Study On The Efficiency Of Advanced Treatment Of Domestic Wastewater By Sulphur Autotrophic Coupled Iron-Carbon Micro-electrolysis Constructed Wetland

Rural domestic sewage contains high concentration of organic matter,nitrogen,phosphorus,pathogens and other pollutants,and the water quality and quantity fluctuate greatly.In recent years,constructed wetlands have been widely studied in wastewater treatment in rural areas.However,the problems such as low wastewater treatment capacity,low efficiency of nitrogen and phosphorus removal,lack of available carbon sources,unsatisfactory removal effect of indicative microorganisms,and large area of constructed wetlands restrict the popularization and use of constructed wetlands.Sulfur autotrophic denitrification has attracted much attention for its advantages of no need to add external carbon source,low sludge yield and good denitrification effect.Iron-carbon micro-electrolysis technology can not only achieve good degradation of organic matter and nitrogen and phosphorus removal effect,but also reduce the harm of sulfur autotrophic denitrification to acid production.If iron-carbon micro-electrolysis coupled with sulfur autotrophy can be applied to constructed wetlands,and tail water disinfection process can be added,it will be conducive to the promotion of constructed wetlands.In this study,sulfur,sponge iron and activated carbon were mixed at a mass ratio of3:3:1 and filled at 20 cm from the outlet of the waveform subsurface flow wetland,with a thickness of 10 cm.With aeration at both ends,the start-up process and treatment efficiency of the coupled wetland were studied,and the effect of plants on the treatment efficiency was studied.The photocatalytic disinfection of wetland tail water by UV-TiO₂was studied using the self-doped TiO₂-NTs as photocatalyst.The sterilization effect and photoreactivation effect of the process under different parameters were analyzed,and the degree of sterilization under different disinfection methods was further analyzed.The results showed that:?1?The membrane was successfully formed on the 38th day after the start-up of the coupled constructed wetland.The effluent pollutant concentration reached the first A effluent standard.The removal rates of COD,TN,NH₄⁺-N and TP increased by 50%,52%,88%and 60%respectively compared with the traditional aerated constructed wetland.?2?Planting plants can enhance the removal efficiency of pollutants in wetlands,and increase the removal rates of COD,TN,NH₄⁺-N and TP by 11.28%,12.00%,2.02%and 4.85%respectively.?3?UV-TiO₂ can destroy the selective permeability of cells and rupture the cell membrane.Its disinfection effect is better than that of UV,and photoreactivation is inhibited.?4?Reaction time,ultraviolet light intensity,distance between ultraviolet lamp and titanium dioxide catalytic plate,water quality and other factors will affect the disinfection effect of ultraviolet-titanium dioxide.?5?The occurrence of photoreactivation can be inhibited by avoiding light emission,increasing disinfection time or ultraviolet radiation dose,cryopreservation and improving disinfection process.The results of this study can provide technical support for wastewater treatment in remote rural areas,and have important significance for the improvement of water ecological environment.