Development of bioreactors

The yield in the standard equipment (stirred tanks and bubble columns) for syngas is generally limited by mass transfer limitations and maximum product concentration. To improve the yield, this project aims to design,

  1. Membrane bioreactor that allows maintaining high concentrations of CO and H2 by either distributed feeding of gas and/or removal of the product
  2. Spinning disk reactor that allows high mass transfer rates and thus increase the yield of products.

Alongside, the project will combine computational fluid dynamics (CFD) with metabolic models to predict the progress of syngas fermentation in industrial bubble columns. These predictions can be used to formulate design rules for scale-up/down of optimal syngas conversions

This workpage consists of 2 projects
Project 1: New designs for syngas converting bioreactors

Developing carbon molecular sieve membranes for membrane bioreactors

Bioreactors offer an efficient solution for harnessing off-gas streams from industrial processes, like those in steel mill plants, to generate value-added products. The crucial step involves the separation of gases such as H2, CO, and CO2 with specific concentration requirements for optimal bioreactor performance. Simultaneously, the extraction of the desired product from the bioreactor could enhance efficiency by increasing selectivity and shifting the equilibrium.

This project centers on the development and fabrication of Carbon Molecular Sieve Membranes (CMSMs) for gas separation and pervaporation. CMSMs are explored as potential candidates for separating H2, CO2, CO, and CH4 from gas mixtures, aiming to concentrate them either as a bioreactor feed or as bioreactor products. Additionally, pervaporation CMSMs are investigated for bioethanol dehydration, bioethanol selective separation, and propionic acid separation. This comprehensive approach aims to optimize processes and advance the utilization of CMSMs in various applications, enhancing the efficiency and versatility of gas separation and pervaporation systems.

New designs for syngas converting bioreactors (spinning disk reactors)

The conventional equipment for syngas fermentation, such as stirred tanks and bubble columns, faces limitations in gas-to-liquid mass transfer and maximum product concentrations. To address these challenges and enhance yield, a system needs to be designed. The primary focus lies on increasing mass transfer rates through elevated pressure and the incorporation of a rotor-stator spinning disc reactor (rs-SDR). This research consists of two parts: characterizing the rs-SDR and optimizing syngas fermentation with Clostridium autoethanogenum (C. autoethanogenum).

The initial research segment involves comprehensive characterization of the rs-SDR through experimental and computational work. The rs-SDR, a novel device exhibiting significant potential for multiphase systems with exceptionally high mass transfer rates, comprises a rotor rotating up to 4000 rpm enclosed by a stator, maintaining a 1 to 10 mm distance between them. The second research line aims to enhance syngas fermentation productivity by focusing on increased solubility through elevated pressures and improved gas-to-liquid mass transfer rates through the implementation of an rs-SDR. This dual-pronged approach seeks to optimize the efficiency of syngas fermentation, promising advancements in mass transfer capabilities and overall process performance.

Project 2: Methods for scale-up of bubble columns for syngas fermentation

The research is focussed on developing scale-up methods for syngas fermentation in bubble-column type reactors. Following the conventional scale-up methodology that commences with envisioning the final outcome, our initial task involves characterizing an industrial-scale syngas fermentation process. A good example of an industrial-scale syngas fermentation process is the LanzaTech process. We use this process as a case study to determine what performance has to be obtained. Based upon this, strategies need to be developed to achieve such performance at the industrial scale. Since in the industrial reactors concentration gradients of CO and H2 are expected to occur, we expect that the micro-organism will experience rapid changes in CO and H2 concentration. Such concentrations could affect the metabolism of the microbe and thus affect the overall process performance. By developing scale-down simulators, that could replicate industrial concentration gradients in the lab, we can study how these conditions would affect the microbe. Using the developed scale-down approach and strategies for high performance, an optimal-type of bioreactor for industrial-scale syngas fermentation could be developed.