Effect of Sulfate Concentration on Up-flow Anaerobic Sludge Blanket Reactor Performance Treating Textile Dyeing Wastewater

Industrial wastewater from textile dyeing industries is typically rich in sulfates and azo dyes, which inhibit biological treatment by disturbing microbial pathways and forming toxic sulfide. The up-flow anaerobic sludge blanket (UASB) reactor is widely used for treating textile dyeing wastewater containing moderate sulfate loads. This study investigated the effect of two sulfate concentrations (۱۹۰ and ۳۹۰ mg/L) on the performance of a lab-scale UASB reactor treating synthetic textile dyeing wastewater with Reactive Red ۱۹۵. The reactor operated for ۷۶ days under controlled conditions, and key parameters chemical oxygen demand (COD) removal, dye decolorization, sulfate removal, and biogas yield and composition were systematically monitored. At ۱۹۰ mg/L sulfate, the system maintained stable biomass (MLVSS/MLSS = ۰.۴–۰.۵), COD removal > ۹۱%, partial color and sulfate removal (۴۷% and ۵۲%), and methane-rich biogas > ۸۵%. Increasing sulfate to ۳۹۰ mg/L reduced biomass stability (MLVSS/MLSS = ۰.۳), COD removal (۸۹%), color removal (۳۰%), and sulfate removal < ۲۰%. Biogas quality declined, with methane dropping to ۶۸% and total gas production decreasing. Despite these inhibitory effects, gradual microbial adaptation occurred, restoring part of the COD removal and biomass activity. Overall, the findings indicate that UASB reactors can maintain efficient treatment at moderate sulfate levels, but higher concentrations disturb microbial balance, enhance sulfidogenesis, and reduce both treatment efficiency and energy recovery. Effective sulfate control is thus essential for optimizing UASB performance in textile dyeing wastewater treatment.

کلیدواژه ها:

Anaeribic wastewater treatment ، Up-flow anaerobic sludge blanket reactor ، Sulfate inhibition ، Textile dyeing wastewater ، Azo dye ، Biogas production