Spatially Informed Multi-Objective Decision-Making Tool for Retrofitting Municipal Wastewater Treatment Plants
The resources embedded in wastewater effluents and residual biosolids have motivated the conversion of traditional energy-intensive wastewater treatment plants (WWTPs) into net energy-positive water resource recovery facilities. Recent food waste regulations, including the New York State (NYS) Food Donation and Food Scraps Recycling Law, created new opportunities to integrate food waste (FW) co-digestion with innovative waste energy and resource recovery technologies. This study develops a spatially informed decision-making tool to facilitate the selection of retrofit design for WWTPs, using NYS as an example. Retrofit configurations for WWTPs were optimized based on two economic and two environmental objectives. In addition, WWTPs in disadvantaged communities (DACs) were identified to prioritize the retrofitting investment in the traditionally underserved areas. FW co-digestion is consistently favored in optimal configurations across economic and environmental metrics. Among effluent thermal energy recovery alternatives, providing heating/cooling to local communities is a preferred option to biosolids drying and is selected in most WWTPs when optimizing environmental objectives. Hydrothermal processes and power-to-gas are only economically viable at large WWTPs but have certain environmental benefits. Finally, four WWTPs were identified as high-priority candidates for retrofitting based on favorable economic and environmental performance, and environmental justice considerations. This study demonstrates a holistic approach to support decision-making processes at WWTPs, and offers potential applicability to any municipality exploring food waste management and other resource recovery opportunities.