USO DA COMPOSTAGEM NA RECUPERAÇÃO DE RESÍDUOS DE LATICÍNIOS

Abstract

Agroindustry activities aim to transform agricultural raw materials into consumer products that meet human needs. The great amount of organic materials generated by the industries is responsible for the greater environmental impact, by the formation of organic acids from the fermentation of the residues, resulting in bad odors, reduction in the amount of dissolved oxygen in the waters and contamination of the soil. At the end of the process, the dairies generate biological sludge as a by-product of the treated effluent obtained and the boiler ashes resulting from the combustion of the wood in the furnaces for steam generation. Another problem in the process is the production of sewage sludge due to the large volume generated and the high organic load and total solids concentration. Composting is a simple technique, considered ideal for recycling organic waste from agroindustry’s. The IN Nº 25/2009 classifies organic compounds obtained through the composting of agroindustry residues as composite organic fertilizer. The objective of this work was to search for technological alternatives to minimize the environmental contamination of dairy residues using the composting method for the generation of a composite organic fertilizer. The treatments were composed of pure sewage sludge (T1) and mixtures of sludge with other residues, being (T2) sludge + manure; (T3) sludge + ash; (T4) sludge + grass; (T5) sludge + grass + ash; (T6) mud + manure + gray and, (T7) mud + grass + manure + gray. A completely randomized design was used in a factorial scheme, with seven treatments and three replications. Composting proved to be an efficient method for the treatment of sludge produced at a dairy effluent treatment plant. It was verified that the stabilization of sewage sludge occurs from 33 days and that composting occurs at mesophilic temperatures. The addition of grass pruning to the sewage sludge in the composting process provided the greatest reductions in weight and volume, adequate pH, moisture content and C / N ratio.