Biomethane Potential of Beef Cattle Slaughterhouse Waste and the Impact of Co-Digestion with Cattle Feces and Swine Slurry

Slaughterhouse waste (SW) poses significant environmental challenges due to its complex composition, but anaerobic digestion offers a way to recover valuable biogas from SW. This study investigated the anaerobic co-digestion of beef cattle slaughterhouse waste (BCSW) with either cattle feces (CF) or swine slurry (SS). The biomethane potential, maximum methane yield (Mmax), lag phase duration, and effective digestion time (Teff) for the individual substrates and the combinations were analyzed. BCSW alone exhibited Mmax of 578.5 Nml CH4/g VSadded with a lag phase of 11 days, while CF and SS alone exhibited Mmax of 397.2 and 289.8 Nml CH4/g VSadded, respectively. Co-digestion of BCSW and SS resulted in Mmax increase of 48–75.5%, with negligible effects on Teff compared to solitary SS digestion. Similarly, co-digestion of BCSW and CF increased Mmax by 6.2–40.4%, with no significant impact on Teff compared to solitary CF digestion. However, both co-digestions led to a reduction in Mmax (12.1–27%) when compared to BCSW digestion alone. Co-digestion with SS shortened the lag phase duration by 2.8–7.8 days and accelerated Teff by 5.8–8.3 days due to SS’s high concentrations of essential micronutrients like cobalt and nickel which aid digestion. This study concluded that co-digestion of BCSW with SS is an effective strategy for enhancing methane production and digestion efficiency, offering a viable approach for proper disposal of BCSW while improving biogas output.