Domestic Drainage System Of Lanzhou City Producing Exhaust Emission Estimates And Control Countermeasures

With its fast economic and social development and the rising levels of urbanization,urban air pollution from coal-burning pollution into a compound pollution, composition andsources of air pollution has become increasingly sophisticated. In densely populated cities,household garbage, sewer, interior decoration, restaurant, toilets and sewage treatment plantsand other facilities are releasing large quantities of harmful gases into the atmosphere,endangers the health of the residents. About interior decorating and cooking oil fume exhausthave more research based, the State has introduced a series of norms and standards to controlsuch pollution. Unfortunately,Exhaust and emissions generated by urban drainage system didnot attract enough attention, is still research gaps in China.Urban drainage systems as one of the city’s most important infrastructure spread all overthe city, this system extremely easy to produce large amounts of toxic gas in sewagecollection and conveyance, such as H₂S, CH₄, NH₃, volatile organic compounds （VOCs）,causes the sewer manhole explosions have happen occasionally. Therefore, study on theemission regularities of the formation and release of the urban drainage system is of importantpractical significance. on the one hand to prevent the occurrence of such incidents, on theother hand for the estimation of total emissions from urban drainage systems to assess itsimpact on urban atmospheric environment, effective pollution control measures.This article through a combination of laboratory experiments and the real-timemonitoring, a typical drainage system for the study of life in Lanzhou, research on domesticwaste gas discharge of drainage system in Lanzhou city, assess its influence on atmosphericenvironment of Lanzhou city, and accordingly work out some effective measures of control.Research shows that:①The COD concentration of sewage show clearly declining trendalong the flow direction in sewage and drainage pipes, the average value of coefficient ofwater quality degradation in the sewers of Lanzhou is0.038gCOD/100m.②Testing found that,because of the septic tank’s anaerobic degree higher than the inspection Chamber, we canonly monitor H₂S and CO₂gas in the well, and the H₂S, CH₄and CO₂in the septic tank, theCO₂,CH₄gas concentrations of the septic tank are also above the well.③District drainagecharacteristics of exhaust gas emission are different due to these different water quality andquantity. derived from the real-time monitoring, the COD concentration of dining wastewateris significantly higher than in the other three areas, the emission rates of H₂S and CO₂indining area are higher than residential area.④The effects temperature on exhaust emissionsin drainage system by affecting microbial activity of drainage system, the degradation oforganic matter of sewage in wastewater drainage system under different temperature are different, the exhaust discharge also varies, in a certain range, temperature increase is goodfor MB, SRB and other micro-organisms breed, promoting the degradation rate ofbiochemical reactions and overall degradation rate.⑤Exhaust emission coefficient ofLanzhou city drainage system compared with the IPCC, the maximum coefficient of CH₄to0.25gCH₄/gCOD provided by the IPCC, septic tanks CH₄emission factor of0.125gCH₄/gCOD. Pollution-producing factor provided by the IPCC is3.58times Lanzhou,the emission coefficient provided by the IPCC is10.7times the coefficient of pollution inLanzhou.⑥We use box-type models to assess the impact of sewage drainage system inLanzhou City on atmospheric environmental quality by estimate pollutant concentrations ofthe atmosphere exhaust emission characteristics in drainage system, H₂S gas has little effecton atmospheric environment, the greenhouse gases CH₄and CO₂discharged by urbandrainage systems have less impact on the area, and greater impact on local.According to some phenomena and problems found in the monitoring process, andthrough the study of exhaust gas emission regularity of urban drainage system, we putforword a number of measures and recommendations for exhaust emission control proposedof urban drainage system.