Emission characteristics of volatile sulfur compounds (VSCs) from a municipal sewage sludge aerobic composting plant

The emission of volatile sulfur compounds (VSCs) causing strong odors is a major problem in municipal sewage sludge composting plants (MSSACPs). Improving the knowledge on characteristics of VSCs emission in MSAACPs is of particular significance to elimate odors, but the studies conducted on-site to identify them are scarce. To this purpose, characteristics of VSCs emission were studied on-site from a MSSACP during different ambient temperatures corresponding with seasonal variations. Results reveal that (1) the total emission of VSCs which included methyl disulfide (DMDS), methyl sulfide (DMS), carbon disulfide, methyl mercaptan, and hydrogen sulfide (H₂S) was 561.89 mg/dry kg in summer, 358.45 mg/dry kg in spring, and 215.52 mg/dry kg in winter, and the greatest amounts of VSCs were emitted during the mesophilic and pre-thermophilic phases; (2) although DMDS and DMS contributed the most towards total VSCs emissions during winter (81.93%), spring (82.55%), and summer (83.90%), their odor contributions were less than that of H₂S; (3) in summer, the odor nuisance of total VSCs was higher than that in winter and spring; (4) sulfur loss in the form of VSCs emissions and total sulfur loss both increased with rising ambient temperatures during the sewage sludge aerobic composting. Results obtained in this study will be beneficial towards the elimation of odors released from MSSACPs.