Advancing the economic and environmental sustainability of the NEWgeneratorTM non-sewered sanitation system

Abstract

Achieving safely managed sanitation and resource recovery in areas that are rural, geographically challenged, or experiencing rapidly increasing population density may not be feasible with centralized facilities due to space requirements, site-specific concerns, and high costs of sewer installation. Non-sewered sanitation (NSS) systems have the potential to provide safely managed sanitation and achieve strict wastewater treatment standards. One such NSS treatment (backend) technology is the NEWgeneratorTM, which includes an anaerobic membrane bioreactor (AnMBR), nutrient recovery via ion exchange, and electrochlorination. Although the system has been shown to achieve robust treatment of real waste streams for over 100 users, the technology’s relative life cycle sustainability across deployment locations remains unclear. This study characterizes the financial viability and life cycle environmental impacts of the NEWgeneratorTM and prioritizes opportunities to advance system sustainability through targeted improvements and deployment. The costs and greenhouse gas (GHG) emissions of the NEWgeneratorTM (general case) leveraging grid electricity were 0.139 [0.113 – 0.168] USD·cap-1·d-1 and 79.7 [55.0 – 112.3] kg CO2-eq·cap-1·yr-1, respectively. A transition to photovoltaic-generated electricity would increase costs to 0.145 [0.118 – 0.181] USD·cap-1·d-1 but decrease GHG emissions to 56.1 [33.8 – 86.2] kg CO2eq·cap-1·yr-1. The deployment location analysis demonstrated reduced median costs (relative to the general case) for deployment in China (-38%), India (-53%), Senegal (-31%), South Africa (-31%), and Uganda (-35%), but at comparable or increased GHG emissions (-2% to +16%). Examining targeted improvements revealed the relative change in median cost and GHG emissions to be -21% and -3% if loading is doubled (i.e., doubled users per unit), -30% and -12% with additional sludge drying, and +9% and -25% with the addition of a membrane contactor, respectively, with limited benefits (0-5% reductions) from an alternative photovoltaic battery, low-cost housing, or improved frontend operation. This research demonstrates the NEWgeneratorTM is a low-cost, low-emission NSS backend technology with the potential for resource recovery to increase access to safe sanitation.