Development of a process model and life cycle assessment for a large water resource recovery facility and comparison of biosolids process upgrade options.

Life cycle assessment (LCA), coupled with process modeling to develop the life cycle inventory, is a valuable tool to assess differences in environmental performance when evaluating alternatives based on sustainability (triple-bottom-line) principles. Coupled with a whole plant process model (SUMO21), an LCA assessed the environmental performance of options to upgrade biosolids management for the Great Lakes Water Authority water resource recovery facility. All five alternatives evaluated (composting plus four anaerobic digestion alternatives) were able to meet the core objectives of the biosolids management system upgrade: (1) address ageing incinerators, (2) minimize the mass of biosolids landfilled, and (3) reduce greenhouse gas emissions, compared to the existing (baseline) system. The mass of solids to be managed was reduced for the anaerobic digestion alternatives but not for the composting alternatives. Environmental impacts were reduced for the composting alternative for all six impact categories considered (global warming, eutrophication, carcinogenics, ecotoxicity, respiratory effects, and fossil fuel depletion) relative to the baseline, and further reduced for all four anaerobic digestion alternatives evaluated. The results allowed a phased implementation plan to be developed, which could be evaluated based on other factors, such as costs and operational factors.