Bioconversion of sludge waste by black soldier fly (Hermetia illucens) larvae: A review of the potential use of food and beverage industry sludge as a rearing substrate

Sludge is a heterogeneous waste stream whose volume and composition complicate treatment and disposal. Black soldier fly (BSF) larvae offer a biological valorisation pathway capable of transforming sludge into protein-rich feed and organic fertiliser. This review synthesises current evidence on BSF-based sludge management with two distinct contributions. First, it consolidates process levers that materially influence bioconversion performance—including substrate physicochemical properties, larval feeding dynamics, moisture management, and thermal and aeration regimes—and provides guidance for standardising experimental and operational conditions across studies. Second, it presents the first structured evaluation of food and beverage industry sludge as a candidate BSF substrate, assessed through both nutrient adequacy and contaminant risk lenses. The analysis indicates that while food and beverage industry sludge exhibits favourable organic content, its nutrient balance and potential inhibitory components are unlikely to support efficient larval development on a standalone basis. Consequently, co-feeding or targeted pre-treatment (e.g., dilution, fermentation, microbial addition, etc.) will likely be required to achieve reliable conversion outcomes. This work establishes a foundation for the systematic optimisation of BSF-assisted sludge valorisation and highlights priority areas for future research. • Sludge valorisation by BSF larvae is attractive in the circular economy concept • F&B industrial sludge is rich in protein, fat, and fibre, suitable for BSF substrate • Additional nutritious substrates promote larval growth and development • Heavy metals, pathogens, and other potential contaminants must be addressed • A pre-treatment is necessary to enhance its solubility and biodegradability