The Research Of Generation And Emission Of H₂S In Sewage Drainage System In The City Of Kunming

As the acceleration and improvement of urbanization, drainage system’s scale was getting huger and huger, city drainage pipe network longer and longer, and the hydraulic retention time (HRT) of sewage in the drainage pipeline was becoming longer. In the long process of transportation of sewage in the drainage pipeline, the dissolved oxygen and nitrate were in anaerobic condition after being completely consumed. Sewage biofilms and sediments microorganism (mainly SRB) in anaerobic environment can produce HoS gas. As city’s primary treatment facilities of sewage such as septic tanks, grease traps were dotted in the in city drainage system. The volume of H2S gas generated by such a large city drainage system counld be quite striking, the effects of which on the pollution of the atmospheric environment and human health counld not be ignored. Therefore, this research carried out static and dynamic simulation experiment and field measure on city sewage drainage system to systematically examines the law of H2S production in city sewage drainage system in a line of city sewage drainage system and influence air.The results of this study indicated that:H2S gas generation and emission in city sewage drainage system were affected by temperature, pH, COD, sulfate, sulfide and turbulence of sewage. The quantity of H2S gas generated by different city sewage was different, but all were well fit for the Boltzmann gas dynamics equations. Sulfur in city sewage under the action of microorganisms forms a complete cycle, there were7significant paths to affect the production of H2S, including nitrateâ†'sulfideâ†'H2S, sulfideâ†'ulfateâ†'H2S, CODâ†'sulfideâ†'2S, sulfideâ†'H2S, pHâ†'2S, timeâ†'2S, O2â†'H2S, among which kraft and COD counld indirectly affect the production of H2S gas through influencing the generation of sulphide.H2S overflow concentration in different position of city life sewage pipes (from bottom to top1/5,1/2,4/5) counld be well fitted Boltzmann gas dynamics equations, and similar to normal distribution, H2S concentration changes with time,which was consistent with the binomial regression time series curve. Sewage drainage pipes’ flow velocity and H2S overflow concentration were positively related. When flow velocity gets larger, the concentration of H2S gets bigger. In the same area H2S gas overflow concentrations in sewage drainage system were different in different seasons. There was a trend:summer> spring> autumn> winter, and H2S gas production in the city sewage drainage system were great different before and after rain.About80.08%H2S produced by city sewage drainage system were released through holes, downstreams of the sewage drainage outlet or other voids overflow and into the atmosphere, causing the pollution of the atmospheric environment. In the simulation, H2S was up to126.562mg/m3and up to62.796mg/m3in field measurement, which was great above the" emission standard for odor pollutants", which is specified in the GB14554-93of fugitive emission source of odor pollutants——H2S in a maximum of0.03mg/m3. Thus the pollution to the environment was self-evident.