| A large amount of vegetable waste produces annually in China, which is the main source of decay, odor and leachate due to their high volatile solids and moisture content. Nowadays, the practical treatments are mainly landfill, incineration, compost and anaerobic digestion. Compared to the other technologies, anaerobic digestion is the most effective to reduce the amount of vegetable waste and produce biogas for energy recovery. The research on different process parameters of the biogas production from vegetable waste by anaerobic fermentation is significant for the resource recovery of vegetable waste. Moreover, the residues produced by anaerobic fermentation can be used with various purposes. As a part of the project'Research of the Cycling Practical Technique of Biomass in ChongMing Island– Biogas Project', this research focuses on the research on different process parameters of the biogas production from vegetable waste by anaerobic fermentation and the comprehensive utilization of anaerobic fermentation residues. The main contents of the paper are as follows:1.Anaerobic batch digestion experiments of cabbage leaves waste were conducted in self-manufactured anaerobic fermentation equipment. The effect of different concentration inoculums(20%,30%,50%), supplement trace metals(Fe2+,Co2+,Ni2+)and different temperature (nature temperature,35±1℃,55±1℃)on anaerobic digestion were studied. The results showed that the anaerobic digestion can fit to the characteristics of vegetable wastes to anaerobic fermentation for biogas production. And among inoculums concentration of 20%, 30% and 50%, the contents of VFA, NH4+-N and pH of the 30% inoculums concentration treatment were normal, and the total biogas content and the maximum CH4 content of it were 7790.81ml and 42.514%, respectively, which were obviously higher than that of other two treatments and the control. Compared with the control, the total biogas content and the maximum CH4 content were increased 37.11% and 40.34% by the supplement of trace metals(Fe2+,Co2+,Ni2+). Besides, among the temperature of nature temperature,35±1℃and 55±1℃, the contents of VFA, NH4+-N and pH of the 35±1℃treatment were normal, and the total biogas content and the maximum CH4 content of it were 5892ml and 77.8%, respectively, which were obviously higher than that of other treatments.2.Field experiments were carried out to study the effect of different anaerobic fermentation residues treatments on yield and quality of Chinese cabbage and nutrient accumulation in soil. The results indicated that the yield of Chinese cabbage was enhanced remarkably by the application of anaerobic fermentation residues. The highest yield of Chinese cabbage was 1364.31 kg/(667 m2)when the low amount of the anaerobic fermentation residues was applied and it was 23% higher than that of the control. The content of Vc and soluble sugar of Chinese cabbage was enhanced obviously by the application of anaerobic fermentation residues. The highest content of Vc of Chinese cabbage was 35.621 mg/(100g)when the high amount of the anaerobic fermentation residues was used and it was 44.948% higher than that of the control. The highest content of soluble sugar of Chinese cabbage was 219.307 mg/kg when the low amount of the anaerobic fermentation residues was used and it was 24.032% higher than that of the control. Furthermore, the content of nitrate of Chinese cabbage was reduced by the application of anaerobic fermentation residues. The lowest content of nitrate of Chinese cabbage was 4.63 mg/kg when the medium amount of the anaerobic fermentation residues was used and it was 52.23% lower than that of the control. And the accumulation of nutrient such as available K,P and N can be increased by the anaerobic fermentation residues and its quantity index was good when the high amount of the anaerobic fermentation residues was used. The pH value of each anaerobic fermentation residues treatment in soil was lower than that of the control, and it reached the lowest when the high amount of the anaerobic fermentation residues was used. This indicated that application of the anaerobic fermentation residues could reduce the alkalinity of soil and had the positive role to enable it to approach the neutrality. So the yield and quality of Chinese cabbage can be increased and the nutrient accumulation in soil can also be improved by the application of the anaerobic fermentation residues.3. Effects of anaerobic fermentation slurry of different concentrations on the biological characteristic and yield of Chinese cabbage were studied through experiment of anaerobic fermentation slurry as supply application with water at different ratio. The anaerobic fermentation slurry as an organic fertilizer had rich nutrient contents, which were helpful to improve the biological characteristic of Chinese cabbage. At the 35th day after seeding stage of Chinese cabbage, the leaf width, leaf length and petiole length of Chinese cabbage were 50.37mm, 58.17mm and 26.34mm, respectively, when the low concentration of the anaerobic fermentation slurry was applied, which were higher than those of the other treatments. The highest leaf numbers of Chinese cabbage was 9.6 when the medium concentration of the anaerobic fermentation slurry was used, which were higher than those of the other treatments. The yield of Chinese cabbage was enhanced remarkably by the supply application of anaerobic fermentation slurry. The highest yield of Chinese cabbage was 730.921 kg/ (667 m2) when the high concentration of the anaerobic fermentation slurry was used and it was 97.74% higher than that of the control. The content of Vc and soluble sugar of Chinese cabbage were enhanced obviously by the supply application of anaerobic fermentation slurry. The highest content of Vc of Chinese cabbage was 20.48 mg/ (100g) when the medium concentration of the anaerobic fermentation slurry was applied and it was 30.20% higher than that of the control. The highest content of soluble sugar of Chinese cabbage was 22.94 mg/kg when the medium concentration of the anaerobic fermentation slurry was used and it was 65.512% higher than that of the control. Furthermore, the content of nitrate of Chinese cabbage was reduced by the application of anaerobic fermentation slurry. The lowest content of nitrate of Chinese cabbage was 44.627 mg/kg when the high concentration of the anaerobic fermentation slurry was used and it was 13.85% lower than that of the control.4.The controlling effects on Pieris rapae L. of the anaerobic fermentation slurry was studied by toxicity experiment in laboratory and pot experiment in green house. The result showed that in terms of insect prevention and environment security, the best controlling effect on Pieris rapae L. was the treatmentⅣwhich add coal oil and eradicator to the anaerobic fermentation slurry. When application of treatmentⅣ, the mortality rate on Pieris rapae L. after treatment in the 24h and 72h was 70.00% and 93.33% in the toxicity experiment in laboratory, and the controlling effect on the Pieris rapae L. after treatment in the 1, 3, 5, 7d was 77.55%,88.35%,93.64%, 96.52%, respectively, in the pot experiment. |
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