Comparative Performance of Coagulation-Sequencing Batch Reactors and Anaerobic-Aerobic Activated Sludge Processes with a High-Rate Filter in Treating Textile Wastewater

High-salt textile dyeing wastewater is difficult to treat using conventional activated sludge processes due to its high levels of solids, organic matter, and chromaticity. The objective of this study is to evaluate the performance of two treatment configurations, namely (i) a sequencing batch reactor (SBR) coupled with a coagulation pretreatment process and (ii) an anaerobic-aerobic activated sludge (ANOAS) system combined with a high-rate filter (HRF), as alternatives to conventional primary settler processes. This study also assessed the performance of activated sludge and biofilter systems that incorporated anaerobic and aerobic zones for the efficient treatment of textile wastewater. Treatment efficiency was evaluated by monitoring pH, suspended solids (SS), color, and chemical oxygen demand (COD). The HRF, operating at a substantially shorter hydraulic retention time (HRT) of 0.3 h, demonstrated performance comparable to coagulation-sedimentation using a high coagulant dose and to conventional settlers operating at a longer HRT of 3.0 h. Notably, under the most efficient configurations, the treatment efficiency of the HRF/ANOAS system was higher than that of the coagulation-SBR system. Moreover, compared to the existing physicochemical-SBR system, the optimized HRF/activated sludge and HRF/biofilter systems achieved not only higher pollutant removal efficiency but also lower sludge production, even at shorter HRTs.