Life Cycle Assessment of a Bacterial-Algal-Zooplankton System for Conversion of Anerobic Digestate into Fishmeal

Abstract

A bacterial-algae-zooplankton system was proposed to cultivate zooplankton on digestate-grown algae as a fishmeal replacement for aquaculture. The proposed system was designed for the purpose of creating a more sustainable alternative to direct land application of anaerobic digestate. This work develops a process model to predict the material flows of a fullscale system based on experimental data and uses this information to perform a life cycle assessment on the system. Seven impact categories were selected for analysis: land use (LU, m2 land/m3 AD), global warming potential (GWP, kg CO2 eq./m3 AD), water use (WU, m3 water/m3 AD), fresh water eutrophication (FWEP, kg P-eq/m3 AD), marine eutrophication potential (MEP,kg N-eq/m3 AD), particulate matter (PM, PM 2.5-eq/m3 AD), and terrestrial acidification (TA,SO2-eq/m3 AD). The results show that the proposed system may provide some environmentalbenefit over direct land application, particularly in the areas of marine eutrophication and terrestrial acidification.