Methane production from vivarium waste using ruminal fluid as inoculum

This study aimed to evaluate the efficiency of anaerobic biodigesters in processing vivarium residues as substrates, using ruminal fluid as an inoculum for methane production and organic matter reduction, thereby mitigating the environmental impacts associated with the improper disposal of these wastes. The experiment utilized 2L Duran® flasks, operated in duplicate as batch reactors, fed with pine bedding (R1), corn cob bedding (R2), and sugarcane bedding (R3). The reactors were maintained under static conditions at approximately 37 °C. The highest accumulated methane production was observed in reactor R1, fed with pine bedding, yielding 12.56 L-CH4, with a maximum daily production of 0.0067 L-CH4/g-VS/d and a methane yield of 256 mL-CH4/g-VS. In comparison, reactors R2 and R3 produced 5.24 L-CH4 and 6.83 L-CH4, with methane yields of 70 mL-CH4/g-VS and 120 mL-CH4/g-VS, respectively. Statistical analysis confirmed the superior performance of R1 (p-value < 0.05). Additionally, the consumption of volatile acids in R1, along with a final pH of 7.2, created favorable conditions for methanogenic microorganisms. In contrast, reactors R2 and R3 experienced medium acidification, which likely inhibited methane production. These findings demonstrate that waste generated at laboratory animal breeding facilities holds potential as a substrate for methane production when processed using anaerobic digestion technologies.