Study On The Degradation Effect Of Aerobic Compost And Vermicompost On Agricultural Waste

Cabbages,corn stalks,and cow dung are ordinary organic wastes.If discarded arbitrarily without adequate treatment,they will waste many resources and seriously pollute the ecological environment.Composting technology is an effective means to deal with organic waste.It can not only convert organic wastes into agricultural fertilizers,promote the construction of a saving and friendly society,but also reduce the toxicity of toxic substances such as heavy metals in organic wastes and avoid environmental pollution.Traditional composting technology has defects such as long decomposing time and severe loss of nutrients in a heap.This thesis adopts aerobic composting and vermicomposting technology in response to this problem.It takes three agricultural wastes,cabbage,corn stalk,and cow dung,as examples,to study the feasibility of aerobic composting and vermicomposting technology to treat three kinds of organic wastes.This thesis monitors the changes in p H,organic matter,total organic carbon and nitrogen,phosphorus,and potassium content of the reactor to explore the evolution law of physical and chemical properties of the reactor in the composting process.Based on the BCR sequential extraction method,the changes in the form and relative content of heavy metals in the compost were analyzed,and the influence of composting methods on the transfer path of heavy metal forms was investigated.Using high-throughput sequencing technology to analyze the microbial community structure in two treatments of aerobic composting and vermicomposting;Combined with the parallel factor method,the three-dimensional fluorescence spectrum variation characteristics of compost dissolved organic matter was analyzed to determine the influence of composting methods on organic matter;The following conclusions are obtained:(1)After aerobic composting and vermicomposting,the organic matter of vegetable waste decreased by 25.94% and 26.98%,respectively,and the organic matter of cow dung decreased by 9.24%,11.29%,respectively.The content of nitrogen,phosphorus,and potassium in the compost piles and cow dung piles after composting were higher than that in the aerobic compost group;After the composting treatment,the GI value of the vegetable waste was as high as 80.16%,indicating that the decomposing level of the vegetable waste after the vermicomposting treatment was significantly higher than that in the aerobic composting group.The GI values of the two experimental groups of cow dung were 85.85% and 86.41%,respectively,with little difference.(2)After aerobic composting and vermicomposting,the total amounts of 5 heavy metals such as Zn,Cu,Pb,Cd,and Cr in the vegetable waste and cow dung were increased;The oxygen compost group was 53.22 mg/kg and 5.62 mg/kg higher respectively,and the content of the other three heavy metals was lower than that of the aerobic compost group;The Zn,Cu and Cr contents of the cow dung compost treated with vermicompost were higher than those of the aerobic compost group 17.19 mg/kg,19.93 mg/kg and 5.19 mg/kg,the contents of Pb and Cd were lower than those of the aerobic composting group;The heavy metals in the vegetable waste pile and the cow dung pile after aerobic composting and vermicomposting were all in a stable state.The transformation effect after vermicomposting was better than the aerobic composting group.(3)After aerobic composting and vermicomposting,the Shannon index and chao1 index of the microbes in the compost were increased,and these two indexes were higher than the aerobic composting group by 0.75 and 675.32 respectively after vermicomposting.For cow manure compost,the Shannon index increased by 0.09 after aerobic composting and decreased by about 0.29 after vermicomposting.After aerobic composting and vermicomposting,the chao1 index of cow dung fell by 67.93 and 142.94,respectively.(4)With the help of PARAFAC technology,it was found that the main components of the DOM of cauliflower were marine humus,terrestrial humus,microbial humus,and protein-like substances.The cow dung pile is mainly composed of microbial humus,protein-like,and fulvic acid-like humus;After aerobic composting and vermicomposting,the DOM-like protein group of vegetable waste decreased by 9.23% and 11.12%,respectively,and the two experimental groups of cow manure decreased by 11.16% and13.05%,respectively;The BIX value of the vegetable waste two experimental groups decreased slightly,and the BIX of the cow dung two experimental groups decreased somewhat.The HIX values of the two experimental vegetable waste groups were increased by about 0.12.The values of the two experimental groups of cow dung were increased by 0.09 and 0.15,respectively.In conclusion,vermicomposting is superior to aerobic composting in terms of waste degradation effect,nutrients,and stability after composting.At the same time,the advantages of vermicomposting technology are more evident when vegetable waste is the raw material of the heap.The results of this thesis are of great significance for improving the effect of waste degradation and improving the quality of compost products,helping to improve the recycling rate of agricultural waste,and providing technical support for soil environmental restoration and rational waste disposal.