Study On Fuel Ethanol Production From Municiple Solid Wastes

With the depletion of fossil energy and the global warming, fuel ethanol has attracted widespread attention as clean and renewable energy. Faced with food crisis, the fuel ethanol is looking for more cheaper and aboundent feedstock. Meanwhile, the rapid growth of municipal solid wastes(MSW) required new disposal methods. On the basis of the MSW classification nowadays, kitchen wastes(KW) and waste papers were selected as raw materials for the ethanol production research in this thesis, and the conditions in the whole process were studied respectively, which provides alternative direction for the reuse of MSW.The enzymatic hydrolysis saccharification of KW with cellulase and glucoamylase was studied, and the microwave pretreatment in different kinds of solvents were carried to investigate the effects on enzymatic hydrolysis saccharification. The results showed that the optimum enzymatic hydrolysis conditions were mass ratio of glucoamylase and cellulase3:7, substrate concentration10%, temperature60℃, pH5, and the time60min, corresponding sugar yield of KW was34.9%; the optimum pretreatment conditions were solid-liquid ratio1:8or1:10,3%H2SO4, microwave80W, temperature105℃, the time40min, corresponding sugar yield of KW pretreated was51.0%.The static fermentation of pretreated KW enzymatic hydrolysis by immobilized Saccharomyces Cerevisiae was carried. The results showed that the optimum conditions were the inoculum10%, fermentation time48h, the sugar concentration120g/L, the initial pH4-5, temperature30-35℃corresponding optimum ethanol volume concentration was6.0%. The ethanol yield achieved to be20.1%, or0.255ml/g. If assisted with shaker (60r/min), the ethanol volume concentration could reach to be6.8%, and dynamic35℃-30℃-35℃increased the ethanol volume concentration to be7.1%.The enzymatic hydrolysis saccharification of waste papers with cellulase was studied, and the microwave pretreatment in different kinds of solvents were carried to investigate the effects on enzymatic hydrolysis saccharification. The results showed that the optimum enzymatic hydrolysis conditions were mass of cellulase0.2g/10g waste papers, substrate concentration8%, temperature50℃, pH5, and the time40h, corresponding sugar yield of waste papers was28.3%; the optimum pretreatment conditions were solid-liquid ratio3:100,5%H2SO4, microwave80W, temperature120℃, the time40min, corresponding sugar yield of waste paters pretreated was43.6%.The static fermentation of pretreated waste papers enzymatic hydrolysis by immobilized Pachysolen Tannophilus and immobilized Saccharomyces Cerevisiae was carried. The results showed that the optimum conditions were the inoculum10%, fermentation time36h, the sugar concentration120g/L, the initial pH5, temperature33℃, corresponding optimum ethanol volume concentration was5.5%. The ethanol yield achieved to be15.7%, or0.199ml/g. If assisted with shaker (50r/min), the ethanol volume concentration could reach to be5.99%, and dynamic35℃-30℃-35℃increased the ethanol concentration to be6.3%.