Greenhouse gas emissions in industrial wastewater treatment: technologies, challenges, and strategies

Abstract

Greenhouse gas (GHG) emissions from industrial wastewater treatment are increasingly acknowledged as a significant contributor to climate change but remain underrepresented in mitigation strategies, especially in developing countries. Methane (CH₄), nitrous oxide (N₂O), and carbon dioxide (CO₂) are emitted through anaerobic digestion, biological nitrogen removal, and energy-intensive operations. In Vietnam, centralized WWTPs have reported emissions as high as 476.1 MtCO₂e from CH₄ and 13,103.9 MtCO₂e from N₂O, emphasizing the need for targeted intervention. It is hypothesized that when equipped with low-emission technologies and supported by integrated approaches, such as energy recovery, optimized nutrient removal, and real-time digital monitoring, industrial wastewater systems can be transformed into climate-resilient infrastructure with significantly reduced emission intensities. In this review, mitigation pathways are synthesized through a critical evaluation of peer-reviewed literature, field-based data, and global policy frameworks. Key emission factors, including 0.0011 g CH₄/g BOD₅ and 0.0017 g N₂O–N/g TN-influent, are analyzed alongside operational metrics. Technologies such as anaerobic membrane bioreactors (AnMBRs), partial nitritation–anammox (PN/A) processes, AME-AD systems, and photovoltaic-supported biogas recovery are comprehensively reviewed. A four-phase roadmap to net-zero emissions by 2050 is proposed, integrating life cycle assessment, AI-enhanced monitoring, and carbon finance mechanisms. Emphasis is placed on the co-benefits of GHG mitigation strategies for public health resilience, energy security, and the achievement of Sustainable Development Goals. By repositioning industrial wastewater as a strategic entry point for climate action, this study outlines actionable, cross-sectoral solutions to support decarbonization and circular economy transformation in rapidly industrializing economies. These findings hold particular relevance for journals focusing on environmental engineering, sustainable infrastructure, climate governance, and low-carbon development pathways.