不同构型湿地氧分布及脱氮效果对比

通过2组对比试验(垂直流与水平流湿地、单段式与三段式水平流湿地),考察了不同构型湿地中溶解氧的分布情况及脱氮效果.结果表明:不同构型人工湿地水力流态的区别,导致了床体溶解氧分布和脱氮效果的差异.垂直流人工湿地独特的结构设计和水力流态更有利于湿地内部的供氧,局部氧浓度可比水平流湿地高0.17 mg/L;脱氮效果优于相同运行条件下的水平流湿地,NH_4~+-N、TN去除率分别可提高约9%、5%.三段式水平流湿地通过接触槽内复氧,有效改善了溶解氧分布,利于硝化反应进行,NH_4~+-N去除率最高达66%,TN去除率最高达71%,分别比单段式湿地提高约8%和5%.此外,三段式湿地在较低水位下运行仍能取得较好的脱氮效果,其最佳停留时间的范围也得以延展.

Comparison of Dissolved Oxygen Distribution and Nitrogen Removal Effect in Wetlands with Different Structures

The dissolved oxygen distribution and nitrogen removal effect in different structures of wetlands were investigated by two groups of comparison experiments (vertical flow with horizontal flow; single-stage with three-stage horizontal flow). It was found that the different hydraulic flow patterns in different structures of wetlands would result in different oxygen distribution and nitrogen removal effect. The special structure design and hydraulic flow pattern of vertical flow wetland were favorable to its dissolved oxygen distribution, which could increase 0.17 mg/L in local area than that in horizontal flow wetland. The nitrogen removal effect of vertical flow wetland was better than that of horizontal flow wetland in the same operation conditions. The removal efficiency of NH_4~+-N and TN could increase 9% and 5% respectively in vertical flow wetland than that in horizontal flow wetland. Because of reaeration in contacting channels of three-stage wetland, the removal efficiency of NH_4~+-N and TN reached 66% and 71% respectively, which improved 8% and 5% respectively than that of single-stage wetland. In addition, three-stage wetland could keep higher nitrogen removal effect even in low operation water level, and the range of its best hydraulic retention time(HRT) was extended.