后置反硝化MBR分段进水工艺脱氮除磷效能研究

Investigation on Nitrogen and Phosphorus Removal in Step-feed Post-denitrification MBR

采用模拟生活污水考察了后置反硝化MBR分段进水工艺的脱氮除磷效能。结果表明,系统对有机物的去除不受进水分配流量的影响,平均出水COD稳定在40 mg/L以下,达到了GB 18918—2002的一级A标准。膜对大分子有机物具有截留作用,且截留量约占总有机成分的10%。分段进水对系统整体硝化效果没有影响,对NH+4-N的去除率在99%左右,平均出水浓度在0.5 mg/L以下。系统两级好氧池的硝化效果有所差异,第一级好氧池的硝化效率在87%左右,而第二级好氧池的硝化效率约为93%。分段进水改变了碳源在系统中的分布,当分配到厌氧池的流量从90%降低至60%时,对总氮的去除率由68.3%提高至79.9%,而除磷率由73%下降至55%。由于微滤膜组件的高效截留作用,系统出水SS、浊度和色度平均值分别稳定在1.28 mg/L、0.2 NTU、20倍左右。间歇抽吸出水的操作模式能够有效地减缓膜污染发展速率,使膜的化学清洗周期延长12 d左右。

The nitrogen and phosphorus removal in the step-feed post-denitrification MBR was in- vestigated using synthetic domestic sewage. The results showed that the removal of organics was not influ- enced by influent flow, and the average effluent COD was below 40 mg/L, which met the first level A criteria specified in GB 18918 -2002. The membrane could intercept macromoleeule organics, and the interception accounted for 10% of the total organic components. Step-feed had no influence on the nitrifi- cation of the reactor. The average removal rate of NH4 - N was 99% , and the average effluent NH4＋ - N was less than 0.5 mg/L. The nitrification efficiency of the two-stage aerobic tanks was different, 87% for the first-stage aerobic tank and 93 % for the second-stage aerobic tank. The distribution of carbon source changed due to the step-feed. When the influent flow of anaerobic tank was decreased from 90% to 60%, the TN removal rate was increased from 68.3% to 79.9%, while the phosphorus removal rate was reduced from 73% to 55%. The average effluent SS, turbidity and color were 1.28 rag/L, 0.2 NTU and 20 times respectively due to the effective interception of microfiltration membrane modules. The operating mode of intermittent suction could retard the development of membrane fouling, and the chemical clean- ing cycle of the membrane was extended by about 12 d.