A review of sanitation technologies to achieve multiple sustainable development goals that promote resource recovery

Abstract

In 2015 the global community approved the seventeen sustainable development goals (SDGs). The SDGs include a goal regarding access to clean water and sanitation with specific targets such as providing access to adequate and equitable sanitation for all, improving water quality by reducing pollution, halving the proportion of untreated wastewater, and increasing recycling and safe reuse globally. There are opportunities to promote sanitation technologies that would achieve these sanitation targets and minimize health risk from exposure to pathogens while also achieving SDGs related to increased food security and sustainable management of waste and natural resources through the recovery of beneficial resources such as energy and fertilizer. To that end, the objective of this paper is to critically review literature that is supported by material flow diagrams developed for nitrogen, phosphorus, and carbon, to determine the ability of existing sanitation technologies and strategies that are deployed in a centralized or decentralized manner to safely recover resources and thus achieve multiple sustainable development goals. The one strategy and six technologies are 1) dig and cover, 2) bucket latrine, 3) ventilated improved pit (VIP) latrine, 4) double-vault composting latrine, 5) urine-diverting composting latrine, 6) pour-flush toilet connected to a septic tank, and 7) sewered toilet. Results showed the six sanitation technologies and one strategy could be grouped into three categories based on their potential to recover resources without further processes added to provide resource recovery. Group 1 (unimproved, no resource recovery), which included the baseline strategy of dig and cover and the unimproved technology of bucket latrines, demonstrated no ability to achieve resource recovery from human waste without further resource recovery treatment. Container based sanitation (not discussed here) may, however, be an appropriate method to safely dispose of excreta while also providing opportunities for resource recovery. Group 2 (improved, no resource recovery), which included the technologies ventilated improved pit (VIP) latrine, pour-flush toilet with septic tank, and sewered toilet, were also shown to have no ability to recover resources without further resource recovery treatment. Group 3 (improved, resource recovery), which included double-vault composting latrine and urine-diverting compositing latrine), demonstrated the greatest ability to recover resources from human waste. However, policies to ensure safe handling of resources generated at onsite locations is needed and resource recovery processes can be integrated with treatment processes to recover embedded resources from bucket latrines, VIP latrines, pour-flush toilets with septic tanks, and sewered toilets. The results provide guidance to achieve multiple sustainable development goals through the implementation of sanitation technologies that have potential to recover beneficial resources.