生物法-人工湿地组合工艺对小城镇混合污水氮素去除效果研究

Studies on the effects of the combined process of A/BCO-CW for treatment of small town mixed sewage

在华南热带亚热带地区,利用生物法-人工湿地组合工艺(A/BCO-CW)处理小城镇片区混合污水。全年运行结果表明,A/BCO-人工湿地组合系统对TN和NH4-N具有好的处理效果,年均去除率分别为57.57%、87.73%,平均去除负荷量达到3.85和3.26g·m-2·d-1。A/BCO预处理系统在停留时间为3～6h条件下,对NH4-N去除效率达57.38%,好氧段充分曝气,有利于硝化过程的进行,有效地解决人工湿地因溶解氧不足造成的硝化过程受限制情况,减少了后续湿地所需面积的25%。在0.30～0.59m·d-1水力负荷率下,垂直流-表面流-水平潜流人工湿地组合系统对TN和NH4-N平均去除负荷达到了2.56、0.90g·m-2·d-1;TN、NH4-N去除速率常数为39.8和41.62m·yr-1,这些数值均处于文献中k值范围的高量程内。在进水NH4-N变动范围为6.27～18.8mg·L-1时,出水水质均能稳定达到GB3838—2002《地表水环境质量标准》的IV类水1.5mg·L-1的标准。通过探讨A/BCO-CW组合工艺用于混合污水处理效率,实现了A/BCO和CW二者间在处理氮素过程中的优势互补。

The process of biological methods combined with constructed wetland（A/BCO-CW）was applied to treating town area mixed sewage in the tropical and subtropical regions in South China.Twelve months running results showed that A/BCO-CW was effective for TN and NH4-N reduction,achieving annual average removal rates of 57.57%and 87.73%,and removal loadings of 3.85 g·m-2·d-1and 3.26 g·m-2·d-1 respectively.The A/BCO pretreatment system removed NH4-N by 57.38%under the condition of HRT 3～6 h.Full aeration at the aerobic section was conductive to nitrification,which helped address the problem of restriction on nitrifi-cation resulting from shortage of dissolved oxygen and with reduced the land occupation of follow-up constructed wetlands by 25%. The average removal loadings of TN and NH4-N reached 2.56 g·m-2·d-1and 0.90 g·m-2·d-1respectively in the combined constructed wetland system of VF-SF-HF under the hydraulic loading rates of 0.3～0.59 m·d-1 .The removal rate constants for TN and NH4-N were 39.8 m·yr-1and 41.62 m·yr-1respectively,both ranging high among the k values recorded in the literature.When the variation of NH4-N contents was within 6.27～18.8 mg·L-1,the effluents could stably meet the typeⅣstandard,namely 1.5 mg·L-1,as specified in the Environmental Quality Standards for Surface Water（GB 3838-2002）.Through the combination of A/BCO and CW for treatment of mixed sewage,the advantages of both complemented each other in removing nitrogen.