Anaerobic membrane bioreactor for the treatment of synthetic wastewater to produce energy and water reusable in agricultural sector

Total utilizable water resource in India has been estimated to be about 1,123 billion cubic meters (BCM). Out of total water usage by different sectors, about 85% (688 BCM) of water usage is being diverted for irrigation, which may increase to 1,072 BCM by 2050. Since the demand for domestic and industrial water usage may increase in near future, the water availability for irrigation is expected to reduce. Overall analysis of water resources indicates that in coming years, there will be a twin edged problem to deal with reduced fresh water availability and increased wastewater generation due to increased population and industrialization. With increasing water demand and depleting water availability, recycling of domestic wastewater has huge potential in India to bridge the water scarcity and provide good source of water for non-potable use like irrigation. Considering various lacunas of conventional wastewater treatment technologies and cost implications of advanced technologies in Indian context, a need exists to develop sustainable technologies which can provide recyclable quality of water with low operating cost. An anaerobic bioreactor coupled with membrane unit is phrased as anaerobic membrane bioreactor (AnMBR) and could be an effective solution to treat low-strength domestic wastewater. The aim of this study was to evaluate the performance of external AnMBR for the treatment of sewage equivalent synthetic wastewater having 365 mg/l chemical oxygen demand (COD). Overall 95% COD removal efficiency was obtained during performance evaluation of AnMBR. The treated effluent with average COD concentration less than 20 mg/l was obtained for 8-h hydraulic retention time in bioreactor at 37 °C. The total suspended solids removal efficiency was 100% in AnMBR. The obtained biogas yield was higher than 0.4 m³/kg of COD removed in the system. The membrane flux was found higher than 60 l/m² h at 1 bar trans-membrane pressure.