Experimental Study On Treatment Of Domestic Sewage By Self Made Ceramsite-based Vertical Flow Constructed Wetland

Straight discharge of domestic sewage in rural areas occurs from time to time,and nitrogen and phosphorus pollution can easily cause eutrophication of water bodies.However,existing fillers(soil)with low porosity in constructed wetlands largely limit the effect of water purification.Therefore,actively develop new water-treated ceramsite rich in pores,apply to constructed wetlands,and develop constructed wetlands as main organisms.The research of treatment facilities to purify domestic sewage is of great significance for the selection and application of wetland fillers.In this paper,from the perspective of the optimization of the properties of the filler itself,the ceramsite was prepared with the feed water sludge as the main raw material.The change of ceramsite properties under different working conditions was studied,and the best technological conditions were obtained.The obtained ceramsite was used in the constructed wetland.The self-made ceramsite-soil(A system)and the simple soil substrate(B system)were separately constructed to carry out experimental research on the purification of domestic sewage by constructed wetland;the high-throughput sequencing of 16S rDNA gene in the two reactor matrix microorganisms was carried out,and different wetlands were obtained.Microbial species and structure relationships,richness and diversity within the system.The main research conclusions are:(1)The ceramsite was prepared by using feed water sludge as the main raw material.The optimum process conditions were determined by experiments:60%of water supply sludge,16%of fly ash,16%of clay,8%of glass powder,and preheating temperature of 500?.The time is 20 min,the sintering temperature is 1170?,the sintering time is 20 min,and the heating rate is 10 ?/min.Under the optimum conditions,the apparent density of the ceramsite sample is 1.388 g·cm-3,and the bulk density is 0.7636 g·cm-3.The water absorption rate is 23.65%,the void ratio is 44.99%,the specific surface area is 5.24×104 cm2·g-1,the heavy metal leaching rate is qualified,and the pores are uniformly connected in three dimensions,which is suitable as the artificial wetland filler.(2)When HRT was lowered,the removal rates of TN,NH4'-N and TP decreased in both systems.The average removal rates of A system for TN and ammonia nitrogen at 6.4d,3.5d,and 1.5d for HRT were 85%,70%,and 50%,and 90%,90%,and 70%.The HRT of B system was 6.4d,3.5.The average removal rates at and 1.5d were 80%,60%,and 37%,and 90%,60%,and 35%.The removal capacity of TP in system A is almost unaffected by HRT(when HRT is 6.4d,3.5d,1.5d,the removal rates of A and B systems are 91.15%,89.79%and 88.08%,and 79.53%,76.52%and 66.57,respectively.%).The TN and TP removal effects are less affected by HRT than NH4+-N.,and the A system is more resistant to hydraulic shock loads.(3)The two systems are similar to the variation of NH4+-N and TN.Compared with other layers,the first layer has the highest removal rate of NH4+-N and TN,and the back removal effect is relatively small.The addition of homemade ceramsite can increase the adsorption capacity,and the rich pore structure is beneficial to the growth and reproduction of microorganisms,and promotes the removal of organic matter and nitrogen.The first matrix layer contributes the most to the removal of TP,and the TP removal is mainly the adsorption of deposition and matrix.(4)The types of microorganisms at different levels of stromal gates,classes and orders in different depth layers of different wetland system installations were obtained.At the genus level,the genus of nitrifying bacteria includes:Stenotrophomonas,Nitrospira,Nitrosomonas,Sphingomonas,and bacteria with simultaneous nitrification and denitrification include:sphingosine Cytobacteria,these two functional bacteria account for a large proportion in the lower layer of the A system;the genus of the methanogenic function includes:desulfurization of bulbous bacteria,which is relatively large in the lower layer of the B system.The Observed species index and the Rank-Abundance curve indicate that the species richness of the A system is higher;the Shannon index indicates that the microbial diversity of the A system is higher;the PCoA map indicates that the species structure difference between the two systems is larger.