Energy-positive wastewater management in urbanizing tropical cities: Integrating membrane filtration and anaerobic digestion in Kanpur, India

Urban wastewater and organic waste management are critical challenges in rapidly urbanizing regions, particularly in tropical developing countries such as Kanpur and India. Conventional treatment methods, such as the activated sludge process (ASP), face limitations, including high energy demands, low efficiency in industrial contaminant removal, and excessive sludge production. This study proposes an integrated system that combines direct membrane filtration (DMF) with anaerobic digestion (AD) to address these issues. The DMF+AD system concentrates wastewater organics for codigestion with food waste, enhancing biogas production while reducing pollutant discharge. The results indicate a 58% COD recovery rate, an 83% reduction in contaminant discharge into the Ganges River, and significant improvements in effluent quality compared to those of the ASP. Additionally, economic assessments reveal that biogas energy production offsets operational energy requirements and costs, making this approach both sustainable and cost effective. This innovative system has potential as a scalable solution for urban waste management in fast-growing tropical cities, contributing to environmental protection and renewable energy generation. • The proposed system recovers 58% COD and cuts pollution by 83% • Biogas offsets energy costs, making wastewater treatment more economically • Membrane tech efficiently removes chromium from tannery wastewater • Co-digestion offers a combined solution for wastewater and solid waste