The Pilot Experiment Of Municipal Sewage In Yinchuan Through The Wetland System

Over the past decade, the use of artificial wetlands treatment of municipal sewagehas risen as an ecological wastewater treatment technology. Artificial wetland systemsare obviously affected by climate; however, the structure forms, packing types andproportions, plant types and quantities of the designed parameters of wetland systems’are short of versatility.In this study, farmland subsiding water and the withdrawal water of the thirdsecondary sewage treatment plant in Yinchuan were regarded as the based water.Through the pilot experiments, we made the study about the removal effect of the mainpollutants in three different flow patterns of wetland system. We obtained the designparameters of Yinchuan wastewater treatment wetland system including structureforms, packing types and proportions, plant types and quantities. The mainlyconclusions are as following:(1) The surface flow, horizontal subsurface flow and complex subsurface flow caneffectively improve the contaminated water and are suitable for application forcontaminated lake wetland and city landscape water in Yinchuan.(2) Matrix fillers in the artificial wetland system with three different flow areround gravels, of which ranges are0～50mm. The compound flow top fillers are0~10mm fine gravels. Additionally, it has a gradual transition from10~30mm gravelsthe bottom the lower layers to30～50mm gravels of bottom layers; horizontal flow topfillers are0~5mm fine gravels, the first class of the lower fillers are30~50mm gravels, second grade are10~30mm gravels, third grade are5~10mm gravels.(3) The surface flow, horizontal subsurface flow and complex subsurface flowconstructed wetland on COD, TP, TN have better treatment effect. The removal effectof COD complex subsurface flow constructed wetland is best, and the removal rates ofCOD for three different regimes are43%,55.6%,60.8%respectively; the surfaceflow on the TP removal effect is the best, removal rates of three artificial wetland onthe TP are85.6%,81.4%and78.6%; the best removal effect on TN is complexsubsurface flow constructed wetland, three kinds of different regimes on the TNremoval reach62.6%,68.6%, and78.4%respectively.(4) Under the environment of horizontal subsurface flow constructed wetland,reeds and cattails on COD, TP, and TN have the better removal effects, of which thebest is cattails that can reach57%; the best removal efficiency of TN can reach66.4%;removal effects of reeds and cattails on the TP have no obvious difference,70.8%and70.6%respectively.(5) The main aquatic plants in the three constructed wetland system are reeds andcattails, of which planting spacing is1.2-0.5strains of/m2. In the ten kinds of aquaticplants of the wetland in Yinchuan, reeds, cattails, aquatic canna, water and water sedgerallies are the better, and have the high ornamental and economic values.