固体污染物,便于后续湿地深度净化.以小试规模在现场自然条件下进行了12个月的连续动态模拟实验,结果表明,水力负荷3-12m3/(m2·d)、气水比为1:1-2:1、DO浓度基本维持在0.1-2.0mg/L时,生物膜反应器对污水中有机物能够有效去除,进水COD负荷低于0.58kg/(m3·d)的情况下,去除率可稳定在60%以上.低溶氧条件下生物膜脱落缓慢,膜厚度达到800μm,增强了对进水SS的拦截、吸附作用,SS平均去除率达到了90.7%.实验发现低溶氧条件下系统对氮、磷仍具有一定的去除效果.降低曝气量后运行能耗明显减小,以4000t/d的处理规模计算,运行费用在0.05-0.1元/t,尽管混合污水中COD、SS浓度波动范围大,但反应器出水及生物膜的生长都能保持相对稳定,为后续湿地系统的稳定运行提供了保障,试验为滇池流域城郊水污染控制提供了新的技术途径与应用参考.

Low dissolved oxygen biofilm reactor was used to treat the mixed wastewater in a village in north bank of Lake Dianchi. The purpose of the operation was to remove the solid waste, which was difficult to settle down naturally, so forth tofacilitatethe next step of wetland purification. A field experiment was undertaken for 12 months in nature conditions. The result showed that when the hydraulic loading rates between 3 and 12m3/（m2.d）, Air/Water ratio between 1 ： 1 and 2：1, DO was controlled between 0.1 and 2.0mg/L, the reactor could remove the organic matter efficiently. When the loading rates of COD under 0.58kg/（m3.d）, removal rates were above 60%. Low dissolved oxygen slowed the desquamation of biofilm and its thickness was reached to 800μm. Process of obstruction and adsorption was enhanced for SS removal and the average removal rate was 90.7%. The experiment found that there was still some removal effect of nitrogen and phosphorous in low dissolved oxygen in the reactor. Energy cost was significantly reduced by decreasing aeration. At the flux of 4000t/d, the calculated treatment expense was 0.05-0.1RMB/t. Although the concentration of COD and SS of mixed wastewater was greatly fluctuated, the outflow quality and biofilm growth was relatively stable. It＇s suitable for further stable disposal and the treatment of suburb low concentration mixed wastewater. It provided a new technical for wastewater control in suburb area of Dianchi basin.