Utilização de lodo de tratamento de efluentes de indústria automotiva e encapsulamento de metais tóxicos em produtos cerâmicos

Abstract

Despite the various existing studies with wastes from wastewater treatments plants for the production of bricks, there is still a lack of further studies on the technological characterization and application only of hazardous industrial wastes originating from the treatment of wastewater from the metal processing automotive industry in the stabilization/solidification with ceramic materials. It was not observed studies, for example, with a joint evaluation of the mechanical properties and encapsulation potential of the contaminants present. Thus, the objective of this work was to evaluate the use of waste obtained from the treatment of wastewater from the metal processing automotive industry for the production of red ceramics, through the evaluation of the mechanical behavior and the potential for encapsulation of contaminants. The waste was initially classified as Class I - Hazardous due to the presence of Se. A clay with a clayey silt character was used to produce ceramic test specimens by pressing and calcining at 950 ºC. In the production of these test specimens, the clay was replaced by 0%, 5%, and 10% waste. The results showed that, after incorporation into the red ceramic, the waste leads to a reduction in flexural and compressive strength, which is accompanied by greater water absorption and porosity, the higher the incorporated percentage. Nevertheless, the parameters are adequate and comply with the requirements and technical regulations with a replacement of up to 5% clay per waste. Changes in mineralogy and chemical composition were observed, but they did not affect the microstructure and mechanical properties. The samples did not show metal leaching above national and international standards for toxicity and limits for groundwater and human consumption, which leads us to conclude that the use of up to 5% of the waste as a replacement for clay ensures compliance with the requirements for good mechanical performance and encapsulation of the metals originally present in the waste.