运行参数对径流人工湿地有机物去除的影响

Effect of Running Parameters on Organic Pollutants Removal in Constructed Wetland Treating Stormwater Runoff

摘要:

通过正交试验考察了表观水力停留时间（hydraulic retention time,HRT）、水深和运行前间隔天数对模拟径流处理人工湿地内有机物去除的影响，结果表明3个运行控制参数对径流处理人工湿地有机物去除效果影响程度大小依次为HRT、水深、运行前间隔天数,其中HRT为关键影响因素，对有机物去除效果的影响程度远大于其他2个参数；有机物去除效果随HRT的增加而增加，但当HRT大于36 h，HRT对CODCr去除效果的影响降低；HRT越短，运行前间隔天数对CODCr去除效率的影响越大；0.2 m和0.4 m水深的CODCr去除率差异并不明显，但0.6 m水深时CODCr去除率显著降低，水深增加导致氧传质能力的减弱和水力效率的下降是有机物去除效率降低的主要原因.停止进水期间，人工湿地水相CODCr平均质量浓度随停进水天数的增加而持续下降，但UV254与CODCr质量浓度的比值上升趋势明显，表明系统内根系分泌、微生物代谢产生的内源有机物占水相有机物组分增加.

Abstract:

The effect of nominal hydraulic retention time, water depth and antecedent resting period on organic matter removal performance of constructed wetland treating runoff under stochastic intermittent constant inflow was investigated through orthogonal experiments. Results indicate that effect rank of the 3 running parameters on CODCr removal rate is: hydraulic retention time (HRT)＞water depth＞antecedent resting days, and HRT has more significant effect on CODCr removal than the other two parameters. CODCr removal rate increases with the increasing of HRT, however, the effect of HRT on CODCr removal rate becomes unobvious when HRT is longer than 36h. The shorter the HRT is, the greater the effect of antecedent resting period on CODCr removal rate is. The difference in CODCr removal rate is not obvious for constructed wetland with water depth of 0.2 m and 0.4 m, however CODCr removal rate decreases significantly when water depth rises to 0.6m which might result from the decreasing ability of oxygen transfer and hydraulic efficiency in wetland bed. Average concentration of CODCr of water column in weland bed decreases with the increasing of antecedent resting days, but UV254/CODCr increases significantly, which indicates that inner system organic production increases from macrophyte roots exudation and metabolic activity of microorganism.