Effectiveness of black soldier fly larvae in composting mercury contaminated organic waste

Black soldier fly larvae composting has been the new composting technology fast rising in most developing countries. Each larva can consume up to 200 mg of food waste per day as well as possessing the ability to accumulate and remove some toxic substances from compost. This research studied the effect of composting organic waste containing heavy metals, mercury (Hg) in particular using the black soldier fly larvae. Organic food wastes (cooked rice, uncooked yam, and vegetables) mixed with chicken faecal matter and sawdust were dosed with varying concentrations of mercury salt of 100 0 mg, 20 00 mg and 30 00 mg. 100, 20 0 and 300 larvae were then introduced to the dosed samples for 13 days period during which they were studied. Triplicates of each sample were analysed at the laboratory, it was observed that the rate of removal of mercury from the compost was relatively proportional to the number of larvae in the sample. Larvae were able to accumulate a reasonable amount of mercury from the sample. Mercury levels in the compost after the 13th day were noted to be below the European Union's (EU's) threshold values of 0.7-10 mg Hg/kg. NPK analysis also proved that the compost was high in the required nutrient to support plant growth. (C) 2019 The Author(s). Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative.