Perchlorate bioreduction in UASB reactor: S2--autotrophic granular sludge formation and sulphate generation control.

Perchlorate ( ClO 4 − ) industrial wastewater requires efficient removal to prevent adverse environmental impacts, however, high concentration and low biodegradability give rise to poor ClO 4 − bioreduction performance. S 2 − -autotrophic granular sludge ( S 2 − -AuGS) was firstly cultivated for high concentration perchlorate ( ClO 4 − ) removal in the upflow anaerobic sludge blanket (UASB) reactor ( ClO 4 − : 150 mg L⁻¹). Simultaneously, the S 2 − was utilized to control the SO 4 2 − generation as electron donor, the effluent SO 4 2 − 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 S 2 − / ClO 4 − molar ratio (2.2), more EPS was secreted, which promoted the S 2 − -AuGS formation and stability. Though acclimation of 146 d, the S 2 − -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 S 2 − -AuGS formation, the highest ClO 4 − and S 2 − 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 S 2 − -AuGS. This study proposed to form a novel S 2 − -AuGS for developing the high ClO 4 − concentration removal performance and to utilize the S 2 − as an electron donor for controlling the excessive SO 4 2 − generation. [ABSTRACT FROM AUTHOR]