Treatment of Bakery Wastewater Using Black Soldier Fly (BSF) Larvae: Operation of a Small Continuous Pilot Plant

The management of high-strength wastewater from the food industry represents a pressing environmental and economic challenge. The conventional aerobic and anaerobic treatments often require high energy inputs and generate excess sludge that has then to be treated, highlighting the need for alternative and sustainable approaches. In this context, the LarWaR process (Larvae for Wastewater treatment and Resource recovery), based on the use of Black Soldier Fly larvae supported by porous media, offers an alternative solution that integrates wastewater treatment with resource recovery. This thesis investigates the feasibility of applying the LarWaR process to a tiramisu wastewater, that consists in a high-strength effluent generated by an industrial bakery facility. The study was structured in three phases: suitability analysis, batch treatability tests and continuous-flow trials. The suitability analysis confirmed that tiramisu wastewater exceeded the minimum TOC threshold and presented a macronutrient composition compatible with larval metabolism, making it a viable substrate for LarWaR. Batch experiments demonstrated a trade-off between treatment efficiency and larval growth and a Michaelis–Menten saturation trend was identified, with optimal compromise conditions emerging around 1.5–3 mgC/larva/day. Continuous trials at two representative loads confirmed the predictive capacity of the batch-derived kinetics, with removal efficiencies closely matching the model expectations. However, larval mortality reached 65% during continuous operation, substantially higher than in batch tests. This was likely due to the choice of supporting material, which, under high larval densities, may have impaired respiration and survival. Despite this limitation, overall biomass yields remained within the expected range, reinforcing the process’s potential while underscoring the importance of reactor design.