Avaliação dos meios filtrantes combinados no tratamento da água residuária da suinocultura

Abstract

The increasing demand for pork and its derivatives stimulated the expansion of the pig sector, culminating in the increase of production and export, the number of animals in the production units, the intensification of the confinement plants and consequently the increase of the solid and liquid residues generated. These residues are highly polluting, and when not properly treated can cause negative environmental impacts to water, soil and air. Thus, the use of materials of organic origin as a filter medium in the treatment of wastewater can be an efficient and low-cost alternative, which can minimize the damages resulting from the discharge of effluents, without prior treatment, in receiving or soil water bodies. The objective of this work was to evaluate the performance of the filtration process using a filter consisting of the combination of different ratios of wood sawdust, sugarcane bagasse and organic compost in the swine wastewater treatment (ARS). Residual water was obtained from the swine breeder's estuarine and, before being stored, the ARS was passed through a 2 mm mesh sieve. It was then transferred to a polyethylene water box, where it was redistributed to the filters, positioned on a support at a lower level by gravity action. The filtration occurred until 100 L, and the filtrate was collected every 20 L. The experiment using organic filters was installed in a randomized block design, with 4 treatments, with four replications totaling sixteen experimental units. The media were characterized according to moisture content, total and particle density, total porosity and pH. The crude ARS and filtered effluents were evaluated for the physical characteristics: total solid (ST), suspended (SST) and sedimentable (SSD), electrical conductivity (EC) and apparent color and chemical, such as hydrogenation potential (pH), Biological oxygen demand (BOD), chemical oxygen demand (COD), phosphorus (P), ammoniacal nitrogen (N-NH3) and metals (Na, K, Ca, Mg, Mn, Fe, Cu and total Zn). According to the results, it was verified that although the crude ARS was very diluted, it still had high polluting capacity evidenced by the contents of SST, SSD, BOD, N-ammoniacal, Mn, Cu and Zn. It was also verified that all evaluated treatments proved to be efficient in the removal of all the physicochemical parameters investigated, especially in the reduction of the total metal’s contents, with the exception of Mg, K, Na, which had their high concentrations in filtered effluents. The insertion of the organic compound in the filter column significantly influenced the BOD, COD, P, K, Mg, EC and pH variables. By means of principal component analysis (PCA) it was possible to verify that no variables (physical and / or chemical) investigated in this research correlated with those of crude ARS. All organic filters evaluated (consisting of double and triple layers and in different proportions of materials) were efficient and presented the potential to be installed in rural properties and to be part of an effluent treatment unit.