Treatment of textile effluent using an anaerobic reactor integrated with activated carbon and ultrafiltration unit (AN-ACF-UF process) targeting salt recovery and its reusability potential in the pad-batch process

Abstract

An on-site anaerobic biological reactor integrated with activated carbon filter (ACF) and ultra-filtration (UF) unit termed as AN-ACF-UF process was used for the decolourization of textile effluent at the industrial premises. The anaerobic reactor containing a microbial consortium enriched from the industrial effluent using a patented method was fed with a mixed inlet consisting of dye and pre-treatment range (PTR) effluents in a ratio of 70:30 (v/v). The PTR effluent consists of effluent generated from desizing, bleaching, scouring, and mercerization process. The anaerobic unit was run in a continuous mode for 32 d with a hydraulic retention time of 2 d. The treated effluent from the anaerobic unit was fed into the ACF unit at 0.7 ml/min. Finally, the outlet from the ACF unit was fed into the UF unit. Daily variations were observed in the inlet effluent with chemical oxygen demand (COD) and colour (hazen value) in the range of 1950–2450 mg/L, and 2500–3100 hazen, respectively. The AN-ACF-UF process was effective in decolourizing 91 ± 3 % of the colour in textile effluent mixture. Germination test with the treated effluent on Vigna radiata did not show any significant difference (p > 0.05) between control (92 ± 1 % germination) and treated effluent group (83 ± 1 % germination). The recovered salt contained high concentration of sodium salt (349.70 mg/g of salt). Integration of this process with the existing industrial ETP (Effluent treatment plant) would enable the industry to partially recover the cost of dyeing and achieve a zero liquid discharge system.