USED DIATOMACEOUS EARTH: CHARACTERIZATION AND POTENTIAL FOR REUSE

Approximately 98% of the brewing industries use diatomaceous earth (TD) as a filter medium due to its efficiency in clarifying beer. However, after use, TD is discarded, presenting a high organic and inorganic load. Improper disposal of this material can generate environmental impacts, such as soil and effluent contamination. This study aimed to characterize DT before and after use and to propose chemical and biochemical treatments capable of enabling the reuse of the material or mitigating its environmental impact, in accordance with the guidelines of the National Solid Waste Plan (PNRS, Law No. 12.305/2010). The virgin TD and the used TD (TDU), used in beer filtration, were collected in a medium-sized brewing industry located in the Metropolitan Region of São Paulo (SP), stored in airtight containers and kept at –18 °C until the analyses. Physicochemical determinations of moisture, ash, proteins, lipids (on a dry basis) and carbohydrates (by difference), as well as pH and total acidity, were carried out according to methodologies of the Adolfo Lutz Institute (IAL, 2008). Morphology was evaluated by scanning electron microscopy (SEM). The physicochemical characterization showed alterations in the LUTT in relation to the virgin LUT. The pH decreased from 9.5 ± 0.1 (TD) to 5.3 ± 0.1 (TDU) and total acidity to 8.3% ± 0.1, indicating adsorption of acidic organic compounds from the beer. Moisture content increased from 0.1% ± 0.0 to 63% ± 0.1, reflecting the liquid holding capacity of the matrix