Influência da carga orgânica, intensidade luminosa e aeração no tratamento do efluente de laticínios pelo consórcio Tetrademus obliquus e Cladosporium halorolerans

Abstract

Whey is a residue from cheese production, containing a high organic load and produced in large quantities, thus having a high polluting potential. One way to reduce the organic load and other polluting components of whey is through biological treatment, in which microorganisms capable of degrading toxic substances present in the environment are used. However, for an efficient process, it is essential to know how the process conditions can affect the remediation capacity of these microscopic beings. Thus, the objective of this study is to evaluate the influence of the organic load, light intensity, aeration and pH applied in the treatment of whey using the consortium of the microalgae Tetradesmus obliquus and the filamentous fungus Cladosporium haloterans in a tubular bubble column reactor. The experimental design used central composite planning using 3 factors at 3 levels, with Chemical Oxygen Demand (COD) of 1200, 2100 and 3000 mg.L-1 , light intensity of 50, 100 and 150 µmol.m -2 s -1 and aeration rate of 1.5, 2 and 2.5 vvm. Mathematical models were obtained for the biological treatment of whey during 7 days of treatment with R² of 0.83 for residual COD, 0.88 for residual Total Phosphorus (TF) and 0.90 for residual Total Nitrogen (TN). In addition, the optimum point found was 1200 mg.L-1 of COD, light intensity of 130 µmol.m -2 s -1 and aeration of 1.8 vvm. The mathematical models calculated for the 4-day treatment had unsatisfactory adjusted R² for COD and residual FT, due to the lack of adjustment of the mathematical models and the high noise of the data, caused by the instability of the system during the pH variation caused by fungal growth, while the residual NT presented a satisfactory R². Finally, the validation of the models was performed, but a problem in the aeration source caused impacts in the last days of treatment, despite this, the residual results obtained were in accordance with some standards and legislation for effluent disposal, mainly for the 7-day treatment. A new validation is necessary to confirm the reliability of the mathematical models found in the study.