Cattle Waste Treatment and Class A Biosolid Production Using Temperature-phased Anaerobic Digester

Abstract The performance of the temperature-phased anaerobic digestion (TPAD) process in the digestion of livestock wastes has never been evaluated, though the process has proven advantages over other high-rate anaerobic digestion processes in the treatment of municipal wastewater sludge. This study investigated the applicability of the TPAD process in the stabilization of dairy cattle manure. For the organic loadings investigated from 1.87 to 5.82 g VS/l/day, volatile solids (VS) reduction in the range 36–41% was achieved with biological conversion efficiency of 0.52–0.62 l methane/g of VS destroyed. Fecal Coliform and Salmonella counts in the residual solids were less than the limits specified by U.S.E.P.A. to meet Class A Standards. The high volatile fatty acid concentrations in the thermophilic effluent were reduced significantly by the mesophilic stage and ammonia nitrogen concentrations in the reactors were below inhibitory levels. The process was stable at all the organic loading rates studied.