Bioconversion of water treatment sludge and food waste with soldier fly larvae to produce fat with energy
Introduction: This article presents the results of research conducted in 2025 at the Universidad de América in collaboration with the Universidad Distrital, entitled “Evaluation of the biotransformation process of food waste for the production of biodiesel and organic fertilizers using black soldier fly larvae (Hermetia illucens).” The study evaluates the bioconversion of wastewater treatment sludge and food waste using Hermetia illucens larvae to obtain lipid-rich biomass for energy production within a circular economy approach.
Problem: The increasing generation of sludge and food waste generates environmental impacts and limits resource recovery, thereby requiring sustainable strategies that convert waste into value-added bioenergy products.
Objective: To assess the feasibility of producing energy-rich lipids through larval bioconversion of sludge–food waste mixtures, optimizing substrate ratios and downstream processes.
Methodology: Four treatments with different sludge/food waste proportions were evaluated. Indicators included survival, growth, waste reduction, and bioconversion efficiency. Batch and countercurrent washing were compared; drying was evaluated at 60 °C, 75 °C, and 100 °C; and oil extraction was performed using Soxhlet (hexane), countercurrent ethanol extraction, and mechanical pressing. Data were analyzed using one-way ANOVA (α = 0.05).
Results: A higher proportion of food waste improved survival (>95%), growth, and lipid yield. Countercurrent ethanol extraction achieved the highest recovery (33.27%), exceeding Soxhlet extraction (27.70%) and mechanical pressing (0.055%). Drying at 100 °C was the most energy-efficient, while countercurrent washing reduced water consumption by 80%.
Conclusion: Optimized feeding conditions and resource-efficient operations enable the sustainable conversion of sludge–food waste mixtures into lipid-rich biomass for bioenergy applications.
Originality: The study integrates substrate design, water-efficient washing, energy-efficient drying, and green extraction techniques within a scalable framework.
Limitations: The study was conducted at laboratory scale.
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