Research On The Domestic Wastewater Treatment And Reuse System Based On Solid Wastes

With the pace of economic development and the high population growth rate,more sewage and solid wastes are discharged into the environment,which have a negative impact on the ecological environment.The comprehensive utilization of sewage and solid wastes do not only avoid material waste,but also protect the ecological environment,which are of great significance.In this study,a domestic wastewater treatment and reuse system based on solid waste(SWDWTRS)was set up with fixed bed biofilm reactor unit(FBBR-U),adsorption solution unit(AFU),disinfection unit(D-U)and solar powered unit(SP-U).Preliminary studies was later conducted with the system and its units.The FBBR-U was used to treat simulated municipal sewage.The removal efficiency of pollutants in MP-FBBR(FBBR-U with modified plastic waste as filler)and that of P-FBBR(FBBR-U with unmodified plastic waste as filler)were assessed,whiles the growth condition of biofilm in MP-FBBR and P-FBBR were also analyzed.The optimum process parameters of the wastewater treatment were explored by single factor and orthogonal test.The feasibility of the practical application of the system was analyzed by using SW-DWTRS to process the simulated and actual domestic sewage.Finally,the mechanism analysis was carried out.The main conclusions were as follows:(1)Modified plastic waste filler had a better effect on biofilm than unmodified plastic waste;When the membrane matured in the fixed bed biofilm reactor and the effluent run stable,the removal rate of COD,ammonia-nitrogen and total phosphorus in MP-FBBR were steady at 93.25%,87.83% and 69.32% respectively,which were better than that of P-FBBR.(2)The results of single factor and orthogonal tests showed that the FBBR-U had the best effect of sewage treatment when HRT was 8h,DO was 3.0mg/L,COD was 400mg/L and filling rate was 5.0g/L.(3)The results of SW-DWTRS on treating simulated and actual domestic sewage showed that the system was efficient and had good effect on the treatment of pollutants in domestic sewage.The average removal rate of COD,ammonia-nitrogen,total phosphorus,SS and the purification rate of turbidity were 94.50%,83.87%,53.83%,82.26% and 61.63% respectively.(4)Mechanism analysis results showed that the surface roughness and specific surface area of modified plastic waste filler were obviously larger than that of the unmodified plastic waste filler.Low temperature plasma modification made the plastic waste filler surface had more carbonyl,hydroxyl and other chemical functional groups,which were more conducive to the biofilm;The growth cycle and hanging period of biofilm on modified plastic waste filler were lower than that of the unmodified;The average biofilm mass per grams of filler on modified plastic waste filler was higher than that of the unmodified.The dehydrogenase activity of the biofilm on the surface of the modified plastic waste filler was significantly higher than that of the unmodified.In the SW-DWTRS,the biofilm reactor and the adsorption filtration units mostly use the solid waste as raw materials.Besides the low cost of materials,the application of waste materials in the system can also realize the comprehensive utilization of solid waste,and minimize environmental pollution.The solar powered unit provided power for the water pump,ultraviolet lamp equipment and air pump in SW-DWTRS,leading to low operation costs;Therefore,the system has a greater potential to promote wider application.