Thermophilic aerobic process for the treatment of slaughterhouse effluents with protein recovery

A pig slaughterhouse effluent was submitted to laboratory runs in order to assess the potential of the thermophilic aerobic process for the treatment of slaughterhouse and meat processing industry effluents with protein recovery. Experiments were conducted at 45 degrees C, 52 degrees C and 58 degrees C with solids retention times of 6, 12, 18, 24 and 30 h in a semi-continuously fed bioreactor. At 45 degrees C and 52 degrees C, over 90% of the Chemical Oxygen Demand (COD) was removed at all retention times investigated. At 58 degrees C, COD decreased by 86%, with the exception of the 6-h retention time. A biomass containing 70% Gross Protein (GP) was recovered. The optimal specific productivity of GP (0.434 mgGP mgCOD(-1) h(-1)) occurred at 52 degrees C with a 6-h retention time. Biokinetic parameters were evaluated by fitting to appropriate mathematical models. Analysis of the GP composition confirmed that the amino acid levels in the recovered biomass meet most animal requirements.