Assessment Of Biomethane Production From Discarded Cured-tobacco Leaves Using Different Pretreatment

As a large agricultural planting country,our country’s crop production ranks among the top in the world.A large amount of agricultural waste is generated during crop planting and harvesting.Random disposal not only fails to effectively use waste resources,but also destroys the ecological environment.The anaerobic biological treatment method is considered to be one of the effective methods for the treatment of agricultural waste due to its low energy consumption,high environmental protection,and large processing capacity.However,cured tobacco leaves,as a huge amount of waste,is rarely explored in anaerobic aspects;for the resource utilization of cured tobacco leaves,medium-temperature batch anaerobic fermentation experiments were carried out using the cured tobacco leaves as a substrate,and the use of steam The blasting and freeze-drying pretreatments explored the effects of different intensity pretreatments on the methane production potential of discarded cured tobacco leaves;the main research results of this experiment are as follows:1)The theoretical error was eliminated for the factors that caused the volume error of the material methane production in the biochemical methane potential(BMP)experiment gas measurement step,and the concentration of the adsorbed lye of various wastes in the BMP experiment was optimized at the same time.It is recommended to use 1.5mol/L for lye concentration of cellulosic agricultural waste,2mol/L for livestock and poultry waste,2mol/L for industrial waste,and 3mol/L for domestic waste.At the same time,according to the characteristics of cellulosic agricultural waste,the AMPTA~3methane tester with more accurate resolution was selected,and the gas measurement error analysis of the methane meter measurement unit was carried out at different flow rates.The results showed that the AMPTA~3methane meter was at different flow rates.The measured data are not significantly different,and the measurement data at low flow rates are highly repeatable;for the phenomenon of low gas production and slow gas production from cellulose agricultural waste,the AMPTA~3tester can be used as a subsequent BMP experiment of discarded cured tobacco leaves reliable equipment.2)The BMP value of the discarded cured tobacco leaves is between202.5～251.7ml/g.VS,and the methane production performance is excellent;and the gas production cycle of the flue-cured tobacco leaves in this study is short,and the fermentation has no lag period,which is excellent for anaerobic fermentation.raw material.3)Steam explosion pretreatment can effectively open the internal structure of cured tobacco leaves,increase the contact area between microorganisms and materials,which is beneficial to enzymatic hydrolysis,but steam explosion cannot increase the methane production potential value of flue-cured tobacco leaves.The sugar content is in the high temperature and high pressure environment of steam explosion.It is easy to lose and thus reduces the gas production.Compared with untreated tobacco leaf L0,the BMP of tobacco leaf L1-L5 after steam explosion decreased by 11.6%～26.3%;in addition,steam explosion pretreatment did not promote the separation of nicotine,which inhibited fermentation gas production to a certain extent.4)Freeze-drying pretreatment can effectively break the wood fiber barrier and increase the methane production potential of flue-cured tobacco waste,which is a feasible pretreatment method.Compared with untreated tobacco,the BMP value of all treatments increased by 3.01～11.61%;compared with freeze-drying treatment,freeze-thaw treatment(T1)had a slightly insufficient increase in the BMP value of flue-cured tobacco leaves;although freeze-drying treatment could be a greater degree Increase the BMP value of cured tobacco leaves,but the freeze-drying time is not as long as possible;if the freeze-drying time is too long,sugars and volatile substances will escape under the pressure difference of the vacuum pump,resulting in less material used by microorganisms and thus affects tobacco leaves produce gas;this experiment shows that for cured tobacco leaves,freeze-drying can completely dry the cured tobacco leaves for 3 hours.At the same time,the tobacco leaves have the highest methane production potential,so this condition is considered as the best freeze-drying treatment duration.