水力负荷对潜流湿地净化效果和氧环境的影响

INFLUENCE OF HYDRAULIC LOADING RATE ON THE PURIFYING EFFICIENCY AND OXYGEN CONDITION OF HORIZONTAL SUBSURFACE FLOW CONSTRUCTED WETLAND

以芦苇水平潜流人工湿地系统作为研究对象,研究水力负荷(HLR)的变化对湿地净化效果和氧分布的影响。结果表明,随着HLR由454下降至91mm.d-1,湿地对NH4+-N、NO3--N、TN、TP、COD的净化能力分别提高了约约35、8、20、25和20个百分点。运行期间,湿地水体溶解氧(DO)在水平方向上从前至后呈下降趋势,在垂直方向上,水体DO上层要高于下层。随着HLR的降低,湿地水体DO水平方向和垂直方向上的差异有缩小之势。同时湿地床层的DO含量随着HLR的下降呈现出升高态势,且湿地床上层的DO波动变化较明显。研究发现,湿地床的耗氧过程和复氧过程能同步协调进行,当污染物降解的耗氧速率大于湿地系统的复氧速率时,会出现湿地水体DO不升而降的现象。

A horizontal subsurface flow constructed wetland planted with Phrogmites communis was developed for experiments. The effect of hydraulics on the removal efficiency and dissolved oxygen （DO） distribution of the CW was investigated. The results showed, as hydraulic loading rate （HLR） decreased from 454 to 91 mm·d^-1, the removal efficiency for NH4^＋-N, NO3^--N, TN, TP, CODhad raised approximately 35, 8, 20, 25, 20 percentage points, respectively. Under these experimental conditions, DO of wetland water decreased horizontally with the water flow, and it also changed with depth, DO of the upper layer higher than the bottom. As HLR decreased, the variation of DO changed with length and depth tended to reduce. Meanwhile, DO of the wetland increased as HLR decreased, and DO of the upper layer showed fluctuation. The oxygen consumption and aeration of the wetland were synchronous, while the rate of oxygen consumption exceeded the rate of aeration, it would be found out DO of the wetland water will reduce.