Process integration

In syngas fermentation (using CO, H2, or CO2), high syngas transfer to an aqueous phase remains the challenge. The complete process needs syngas conditioning, downstream separations for liquids and gases, and recycling of unconverted species. This work package links the microbial conversion and bioreactor to overall processes (from crude syngas to recovered product) and further to the economic and environmental impact from cradle to grave. 

This workpackage encompasses 2 projects
Project 1: Process development 

Process development (membrane reactor)

In syngas fermentations (using CO, H2 or CO2), gas-to-liquid mass transfer is often regarded as one of the limiting step. The research project focusses on the investigation of membrane bioreactors as a configuration to overcome mass transfer limitations in syngas fermentation to non-volatiles. It aims to answer the research question: “How  can the membrane bioreactor systems be used to achieve syngas conversion processes with the required productivity?”. The objective is to find and to study the best operational window of a scalable membrane bioreactor system for the permeation and fermentation of syngas to chemicals by a microbial culture (with well-defined stoichiometry and kinetics). The project research framework is organized in several work packages:  “Fixing default conditions”, “Experimental methods development” , “Mathematical modelling”, “ Simultaneous cell retention and in-situ product removal” and “Membrane bioreactor operation”.

Process development (membrane and spinning disc extractor designs)

The production of carboxylic acids by fermentation has gained research attention to achieve a renewable option as compared to fossil carbon-based benchmarks. A major bottleneck lies on the recovery from fermentation broths of these acids, which are normally present at dilute concentration (ca. 5 wt.%). Reactive extraction is an alternative to solvent extraction. The process involves a reaction between an extractant, a diluent, and the carboxylic acid. The extractant, often a tertiary amine, form complexes with the acid that are soluble in the organic phase. Back-extraction of these acids is equally important, and both processes must be considered when optimizing process and costs. Reactive extraction of carboxylic acids outperforms conventional solvent extraction, due to its superior partition coefficients obtained when selecting a suitable extractant and diluent. Most reactive extraction studies has been carried out in batch systems at relatively low stirring speeds (< 150 rpm), where the reaction takes place in the liquid-liquid interfacial area. In this concept, vigorous stirring is preferred to quickly reach equilibrium leading to the formation of un-wanted, stable emulsions which often require a subsequent centrifugation stage. This work deals with the study of a novel reactor, membrane-assisted spinning disc reactor (MASDR) to intensify the process of reactive extraction.

Project 2: Process design and sustainability assessment

Conceptualization of the sustainable production of chemicals via syngas fermentation

The primary aim of this project is to outline the conceptual framework for the forthcoming commercial production of chemicals through syngas fermentation. An encompassing and systematic methodology is imperative, considering the vast array of technical alternatives spanning feedstocks, products, and technologies. The initial project phase involves categorizing potential products into volatile and non-volatile categories, with acetate serving as the benchmark. Focusing on volatile products, a decision-making framework will be devised to explore the plausible configurations of diverse feedstocks and products.

Among the considered feedstocks are Basic Oxygen Furnace Gas (BOFG) and Blast Furnace Gas (BFG) emissions from the steel manufacturing industry, as well as syngas derived from biomass gasification (BioSyngas). This analysis identifies the most viable products for commercial-scale production and their associated feedstocks. Additionally, the study delves into the economic feasibility of these pathways, potential enhancements, and their adaptability to various production strategies.