Estudo da eficiência da estação de tratamento de efluentes de uma indústria de extratos naturais

Abstract

Water is an abundant resource used in food production processes. However, with the rapid population growth and rising consumption patterns of society in recent decades have made the consumption of foods that require large amounts of water for their production to increase, this accentuating the problems related to the generation of effluents. Wastewater from food industries has a high organic load and can be markedly colored, being a potential pollutant of the waterbody when not properly treated. Dyes are added to foods with the function of providing color, but these compounds cause bioaccumulation in water bodies causing inhibition of the photosynthesis process by aquatic organisms. Therefore, this work aimed to study the efficiency of the effluent treatment plant of a natural extracts industry from the food additives segment. The parameters chemical oxygen demand, apparent color, temperature, settleable solids, pH and dissolved oxygen were evaluated and compared with the applicable environmental legislation. All tests were performed in triplicate except the chemical oxygen demand test which was performed only in duplicate. Laboratory analysis were performed in accordance with the reference bibliography for wastewater analysis, Standard Methods for the Examination of Water and Wastewater. Microsoft Excel® software was used for the statistical analysis, charts and tables. The results obtained were compared with the Resolution n°430 of the National Environmental Council and with the release history maintained by the company in order to verify the similarity of the data. The study found an average reduction efficiency for the chemical oxygen demand parameter was 81%, reaching the maximum value of 92,5%. For the pH, color, temperature and settleable solids tests, all results were satisfactory and comply with the environmental standards. The dissolved oxygen analyzes indicated a deficiency in the aeration process, although this result does not affect the performance of the WWTP and is not in compliance with current environmental legislation. With the study of the treatment system, it became possible to state that the hypothesis that the wastewater treatment plant, primary flocculation/coagulation treatment and secondary activated sludge treatment, does not work efficiently is not true, since the treatment system used by the company is being effective for the studied parameters. For future work, it is suggested to study the effluent treatment plant efficiency over a longer period in order to verify the influence of seasonality, to evaluate a larger number of parameters such as turbidity, biochemical oxygen demand, total solids, suspended solids, free chlorine, total chlorine, flow rate, total organic carbon and to characterize wastewater to identify compounds that may negatively impact the performance of the WWTP.