Study On The Distribution Law Of Toxic Gas In Sewerage In Different Areas Of Cities

With the accelerating pace of urban construction in our country,the scale of the urban drainage pipe network system is bigger and bigger.The urban drainage pipe network system,as the city’s infrastructure,undertakes the major task of wastewater’s collection and transmission,like domestic sewage and industrial wastewater,which plays an irreplaceable role in the process of circulation of urban water environment.The growing sewer system creates a more ideal biochemical reaction environment for microbes,resulting in the generation of methane,hydrogen sulfide and other toxic gases in the bottom sediment and sewage,causing pollution to the atmosphere and causing a problem to people’s health.In order to control the hazards of methane gas and hydrogen sulfide gas generated by urban sewer system to the atmosphere and people,we should first monitor the basic fugitive situation and recognize the law of poisoning gas in urban sewer system.This study is carried out in a city in the south to monitor the production of methane and hydrogen sulfide in specific monitoring places of the city’s drainage system,such as vegetable market,sewage branch,residential area,sewage main pipe,lifting pump station and sewage plant.The residential area of the system is monitored to explore the law of hydrogen sulfide gas fugitive.And the method are given to control the toxic gas.The main conclusions of the paper are as follows:(1)The monitoring results of different feature sources show that the concentrations of hydrogen sulfide and methane in the wells / tanks are different at different source sites.The hydrogen sulfide gas fugitive concentration follows: sewage pipe> residential area> vegetable market> pump station> sewage pipe> sewage plant;methane gas fugitive concentration follows: pumping station> sewage plant> residential area> sewage pipe> vegetable market,sewage trunk.(2)The concentration of hydrogen sulfide gas fugitive in the residential area in summer was significantly higher than that in winter.During the summer,the temperature in the well was gradually decreased from shallow to deep,and the concentration of hydrogen sulfide gas gradually increased.In the winter,the temperature in the well was gradually increased from shallow to deep,and the concentration of hydrogen sulfide gas gradually decreased.(3)In the drainage area where the rainwater pipes and the sewage pipes are mistaken,the rainfall has a significant effect on the fugitive of hydrogen sulfide gas in the sewage inspection well.The initial rainwater mixing causes a large amount of hydrogen sulfide gas spill,but the rainfall process can effectively reduce the amount of hydrogen sulfide gas fugitive.(4)In the residential drainage network,the concentration of hydrogen sulfide in the branch pipe well was significantly lower than that in the main pipe well,and the concentration of hydrogen sulfide gas increased from the branch well to the main well.The content of sulfate and COD in the branch pipe well is higher than that in the main pipe well,and the concentration of ammonia nitrogen,phosphate and sulfide gradually increases with the residence time of the sewage in the pipe network.