The Research Of Production And Emission Coefficients Of CH₄in Sewer In The City Of Kunming

With the development of economy, the urbanization process becomes faster than several years ago, and the scale of the urban sewage drainage system expands increasingly. Since there are rediduals existing in sewer line for a long time, the pipeline is easy to form an anaerobic environment. Thus, gases will be produced in sewer, such as methane, hydrogen sulfide, ammonia and so on. The methane is flammable and explosive, and it will bring security problems if the methane concentration outweigh its’limiting value. As can be seen, the sewage is closely related to our life, therefore, it is important to prevent and control the methane production and emission.The methane production and emission coefficients are a method of calculating the gas production and output. So calculating methane production and emission coefficients is the key to measure the gas production and output in sewage. To research the regulation of methane production in sewage and the coefficients of methane production and emission are benefit to establish the list of greenhouse gas emission in Kunming. This research uses field measurement and laboratory simulation to calculat the methane production and emission coefficients. There are six conclusions.(1) The water qualities, temperature. pH, flow velocity and hydraulic retention time influence the methane production and emission. Different functional areas have different methane production and emission. The methane concentration of residential area is higher than other areas, while the methane concentration of institutes and college district is lower than other districts.(2) The methane production coefficients are0.2544gCH4/gCOD in residential area,0.0147gCH4/gCOD in dining area,0.0078gCH4/gCOD in institutes and college district,0.0114gCH4/gCOD in mixed use district.(3) It was hardly to monitor the methane in manhole, but it can be monitored in septic-tank. The methane concentration depends on water yield.(4) The methane emission coefficients are0.0091gCH4/gCOD in residential area,0.0028gCH4/gCOD in dining area,0.0017gCH4/gCOD in institutes and college district,0.0010gCH4/gCOD in mixed use district.(5) The methane production and emission coefficients are0.0531gCH4/gCOD and0.0029gCH4/gCOD. The methane production coefficient which provided by Intergovernmental Panel on Climate Change is5times moer than our conclusion. The methane emission coefficient which provided by Intergovernmental Panel on Climate Change is43times more than our conclusion.(6) The theoretical value of methane production was1000.10t in Kunming in2012. The measured value of methane emission was54.62t in Kunming in2012, which accounted for0.0036%in1994. It showed that the influence in local will be greater than in region.