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Licentiate thesis, 2021

Process efficiency in black soldier fly larvae composting of plant-based food industry waste

Lindberg, Lovisa

Abstract

Black soldier fly larvae (BSFL) composting, in which biodegradable wastes are converted into animal-feed protein, is a technology that meets circular economy principles. The greatest potential BSFL composting is for mixed food waste, but only plant-based waste is permitted as feed for the larvae. It has lower biomass conversion efficiency (BCE), but this could be improved by pre-treatment.

This thesis investigated process efficiency and GHG and ammonia emissions from BSFL composting using orange peel and broccoli and cauliflower, with ammonia or fungi pre-treatment. The impact of enzyme and ammonia pre-treatment time on process efficiency when using mixed lettuce and cabbage waste was also assessed. Following two weeks of substrate pre-treatment with ammonia and fungi, direct emissions of GHG and ammonia were evaluated. Lettuce and cabbage was pre-treated with enzymes or ammonia for 0-8 days prior to BSFL composting.

BCE on a volatile solids (VS) basis was greater overall for food waste and lettuce and cabbage (~20%) than for orange peel and broccoli and cauliflower (~7%). The BCE was low (6%) in the orange peel control and even lower in both orange peel pre-treatments. Direct addition of enzymes at the start of BSFL composting gave 22% higher BCE compared with the control.

Total emissions of N2O and CH4 were almost four-fold larger for the broccoli and cauliflower control than when pre-treated, indicating that ammonia pre-treatment significantly reduced total GHG emissions with no negative impact on BCE during BSFL composting, but with increased ammonia emissions.

Keywords

Biological treatment; plant-based waste; Hermetia illucens; pre-treatment; ammonia; Trichoderma reesei; enzyme

Published in


ISBN: 978-91-576-9896-4, eISBN: 978-91-576-9897-1
Publisher: Department of Energy and Technology, Swedish University of Agricultural Sciences

Authors' information

Swedish University of Agricultural Sciences, Department of Energy and Technology

UKÄ Subject classification

Environmental Sciences related to Agriculture and Land-use

URI (permanent link to this page)

https://res.slu.se/id/publ/113633