Recycling Hydroalcoholic Waste as a Low-Cost and Sustainable Management Strategy

Laboratory routines in Botany and related fields generate substantial volumes of hydroalcoholic waste, which is frequently thrown away despite its potential for recovery. This study aimed to develop and evaluate a low-cost distillation apparatus constructed from readily available materials for recycling such residues in university laboratories. Hydroalcoholic waste collected from four Botany laboratories was homogenized and subjected to simple distillation, followed by adsorption with activated carbon and filtration. From 1500 mL of waste (~70 °GL), 1100 mL of ethanol at a volume-weighted concentration of 73.6 °GL were recovered. After dilution to 70 °GL for comparison with commercial ethanol, the final volume corresponded to 1156 mL. The mean electrical energy cost per distillation run was R$ 1.68, resulting in an estimated production cost of R$ 1.45 per liter of 70% ethanol. This value represents an approximate 85% reduction relative to the average market price, as the average market price of 1 L of 70% ethanol was R$ 9.95. The proposed protocol demonstrates technical feasibility and economic viability while reducing the volume of hazardous liquid waste generated in teaching and research laboratories. By integrating accessible materials and fundamental physicochemical principles, the method offers a practical and sustainable alternative for decentralized laboratory waste management in public institutions.