CHEMICAL AND BIOCHEMICAL ASPECTS OF SLAUGHTERHOUSE SLUDGE INTENDED FOR FEED PURPOSES

The protein and fat qualities of both chemically flocculated and aerob ically activated sludge from pig and poultry slaughterhouses were inve stigated. Protein and total volatile nitrogen levels varied considerab ly between and within sludge types and animal species slaughtered. The biogenic amines cadaverine, histamine, and putrescine could be detect ed at various levels. Iron chloride, used as a flocculant, resulted in high peroxide values (148-568 mequiv/kg of fat). Low peroxide values were detected in aerobically activated sludge and chemically flocculat ed sludge in which calcium lignosulfonate was used as a flocculant. Fr ee fatty acid (FFA) concentration ranged from 5 to 10% in activated sl udge and from 10 to 71% in chemically flocculated sludge. Binding of C a2+ from calcium lignosulfonate with FFA most probably accounted for t he high level of FFA detected in this flocculated sludge.