Inorganic Sulfide Gaseous And Odor Emission Characteristics Of Typical Municipal Wastewater Treatment Plants

A large number of inorganic sulfide gaseous will be released from the municipal wastewater treatment plants (WWTPs), such as H2S and CS2. In this study, the emission characteristics of inorganic sulfide gaseous and odor from three typical wastewater treatment processes including SBR, oxidation ditch and A2/O had been confirmed. Based on the above, the emission sites from WWTPs were identified and the monitor and control technology was suggested to WWTPs.Firstly, the analysis method of H2S and CS2 were established based on GC-FPD equipped with a online-preconcentrator. The detection limits were 1.89×10-4 mg/m3 and 2.80x 10-5 mg/m3 for H2S and CS2, respectively. This analytical method could meet the monitoring demand of H2S and CS2 emitted from WWTPs.H2S, CS2 and odor concentration from WWTPs had been monitored in North China, the pearl river delta and the yangtze river delta. The results show that, for the SBR process, H2S and CS2 emissions per ton wastewater are the largest in feeding and aeration period in WWTPs in North China, their value are 1.044mg/m3 and 0.252 mg/m3, respectively. CS2 emissions per ton wastewater are the largest in aeration period in WWTPs in the pearl river delta and the yangtze river delta, their value are 0.1955 mg/m3 and 0.0322 mg/m3 for each. For the oxidation ditch process, in WWTPs in North China, the maximum value of H2S emission per ton wastewater is 0.112 mg/m3 from aerated grit tank and CS2 emission per ton wastewater is 0.019 mg/m3 from aerated area. H2S emission per ton wastewater is 0.0215 mg/m3 from aerated grit tank and the maximum value of CS2 is 0.0031 mg/m3 from aerated area in WWTPs in the peral river delta. The maximum value of CS2 emission per ton wastewater is 0.0202 mg/m3 from aerated area in WWTPs in the yangtze river delta. For the A2/O process, H2S and CS2 emission per ton wastewater are the highest in primary sedimentation tank in WWTPs in North China, their value are 0.422 mg/m3 and 0.074 mg/m3, respectively. CS2 emission per ton wastewater is the highest in anaerobic tank in WWTPs in the pearl river delta, the value is 0.0010 mg/m3. CS2 emission per ton wastewater is the highest in oxic tank in WWTPs in the yangtze river delta, the value is 0.0827 mg/m3.A control strategy was proposed based on emission characteristics and sites.The key emission points of H2S and odor concentration were grid, grit tank and aeration period in SBR process; grid, grit tank, aeration areas, anaerobic areas and sludge dewatering room in oxidation ditch process; grid, grit tank, primary sedimentation tank, hydrolytic acidification tank, oxic tank and sludge dewatering room in A2/O process. The H2S concentration would be monitored online by electrochemical sensors and odor concentration would be detected by E-nose in key units of WWTPs. Several physical, chemical, biological methods or combined the three methods could be chose to treat the odor to avoid the emission out of the WWTPs.