Using Chrysomya Megacephala Larvae Fed With Food Waste To Integrated Pond Fish Farming

With the development of economy and improvement of living standards,the tourism and catering industry has developed rapidly,and the production of food waste has increased rapidly.The existing treatment methods of food waste has the disadvantages of high cost,imperfect technology,cause secondary pollution,low utilization rate of resources,low safety and potential food chain risks.Therefore,it is necessary to find an efficient and safe method to realize the resource utilization of food waste.Fly insects are sensitive to smell and have wing,it could find organic waste and breeding quickly.Chrysomya megacephala is a dominant species of flies in landfills,with the characteristics of large production of egg and high rate of reproductive.The Chrysomya megacephala larvae grow for 5 to 6 days,which is the period of convert organic waste.In the present study,the larvae were used to convert food waste,and the cultivating of fish by the larvae was conducted.The effect of food waste on the quality of products and the effect of larvae on the influence of breeding effect of Cyprinus carpio var.color were explored.Revealing the enrichment effect of heavy metals and PAHs in the food chain of food waste-larvae-Cyprinus carpio var.color,with the environmental risk and human health risk of heavy metals and PAHs were evaluated.The main research results are as follows:?1?The optimal method of larvae convert food waste is when the inoculum density is2.0 g/kg and the proportion of dish food waste is 80-100%.1 kg food waste could produce about 200 g of fresh larvae,and the conversion rate of food waste more than 60%.?2?Crude protein content,crude lipid content and the sum of them in larvae were40-50%,more than 35%and 80%,respectively.Essential amino acids content accounted for 47.1%of the total amino acids,and the ratio of essential amino acids to non-essential amino acids was 0.89,and met the ideal protein model of the WTO/FAO requested.The pH value of the residue is 5.5-6.9,which met the organic fertilizer standard of China?pH:5.5-8.0?.The total nitrogen content of food waste reduced by 17-66%,total phosphorus content increased by 94-630%,and total potassium content increased by 38-119%.?3?The Fe,Cu,Zn,As,Ni,Cr,Cd and Pb in food waste could be enriched by the larvae.The concentration of As,Cr,Cd and Pb met the feed hygiene standard of China.The heavy metals of excreted or not enriched by larvae enter into the residue,and the concentration of As,Cr,Cd and Pb met the standard of organic fertilizer of China.The potential ecological risk of heavy metals in the residue is slight harm.The mean concentration of PAHs in larvae was 183?g/kg,and the BaP concentration was the highest?46.7%?,with a highest bioconcentration factor?19.8?.The concentrations of 5,6 rings PAHs are higher than 2,3 rings PAHs than 4 rings PAHs.The mean concentration of PAHs in residue was 135?g/kg,and the BaP concentration was the highest?72.5%?.The concentration of 5,6 ring PAHs is higher than 2,3 ring PAHs than 4 ring PAHs.About72%of the residue samples exceeded the limit of TEQ_BaP10aP10 concentration?33.0?g/kg?of Netherlands soil standard,which posed potential ecological risks.?4?When replacing 50%of the fish meal by the larvae,the rate of weight gain,specific growth rate,food intake,feed coefficient and protein efficiency of fish were the best,and when replacing 100%of the fish meal,these indicators were significantly reduced.The replacement of fish meal by larvae had no significant effect on the content of water,crude protein and crude lipid in fish muscle.The variation coefficients of glycine and alanine were 17.1%and 21.6%.The total amino acids increased first and then decreased with the increase of replacement ratio of fish meal.In conclusion,50%is the optimal replacement ratio.?5?The concentration of As,Cr,Cd and Pb in fish muscle met the food safety standard of China.The concentration of 2,3 ring PAHs,4 ring PAHs,5,6 ring PAHs and total PAHs in fish muscle increased first and then decreased as the increase of the replacement ratio,and the group of 50%replacement ratio is significantly higher than the group of 0%and100%replacement ratio.The concentration of BaP is 0.5-0.6?g/kg,ww,met the food safety standard of China?5?g/kg,ww?.Heavy metals and PAHs have no non-carcinogenic risk and carcinogenic risk for adults and children via the consumption of fish.