Greenhouse gas emissions from sanitation and wastewater management systems: a review

Abstract

There is growing awareness of the contribution of sanitation systems to greenhouse gas (GHG) emissions globally, and hence to climate change. However, there is a lack of comprehensive insight into emission sources disaggregated across the entire sanitation chain. This study presents a detailed review and analysis of emission sources from both sewer-based and non-sewered sanitation systems, with a focus on both fugitive emissions and those related to system operation. Our analysis highlights evidence gaps in several areas in the literature: quantifying emissions from non-sewered sanitation systems, with particular gaps related to technologies like biogas toilets and composting toilets; oversight of contextual factors such as environmental conditions and infrastructure operational status in GHG accounting; a dearth of holistic GHG emission studies across the entire sanitation chain comparable to those in the solid waste management sector; and inconsistencies in GHG measurement methods. By pinpointing these gaps, this review provides a robust reference for planning climate mitigation strategies for sanitation and wastewater management systems, emphasizes the urgent need for the incorporation of climate-smart solutions in the sector, e.g. in the design of new and retrofitted infrastructure, and aims to bridge the sustainable development goals related to sanitation and climate action. HIGHLIGHTS Comprehensive mapping of GHG emission sources in sewer-based and non-sewered sanitation systems.; Identifies crucial evidence gaps in non-sewered sanitation systems’ GHG emissions.; Highlights overlooked aspects of environmental and operational conditions in GHG accounting.; Emphasizes the need for holistic GHG emission studies and provides insights for developing climate-smart sanitation and wastewater management strategies.;

Keywords

• climate change
• faecal sludge management
• ghg emissions
• mitigation
• non-sewered sanitation
• wastewater