LAUSR

Cow manure with bedding is a renewable organic biomass, available around the year on dairy farms. However, its reuse is hampered by many factors including existence of potential pathogens. Efficient and cost-effective dry anaerobic digestion at low temperatures (20 °C and 28 °C) can be used to eliminate pathogens. At the same time, it can provide energy and income to dairy farms. A dry anaerobic digestion process was used in this study to investigate its effect on methane production and removal of pathogens. This operational feasibility study showed that (i) the digester operating at 28 °C obtained 50% higher specific methane yield (0.229–0.286 LCH4/gVSfed) compared to 20 °C. This value was similar to those obtained by mesophilic (35–38 °C) digesters (0.228–0.302 LCH4/gVS), while the net heat energy requirement to maintain the digester temperature was lower in our digesters; (ii) approximately 90–100% pathogens (E. coli, streptococcus, total gram-negative bacteria, Salmonella and Klebsiella) were eliminated in the dry anaerobic digestion process. These results are encouraging to reuse digested material as an alternate economical bedding source for dairy cows.