Low temperature anaerobic digestion response to organic loading rate and bioaugmentation

Experiments were conducted to determine the influence of organic loading ra te (OLR) and Yucca schidigera extract bioaugmentation on the performance of attached-film anaerobic digesters under low temperature conditions (10 deg rees C). The digesters were packed with layered media (polyester above lime stone). Digester performance was evaluated with respect to biogas productio n, methane production, and methane yield based on volatile solids added. Me thane yield increased as OLR was reduced, apparently because of continued d igestion of solids that had accumulated at the higher OLRs. After the OLR w as reduced to its lowest value (0.01 kg VS/m(3).d), yield began decreasing as stable operation was approached. Bioaugmentation appeared to improve met hane production in a digester operated under stress (10 degrees C and a ver y low OLR of 0.01 kg VS/m(3).d).