Department of Civil, Biochemical and Chemical Process Engineering, Division of Sustainable Process Engineering, Environmental and Natural Resources Engineering, Luleå University of Technology, SE 971 87 Luleå, Sweden.
Biotechnol Biofuels. 2014 Jan 8;7(1):4. doi: 10.1186/1754-6834-7-4.
Environmental issues and shortage of fossil fuels have turned the public interest to the utilization of renewable, environmentally friendly fuels, such as ethanol. In order to minimize the competition between fuels and food production, researchers are focusing their efforts to the utilization of wastes and by-products as raw materials for the production of ethanol. household food wastes are being produced in great quantities in European Union and their handling can be a challenge. Moreover, their disposal can cause severe environmental issues (for example emission of greenhouse gasses). On the other hand, they contain significant amounts of sugars (both soluble and insoluble) and they can be used as raw material for the production of ethanol.
Household food wastes were utilized as raw material for the production of ethanol at high dry material consistencies. A distinct liquefaction/saccharification step has been included to the process, which rapidly reduced the viscosity of the high solid content substrate, resulting in better mixing of the fermenting microorganism. This step had a positive effect in both ethanol production and productivity, leading to a significant increase in both values, which was up to 40.81% and 4.46 fold, respectively. Remaining solids (residue) after fermentation at 45% w/v dry material (which contained also the unhydrolyzed fraction of cellulose), were subjected to a hydrothermal pretreatment in order to be utilized as raw material for a subsequent ethanol fermentation. This led to an increase of 13.16% in the ethanol production levels achieving a final ethanol yield of 107.58 g/kg dry material.
In conclusion, the ability of utilizing household food waste for the production of ethanol at elevated dry material content has been demonstrated. A separate liquefaction/saccharification process can increase both ethanol production and productivity. Finally, subsequent fermentation of the remaining solids could lead to an increase of the overall ethanol production yield.
环境问题和化石燃料短缺使公众对利用可再生、环保燃料（如乙醇）产生了兴趣。为了尽量减少燃料与粮食生产之间的竞争，研究人员正致力于利用废物和副产品作为生产乙醇的原料。在欧盟，家庭食物垃圾的产量非常大，其处理可能是一个挑战。此外，它们的处置可能会导致严重的环境问题（例如温室气体排放）。另一方面，它们含有大量的糖（包括可溶性和不可溶性），可以作为生产乙醇的原料。
家庭食物垃圾在高干物质浓度下被用作生产乙醇的原料。该过程中包括了一个明显的液化/糖化步骤，该步骤迅速降低了高固含量底物的粘度，使发酵微生物更好地混合。这一步对乙醇的生产和生产力都有积极的影响，使这两个值都显著提高，分别提高了 40.81%和 4.46 倍。在 45%w/v 干物质（其中还含有未水解的纤维素部分）下发酵后剩余的固体（残渣），经过水热预处理后，可作为后续乙醇发酵的原料。这使得乙醇的产量提高了 13.16%，最终达到了 107.58g/kg 干物质的乙醇得率。
总之，已经证明了在高干物质含量下利用家庭食物垃圾生产乙醇的能力。单独的液化/糖化过程可以提高乙醇的生产和生产力。最后，剩余固体的后续发酵可能会提高整体乙醇生产的产率。
