Estudo da remoção de arsênio e de outras espécies potencialmente tóxicas presentes no chorume de aterro sanitário utilizando fibra de coco verde

Abstract

The industrial production chain is responsible for generating large volumes of waste and effluents, which are generally disposed of inappropriately in the environment, causing environmental impacts. In the coconut industry, the main waste is shell, while in landfills, leachate is generated as a liquid that has a high pollutant load, mainly potentially toxic metals. The disposal of effluents containing potentially toxic metals into water bodies is permitted if it meets the concentration conditions required by resolution no. 430 of the National Environmental Council (CONAMA). Given this scenario, the development of clean and renewable technologies to mitigate these problems and contribute to sustainability. In this context, the objective of this work was to study the removal of arsenic and other potentially toxic inorganic species present in a leachate generated in a landfill, using green coconut fiber as a remedial material. The leachate was characterized in terms of biochemical oxygen demand (BOD5), pH measurement, and determination of potentially toxic inorganic species. In relation to coconut fiber, beyond untreated fiber, three pretreatments were carried out (thermal, alkaline, and acid/basic). In thermal treatment, the coconut fiber was treated with water at 80 °C; in the alkaline treatment, the fiber was treated with sodium hydroxide; and in the acid/basic treatment, nitric acid and sodium hydroxide were used to treat the fiber. The characterizations performed on the four types of fiber were the determination of ash, moisture, chemical composition, and chemical structure by means of Fourier transform infrared spectroscopy (FTIR). For the experiments to remove potentially toxic inorganic species, the four coconut fibers were used. In addition to fibers with different treatments, the pH, time, and temperature were varied in the removal processes of arsenic and other inorganic species. For the leachate analysis, the possibly toxic metal outside the specified standard was arsenic, with an initial concentration of 0.73 mg L-1 . The greatest reduction in arsenic concentration in the leachate studied occurred with the use of untreated fiber. This arsenic reduction was obtained in 250 minutes, at room temperature (22 °C), at the original pH of the leachate (8.3), and using 50 g of coconut fiber per liter of leachate. Under these conditions, the arsenic concentration decreased from 0.73 to 0.58 mg L-1 , with a reduction of more than 20% in the original arsenic concentration. The results indicate that untreated coconut fiber showed promise in removing arsenic from leachate, highlighting the simple operating conditions, eliminating the need for chemicals, and contributing to the environment. This highlights the potential of coconut fiber as a natural adsorbent for removing arsenic from contaminated effluents.