Time-varying characteristics of influent and effluent quality and purification performance of Zizania latifolia(Zl)subsurface flow wetland(SFW)in the water network area of central China
The inflow time varying characteristics of nitrogen,phosphorus and CODCr pollution and the purification performance of Zl-SFW were studied from the angle of small catchment area in this study.The results showed that the inflow nitrogen,phosphorus and CODCr of Zl-SFW fluctuated greatly with season,in which TN and TP of the wetland inflow were the highest during the Spring Festival,followed by the first month of surface runoff generated after the application of fertilizer in the farmland,CODCr concentration in the wetland inflow under moderate rainfall was higher than that under heavy rainfall.Affected by the regulation and buffer of the sedimentation tank,NH3-N and NO-x-N in the wetland inflow were the highest in autumn,followed by the date after the Spring Festival.Buffering capacity and purification performance of SFW were good for the shock loading of nitrogen,phosphorus and CODCr in the small basin,with(82.1±10.5)%、(72.9±8.1)%and(65.6±6.2)%of average removal efficiencies of TP,TN and CODCr,respectively.During the transition period from autumn to winter,the seasonal inflection point of nitrogen and phosphorus uptaked by plants was not obvious due to the combined actions of microbial degradation and substrate adsorption.In winter,the wetland was of the ability to withstand low temperature in the water network area of central China.However,low temperature in winter was easy to cause the accumulation of NH3-N from decomposed organic nitrogen as the result of adsorption by zeolite and other substrates in SFW,and at the same time,the oxygen consumption caused by degradation of organic matter could lead to aggravation of anaerobic environment under long hydraulic retention time(HRT).In addition,proportion of dissolved organic phosphorus(DOP)in effluent would increase in winter.In summary,this subsurface wetland can effectively improve the drainage quality polluted by non-point source in villages and towns,improve the rural water environment,but the management for the above time-varying factors greatly affected by seasons should be strengthened.
SFWZizania latifolianitrogen and phosphorusCODCrrainfall and runoffseasonal variation
NETL
NSTL
万方数据
