| With the development of the world economy,mankind’s demand for energy is increasing.The energy crisis has become a great challenge to the development of today’s society.Therefore,we urgently need to seek renewable biomass energy to alleviate the problem of energy shortage.Sorghum straw is a lignocellulosic renewable biomass resource that can produce bioenergy such as liquid fuel ethanol and gas fuel methane.In this paper,sorghum stalks are used as raw materials to study the effect of MC1 pretreatment on the integrated conversion of ethanol and methane to provide theoretical basis and technical support for energy utilization of sorghum stalks.The main results are as follows:(1)The effect of MC1 on the decomposition characteristics and productivity of sorghum stalks was studied at different pretreatment times.The results showed that sorghum stalks maintained a high degradation ability within 5 days of pretreatment.The concentration of COD in the hydrolysate after 5 days of pretreatment was the highest,being 7.84 g/L,and the total amount of organic acids was as high as 2529.45 mg/L.In the subsequent ethanol-methane production process,the ethanol content of pretreatment for 5 days increased by 39.9% compared with the control(CK-0d).MC1 pretreatment effectively increased the ethanol content of sorghum straw.In the anaerobic fermentation process,the pretreatment for 5 days(EG-5d)had the highest VFAs content at 5 days of fermentation,which was 1.28 times higher than the control.Compared with other treatments,EG-5d fermentation starts faster,the cumulative methane production is the highest,reaching 239.50 m L/g VS,and the maximum methane production rate is 13.96 m L/d/g VS,indicating that 5 days of pretreatment is beneficial to anaerobic digestion.Progress,the anaerobic fermentation of sorghum stalks to produce methane has been significantly improved.The integrated conversion capacity of sorghum straw at different times of MC1 pretreatment was higher than the integrated capacity without treatment,indicating that pretreatment can effectively increase the capacity of sorghum straw.The integrated energy output value of straw pretreated for 5 days is the highest,which is 76.52% higher than that of methane production.The results show that the integrated ethanol-methane conversion of sorghum straw has a significant effect on energy production during the pretreatment for 5 days.(2)To study the effect of MC1 pretreatment on the decomposition characteristics of sorghum stalks with different particle sizes and the productivity.The concentration of COD in the hydrolysate of the straw with a particle size of 1 mm was the highest when pretreated for 5 days,which was 11.59% higher than the initial stage,and the content of VFAs was as high as 2706.67 mg/L.And when the particle size is 1 mm,the fermentation effect of sorghum stalks is the best,and the maximum ethanol production is 0.18 g/g VS after 48 hours of fermentation,which is 20% higher than the control.In the process of methanogenesis,the 1 mm particle size treatment had the highest accumulation of acetic acid at 5 days of fermentation,accounting for 65.56% of the total VFAs.After the end of gas production,the maximum methane production was 307.97 m L/g VS,which was an increase of 48.83% compared to the control.,The methane output is significantly higher than that of 5 mm and 1 cm treatments.The results show that when the particle size is 1 mm,it is more conducive to the biotransformation of sorghum straw.The integrated conversion capacity of MC1 pretreated sorghum straw with different particle diameters is higher than the untreated integrated capacity.The energy output of the integrated conversion with the pretreated straw diameter of 1mm is up to 13226.31 k J/kg,which is higher than the control CK-1mm The energy output increased by 56.68%,indicating that MC1 pretreatment can effectively increase the productivity of sorghum straw.The integrated production capacity of MC1 with a pretreatment particle size of 1mm is 56.68% higher than the production capacity of methane per unit,and the effect of increasing the production capacity is the most obvious.(3)To study the effect of MC1 pretreatment on the decomposition characteristics of different concentrations of sorghum stalks and productivity.When the pretreatment straw concentration is 5%,the COD concentration and VFAs in the hydrolysate are the highest when the pretreatment is 3 days.Straws with a pretreatment concentration of 3% and 5% during ethanol production were 0.15 g/g VS and 0.16 g/g VS after fermentation for 48 h,which increased by 17.6% and 12.5% respectively compared with the control.In the process of methane production,the pretreatment with a concentration of 3% had the highest accumulation of acetic acid at the peak of gas production,accounting for 56.42% of the total VFAs,which was significantly higher than other treatments and controls(p<0.05).The cumulative methane production reached the maximum value of 253.08 m L/g VS,and the maximum methane rate was 16.42 m L/d/g VS.It shows that when the concentration of MC1 pretreated sorghum straw is 3%,the gas production capacity and methane production potential of anaerobic fermentation are the largest.The integrated conversion capacity of sorghum straw with different concentrations of MC1 pretreatment is higher than the integrated capacity without pretreatment.The integrated conversion capacity of EG-3% treatment is 42.73% higher than the control,indicating that MC1 pretreatment can effectively improve sorghum straw Capacity.The integrated energy output of EG-3% is 39.61% higher than that of single methane production,and the integrated production capacity of pretreated sorghum straw is significantly increased(p<0.05).In summary,MC1 pretreatment of sorghum straw can effectively increase its ethanol-methane production,and the total production capacity is increased by more than 25.22% compared with untreated,and the ratio of methane production per unit is increased by more than 18.03%.This research aims to provide theoretical basis and technical support for the efficient biotransformation of sorghum stalks. |
