Diagnóstico e prognóstico de um sistema de efluente de frigorífico de suínos para remoção de nitrogênio amoniacal

Abstract

Due to the great amount of pollution of water bodies, the treatment of effluents has gained importance in the national scenario to guarantee the environmental quality of the aquatic biota. However, the difficult to remove pollutants, such as ammoniacal nitrogen, make treatment difficult, requiring large investments in treatment systems to meet the legal standards. Thus, the present study aims to characterize an effluent plant of a pork slaughterhouse, which consists of preliminary and primary treatment, secondary treatment and post-treatment. After the evaluation of the system, it was identified that there is a large presence of solid material due to the inefficiency of the primary treatment, and the insertion of biofertilizer at the beginning of the secondary treatment causes a higher concentration of ammoniacal nitrogen in the final effluent, because the lagoon of complete mixture do not present the necessary power to remove this pollutant, besides having disposition is erroneous. Therefore, with the detailed evaluation of the system, four improvements were proposed for a better removal of ammoniacal nitrogen, being the installation of an air dragging column - Stripping - restructuring and installation of new aerators in the aerated lagoon of complete mixing, installation of a activated sludge or the installation of a sludge thickener after the biodigester. All treatments have high efficiency, however, they are not able to remove the inserted load of ammoniacal nitrogen when installed separately. Thus, the study showed that the best option is the thickening of the sludge for later use in agricultural soil and modification in the aerated lagoon system to an activated sludge system, which has the capacity to remove 50% of the ammoniacal nitrogen present in the effluent. These modifications allow the continuous improvement of the effluent treatment system as well as the reduction of possible impacts that effluent discharge into the receiving body could cause to the aquatic biota, such as eutrophication.