Research On Anaerobic Co-digestion Characteristics Of Muskmelon Stems And Leaves And Mixed With Corn Stalk

With the steady growth of muskmelon planting area, and its by-product muskmelon stems and leaves is rising year by year. As the agricultural waste, it was simply abandoned on the field or let it rot or burned, and thus would pollute the rural environment. Muskmelon stems and leaves is a good biogas fermentation raw material because of it contains good levels of nutritious elements. Using the anaerobic fermentation technology to process the muskmelon stems and leaves which can improve the environment and can obtain methane. This text carried out the batch anaerobic digestion experiment used the natural dried muskmelon stems and leaves as fermentation raw material under the condition of medium temperature(35±1)℃. On the basis of the anaerobic fermentation rules of different part of the muskmelon stems and leaves, to explore the total solid(TS) concentration, inoculum concentration, particle size effects on anaerobic fermentation of muskmelon stems and leaves. And further study the characteristics of anaerobic co-digestion of muskmelon stems and leaves with corn straw in use of quadratic regression orthogonal rotation combination design, to find the optimum conditions of anaerobic co-digestion of the two materials.In this paper, the main research contents and results are as follows:(1) The research on the characteristics of anaerobic fermentation in different part of muskmelon stems and leaves. The results showed that the gas rate of TS from high to low is muskmelon stems > whole plant > muskmelon leaves, the number is 297.6、256.9、235.8 mL·g﹣1 respectively. The average methane content of whole plant, muskmelon leaves, muskmelon stems is 62.99%、59.47%、57.36% respectively. The biogas production peak of muskmelon stems appeared at the latest. The fermentation period of muskmelon stems is the longest, muskmelon leaves is the shortest, and the whole plant is in the middle.The cumulative gas production of whole plant and muskmelon leaves was 86.39% and 79.37% of muskmelon stems respectively.(2) The research on the characteristics of anaerobic co-digestion of different part of muskmelon stems and leaves mixed with corn straw. The results showed that the gas rate of TS from high to low is whole plant + corn straw > muskmelon leaves + corn straw > muskmelon stems + corn straw, the number is 292.3、289.9、252.7 mL·g﹣1 respectively. The TS gas rate of muskmelon leaves + corn straw and whole plant + corn straw were 22.9% and 13.8% higher than that of muskmelon leaves and whole plant respectively, compared with muskmelon stems the TS gas rate of muskmelon stems + corn straw was down 17.8%. The average methane content of whole plant + corn straw, muskmelon leaves + corn straw, muskmelon stems + corn straw were 59.41%、62.23%、64.60% respectively. After mixed with corn straw, the biogas production peak of the mixed groups were both delayed, and the fermentation period were both extended compared with single muskmelon stems and leaves.(3) The research on factors of anaerobic fermentation of muskmelon stems and leaves. The results showed that the TS gas rate of 8% is highest, respectively 257.1 and 248.1 mL·g﹣1 under the inoculum concentration of 30% and 35%. The TS gas rate of 6% is the highest of 249.2 mL·g﹣1 under the inoculum concentration of 40%. The methane content of different TS concentration groups show similar trends and stable in the range of 50% ~ 70%. The cumulative gas production of inoculum concentration 35% slightly less than 30%, is 9812.5 mL, but gas rate of TS, gas rate of VS, gas rate of fresh raw material are the highest, were 257.1、334.0、227.0 mL·g﹣1 respectively. The biogas production peak of 60 mesh group is the earliest, the fermentation period is the shortest, but the total gas production and TS gas rate is the lowest. The biogas production peak of >20 mesh group is the latest, the fermentation period is the longest, but the total gas production and TS gas rate is the highest. The total gas production and TS gas rate of no screening group than >20 mesh group was reduced by 7.09%, but the fermentation period ahead of >20 mesh group 10 d.The research on the optimization process of anaerobic co-digestion of muskmelon stems and leaves mixed with corn straw. The influence of three factors on the total gas production is TS concentration > C/N > inoculum concentration. The best process parameters are TS concentration 12%, inoculum concentration 45%, C/N 20.1:1 respectively. The influence of three factors on the average methane content is incoulum concentration > TS concentration > C/N. The best process parameters are TS concentration 9.15%, inoculum concentration 41.44%, C/N 15.3:1 respectively.