Sulfur-autotrophic treatment of Sb(V)-contaminated water across concentration levels: Toward effective antimony pollution control

This study developed a sulfur autotrophic bioreactor that could effectively remove Sb(V) of ppm (10 mg/L) and ppb (500 μg/L) levels in water through sulfur autotrophic reduction, sulfur disproportionation and in-situ precipitation. At the longest hydraulic retention time (i.e., HRT = 5.42 h for ppm Sb(V) level and HRT = 12.0 h for ppb Sb(V) level), the bioreactors performed well, with removal efficiencies of 97.1%, 96.2% for Sb(V), and 96.3%, 47.0% for the total Sb (TSb), respectively. Sb(V) removal by sulfur autotrophic reduction matched well with First-order kinetic model, implying that Sb(V) concentration was the main controlling factor limiting its removal. The measured SO 4 2- increment and alkalinity consumption in effluent were higher than the theoretical values owing to the occurrence of sulfur disproportionation. At the end of bioreactor operation, the in-situ precipitates were characterized and confirmed to be Sb 2 S 3 . Given arsenic (As) toxicity mechanism in KEGG database, the mechanistic response of organisms to Sb(V) was attributed to the reactive oxygen species (ROS) from the highly toxic methyl compounds of Sb(III). Proteobacteria was the dominant phylum for Sb(V) removal, and Sulfuricurvum and Microbacter (at genus level) played key roles for Sb(V) reduction and sulfur disproportionation, respectively. Download: Download high-res image (291KB) Download: Download full-size image