Life Cycle Assessment and Techno-Economic Analysis of Utilizing Waste Nitrogen to Develop Microbial Protein from Cyanophycin Accumulating Organisms.

To advance a nitrogen circular economy, wastewater treatment plants (WWTPs) must use technologies that recover waste nitrogen and transform it into valuable products. One emerging option is partition-release-recover (PRR) technology. It transforms waste nitrogen into cyanophycin-accumulating organism microbial protein (CAO MP), which can be used as a protein source in animal feed. In this study, we perform a life cycle assessment and techno-economic analysis of a prospective WWTP configuration that incorporates this technology and assess whether it merits further development. Conventional activated sludge and anaerobic/anoxic/oxic WWTP systems are comparator baseline systems. We compare CAO MP to five different protein sources (soybean meal, alfalfa feed, fishmeal, cottonseed feed, and dried distiller grain solubles). The PRR approach has a median GWP that is 1-32% lower than the comparator WWTP systems. The median levelized cost of wastewater treatment using the PRR technology is 34-58% lower than the A2O configuration. Finally, CAO MP shows substantially lower global warming potential and water consumption compared to traditional protein sources. We conclude that the PRR pathway to transform waste nitrogen into CAO MP is a promising pathway toward more sustainable nitrogen recovery technology and protein production, warranting further research and development.