【作者】 江丹；

【导师】 朱明军；

【作者基本信息】 华南理工大学 ， 发酵工程， 2010， 硕士

【摘要】 造纸污泥是制浆和造纸工业废水处理过程的固体残渣,含有大量的纤维素和半纤维素。本论文对造纸污泥的成分进行了测定,建立了以造纸污泥、纤维素酶和酵母为基础的同步糖化发酵工艺(simultaneous saccharification and fermentation,SSF)和同步糖化共发酵工艺(simultaenous saccharification and co-fermentation,SSCF);对利用SSF和SSCF工艺发酵造纸污泥产乙醇进行了研究。化学制浆污泥湿污泥含水率为75.23%,pH值为7.6;干污泥中灰分含量为38.32%,纤维素含量为25.77%,半纤维素含量为5.86%,蛋白质含量为1.52%,脂肪含量为2.74%。脱墨造纸污泥湿污泥含水率为41.47%,pH值为7.6;干污泥中灰分含量为43.96%,纤维素含量为11.99%,半纤维素含量为3.92%,蛋白质含量为1.78%,脂肪含量为1.11%。对酿酒酵母(Saccharomyces cerevwasiae)SHY08-3和融合酵母SHY07-1基本特性进行了研究。种子液好氧培养18-21h时已进入对数生长期的中后期,转接最为适宜。商业纤维素酶无需过滤除菌即可用于SSF发酵研究。化学制浆污泥具有较好的可酶解发酵性能,脱墨污泥对酶解具有一定的抗性。在底物浓度(以纤维素计)35g/L、纤维素酶添加量55FPU/g有效纤维素浓度(effective cellulose)、接种量6%、反应温度37℃和摇床转速200r/min下发酵72h,乙醇发酵效率达最大值,分别为72.71%和95.97%。同步糖化共发酵脱墨造纸污泥的最佳工艺参数为初始pH6.0,发酵温度30℃,底物浓度40g/L,纤维素酶添加量40FPU/gEC。在最优条件下实验获得的乙醇浓度为14.80g/L,乙醇发酵效率为65.96%。通过正交设计实验的极差和方差分析,确定了SSCF中影响最显著的因素是纤维素酶的添加量,其次是底物浓度,第三是发酵温度,接种量对乙醇发酵影响最小。在相同底物浓度和纤维素酶添加量的情况下比较酿酒酵母同步糖化发酵脱墨造纸污泥和融合酵母同步糖化共发酵脱墨造纸污泥产乙醇情况,可以看出SSCF工艺相对于SSF工艺而言,有一定的优势,但还需要提高菌种利用葡萄糖的能力。半连续发酵能够在较低的纤维素酶添加量的情况下使得原料被更充分的利用,同时也有利于乙醇的积累。通过半连续发酵,使得乙醇的浓度相对于分批发酵增加了一倍,浓度达到32g/L。副产物在分批发酵过程中积累后在整个半连续发酵过程中浓度不再增加,始终处于较低的浓度。更多还原

【Abstract】 Paper sludge is solid waste from wastewater treatment of pulp and paper making mill, which consists of cellulose and hemicellulose. A study was taken up to determinate the composition of paper sludge and to esatablish simultaneous saccharification and fermentation (SSF) and simultaneous saccharification and co-fermentation (SSCF) using paper sludge, yeast and commercial cellulase. Ethanol production from paper sludge using SSF and SSCF were investigated.The moisture content of wet chemical pulping sludge was 72.70%, pH value was 7.6; the average ash in dried sludge was 38.32%, protein was 1.52% and fat was 2.74%. Based on the amount of glucose and xylose present after dilute acid hydrolysis, the amount of cellulose and hemicellulose was estimated to be 25.77% and 5.86% respectively. The moisture content of wet deinking paper sludge was roughly 41.47%, pH value was 7.6, and the composition of the dried deinking paper sludge was determined to be: 43.96%ash, 11.99%cellulose, 3.92% hemicellulose, 1.78%protein and 1.11%fat. The characteristics of Saccharomyces cerevwasiae SHY08-3 and fusion SHY07-1 were investigated.The results showed that the culture with 18-21h was suitable inoculum.The experiment results showed that commercial cellulase can be used for SSF without filtration sterilization. Chemical pulping sludge had good enzymability and fermentability, whereas deinking paper sludge was not susceptible to cellulase. The maximum ethanol production efficiency of chemical pulping sludge and deinking paper sludge, 95.97% and 72.71% respectively, were reached at 72h of fermentation under the conditions of substrate concentration of 35g/L (according to cellulose), cellulase loading of 55FPU/gEC(effective cellulose), inoculum size of 6%, temperature of 37℃and rotation speed of 200rpm.The optimum technical conditions for ethanol production using SSCF were as follows: pH6, temperature 30℃, substrate concentration 40g/L, cellulase loading 40FPU/gEC. Under such conditions, the final ethanol concentration was 14.80g/L, and ethanol production efficiency was 65.96%. The orthogonal design was used for estimating significance of the factors for ethanol production. The results showed that cellulase loading was the most significant factor, and substrate concentration and fermentation temperature had significant effect on ethanol production too. However, inoculum size had no significant effect on ethanol production. Compared to SSF, SSCF had certain advantages at the same substrate concentration and enzyme loading, but it needed to improve the ability of fusion yeast SHY07-1 to utilize glucose.The semicontinuous fermentation made more paper sludge utilized for ethanol production at lower enzyme loading than batch fermentation. The concentration of ethanol increased twice after semicontinuous fermentation and the concentration reached 32g/L. Meantime, byproducts were no longer increased in semicontinuous fermentation and maintained at low concentration.更多还原