Study On Hydraulic Regulation Mechanism Of Methane And Sulfide In Sewage Pipeline

The sewage flow rate in urban sewage pipelines is a crucial factor affecting the distribution and metabolism of Methanogenic Archaea（MA）and Sulfate-Reducing Bacteria（SRB）.This work systematically studied the response characteristics of flow velocity in sewage pipes on methane and sulfide generation,explored the change rule of bacterial distribution and metabolic function transformation characteristics of MA and SRB under different sewage flow velocities,and analyzed the metabolic correlation between MA and SRB and their hydraulic disturbance mechanism.This work provides a theoretical basis for hydraulic control of methane and sulfide in municipal sewage pipes.The metabolic correlation between MA and SRB in sewage pipes was investigated by microbial sequencing and bin analysis methods.The results showed several critical genes in methane metabolism and sulfide metabolism in some of the bins.These bins had the potential function of synchronously producing methane and sulfide.However,other compartments contain only a critical gene for methane or sulfide metabolism.Such compartments require collaborative metabolism to complete the formation process of methane and sulfide,thus constituting two metabolic associations between MA and SRB.By exploring the distribution of MA and SRB bacteria at different flow rates,it was found that Methanothrix and Methanobacterium dominated the methane release in the pipeline.Desulfomonile,Desulfobulbus,Desulfovibrio are the dominant sulfide-releasing bacteria.The relative abundance of MA bacteria is going up,and the relative abundance of SRB bacteria is going down with the increase in flow rate,indicating that the flow rate is changing the distribution of MA and SRB bacteria,thereby affecting their metabolic correlation.The sequencing results were compared with the KEGG database.The functional gene annotation results of MA and SRB metabolic levels showed that the relative abundance of functional genes of carbon metabolism,nitrogen metabolism,and energy metabolism increased by 0.12%,0.08%,and 0.13%,respectively,when the flow velocity increased from 0.1 m·s^-1 to 0.7 m·s^-1.Its corresponding function will be gradually enhanced In the energy metabolism group,the relative abundance of methane metabolism functional genes increased by 0.21%,while the relative abundance of sulfide metabolism functional genes decreased by 0.12%.It can be seen that the increase in sewage flow rate will weaken the sulfide metabolism capacity of SRB,thus affecting the symbiotic association between MA and SRB and inhibiting the production of pollutants to some extent.The hydraulic regulation mechanism of MA and SRB in sewage pipes was studied by detecting and analyzing the relative abundance changes of critical enzymes and genes in methane metabolism and sulfide metabolism pathway and the process of regulating bacterial metabolism and gas production under the control of flow velocity.The results showed that when the flow velocity increased from 0.1 m·s^-1 to 0.7 m·s^-1,the relative abundance of key enzymes and genes in the methane metabolic pathway increased.As a result,the methane concentration in the sewage pipe will increase about once,while the relative abundance of key enzymes and genes in the sulfide metabolic pathway will decrease.The sulfide concentration will also decrease rapidly to 72%.Therefore,the process of methane metabolism and sulfide metabolism is affected by controlling the flow velocity to reduce the material exchange between methane metabolism and sulfide metabolism,weaken the metabolic correlation between the two,and achieve the purpose of regulating the release of methane and sulfide in the pipeline.