Biodegradation of carbon disulfide and hydrogen sulfide using a moving bed biofilm reactor coupled with sulfur recycling: Performance, mechanism, and potential application.

In this work, a moving bed biofilm reactor (MBBR) was equipped for simultaneous biodegradation of CS2 and H2S. MBBR was started up and operated with different inlet concentrations and retention time; results indicated that approximately 81.9% CS2 and 93.9% H2S could be degraded, and the maximum elimination capacities of 209.3 g/(m3·h) and 138.5 g/(m3·h) were achieved for CS2 and H2S, respectively. The biodegradation mechanisms, including mass transfer, kinetics, and electron transfer, were then investigated. The mass transfer fraction and the maximum degradation rate per unit filter volume were calculated for evaluating the characteristics of mass transfer in MBBR. The variations of extracellular polymeric substances secretion, electron transport system activity and ATP enzyme activity showed that MBBR had an excellent performance for waste gas purification. Subsequently, the recovery of sulfur was explored via morphology, crystal structure, and generation kinetics, indicating that a modified Gompertz model could precisely describe the kinetics of sulfur recovery, and the product selectivity of 51.7% was achieved for sulfur. The microbial community analysis suggested that the dominant genera for biodegradation and sulfur recovery were Acidithiobacillus and Mycobacterium. Finally, MBBR system was validated for treatment of actual waste gas; results indicated that maximum elimination capacities of 134.1 g/(m3·h) and 117.1 g/(m3·h) were obtained for CS2 and H2S, respectively, suggesting that MBBR had the potential for application.