Biological Transformation Of Cassava Straw And Lotus Seedpod To Produce Ethanol

In this paper, it has reviewed about the structure and pretreatment of the raw materials of lignocellulose, the craft of biological transformation of lignocellulose to ethanol, the research status of cassava straw and lotus seedpod. Through the summarization of the old related work, it has been found that cassava straw and lotus seedpod are stacked in the field or used in the production of fungi. These may not only lead to low degree of energy utilization, but also lead to environmental problem and influence the quality of life of the residents around. In order to solve this problem, conversion of cassava straw and lotus seedpod to fuel ethanol was studied as two points.The first point is pretreatment and biological transformation of cassava straw to produce ethanol.(1)Firstly, Trichoderma Viride is used to hydrolysis and saccharify cassava straw and gets the result 1.74mg reducing sugar/g cassava straw.(2)Because of the relatively low amount of sugar, the change of pretreatment methods is put forward in order to improve the reducing sugar production. In this paper, the normal alkali, microwave/alkali and ultrasonic/alkali are used in cassava straw pretreatment. Compared the weight loss, chemical components, reducing sugar yield and ethanol yield, it can be seen the optimal pretreatment process is 2% NaOH microwave/alkali treatment 40 min. The substrate of the optimal pretreatment condition is used to hydrolysis and the reducing sugar yield gets 3.38 mg reducing sugar/g cassava straw while the ethanol yield gets 3.16 mg ethanol/g cassava straw. As a result, reducing sugar yield has increased 94.25% compared with 1.74mg reducing sugar/g cassava straw, which without microwave/alkali pretreatment.(3)Separate Hydrolysis and Fementation (SHF) is used in the step of degradation of cassava straw. After that, Response Surface Method (RSM) combining single factor method is used to optimize the craft and achieves the best sugar production. The best condition of the craft to produce reducing sugar is that inoculation amount of 4×108CFU spore suspension, outfit fluid initial pH4.6, fermentation temperature 30 ℃, liquid volume 100 mL,150r/min,84h, concentration of substrate 1% and the highest yield could get 4.30 mg reducing sugar/g cassava straw.(4)The best condition of the craft to produce ethanol is that inoculation amount of 4×10 CFU spore suspension, outfit fluid initial pH 5.0, fermentation temperature 29℃, liquid volume 100 mL,150r/min,120h and the highest yield could get 3.81 mg ethanol/g cassava straw. As a result, ethanol yield has increased 20.57% compared with 3.16mg ethanol/g cassava straw, which without Response Surface Method for optimization.The second point is pretreatment and biological transformation of lotus seedpod to produce ethanol.(1) Lotus seedpod is also used in the pretreatment of the normal alkali, microwave/alkali and ultrasonic/base in this paper. Compared the weight loss and chemical components so it can be seen optimal pretreatment process is 2% NaOH microwave/alkali treatment 30 min. At the same time, the substrate has been biological transformated the substrate and ethanol production rate could get 0.147 g ethanol/g lotus seedpod.(2)Stimultaneous Saccharification and Fermentation (SSF) is used in the craft of degradation of lotus seedpod. The craft of lotus seedpod is optimized on the single factor and the Response Surface. The result of Response Surface is inoculation amount of 4×10 CFU spore suspension, the enzyme 40mg/g lotus seedpod, initial pH 4.9, temperature 35℃, liquid volume 100 mL,150r/min,48h and concentration of substrate 1%. The highest ethanol yield is 0.241g ethanol/g lotus seedpod, increased by 63.94% compared with 0.147 g ethanol/g lotus seedpod without Response Surface optimization.