Life cycle assessment and costing of urine source separation: Focus on nonsteroidal anti-inflammatory drug removal

Urine source separation has the potential to reduce pharmaceutical loading to the environment, while enhancing nutrient recovery. The focus of this life cycle assessment (LCA) was to evaluate the environmental impacts and economic costs to manage nonsteroidal anti-inflammatory drugs (NSAIDs) (i.e., diclofenac, ibuprofen, ketoprofen and naproxen) and nutrients in human urine. Urine source separation was compared with centralized wastewater treatment (WWT) (biological or upgraded with ozonation). The current treatment method (i.e., centralized biological WWT) was compared with hypothetical treatment scenarios (i.e., centralized biological WWT upgraded with ozonation, and urine source separation). Alternative urine source separation scenarios included varying collection and handling methods (i.e., collection by vacuum truck, vacuum sewer, or decentralized treatment), pharmaceuticals removal by ion-exchange, and struvite precipitation. Urine source separation scenarios had 90% lower environmental impact (based on the TRACI impact assessment method) compared with the centralized wastewater scenarios due to reduced potable water production for flush water, reduced electricity use at the wastewater treatment plant, and nutrient offsets from struvite precipitation. Despite the greatest reduction of pharmaceutical toxicity, centralized treatment upgraded with ozone had the greatest ecotoxicity impacts due to ozonation operation and infrastructure. Among urine source separation scenarios, decentralized treatment of urine and centralized treatment of urine collected by vacuum truck had negligible cost differences compared with centralized wastewater treatment. Centralized treatment of urine collected by vacuum sewer and centralized treatment with ozone cost 30% more compared with conventional wastewater treatment.