Progress Optimization Anaerobic Digestion Of Corn Stover Based On Ultrasound

Our country is very rich in the straw resource, there are about 800 million tons stalks that we can collect every year in China. Anaerobic digestion can convert biomass stored in the straw into renewable clean energy, it is an effective means to use the straw. However, due to the complicated structure of straws, limit the rate of anaerobic digestion, so the anaerobic digestion of corn stover has not been able to promote the practical production in a wide range. Ultrasound has the advantage of energy concentration and no pollution, it is a kind of clean and efficient method, we did the research on the ultrasound which was used in the anaerobic digestion of corn stover, combined ultrasonic effect in this paper. The anaerobic fermentation process included two parts, one is the pretreatment process, and the other is anaerobic digestion.The research will provide the guidance for application in the anaerobic digestion field.Firstly, in order to ascertain the impact of dual-frequency ultrasound pretreatment to anaerobic digestion, on the basis of dilute alkali pretreatment, we combined dual-frequency ultrasound to pretreat corn stover, and did the anaerobic digestion experiments. Compared the digestion performance about the dilute alkali pretreatment, single-frequency ultrasound with dilute alkali pretreatment, dual-frequency ultrasound with dilute alkali pretreatment. Results showed that the dual-frequency ultrasound pretreatment can make the corm stover more available and biodegradable, and increase the efficiency of digestion.Secondly, optimize the process parameters when the ultrasound was used in the process of pretreatment. Combined dual-frequency ultrasound with dilute alkali to pretreat corn stover, we used orthogonal experiment design and response surface methodology to optimize process parameters, got the optimal parameters combination and did the experiment to verify if it was the best. But because two methods had some disadvantages, we combined support vector machine and orthogonal experiment design, used the data to establish the model, and predicted the optimal parameter about anaerobic digestion.Finally, on the basis of the ultrasonic mechanism, we used ultrasound during the whole process of anaerobic digestion. We improved the conventional constant temperature water bath device, combined ultrasonic transducer with the stainless steel sink, and achieved to add ultrasound to anaerobic digestion process of the corn stover. Then we did experiments by using the improved constant temperature water bath device, the experimental results showed that ultrasound can significantly improve the biodegradation of the corn stover. With the increase of loading rate, the organic matter which can be used in the anaerobic digestion is increased, anaerobic digestion time was prolonged, so gas production increased significantly.