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System evaluation and microbial analysis of a sulfur cycle-based wastewater treatment process for Co-treatment of simple wet flue gas desulfurization wastes with freshwater sewage
- Qian, Jin, Liu, Rulong, Wei, Li, Lu, Hui, Chen, Guang-Hao
- Water research 2015 v.80 pp. 189-199
- bacteria, bacterial communities, biological treatment, chemical oxygen demand, denitrification, energy, flue gas desulfurization, freshwater, methane, nitrates, nitrification, nitrites, nitrogen, pH, seawater, sewage, sludge, sulfates, sulfides, sulfur, thiosulfates, wastewater treatment, China
- A sulfur cycle-based wastewater treatment process, namely the Sulfate reduction, Autotrophic denitrification and Nitrification Integrated process (SANI® process) has been recently developed for organics and nitrogen removal with 90% sludge minimization and 35% energy reduction in the biological treatment of saline sewage from seawater toilet flushing practice in Hong Kong. In this study, sulfate- and sulfite-rich wastes from simple wet flue gas desulfurization (WFGD) were considered as a potential low-cost sulfur source to achieve beneficial co-treatment with non-saline (freshwater) sewage in continental areas, through a Mixed Denitrification (MD)–SANI process trialed with synthetic mixture of simple WFGD wastes and freshwater sewage. The system showed 80% COD removal efficiency (specific COD removal rate of 0.26 kg COD/kg VSS/d) at an optimal pH of 7.5 and complete denitrification through MD (specific nitrogen removal rate of 0.33 kg N/kg VSS/d). Among the electron donors in MD, organics and thiosulfate could induce a much higher denitrifying activity than sulfide in terms of both NO3− reduction and NO2− reduction, suggesting a much higher nitrogen removal rate in organics-, thiosulfate- and sulfide-based MD in MD–SANI compared to sulfide alone-based autotrophic denitrification in conventional SANI®. Diverse sulfate/sulfite-reducing bacteria (SRB) genera dominated in the bacterial community of sulfate/sulfite-reducing up-flow sludge bed (SRUSB) sludge without methane producing bacteria detected. Desulfomicrobium-like species possibly for sulfite reduction and Desulfobulbus-like species possibly for sulfate reduction are the two dominant groups with respective abundance of 24.03 and 14.91% in the SRB genera. Diverse denitrifying genera were identified in the bacterial community of anoxic up-flow sludge bed (AnUSB) sludge and the Thauera- and Thiobacillus-like species were the major taxa. These results well explained the successful operation of the lab-scale MD–SANI process.