Fine Bubbles for Biocatalytic Processes

工艺工程对具有低压降、低剪切应力和避免发泡的高传质性能的曝气的需求日益增长，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是用直径小于100微米的细气泡进行曝气。在日本，可以找到许多精细气泡的应用，并且已经建立了几家公司，提供精细气泡发生器（FBG）和精细气泡分析设备。2013年，精细气泡技术（FBT）技术委员会成立，并获得标准化组织（ISO）批准。在德国，细气泡与浮选过程有关，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问题还没有得到满意的回答。几位作者报告说，细泡沫的存在周期在几周和几个月之间，这比预测的要长得多。这种影响的讨论非常矛盾，并归因于污染或表面充电。然而，小尺寸气泡的引入会导致较大的体积比界面面积，从而导致高传质率。德国和日本在多尺度多相工艺工程（MMPE联合会议2011年和2014年，由DFG支持）领域的强大合作，为德国和日本之间深入交流有关细气泡及其应用的知识提供了独特的可能性，并使这一新兴技术领域的有效研究成为可能。本项目旨在研究细气泡在生物催化过程中的潜力。高传质性能、可忽略的两相压降和剪切应力以及避免起泡和反应物蒸发是细泡曝气与传统系统相比最有前途的优点。多相流研究所的测量方法将为细泡两相流的流体动力学和传质过程提供深入的见解，具有高时间和空间分辨率，而技术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细泡对搅拌槽和填充床反应器中生物催化反应的影响的详细研究成为可能。在知识转移方面，日本庆应义塾大学的Koichi Terasaka教授将以墨卡托研究员的身份加入该项目。此外，庆应义塾大学和TUHH之间的学生，博士生和教授之间的密集科学交流将促进大学之间的研究，并在日本富山举行的下一届MMPE 2017国际研讨会上展示成果，旨在激励与细气泡研究相关的进一步举措。

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.