The Study On Anaerobic Fermentation Influencing Factors And Products Properties Of Mixed Swine Manure And Corn Stalks

In resent years,the residues of agricultural and animal husbandry have causesd increasingly serious environmental problems.The air,water and soil have been seriously polluted by improperly disposal of livestock manure and crop stalks.There is large amount of organism in Crop stalks and livestocks' manure,so it will be very potential substrates to produce biomass energy,because of that,the fossil energy crisis could be released.It could not only achieve biogas,this kind of clean energy,but also produced digested residues which applied as fertilizer.Wheras,there were some problems on improving biogas yield and application of digested slurry.In this thesis,we conducted a reseach on biogas fermentation of different TS ratio of livestock manure and crop stalks and the properties of digested slurry,to determine the optimum conditions for fermentation,and offer suggestion on rural biogas engineering and disposal of biogas slurry.In this study,swine manure and corn stalks were selected as substrate.Total biogas yield,fermentation time,methane concentration and the concentration of each pollutant in biogas slurry were studied in different manure and stalk ratio(calculated in TS,4:1,3:1,2:1,1:1,1:2)with temperature in increment of 5? from 30? to 40?.Summary of the result as follows:(1)Biogas was produced in each group normally.By increasing temperature and decreasing manure and stalk ratio,biogas produced rapidly at the beginning of fermentation and it could abridge effective fermentation time.Wheras,temperature was observed to affect start-up time and effective fermentation time more significantly than ratio of manure and stalk.Start-up time and effective fermentation time get shortest at 40?,when manure and stalk ratio was 4:1,and get longest at 30?,when manure and stalk ratio was 1:2.The longest and shortest effective fermentation time were 65 d and 31 d,respectively.(2)Both the temperature and manure and stalk ratio have significant effect on total biogas yield and total methan yield.With the increasing of temperature,total biogas yield and total methan yield increased.On same temperature,total biogas yield and total methan yield have increasing tendency with manure and stalk ratio increased.The maximum total biogas yield and total methan yield was 11692 mL and 8106 mL,respectively,and observed on 40?,with the manure and stalk ratio of 1:2,here,TS biogas yield was 243.6 mL /g-TS.The minimum total biogas yield and total methan yield was 7694 mL and 5185 mL,respectively,and observed on 30?,with the manure and stalk ratio of 1:2,here,TS biogas yield was 160.3 mL /g-TS.(3)During rapid gasing period,methan concentration of each group varied from 70% to 80%,then got slightly decrease and varied from 60% to 70% duaring later period.Methan concentration was non-significant affected by temperature and manure and stalk ratio.With increase of the temperature,methan concentration have merely increased,the maximum and minimum methan concentration of each group was 67.3% and 69.3%,respectively.(4)The mathematic model showed that anaerobic fermentation was significantly affected by temperature and manure and stalk ratio as well as their interaction effect.The degree of influence of factors above on total biogas yield and total methan yield as follows:temperature>interaction effect of temperature and ratio of manure and stalk>ratio of manure and stalk.(5)It showed that biogas slurry contain high level of pollutant concentration.The COD concentration varied from 2500 mg/L to 3500mg/L,total nitrogen concentration varied from 700 mg/L to 1000mg/L,ammonia nitrogen accounted for about 80% to 90% of total nitrogen.In addition,carbon nitrogen ratio was much less than domestic wastewater.Temperature has a certain influence on concentration of each pollutant in biogas slurry,fermenting in higher temperature could decline concentration of each pollutant in biogas slurry.The pollutant concentration in biogas slurry were affected significantly by the change of ratio of manure and stalk,wheras,there were no specific rules of pollutant concentration in biogas slurry when manure and stalk ratio changes.