Perchlorate bioreduction in UASB reactor: S^2--autotrophic granular sludge formation and sulphate generation control

Perchlorate ($$) industrial wastewater requires efficient removal to prevent adverse environmental impacts, however, high concentration and low biodegradability give rise to poor $$ bioreduction performance. $$-autotrophic granular sludge ($$-AuGS) was firstly cultivated for high concentration perchlorate ($$) removal in the upflow anaerobic sludge blanket (UASB) reactor ($$: 150 mg L^-1). Simultaneously, the $$ was utilized to control the $$ generation as electron donor, the effluent $$ concentration (190 mg L^-1) was satisfied with drinking water standard (250 mg L^-1). Under the optimized condition of hydraulic retention time (HRT) (6 h) and $$/$$ molar ratio (2.2), more EPS was secreted, which promoted the $$-AuGS formation and stability. Though acclimation of 146 d, the $$-AuGS was formed with a large average granular sludge size (612 μm) and an excellent settleability (sludge volume index: SVI₅/SVI₃₀= 1). With the mature $$-AuGS formation, the highest $$ and $$ loading was increased to 1.06 and 0.75 kg m^-3 d^-1. Interestingly, Georgfuchsia, Methyloversatilis, Sulfurisoma, and Exiguobacterium were the main microbial community in the $$-AuGS. This study proposed to form a novel $$-AuGS for developing the high $$ concentration removal performance and to utilize the $$ as an electron donor for controlling the excessive $$ generation.