Characteristics And Simulation Of Hydrogen Sulfide Emission In A Municipal Wastewater Treatment Plant

With the municipal wastewater treatment plant （WWTPs） coming into operationcontinuously, as contributing on preventing water pollution and improving urbanenvironment, the WWTPs brought the odor problems to their surroundings at the sametime. And in this study, the emission characteristics mechanism of a Suzhou WWTP wasanalyzed, in order to provide the theoretical basis for odor assessment and control ofWWTPs.The concentrations of odorants in the WWTP showed that the hydrogen sulfide wasone of the most typical odorants in wastewater treatment plant, and the concentrationsof odorants emitted from fine screen, aerated grid chamber and sludge storage tank werehigher than the rest of treatment units. The H₂S concentrations in pump station, finescreen, aerated grit chamber were low in winter while were high in summer, and theywere reduced significantly after rainfall. The H₂S concentrations in pump station, finescreen and aerated grit chamber had significant positive correlation with wastewatertemperature and significant negative correlation with pH or dissolved oxygen of thewastewater. And the H₂S concentrations in the sludge thickening tank and sludgestorage tank had significant positive correlation with sludge acid volatile sulfide andsignificant negative correlation with sludge oxidation-reduction potential. When thewastewater temperature is under15℃, or dissolved oxygen is above0.2mg/L, or pH isabove7.2, the H₂S concentrations in pump station, fine screen and aerated grit chamberwere quite low compared with those in other conditions. In these conditions, the H₂Sconcentrations in pumping station, fine screen and aerated grid chamber was kept under0.27mg/m3,3.90mg/m3and7.34mg/m3.The release kinetics of H₂S from wastewater showed that the release flux of H₂Swas increasing with the rise of pH, temperature, sulfide, flow rate and aeration load ofwastewater. The mass transfer coefficient of H₂S was increasing with the rise oftemperature, flow rate and aeration load of wastewater, the effect of flow rate andaeration load of wastewater on mass transfer coefficient of H₂S was more significantthan temperature, and the maximum of mass transfer coefficient of H₂S was2×10-4m/min. The analysis of sludge adsorption of sulfide showed that the adsorption wasfollowing the Langmuir equation, and it was a spontaneous and endothermic reaction. The result also showed that the sludge adsorption of sulfide could reduce the release ofH₂S significantly.According to the result of release kinetics of H₂S from wastewater, established amodel that was using to calculate the release flux of H₂S from wastewater in WWTPs,and it was verified with the monitoring data on the real conditions of WWTPs. Usingthe result of the model to calculate the H₂S emission load of fine screen, grit chamber,biological reaction tank and sludge thickening tank, they were3.34mg/m2,28.32mg/min,86.71mg/min and0.44mg/min, they demonstrated that the biologicalreaction tank had the most H₂S emission load in the WWTP.