| China is a big producer of apples.Annual apple production accounts for more than half of the world's total production.And worldwide,apple production accounts for up to 16%of total fruit production,about 40 million tons per year.The annual losses due to bad weather,improper transportation and storage,sales links,etc.are about 10%.At present,most of the treatment methods for apples that cannot be sold are directly discarded.The simple disposal process not only pollutes the environment but also causes huge waste of renewable resources.This paper explores the separate anaerobic fermentation experiment of apple waste,the mixed fermentation experiment of apple waste with chicken manure and cow dung,and the mixed fermentation experiment of apple waste with chicken manure and cow dung.The gas production,pH and methane content of the anaerobic fermentation process of the two raw materials were compared to find out the effects of different manure on the anaerobic fermentation process.On the basis of the mixed fermentation of the two raw materials,the appropriate mixing ratio of the three raw materials anaerobic fermentation materials was selected,and the synergistic analysis between the raw materials,the calculation of COD removal rate and the gas production kinetics were carried out.The main conclusions are as follows:(1)The anaerobic fermentation experiment of apple and chicken manure reached the peak of gas production in 2-3 days,the maximum value was 2790 mL/d.After that,the gas production decreased slowly and stabilized after the 10th day.The maximum methane content was 72%.The apple and cow dung fermentation experiments reached the first gas production peak on the 2nd-5th day,after which the gas production rate slowly decreased,and the second gas production peak appeared in 15-20 days,up to 1960 mL/d.The maximum methane content of the mixed cow dung experimental group was 72%measured on the 15th day.Compared with the medium temperature fermentation experiment,the high temperature fermentation experiment has similar gas production rules,but the gas production peak is advanced,and the daily gas production in the stable stage is higher.(2)Mixed fermentation of three raw materials When the mixing ratio of apple,chicken manure and cow dung is 4:5:5,the unit VS has the highest methane production,reaching 348mL/g,and the COD removal rate is the largest,reaching 82.69%.When the mixing ratio of apple,chicken manure and cow dung is 4:3:3,the unit VS has the lowest methane production,and its value is 212 mL/g.When the mixing ratio of apple,chicken manure and cow dung is 4:4:4,the COD removal rate is the lowest,and its value is 59.68%.(3)In the mixed fermentation experiment of three raw materials,apple:cow dung:chicken manure=4:3:3,the anaerobic digestion index CPI<1,indicating that there is antagonism between the fermentation materials at this time,the apple mixing ratio reaches 40%.The CPI of the other experimental groups were all greater than l,indicating that the three raw materials exhibited synergistic effects on the mixed fermentation.Apple:Cow dung:When chicken manure=4:5:5,the CPI reached a maximum of 1.59.The apple mix ratio is up to 40%and the mixing ratio is lower,the CPI index is larger.(4)The Cheynoweth equation equation has a large deviation from the cumulative gas production in the first 15 days.The maximum deviation between the fitted cumulative gas production and the actual cumulative gas production is 19.79%.However,the equation has a good effect on the cumulative gas production for 30 days in the whole experimental process,with a maximum deviation of 7.59%.The higher the proportion of fecal mixing(ie,the apple mixing ratio is less than 40%),the stronger the stability of the fermentation environment,the better the equation fits the cumulative gas production in the previous period,and the minimum deviation in the experiment is 0.14%. |
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