Pre-treatment of fruit and vegetable waste prior to BSFL composting does not improve efficiency but simplified processing

In our latest publication on black soldier fly larvae (BSFL; Hermetia illucens) composting, we investigated the impact of pre-treatment on process efficiency and greenhouse gas emissions. We evaluated BSFL composting of broccoli and cauliflower cuttings and orange peel with and without pre-treatment, and compared the results to those for food waste (control). The two pre-treatments we investigated were a 2 w inoculation with 1) the fungi Trichoderma reesei or 2) ammonia solution. The hypothesis was that the fungi would break down cellulose and hemicellulose to easily available carbohydrates, while the idea with the ammonia pre-treatment was that it would both break cellular structure and add nitrogen for the microbial community to assimilate into proteins.

We found that none of the pre-treatments increased process efficiency.  The fungi pre-treatment even lowered the efficiency, but dried the substrate, simplifying the separation of larvae from the treatment residue (frass) while also increasing the waste processing capacity. The ammonia pre-treatment did not reduce the overall efficiency, but it did lower the overall greenhouse gas emissions of the cuttings, albeit increasing the ammonia emissions. We conclude that pre-treatment prior to BSFL composting may be of interest under certain circumstances, potentially when dealing with wet substrates (such as vegetables) or when high waste throughput is advantageous.

Contact: Cecilia Lalander

Leave a comment

Your email address will not be published. Required fields are marked *