Evaluation of an up-flow anaerobic sludge blanket reactor integrated by electro-coagulation in textile dyeing wastewater treatment

Textile and dyeing industries consume huge amounts of water in the dyeing processes, making it hard to treat the enormous quantities of this hazardous wastewater. Among the biological processes, anaerobic treatment is considered as an efficient method for dyeing wastewater treatment, which also leads to the production of biogas as a source of renewable energy. In this research, for the first time, the integration of an electrocoagulation (EC) in the up-flow anaerobic sludge blanket (UASB) system was used to treat synthetic textile dyeing wastewater containing Reactive Red 195. For this purpose, this research was conducted in two operational phases. Initially, it worked in the control phase of the UASB reactor for 35 days with a hydraulic retention time of 24 h and organic loading rate of 0.9 COD/m3.d. In the next operational phase, the effect of EC (iron electrodes, current density of 0.3 mA/cm2 and an exposure mode of 10-min-ON/ 60-min-OFF) on pollutant removal performance and biogas production of the UASB reactor was examined for another 14 days. The results indicated that the integration of the EC to the UASB reactor increased the color and chemical oxygen demand removal efficiency form 70.5±0.2% and 88.4±1.3% to 81.5±0.0% and 90.5±0.7%, respectively, meanwhile the volume of daily generated biogas and the methane content from 4533±57 mL/day and 71.2% to 4866±57 mL/day and 74.9%, respectively.