Techno-economic analysis of an integrated process for cyanobacteria-based nutrient recovery from livestock waste

Abstract

The dairy industry operates as a linear economy in which large amounts of non-renewable energy and mining resources are used for the production of synthetic chemical fertilizers (e.g., phosphate rock and ammonia). Moreover, significant greenhouse gas emissions and nutrient emissions result from the improper management of manure waste, leading to the simultaneous degradation of valuable air, soil, and water resources. In this work, we present a techno-economic analysis (TEA) framework to investigate the viability of an integrated process that aims to recover nutrients from dairy manure. A central tenet of the proposed process (which we call ReNuAl) is that it uses cyanobacteria (CB) as a key integrative component that simultaneously: (i) harnesses renewable energy to capture waste nutrients and (ii) captures carbon dioxide that results the anaerobic digestion of waste. In this way, ReNuAl provides a pathway to a more circular fertilizer economy that helps manage air and water pollution. Our TEA framework is used to evaluate the phosphorus recovery costs (PRC) under varying levels of process integration. Our analysis reveals that ReNuAl reduces emissions by 57% compared to land-application of manure and has a PRC of $119/kg. A sensitivity analysis show that the PRC can be reduced if P density is improved. This analysis highlights key aspects of the process that have the most impact on economic/environmental performance and to provide performance targets for new CB strain variants.