Food waste (FW) is a common source of contamination, contaminating both soils and water bodies by releasing greenhouse gases. FW holds great potential for biofuel and bioproduct production, which can mitigate its environmental impact and become a valuable addition to the circular bioeconomy. Therefore, this work aimed to investigate the use of food waste as a substrate to produce fermentable sugars and bioethanol. FW was pretreated by lipid removal. Raw and treated FW was hydrolyzed by amylases. Also, FW was hydrolyzed using sulfuric acid under different residence times (20, 40, and 60 min), sulfuric acid concentrations (0.5, 1.0, and 1.5% v·v⁻¹), solid loads (5, 10, and 15% m·v⁻¹), and temperatures (111, 120, and 127 °C). The best reducing sugar concentration was obtained at a 1.5% concentration of sulfuric acid and a 15% solid load applied for 1 h at 127 °C. The acid hydrolysis process was more efficient (76.26% efficiency) than the enzymatic one (72.7%). Bioethanol production was carried out as static submerged fermentation, with Saccharomyces cerevisiae at 10% (humidity m·v⁻¹) being used as the producer and the acid and enzymatic hydrolysates being used as carbon sources. Lipid removal from FW did not influence the acid or enzymatic hydrolytic processes. For fermentation, the highest bioethanol yield was obtained from the acid hydrolysate of raw FW (0.49 kg·kg glicose⁻¹). Thus, the processes used were efficient for bioethanol production, presenting alternatives for sustainable food waste destinations and low-cost biofuel production.

Food waste (FW) presents a critical issue, representing an environmental liability and a largely untapped resource. Its heterogeneity and low valorization rate among main-stream alternative treatments challenge its integration into economically and environmentally sustainable bioprocesses. We explore biorefineries as a solution that can address the complexity of urban food waste through biological strategies capable of converting food waste into valuable products. Exploring the current landscape of FW biorefineries, this study focused on the interplay between feedstock heterogeneity, pretreatment strategies, microbial dynamics, and integration potential. We propose a framework distinguishing between robust fermentations that can use minimally treated FW and tailored fermentations, which require refined media pretreatment and/or supplementation to yield higher-value compounds. Drawing on recent techno-economic and life cycle assessments, this article evaluates process viability and environmental impacts across multiple scales, reinforcing the need for robust analysis to support decision-making. Real-world initiatives and policy frameworks are analyzed to contextualize technological advances within regulatory and infrastructural realities. By linking practical constraints to biochemical and operational strategies, this work outlines how food waste biorefineries can contribute meaningfully to circular economy goals. Instead of treating FW as an intractable problem, it is seen as a versatile feedstock that demands integration, investment, and adaptive process design.

The search for alternative and sustainable energy sources becomes urgent as energy demand increases and fossil fuels become less available, especially in water‐scarce regions such as the Brazilian semi‐arid region, where current projections of global warming and the expansion of arid and semi‐arid zones point to a future of desertification. Prickle pear is a forage Cactaceae adapted to arid environments due to its crassulacean acid metabolism, standing out as a promising plant for biogas production. Its high water use efficiency, low lignin content, and high soluble carbohydrate and mucilage content favor anaerobic digestion without the need for costly pretreatments. The biogas production potential from the anaerobic digestion of the Orelha de Elefante Mexicana variety, cultivated at the Agronomic Institute of Pernambuco, was evaluated through the physical–chemical characterization of the biomass and biochemical methane potential tests, with three organic loads of volatile solids (5, 10, and 15 g VS L ⁻¹ ) over three sequential cycles, creating a recycling‐type experiment. The 5 g VS L ⁻¹ load resulted in the highest biogas yield (0.391 L g ⁻¹ VS ⁻¹ ) and the highest‐quality gas, achieving 63.8% methane in the third cycle. The identification of the predominant microorganisms in the process through metagenomic analysis provided insights into process optimization and a better understanding of the microbial ecology involved. The results highlight the potential of forage cactus as a viable and sustainable alternative for bioenergy generation in the Brazilian semi‐arid region, contributing to the diversification of the regional energy matrix.