Comparative performance of osmotic and thermal driven anaerobic membrane bioreactors for hazardous textile wastewater treatment

Textile wastewater is hazardous in properties and adequate treatment should be administered prior to the release of water into natural bodies. Hybrid biological and membrane treatment technologies are suitable for textile wastewater treatment. In this study, osmotically driven submerged anaerobic forward osmosis membrane bioreactor (An-FOMBR) and thermally driven submerged anaerobic membrane distillation bioreactor (An-MDBR) were studied for the highly polluted wastewater treatment produced from textile industries. The systems were operated in parallel for 73 and 47 days for An-FOMBR and An-MDBR, respectively. The concentration of chemical oxygen demand (COD) and color in textile wastewater were 3000 ± 150 mg/L and 1000 ± 100 platinum cobalt, respectively. 1 M mono-ammonium phosphate was used as a fertilizer draw solution with a direct reuse potential of diluted draw solution in fertigation. Woven fiber microfiltration was used to avoid salinity buildup in the bioreactor. At an operating temperature of 40 °C the An-MDBR depicted 27 % higher flux and 14 % less salinity buildup in the bioreactor compared to An-FOMBR. Similarly, with 1 % higher COD removal, 5 % higher color removal and 10 % higher biogas generation, the An-MDBR proved to be a better variant. However, after 43 days of continuous operation, a spike in MD permeate conductivity was observed due to partial pore wetting caused by foulants interaction with the membrane surface. Therefore, timely cleaning of the membrane is essential to avoid pore wetting and process stability. With high quality effluent production and potential to utilize the waste heat, MD filtration is a better process to combine with anaerobic degradation than FO.