Heterogeneous photocatalysis using rock powder for effluent treatment

Abstract

The industrial sector is constantly looking for methods that boost production, reduce costs and are ecologically viable for its by-products and waste Vinasse, a by-product of the sugar and alcohol industry produced in impressive volumes - between 13 and 18 liters for every liter of ethanol produced - is commonly used for fertigation. However, excessive disposal of this waste in the soil can result in significant damage over time. In this context, several research projects are underway to identify viable techniques for treating this effluent. Heterogeneous photocatalysis, an advanced oxidative process, has been shown to be efficient in many cases, although the use of by-products as photocatalysts is still little explored in the literature. This study investigates heterogeneous photocatalysis as an efficient technique for treating both vinasse and synthetic effluents containing methylene blue dye. By using different concentrations of basalt rock powder as a photocatalyst, the experiments showed a reduction of up to 98.3% in the concentration of dye and reductions in the chemical oxygen demand (COD) and biochemical oxygen demand (BOD) of vinasse of up to 4.4% and 70.8%, respectively. Although COD did not vary significantly, the significant reduction in BOD indicates considerable treatment efficiency. These results not only offer an alternative for the management of vinasse and the use of by-products such as rock dust, but also contribute to the advancement of knowledge about the treatment of industrial effluents, promoting a more sustainable and environmentally conscious industry.