Technology choices in scaling up sanitation can significantly affect greenhouse gas emissions and the fertiliser gap in India

Abstract

Nearly 800 million people in India lack access to adequate sanitation. The choice of technology for addressing this need may have important sustainability implications. In this study, we used life cycle assessment to compare environmental impacts and nutrient recovery potentials of four different options for providing everyone in India with access to improved sanitation: (i) centralised wastewater treatment with sequential batch reactors (SBR), (ii) twin-pit latrines, (iii) latrines with source separation only and (iv) latrines with source-separation of urine and faeces connected to biogas plants. Results revealed large variability. Closing the sanitation gap through pit latrines would be expected to cause large increases of India's annual greenhouse gas (GHG) emissions, equivalent to 7% of current levels. Source separation only and centralised plants with SBR will be associated with lower GHG emissions, while the biogas scenario shows a potential to provide net emission reduction. The study revealed that source separating systems can provide significant quantities of plant available nitrogen and phosphorus at the country level. Future research should include more technological options and regions. Methodology piloted in this study can be integrated into the planning and design processes for scaling up sanitation in India and other countries.