Avaliação e dimensionamento do sistema de tratamento de efluentes de laticínios da região Sudoeste do Paraná

Abstract

The milk industry and it is derivatives has a great impact on the national, state and regional economy, with milk accounting for about 6% of the coutry’s agricultural production. This work aimed to investigate the effluent treatment system of small and mediumsized milk industry situated in the Southwest of Paraná, analyzing if the effluent meets the demanding environmental standards for launching in the hydrous body or incorporation into the soil, for the parameter: BOD, COD, vegetable oils and animal fat, Daphinia magna e Vibrio fischeri toxicity, established in environmental resolutions, and in case of noncompliance, propose a system with adjustments, through a resizing of systems, providing the fulfilling legislation. The methodology consisted on collecting of the effluent at the entrace and exit of the four milk industry treatment system, preceded by laboratory analyzes made in accredited laboratories to quantify the parameters. The results were compared with the demanding environmental standards for launching values, and the four enterprises did not meet the standard in at least one of the parameters analyzed, and the adaptation proposal was made through a new resizing for all milk industry. The new dimensioning resulted in the installation of a Parshall, with one inch opening for the four projects, the efficiency expected by the screening for removing coarse substances is 71%, being adopted the manual screening for cleaning due to the low flow. The grease box and the equalization tank have had different dimensions for each project, to the detriment of the different flow rates, the hydraulic retention time was the same for all, was adopted three hours for the grease box and 6 hours for the equalization tank. The anaerobic lagoon was dimensioned based on the hydraulic retention time, been adopted five days, the length measurement is twice the width, the expected efficiency was 42% for BOD removal. The facultative aerated lagoon was dimensioned considering the organic load of the effluent, resulting in lagoons with times of 50, 31, 105 and 21 days, for milk industry 1, 2, 3, and 4, was calculated the required energy demands for the correct aeration of the lagoon with the installation of aerators, achieve an 85% conversion efficiency. In place of the lagoon treatment system, a biodigester was designed as a secondary treatment, aiming at reduction parameters and power generation, he projected biodigester presented a time of one day and expected efficiency of 95%, At the end of both methods, the installation of a membrane bioreactor was designed to promote the microfiltration of the effuente, resulting in a 90% removal of the BOD, resulting in an effluent that complied with all the requirements established for the four companies. It was concluded, therefore, the enterprises in operation in the southwest of Paraná, studied in this work, do not meet the standards regarding the release of effluents, requiring adjustments to reduce the impacts caused to the environment.