Production de microalgues à partir de carbone résiduel pour une implantation dans la bioraffinerie de 2e génération

纤维素乙醇生产过程不仅需要可发酵的糖，还需要补充的微量和大量营养素，这些营养素将有助于这些碳水化合物的吸收，并有助于酵母将其转化为乙醇。然而，木质纤维素生物质通常缺乏这些化合物，因此需要添加营养混合物，如酵母提取物或补充氮和矿物源，以有效发酵纤维素碳水化合物。此外，木质纤维素糖流将产生一种新型残留物，这将成为当前第一代乙醇工业增值链（谷物和可溶物）的挑战。例如，通过微藻生物量补充营养物可以为该过程带来价值，从而使第二代乙醇相对于第一代更具竞争力。除了这些现实之外，第一代乙醇生产过程产生了大量的人为二氧化碳，特别是在加热要求很重要的加拿大。因此，这些二氧化碳排放显著影响了第一代和最终第二代乙醇生产过程的碳平衡。然而，与此同时，这些二氧化碳代表了一种有价值的碳源，特别是通过自养微藻，可以潜在地转化为生物质。酒精发酵过程产生了一种富含蛋白质的低附加值侧流——背流，可以作为微藻的培养基。因此，本项目旨在通过利用第一代乙醇生产过程产生的废水来支持第二代乙醇技术的实施，同时减少其二氧化碳足迹，将乙醇工业面临的两个最重要的限制转化为机会。

The cellulosic ethanol production process requires not only fermentable sugars but also complementary micro- and macro-nutrients which will aid the uptake of these carbohydrates and their conversion to ethanol by the involved yeast. However, the lignocellulosic biomass generally lacs these compounds and thus requires the addition of nutrient mixtures such as yeast extract or complementary nitrogen and mineral sources for the efficient fermentation of the cellulosic carbohydrates. Furthermore, the lignocellulosic sugar streams will generate a new type of residue which will become a challenge for the valorization chain of the current first generation ethanol industry (grains and solubles). A complementary nutrient addition through microalgal biomass for instance could bring value to the process, making thus the second generation ethanol more competitive with respect to the first generation. Besides these realities, the first generation ethanol production process generates significant anthropogenic CO2, especially in Canada where heating requirements are important. These CO2 emissions significantly impact thus the carbon balance of the first and eventually second generation ethanol production processes. In the same time however, this CO2 represents a valuable carbon source which could potentially be converted, especially by autotrophic microalgae, to biomass. The alcoholic fermentation process generates a protein-rich sidestream with low added value, the backset, which could be used as cultivation media for these microalgae. Thus, the present project aims to transform two of the most important constraints faced by the ethanol industry into an opportunity by utilizing the effluents generated by the first generation ethanol production process to support the implementation of second generation ethanol technologies while simultaneously reducing their CO2 footprint.