Fine Bubbles for Biocatalytic Processes

工艺工程对曝气的要求越来越高，要求曝气具有高传质性能、低压降、低剪应力和避免起泡，这为新技术开辟了一个有趣的领域。实现这些目标的一种可能性是用直径小于100微米的细小气泡进行曝气。在日本，可以找到许多细微气泡的应用，并且已经成立了几家公司，提供细微气泡发生器(FBG)和细微气泡分析设备。2013年，精细气泡技术技术委员会(FBT)成立，并得到标准化组织(ISO)的批准。在德国，人们所知的最多的是与浮选过程有关的细小气泡，但它们在两相流中的传质潜力迄今尚未得到解决。特别是物理性质和有效性的问题没有得到令人满意的回答。几位作者报告了几个星期到几个月的微小气泡的寿命，这比预测的要长得多。这种影响的讨论是非常矛盾的，并归因于污染或表面电荷。然而，小尺寸气泡的引入会导致大体积比表面积，从而导致高传质速率。德国和日本在多尺度多阶段工艺工程领域的强大合作(MMPE联席会议2011和2014，由DFG支持)提供了一种独特的可能性，可以在德国和日本之间深入交流关于细微气泡及其应用的知识，并使这一新兴技术领域的研究变得高效。该项目旨在研究微小气泡在生物催化过程中的潜力。与传统系统相比，微泡曝气具有传质性能好、两相压降和剪应力可忽略不计、避免发泡和避免反应物蒸发等优点。虽然多相流研究所的测量方法将以高时间和空间分辨率深入了解微气泡两相流中的流体动力学和传质过程，但生物催化研究所的反应工程专业知识和生物催化知识将使详细研究微气泡对搅拌槽和填充床反应器中的生物催化反应的影响。在知识转移方面，日本庆应大学的Terasaka Koichi教授打算以墨卡托研究员的身份加入该项目。此外，庆应大学和东京大学之间密集的学生、博士生和教授的科学交流将促进两所大学之间的研究，并在下一届在日本富山举行的MMPE 2017国际研讨会上展示结果，旨在推动与微小气泡研究有关的进一步举措。

The rising demand in process engineering for aeration with high mass transfer performance with low pressure drop, low shear stress and avoidance of foaming opens an interesting field for new technologies. One possibility to achieve these goals is the aeration with fine bubbles whose diameter is less than 100 micrometers. In Japan, many applications of fine bubbles can be found and several companies have been established that are offering fine bubble generators (FBG) and analyzing devices for fine bubbles. In 2013, the technical committee for Fine Bubble Technologies (FBT) was established and approved by the Organization for Standardization (ISO). In Germany fine bubbles are known at the most in connection with flotation processes but their potential for mass transfer in two phase flows has not been addressed so far. Especially the question of physical properties and effectiveness has not been answered satisfactorily. Several authors are reporting a lifetime of fine bubbles in the range of several weeks and months, which is much longer than the predicted one. This effect is discussed very contradictorily and attributed to contaminations or surface charging. Nevertheless, the introduction of small-sized bubbles leads to large volume-specific interfacial areas and therefore to high mass transfer rates. The strong collaboration between Germany and Japan in the field of Multiscale Multiphase Process Engineering (MMPE joint conferences 2011 and 2014, supported by the DFG) provides a unique possibility to intensively exchange knowledge about fine bubbles and its applications between Germany and Japan and enables efficient research in this emerging field of technology. This project is intended to investigate the potential of fine bubbles for biocatalytic processes. High mass transfer performance, negligible two-phase pressure drop and shear stress as well as the avoidance of foaming and reactant evaporation are the most promising advantages of fine bubble aeration in comparison to conventional systems. While the measurement methods of the Institute of Multiphase Flows will provide a deep insight into hydrodynamics and mass transfer processes in fine bubble two-phase flows with high temporal and spatial resolution, the reaction engineering expertise and knowledge in biocatalysis of the Institute of Technical Biocatalysis will enable the detailed investigation of the effect of fine bubbles on biocatalytic reactions in stirred tanks as well as packed bed reactors. For the transfer of knowledge, Prof. Koichi Terasaka from Keio University, Japan is intended to join the project as Mercator Fellow. Furthermore, an intensive scientific exchange of students, PhD students and professors between Keio University and TUHH will foster research between the Universities and the presentation of results at the next International Symposium of MMPE 2017 in Toyama, Japan, is intended to motivate further initiatives related to research on fine bubbles.