Study On The Efficiency Of Rural Domestic Sewage By Electrolysis Intensified Constructed Wetland

Based on the pollution status of rural domestic sewage,the Study on the efficiency of rural domestic sewage by electrolysis intensified constructed wetland was carried out in this paper,a hybrid horizontal subsurface flow constructed wetland system and two electrolysis-subsurface flow constructed wetland devices with different filler and a electrolysis-hybrid horizontal subsurface flow constructed wetland system were constructed.The removal efficiency of different systems on the main pollutants in rural domestic sewage,the total phosphorus content of the matrix and the form of phosphorus,the microbial community structure and diversity in all levels of wetlands in the composite system were explored.The main results were summarized as below:The hybrid horizontal subsurface flow constructed wetland system had a good removal effect on nitrogen and COD in rural domestic sewage,but the treatment effect of phosphorus was not good.Among them,the removal of COD and nitrogen mainly occurred at the front end of the wetland,while the removal of phosphorus mainly occurred at the rear end.In the composite system,a total of 7 dominant phylum,5dominant class and 17 dominant genera were found.Among them,the dominant phyla were Proteobacteria,Cyanobacteria,Bacteroidetes,Firmicutes,Chloroflexi,Acidobacteria,and Actinobacteria.The dominant class were Cyanobacteria,Alphaproteobacteria,Bacilli,Gammaproteobacteria,and Betaproteobacteria.Proteobacteria were the most abundant in the dominant phylum of wetlands,and there was not much difference in the wetlands,which played an important role in the removal of major pollutants in the system.Cyanobacteria was abundant in H₂and had a nitrogen-fixing effect,but would affect the removal of organic matter.Bacillus in the Firmicutes phylum,was widely distributed in H₃,has a good purification effect on nitrogen and organic matter.In the start-up phase of the two electrolysis-subsurface constructed wetlands,the zeolite-based electrolysis system A had a better removal efficiency of NH₄⁺-N,but the ability of PO₄^3--P removal was weaker,while the brick-based electrolysis device had a better efficiency to removes PO₄^3--P,but the ability to remove NH₄⁺-N was weaker.However,compared with the respective blank experimental groups a and b,the combination of the electrolytic system and the constructed wetland significantly improved the ability of A to remove nitrogen and phosphorus,and improved the efficiency of B to remove phosphorus.In the stable operation stage,the results of two electrolysis-subsurface flow constructed wetlands with different substrate ran under different current intensity showed that the phosphorus removal efficiency of the them would continue to increase with the increase of the current intensity,when the current intensity was 100 m A,The rate removal of phosphorus had reached the maximum.When A had a current intensity of 30 m A,the nitrogen purification effect was the best,while B had a current intensity of 50 m A,the nitrogen removal rate was the highest,and after the two electrolysis devices reached the optimal current intensity,as the current intensity increased the nitrogen removal capacity of both devices would decrease.Therefore,considered the purification capacity of nitrogen and phosphorus pollutants and the production of by-products during the operation of the two systems,the optimal operating current intensity of A was 30 m A,and the optimal operating condition of B was 50 m A.The electrolysis-composite subsurface flow constructed wetlands had strengthened the ability of system to remove nitrogen and phosphorus pollutants for rural domestic sewage,and reduced the by-products generated during the operation of the electrolysis system.Phosphorus removal mainly depended on the adsorption and precipitation of the filler,and Al-P and Fe-P were the main ways for them to precipitate phosphorus.Nitrogen removal mainly depended on the action of microorganism.The matrix microbial community structure in all levels of wetlands was different.Ten common dominant phyla were found,Proteobacteria,Bacteroidetes,Patescibacteria,Chloroflexi,Firmicutes,Acidobacteria,Actinobacteria,Spirochaetae,Caldiserica,Nitrospirae.Among them,Proteobacteria and Bacteroidetes had the higher sum of relative abundance in wetlands at three levels,which played a major role in the removal of nitrogen and phosphorus pollutants.