Abstract/Summary

BACKGROUND: The aim of the present study was to assess the environmental impacts of End-of-Life Dairy Products (EoL-DPs) management via their co-treatment with agro-industrial wastes (AgW) in a centralized biogas facility located in Cyprus using a gate-to-gate LCA approach. Two different scenarios were examined under the framework of this project. In the first one, co-treatment of EoL-DPs with various AgW (in a 20/80, w/w, ratio) was evaluated in a one-stage mesophilic anaerobic digestion (AD) process. In the second scenario, the same amount of EoL-DPs were acidified before methanogenesis with AgW in order to improve biogas production. RESULTS: Prior acidification of EoL-DPs showed a better environmental performance compared to the results obtained upon direct co-digestion in a mesophilic digester, having a total impact of 52.44 Pt against 57.13 Pt respectively. Biogas production upon acidification, and therefore energy yield, was higher reaching up to 22.88 m3 CH4/ton of feed (229.25 kWh/ton of feed), compared to 17.45 m3 CH4/on of feed (174.85 kWh/ton of feed) for the case where no pretreatment was performed. CONCLUSIONS: The acidification of EoL-DPs enhanced the environmental performance of the process by reducing its impact by 8.2% (in Pt equivalents). The energy consumption of the biogas plant mixing equipment was identified as the process hotspot. However, further analysis of the environmental performance of the proposed process is required by extending the system’s boundaries towards a Cradle-to-Grave approach.