Despite their potential as biofuel resources, large-scale production of biofuels from microalgae is still uncertain primarily due to a lack of feasibility of the process and that it proves to be capital and energy intensive. Therefore, an integration of microalgal cultivation with other processes for achieving an inexpensive nutrient and energy use is an important issue. In the present study, the potential of the flue gas and the wastewater of a sugar factory to support microalgae growth for biofuel and bio-fertilizer production is evaluated. The study was carried out by following a case study approach; an Ethiopian sugarcane-processing factory, Metahara sugar and ethanol production factory, was selected for this purpose. Conceptual microalgal biofuel production was integrated with the real sugarcane-processing factory, and the process was evaluated with regard to the product outputs and energy requirements. The integrated process model shows that three products, biodiesel, upgraded biogas, and bio-fertilizer with production capacities of 188 tons/year, 1,974,882 m3/year and 42 tons/year, respectively, were produced. For the production of these products, the electricity and thermal energy demand of the integrated process amounted to 1822.13 and 3244.99 MWh/year, respectively. A sensitivity analysis shows that the oil content of the algae, the nitrogen content of the waste, the oil extraction efficiency, and the transesterification efficiency are the main factors which affect the biodiesel production capacity of the integrated process. This case study approach investigated the potential of a future possible bio-refinery and environmental pollution reduction concept by integrating microalgae biomass production with sugarcane-processing factory wastes and by-products. It was found that the factory wastes and by-products have a significant potential for a viable biofuel production from microalgae.

中文翻译：

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培养用于生物燃料生产的微藻：与甘蔗加工厂结合

尽管它们具有作为生物燃料资源的潜力，但仍主要由于缺乏该方法的可行性而无法确定由微藻大规模生产生物燃料的能力，而且该过程证明是资本和能源密集型的。因此，将微藻栽培与其他工艺相结合以实现廉价的营养和能源利用是一个重要的问题。在本研究中，评估了糖厂的烟道气和废水支持微藻生长以生产生物燃料和生物肥料的潜力。该研究是通过个案研究方法进行的；为此，选择了埃塞俄比亚的甘蔗加工厂，原原糖和乙醇生产厂。将概念性微藻类生物燃料生产与真正的甘蔗加工厂整合在一起，并根据产品产量和能源需求对过程进行了评估。集成过程模型显示，生产了三种产品，分别为188吨/年，1,974,882立方米/年和42吨/年的生物柴油，沼气和生物肥料。对于这些产品的生产，集成过程中的电力和热能需求分别为1822.13 MWh /年和3244.99 MWh /年。敏感性分析表明，藻类的含油量，废物中的氮含量，油的提取效率和酯交换效率是影响整个过程生物柴油生产能力的主要因素。该案例研究方法通过将微藻类生物质生产与甘蔗加工厂的废料和副产品整合在一起，研究了未来可能的生物精炼和减少环境污染概念的潜力。人们发现，工厂废物和副产物具有从微藻生产可行的生物燃料的巨大潜力。