The Control Of Harmful Gas In Sewer Systems By Pulse Ventilation And The Law Of Biological Community Evolution

Hydrogen sulfide?H₂S?,methane?CH₄?,carbon monoxide?CO?and other gases produced in the operation of urban sewer systems and septic tank cause malodor,explosion,poisoning and environmental pollution.Discusses the building drainage riser attached directly to the sewer systems pulse ventilation system,by constructing a set of completely mixed reactor simulation actual sewer system,which was studied under different pulse ventilation effect on inhibition of harmful gases and sediment in biological community structure changes in succession.In view of the septic tank in the building community,this paper proposes to transform the internal structure of the septic tank to control the harmful gas accumulation and direct discharge.the results show that:?1?In the anaerobic environment of sewer systems,when the thickness of sediments and flow rate are constant,pulse ventilation has a great influence on the generation of harmful gases such as H₂S,CO and CH₄ in the sewer systems,among which the pulsed high ventilation?50%?is H₂S,CO and CH₄ have the best inhibitory effect,and the inhibition rates are 54.3%,60%and 30.3%,respectively.At the same time,pulse ventilation destroys the original anaerobic micro-environment of the sewer systems,promotes the diffusion of oxygen into the liquid phase,and also increases the ORP in the sewage,affecting the activity of sulfate-reducing bacteria?SRB?and methanogens?MA?.Pulsed low ventilation?25%?29.02%of sulfate reduction was inhibited,pulsed high ventilation?50%?33.6%of sulfate reduction was inhibited,and sulfide was reduced from0.753mg/L to 0.578mg/L.This inhibitory effect resulted in a negative correlation between pulsed ventilation and SCOD consumption.?2?The amount of pulse ventilation is negatively correlated with the diversity of biocoenoses.Pulsed ventilation conditions decreased the abundance of biological communities such as Anaerolineae,Clostridia,Methanomicrobia,Methanobacteria,and increased the abundance of microbial communities such as Bacteroidia,Betaproteobacteria,and Alphaproteo-bacteria.these microorganisms were closely related to the production of harmful gases?H₂S,CH₄,and CO,etc.?in the sewer system.There were differences in the abundance of biocommunities in the sediments under different pulse ventilation conditions.The pulse high ventilation reduced the abundance of the communities of Methanomicrobia,Betaproteobacteria,Alphaproteobacteria,Bacteroidia and Clostridia.The puls low ventilation decreased the abundance of biological communities such as Anaerolineae,Gammaproteobacteria and Methanobacteria.?3?Pulsed ventilation has an effect on the activity of sulfate-reducing bacteria,sulfur-oxidizing bacteria and methanogens in the sediment.Among them,pulse ventilation has a great influence on the activity of sulfate reducing bacteria and sulfur oxidizing bacteria.Pulsed ventilation inhibited the activity of biological communities such as Desulfobulbaceae,Desulfobulbus,Desulfomonile,etc.,and the number of biological communities the long-term operation of the sewer systems decreased gradually,while the number of biological communities of Desulfomicrobiaceae,Desulfobacteraceae,Desulfovibrio and other communities under pulse aeration increased gradually.However,such biological communities as Methanoregulaceae and Methanobrevibacter proliferated under pulsed ventilation,indicating that pulsed ventilation had changed the internal structure of methanogenic bacteria,but the total methanogenic bacteria population had not changed much.?4?the air introduced by the building drainage riser into the septic tank during the drainage process has no effect on the discharge of harmful gas and the anaerobic environment in the tank.By adding a guide plate to the septic tank and letting the incoming air flow up and down to promote the flow of harmful gas and improve the flow dead Angle,it can avoid the accumulation of harmful gas in the top space.At the same time,adding a harmless gas treatment device at the end of the septic tank can achieve the effect of automatic removal of harmful gas by means of the pulse airflow introduced into the septic tank through the drainage riser.