Characterization of raw swine waste and effluents treated anaerobically: parameters for Brazilian environmental regulation construction aiming agricultural use

Abstract

In Brazil, swine raw waste from pig stall cleaning (SRW) represents an important water and nutrients sources for crops. However, treatment systems have been searched for to reduce its contaminant loads, making swine effluent agricultural use possible. Therefore, the study purpose was to evaluate agricultural use potential of swine effluents from anaerobic treatment system, considering current legislations. SRW was sieved and treated in anaerobic digester, with hydraulic retention times (HRT) equal to 100, 130, 30, 180 and 210 days. Treated effluent from digester (SEB) was diluted with water (SED) (1:50, v:v), simulating effluent characteristics from a complete treatment system. Chemical, physico-chemical, and microbiological parameters were determined in effluents. There were reductions of 80 to 90% in organic load, P, Ca, Cu, Zn, Fe, Mn and Mg contents. There were fecal coliforms and Salmonella spp. elimination. Nevertheless, there was other coliform bacteria growth. SEB presented EC, N-NH4+, and Na values higher than standards for agricultural use. Cu and Zn contents of SEB were reduced only when HRT were higher than 100 days. Thus, treated swine effluent use should be regulated by agricultural and environmental criteria established by future legislation, considering most pollutants elements, such as N, Na and pathogens.