Green initiative with cow-dung slurry for treatment of industrial effluent

Abstract The available literature suggests anaerobic digestion (AD) improves biogas yield by 30–50% and COD reduction exceeds by 80% along with cow-dung slurry. This makes AD a strong alternative to conventional treatment methods. Treatment of excessively organic loaded industrial effluents remains a critical environmental challenge due to their high chemical oxygen demand (COD) that depletes dissolved oxygen in water bodies causing severe ecological harm. AD outperforms other treatment methods by offering dual benefits of waste reduction and renewable energy generation. Studies show up to 98% BOD, 97% COD, and 86% TDS reduction with AD, producing a significant amount of biogas as an added advantage. This review explores AD as a solution to treat toxic effluent streams that are high in organic load as compared to other wastewater treatment technologies, such as chemical treatments and aerobic processes. This further highlights advantages of AD in terms of energy efficiency, lower sludge production, and resource recovery. The AD performance is suggested to be enhanced using cow-dung slurry as a co-substrate due to its optimal carbon-to-nitrogen ratio, buffering capacity and high microbial diversity. Furthermore, this process yields a nutrient-rich digestate, which could be used as an organic fertilizer, promoting circular economy principles. This review emphasizes on recent advances in AD technology, such as microbial consortia optimization, and process automation while identifying challenges in large-scale implementation, including process stability and economic feasibility. It more precisely focuses on a new perspective of integrating bioresource-based solution – cow dung slurry as a potential synergistic substrate – for enhancing AD of high COD industrial effluent. The review provides a comprehensive analysis of AD and its potential that aligns with global sustainability goals and promotes it as the only green, economically viable, and scalable solution.