Enhanced Ammonia Content in Compost Leachate Processed by Black Soldier Fly Larvae

Black soldier fly (BSF) larvae (Hermetia illucens), feeding on leachate from decaying vegetable and food scrap waste, increase ammonia (NH₄⁺) concentration five- to sixfold relative to leachate unprocessed by larvae. NH₄⁺ in larva-processed leachate reached levels as high as ∼100 mM. Most of this NH₄⁺ appears to have come from organic nitrogen within the frass produced by the larvae as they fed on leachate. In nitrate-enriched solutions, BSF larvae also facilitate dissimilatory nitrate reduction to ammonia. The markedly higher concentration of NH₄⁺ recovered in leachates processed with BSF larvae and concomitant diversion of nutrients into insect biomass (itself a valuable feedstock) indicate that the use of BSF larvae in processing leachate of decaying organic waste could be advantageous in offsetting capital and environmental costs incurred in composting.