Study On The Effect On The Wastewater Purification By Wetland Sediment Environment

At present, a large number of wastewater discharging and point source pollution, so that vast majority of rivers, lakes and other surface water bodies are in moderate or serious eutrophication and organic pollution。The traditional activated sludge process is not suitable for surface water Eutrophication control, the physical and chemical remediation technology requires high capital cost.It is not cost-effective control technology. Based on the conception of sustainable development, people began to realize the importance of ecological management. Constructed Wetland receives much concern,due to its low running costs of investment,,excellent performance and significant ecological benefit.It is importance technology of water remediation and nitrogen and phosphorus removal.In recent years, due to unreasonable operating conditions,the use of wetlands for wastewater treatment is not good treatment effect, but increasing water pollution,not reaching the effect of the effective use of wetlands.Study scientific and reasonable operating conditions and influencing factors, take advantage of natural conditions,optimize the treatment process of wetlands water and play vital ecological functions of wetlands. It has important practical significance for the protection of the aquatic environment and the sustainable use of water purification.The effect factors of purification efficiency are exogenous wastewater concentration,sediment and redox potential。Wetland sediment provides necessary habitat for plant and microorganism. The redox environment on the microbial activity,community distribution,nitrification and denitrification system has an important influence, but also determines the purification process and efficiency of the organic pollutants and nutrients. Different wetland sediments show that different purification characteristics,while exogenous wastewater quality and Eh directly affects the Zhalong wetland purification.Taking it for research background.The experiment taking Zhalong wetland sediment as medium,through the three repeated experiments,using orthogonal test,study the effects on the surface flow wetland purification efficiency of various sediments with the plant system,different influent concentrations and different oxidation reduction environments. Through the comprehensive analysis of removal rate mean, coefficient of variation and variance to study surface flow wetland purification mechanism, discuss the effects of Sediment factors(Silt Soil,Sandy loam,Clay), Eh factors (Eh =- 200mV,0mV,200mV ) and concentration factors (high,medium,low) on the surface flow wetland purification efficiency and stability,providing theoretical basis for Zhalong wetland ecological purification function and theoretical guidance to improve the wetland environment and purification efficiency. The results show that:(1)Study the effects of the reed wetland and non-plant systems on the N,P,COD removal efficiency and stability. The results showed that: Sediment factors had significant effects on N,P,COD removal.Clay on NO₃^-- N,TN,TP,P0₄^3- - P removal efficiency is the best.Clay with or without plants on NO₃^-- N, TN removal is no significant different, but for TP, P0₄^3--P removal ,Reed wetland system removal effect significantly is higher than non-plant system effect. Silt Soil on the NH4 +-N, COD removal efficiency is the best, and the impact of plants is very limited.(2) Study the effects of various sediments and environmental factors Eh on the N,P,COD removal efficiency and stability. The experiment indicates that in three Eh gradients, Eh=-200mV was beneficial to the removing of the TN,NO₃^--N ,Eh=200mV was beneficial to the removing of the NH₄⁺-N,P,and COD. The removal efficiency of Clay for TN,NO₃^--Nå’ŒP was best . The removal efficiency of the Silt Soil for NH₄⁺-N,COD was best . In addition, with Eh differents, sediment factors also change accordingly. That the change of clay removal rate along with Eh change is small, the removal effect of silty sand and sandy loam along with Eh change changes greatly.(3) Study the effects of various sediments and different influent concentrations on the N,P,COD removal efficiency and stability. The experiment indicates that in three concentration gradients, the highter the influent concentration, the better purification efficiency of the wetland sediment. The removal efficiency of Clay for TN,NO₃^--N was best . The removal efficiency of the Silt Soil for NH₄⁺-N,COD was best .Three sediments on the removal of phosphorus is not significant In addition, with the various influent concentrations, the effect of sediment factors also change accordingly. The influence for the removal rate of Clay and Silt Soil by the influent concentration is larger, Sandy loam is relatively stable.The results objectively reflect the water purification function of Zhalong wetland different sediments and the effect on the removal of pollutants of different concentrations of exogenous water and sediment redox environment.Provide the theoretical basis to optimize the surface flow wetland purifying effect and reasonable regulation of impact factors (concentration,sediment,Eh).