Produção de biocarvão com propriedades adsorventes proveniente de lodo biológico de Estação de Tratamento de efluentes industriais

Abstract

Biological sludge originated during the industrial effluent treatment process constitute one of the main residues of a refinery. Allied to this, hydrocarbons such as toluene are continuously released into the environment. Therefore, methods of removing these contaminants are being studied in order to reduce the high concentrations present in soil and groundwater. The present work aims to evaluate the effectiveness of biochar obtained from the pyrolysis of biological sludge from an industrial effluent treatment plant as an oil adsorbent. In the biochar synthesis process, a pyrolysis of the biological sludge was developed at a temperature of 600ºC, for 30 minutes. The biological sludge was evaluated according to CONAMA Resolution nº 498/2020, which defines the procedures for the production and application of biosolid in soils. A drying bed was implemented on a pilot scale in the Waste Center of a refinery, to reduce humidity and enable the pyrolysis of the sludge. The biochar was characterized in terms of physical and chemical parameters, thermogravimetric analysis (TG), scanning electron microscopy (SEM), energy dispersion spectroscopy (EDX), specific surface area using the BET method and porosimetry. To assess the adsorption capacity of hydrocarbons by biochar, toluene was chosen as a target contaminant because it is soluble in the aqueous phase and is soluble in hydrophobic organic contaminants. The adsorption studies were carried out evaluating the effects of the mass of biochar (m = 0.02 g), toluene concentrations in natural marine water (30 to 350 mg L-1) and the contact time between adsorbent and adsorbate (0.02 to 22 hours). The 1st order pseudo-kinetics model presented a slightly better fit to the experimental data. In addition, it was possible to observe that the isotherm model that best fits these data was the Sum of two Freundlich model. The results obtained in this work showed excellent study conditions, achieving a removal of approximately 87% for toluene, in order to prove the efficiency of the applied adsorption technique, being an important stimulus to the development of technologies for the reuse of this material and cost reduction with its transport and destination. As technical products of this work include the production of biochar from biological sludge, the elaboration of a methodology to reduce the humidity of this sludge and the communication of a patent for biochar