Studies On The Continuous Opening-pretreatment Of Corn Straw With Basidiomycetous For Ethanol Production

Pretreatment, during the process of fuel ethanol production from lignocellulose, is one of the main technical bottleneck. Because of reduced energy and less pollution, biological pretreatment attracts a wide spread attention. Large-scale utilization is limited as the high cost of reactor and sterile-culture process. Based on the selected strains which have potential to use ,the continuous opening-pretreatment process of corn straw with basidiomycetous for ethanol production is established. The process parameters of purification method,biological pretreatment,ancillary physical&chemical methods,enzymatic hydrolysis and ethanol fermention were improved and optimized,which Lay the foundation for the industrial application of biological pretreatment.At first, with the strain of Irpex lacteus CD₂ and the Biological-alkaline/oxidative pretreatment(BAO) technique, which can increase the saccharification rate significantly under sterile condition. According to the comparison and optimization of purification, the BAO technique can be operated under continuous and opening conditions. The results show that: Irpex lacteus CD₂ can only grow on the corn straw which were purified by steam. the optimum conditions were as follows: steam purification for 1.5 hours under 0.5MPa, the inoculative proportion was inoculum : material (w/w) = 1 : 3, biological pretreatment for 15 days. On this basis, three batches of continuous opening-pretreatment with Irpex lacteus CD₂ were successful ,and the saccharification rate were all above 75%In order to reduce the cost of purification,Lime purification was selected as the purification method. During the 73 basidiomycetes ,there ware 10 basidiomycetes growing on the corn stover,which were purified by lime. Coprinus comatus XY7,with the highest saccharification rate , was supposed to be the starter of continuous opening-pretreatment .A new continuous opening-pretreatment technique, which consisted of lime purification,biological pretreatment,ancillary physical&chemical method, was estabilished, and process parameters were optimized. the optimum conditions were as follows: the strains, Coprinus comatus XY7, were inoculated with proportion of inoculum:material (w/w) = 1:3 on the corn stover ,which were purified by 0.1% lime. When the 6th day of biological pretreatment, 1/5 of the corn stover were used as the inoculum for the next batch. While the rest were biological pretreated for another 9 days, and then being alkaline/oxidative pretreated for 24 hours with 1%NaOH and 1% H₂O₂ at room temperature. Under these conditions, three batches of continuous opening-pretreatment with Coprinus comatus XY7 were accomplished successfully. The corn stover were enzymolysised at the enzyme load of 30 FPU/g, and the saccharification rate were all above 80%, increased by 10%In order to evaluate the influence of pretreatment to ethanol fermentation, the corn stover, which were pretreated, were fermented by the simultaneous saccharification and fermentation(SSF). The results show that: when fermented for 24 hours under the conditions: substrate concentration 20 g/L, enzyme load 30 FPU/g, yeast inoculum 0.7%. The ethanol conversion was 14.4% , which increased by 18.1%The establishment of the technology provides a possible way for biological pretreatment which is going to be used in fuel ethanol production from lignocellulose for the future...