A full-scale house fly (Diptera: Muscidae) larvae bioconversion system for value-added swine manure reduction

Manure produced from confined animal farms can threaten public and environmental health if not managed properly. Herein, a full-scale commercial bioconversion operation in DeQing County, China for value-added swine manure reduction using house fly, Musca domestica L., larvae is reported. The greenhouse-assisted larvae bioreactor had a maximum daily treatment capacity of 35 m(3) fresh raw manure per day. The bioconversion process produced a fresh larvae yield of 95-120 kg m(3) fresh raw manure. This process provided an alternative animal foodstuff (having 56.9 and 23.8% protein and total fat as dry matter, respectively), as well as captured nutrients for agricultural re-utilization. Bioconversion reduced odour emission (characterized by 3-methylindole) and the Escherichia coli (E. coli) index by 94.5 and 92.0%, respectively, and reductions in total weight, moisture and total Kjeldahl nitrogen in solids were over 67.2, 80.0 and 76.0%, respectively. Yearly profit under this trial period ranged from US$33.4-46.1 per m(3). It is concluded that swine manure larvae bioconversion technology with subsequent production of value-added bio-products can be a promising avenue when considering a programme to reduce waste products in an intensive animal production system.