Bio-translating Food Waste By Chrysomya Megacephala Larvae

Food waste is characterized by high moisture, salinity and organic mattercontent, which makes it possess duplicity of the perishable and smelly as a waste andthe potential as a recycling biotic resource. There are significant spatial and temporalvariations in components of food waste from different areas due to geographicdifferences, eating habits and cultural traditions. Thereby it is usually difficult toprocess various food wastes with a unitary approach. At present, commonly useddisposal technologies for food waste include incineration, sanitary landfill, ecofeed,anaerobic digestion, aerobic composting, and vermicomposting. However,incineration is featured with heavy energy consumption because of the high moisturecharacter and sanitary landfill occupies a lot of places with the possibility of thesecondary pollution. Other unconventional approaches (except for incineration andsanitary landfill) also have common limitations, such as a long processing period,complex operation, inefficient reclamation and low economic value, when referredto the principle of decrement, innoxiousness, and reclamation. In recent years,more and more attentions have been paid to the food waste reclamation in view ofthe gradually serious predicament of garbage siege. Nevertheless, the food wastereclamation is still in its infancy with many problems of management and disposal.It was found that Chrysomya megacephala (Fabricius), a dominant fly species in the rubbish fields which grew fast (the developmental periods of the larvae justwas4-5days in summer) and laid vast eggs, was easy to be mass reared and had thepotential of bio-translating food waste into insect materials and organic fertilizer.Based on the previous investigation on population selection and domestication adultmass rear, and pure egg acquisition, the C. megacephala larvae were used tobio-translate food waste into maggot and organic fertilizer in the present studies. Themajor results are as follows.(1) There were differences in physical and chemical characters, such as watercontent, pH, and nutrition component, etc, among three sources of food wastes fromfamilies, school canteens, and restaurants. The difference could be reduced byfiltrating water and keeping five days, and then was in favor of C. megacephalalarvae growth in a stable process formula with good translating effects.(2) During the process of using C. megacephala larvae to bio-translate foodwaste, different formulas affected the disposal effects greatly. When water wasfiltrated from food waste, P11formula was favorable (85%food waste+15%accessory A) with the advantage of the least operating costs, the most yield and thebest disposal effects. If water was not filtrated, P12formula was preferred (80%foodwaste+20%accessory A), which had the similar effects to P11.(3) When bio-translating food waste, the suitable egg density, introduced intofood waste, of C. megacephala was0.5g/kg (or could redress inappreciablyaccording to the factual nutrition level of food waste). If the produced maggots wereprepared to be used as stud for next generation, the suitable quantity of eggsintroduced was0.3g/kg.(4) C. megacephala larvae could dispose three sources of food waste deposited1-7days. However, food waste deposited5days produced the most larvae yield withthe heaviest body weight, the longest body length and the best disposal effects. Thecrude fat content of the dry larvae was between25.0%and30.0%, which wouldmake it to be a potential oil insect having huge potential applications in bio-diesel oil,chemical oil and health-care oil. The crude protein content of the dry larvae wasabout50%and even exceeded70%when defatted, which was comparable with the import fish powder. The organic substance content of the organic fertilizer outputwas between48.0%and52.0%, nitrogen (N) was between3.9%and4.3%,phosphorus (P) was between2.0%and3.1%, kalium (K) was between1.8%and2.6%, crude fat was between1.6%and9.7%, NaCl was between2.6%and3.6%,water was between5.0%and6.0%, and five heavy metal content (Pb<10mg/kg,Cr<10mg/kg, Cd<3mg/kg, Hg<1mg/kg, As<10mg/kg) were all within the permissionrange of the national standard, which revealed that the organic fertilizer output was akind of high quality organic fertilizer. One ton food waste disposed by C.megacephala larvae could obtain about120kg maggots and300kg organic fertilizer(water content was10%), and food waste utilization rate reached nearly100%.(5) C. megacephala larvae could translate and utilize animal, botanic and mixedgrease effectively, and reserve them into their body consequently, advancing thelarvae yield and the disposal effects on food waste.(6) In the condition of a certain translating formula, it's possible to confirmsuitable stuff weight according to the average temperature in each season, forexample,30kg stuff per m~2in summer and40kg invert stuff per m~2in winter, to getbetter loosen degree, ventilation, suitable zymosis temperature, and the best disposaleffect.In summary, using C. megacephala larvae to bio-translate food waste, whichdisposal period was short (5~6d), and the food waste was completely used withoutsecondary pollution, and resource utilization level was high, which was inconformity with the "3R" principles (reducing, reusing and recycling) of organicwaste disposal absolutely, and economic benefit, social benefit and ecologicalbenefit were remarkable.