Effect of substrate structure on purification performances of horizontal subsurface flow constructed wetlands
基质结构对水平潜流人工湿地净化效果影响

In order to investigate the effect of substrate structure on the pollutant removal performance of horizontal subsurface flow constructed wetlands (HSCWs),two pilot-scale HSCWs were constructed to treat the effluents of municipal wastewater treatment plants in parallel experiments.The experimental results showed that the COD,NH4+-N and TP removal efficiencies of the HSCWs filled with well-mixed quartz sand (range 1~7 mm) were 49.5%,40.1% and 56.1%,respectively.In contrast,the HSCWs with multi-layered filling structure of quartz sand (range 1~7 mm) reached on an average 53.7%,60.4% and 68.6% for COD,NH4+-N and TP,respectively.The statistical results showed that there was significant difference on all pollutants removal between the well-mixed substrate structure and multi-layered structure (p<0.05).Furthermore,significant difference among the various HRTs was also observed (p<0.05).The removal efficiencies increased with an increase of HRTs.It seemed that the 36 h HRT was adequate for acceptable removal efficiencies.