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.