浸润线高度对垂直潜流湿地处理效果的影响研究

针对污染物浓度较高的猪场沼液,开展了不同浸润线高度下垂直潜流湿地处理效果的对比研究。试验结果表明:湿地浸润线可改变湿地填料层中的溶解氧分布和水力流态,从而造成了3种类型湿地系统对猪场沼液处理效果的差异;在不同水力负荷下,中浸润线垂直潜流湿地(VSSF-M)对猪场沼液中各项污染物的去除效果均好于低浸润线垂直潜流湿地(VSSF-L)和高浸润线垂直潜流湿地(VSSF-H);中浸润线垂直潜流湿地利用溶解氧梯度在填料层内实现了好氧区、缺氧区和厌氧区的共存,从而使硝化作用与反硝化作用在同一系统内完成,提高了系统的脱氮能力;中浸润线垂直潜流湿地系统还可适当增大系统的水力停留时间(HRT),并可优化水力流态,从而进一步改善湿地系统的净化效果。因此,结合处理效果和出水水质的稳定性,中浸润线垂直潜流湿地对浓度较高的猪场沼液具有较高的去除效率。

Influence of Water Level on Treatment Performance of Vertical Subsurface Flow Constructed Wetlands

Comparison study of three vertical subsurface flow constructed wetlands with different water level to treat digested swine wastewa- ter was carried out under different hydraulic loading rate(HLR). The results showed that, vertical subsurface flow constructed wetland with high water leve(lVSSF-H), vertical subsurface flow constructed wetland with middle water leve(lVSSF-M)and vertical subsurface flow constructed wetland with low water leve(lVSSF-L)were highly effective in removing SS under three different HLR, whereas their removal rates of COD, NH 4+ -N, TN and TP decreased with increasing HLR, respectively; VSSF -M had the best effect on treating digested swine wastewater under three different HLR, especially NH4+ -H and TN, as HLR was 0.02 m·3m-·2d-1, average removal efficiencies of VSSF-M were as follows:83.59% for SS, 90.94% for COD, 87.39% for NH4+ -N, 82.68% for TN, 95.42% for TP, respectively. It was indicated that there was significant differences among VSSF-H, VSSF-M and VSSF-L due to their different distribution of dissolved oxygen and hydraulic flow state caused by water level; VSSF-M could make aerobic zone, anoxic zone and anaerobic zone coexist in the system in order to improve nitrogen removal rate by nitrification and denitrification; in addition, wastewater treatment effect of VSSF-M could be strengthened because VSSF-M could prolong the hydraulic retention time and optimize hydraulic flow state. Accordingly, VSSF-M was more effective in treating livestock wastewater with high concentration of pollutant due to its high efficiency and stability.