Co-Digestion of Abattoir Effluent and Rumen Content for Waste Management and Biogas Production

Abstract

This study examined the feasibility of using two primary waste types from a local abattoir for waste management and subsequent biogas production. In the study, wastewater (WW) and rumen content (RC) found at a red meat abattoir were used as substrates during anaerobic digestion (AD). An automated methane potential test system (AMPTS III) was employed to digest the substrates at different doses at 35°C. The raw WW exhibited a soluble chemical oxygen demand (sCOD) of 74 g/L, indicating excessively high levels. Following AD, the maximum COD removal was observed during mono-digestion of RC, achieving a removal rate of 92.6% and a final sCOD of 3.2 g/L. The production of biogas was attributed to high RC loadings, wherein a cumulative biogas production of 1791 NmL/gCOD_removed was produced over 24 days, while biomethane and carbon dioxide production was 491.1 NmL/gCOD_removed and 1300 NmL/gCOD_removed over the same period. The study indicated that the inclusion of RC reduced the rate of pH decline in the digester, suggesting its viability as a material for AD. Typically, mono-digestion of the abattoir WW yields biomethane with a purity of up to 96.96%, while mono-digestion of RC yields high amounts of carbon dioxide.