An alternative for the energetic exploitation of sludge generated in the physico-chemical effluent treatment from poultry slaughter and processing in Brazilian industries

Abstract

Brazil is noteworthy in the chicken meat production and processing scenario, consequently, generates effluents with high organic load and high levels of fat that require specific treatment. The effluent treatment system used for this activity is the physico-chemical flotation process, followed by stabilization ponds. The sludge generated in the flotation system requires processing, generally carried out through the cooking of the sludge and separation in centrifugal decanters for separation into 3 phases. Aiming at the development of alternatives for the use of this residue, this sludge was characterized using two coagulant. Samples containing different percentage of sludge added to chips were prepared, and calorific value, proximate analysis and differential thermal analyses were carried out. Both sludge samples were classified as Class II A, i.e., non-inert residues. Sludge II presented low pollutant by-products in its composition, but due to the cost of the organic coagulant being higher, sludge I (generated with the coagulant ferric chloride) was used in the plant test. A boiler combustion test was carried out using 10% of the sludge I added to the chips, where it was evidenced that the addition of sludge to the chips led to more stable boiler pressure and a decreased of the fuel supply screwthread speed. The combustion of this sludge together with chips reduces significantly the costs, avoids risks of possible environmental liabilities due to transportation, reduces the use of primary fuel (chips) and stimulates the use of biofuels generated from the residual biomass in the industrial unit itself.