Avaliação do tratamento de águas residuárias em reatores de leito móvel com biofilme de um laticínio da Zona da Mata de Minas Gerais

Abstract

The dairy sector has social and economic prominence. The dairy industries demand water resources in their production activities. It is estimated that each liter of processed milk generates, on average, one to three liters of dairy wastewater (ARL). Such segments require effluent treatment systems that are effective and meet environmental requirements. This study proposes to investigate the use of a Moving Bed Biofilm Reactor (MBBR) in a dairy industry. Therefore, parameters such as pH, biochemical oxygen demand (BOD5), chemical oxygen demand (COD), oils and greases and total suspended solids (SST) were characterized, in addition to the removal efficiencies of BOD5 and COD in the primary effluent. and secondary. These results were compared with the limits established in the Joint Normative Deliberation COPAM/CERH nº 01/2008 for the discharge of effluents into water courses. Control parameters such as: Hydraulic Detention Time (HRT), F/M Ratio, Volumetric Organic Load - VOC, Sludge Volumetric Index - IVL and Total Suspended Solids in the Aeration Tank - SSTA were evaluated. The bacterial growth curve, biological floc quality and the characterization of microorganisms present in the suspended biomass were analyzed. Finally, kinetic constants of organic matter removal (BOD5 and COD) were determined along the length of the MBBR 1 and 2 reactors. The system operates in full scale in a dairy located in the Zona da Mata region in the state of Minas Gerais. It has a useful volume of 180 m³, Hydraulic Detention Time - TDH of 14 (±1) hours and an influent flow of 13.5 (±2.6) m³/hour. For the characterization study of the discharge parameters in the watercourse, the collections of the primary effluent were carried out at the outlet of the primary treatment system (flotation tank) and the secondary effluent at the outlet of the decanter for a period of 9 consecutive months. For the kinetics study, collections were carried out every 3 days at 9 points totaling 27 samples, the first point (primary effluent) and the second point (beginning of MBBR 1) being collected simultaneously, the other points (MBBR 1 and 2), with collection intervals of 2 hours and with a distance of 1.18 m throughout the reactor. Microscopic analysis was carried out through 3 collections carried out in MBBR 1 in a period of 2 years. The parameters analyzed meet the legislation with the exception of SST in two specific months. The system showed an average efficiency of 98% in the removal of BOD5 and COD, being an efficient alternative for the treatment of ARL when operated in conjunction with the float. The operational parameters are consistent with the typical parameters for the operation of MBBR reactors. The microscopy analyzes demonstrated the presence and performance of the microbiological community that acts in the removal of organic load from industrial effluents and its variations in the face of changes in the characteristics of the affluent as a result of the production processes of the dairy. In the study of degradation kinetics of BOD5 and COD, the removal averages found in MBBR 1 and 2 are significant for both parameters, that is, 94.9% and 94.8% respectively. The MBBR mobile milk biological reactor demonstrated satisfactory efficiency when operated in conjunction with the primary treatment system (flotter).