Development of an automated adsorbent selection strategy for liquid–phase adsorption

A systematic and automatic approach for adsorbent selection for liquid–phase adsorption is proposed. Based on physical properties like polarity, pore size, and specific surface, a screening strategy is developed and automated on a robotic platform. Key performance indicators are applied ensuring economically based decisions. The approach developed is verified by adsorption of caffeine out of an aqueous solution with vanillin, uracil, and α–ionon as impurities. The adsorbent selection strategy leads to the polymeric adsorbent SP207 and a specific surface of 15 m2mL−1 ending in a separation cost indicator of 16 € gCaffeine−1. This work proposes an opportunity for accelerated process design strengthened by the usage of robotic devices

Extraction on a robotic platform - autonomous solvent selection under economic evaluation criteria

Steps and necessary decisions for a liquid-liquid extraction were pointed out for its automatic design on a robotic platform. A tool for solvent selection based on Hansen parameters was developed to simplify solvent selection. An approach was developed for automatic, visual phase boundary detection. Key performance indicators are used to ensure economically motivated decisions. The autonomous design of an extraction process is demonstrated for the separation of progesterone from a fermentation broth. The method leads to the selection of methanol and acetonitrile, with separation cost indicators of 146 and 183 € gProg.−1. This work constitutes the prospects of using autonomous robotic systems to design entire production processes

Application of rotating packed bed for in-line aroma stripping from cell slurry

BACKGROUND Nowadays, biotechnological production receives increasing interest as an alternative source of natural aromas. Unfortunately, especially for hydrophobic and semi-volatile aromas, the heterogeneous product partitioning between all phases present in fermentation makes recovery challenging. Additionally, when an aroma displays an inhibitory effect on the production microorganism, product removal during fermentation is recommendable. In-line aroma stripping offers an elegant way to deal with such challenges. This study reports the use of rotating packed bed (RPB) technology for the intensification of stripping of α-ionone, a key aroma of raspberry, from a model fermentation slurry containing Saccharomyces cerevisiae cells in a concentration of 250 g-CWW L−1. RESULTS Throughout all experimental investigations, yeast cells were robust towards both the chemical stress from aroma exposure at a concentration of up to 400 mg L−1 and the mechanical stress from peripheral equipment and rotation of up to 2750 rpm, as a maximum of 11.3 ± 0.5% disrupted cells were measured during continuous processing in an RPB. An increase in the rotation speed led to an enhanced transfer of α-ionone from the fermentation slurry to the gaseous phase. CONCLUSIONS RPB technology is found to be promising for the intensification of in-line stripping of biotechnologically produced aromas from crude fermentation broth without cell separation. The use of subsequent RPBs equipped with custom packings and flexibly adjustable rotation speed displays a holistic aroma recovery process supporting the way to commercial competitiveness of biotechnological aromas. © 2020 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry

Aroma absorption in rapeseed oil using rotating packed bed

An increasing consumers’ call for natural aromas fuels the development of biotechnological aroma production. Although aroma fermentation is quite advantageous, especially severe product losses of volatile compounds through the bioreactor off-gas may challenge the downstream processing. The application of novel process intensification methods to overcome the common drawbacks of conventional apparatuses might be helpful on a way to commercial competitiveness of biotechnological aromas. This study explored the suitability of rotating packed bed (RPB), a rotating mass transfer enhancing machine, for the absorption of model aroma compounds in rapeseed oil. Increasing the rotation speed from 500 to 2750 rpm led to two- to threefold higher absorption efficiencies at elsewise constant conditions. Aiming for an enriched aromatic intermediate, 2.5 L of rapeseed oil was processed in a recycle for 200 minutes, and a final concentration of benzaldehyde of 0.323 ± 0.026 g/Loil was achieved. Compared to packed columns, the RPB outperforms at equal packing depth or requires less packing area to deliver same efficiency. Especially, the use of custom 3D-printed spiral packing with elaborated wall film flow combined with rotation supported liquid distribution allows using absorbents with viscosities as high as 100 mPa·s at low pressure drop increase. However, small dimensions severely limit the performance of a laboratory-scale RPB as the casing contributes disproportionally to mass transfer

Towards continuous aqueous two-phase extraction (CATPE)

Aqueous Two-Phase Extraction (ATPE) in mixer-settlers offers a gentle and biocompatible environment to separate proteins from complex mixtures. We have developed an aqueous two-phase system with inexpensive and biocompatible PEG 1500 or 4000 and ammonium citrate. We have purified several dehydrogenases [1] to near homogeneity after forward extraction into a PEG-heavy top phase at pH \u3e 9 and back extraction into a bottom phase at pH 4-6; in selected cases, we were able to obtain pure protein in the bottom phase without forward extraction into the top phase. We have scaled up the PEG 1500/4000-ammonium citrate to a 5-10 L scale, with phase separation times of less than five minutes.[2] We currently extend the system to the separation of Qα virus-like particles. However, ATPE technology is characterized by complex phase separation and very limited number of separation stages not offering enough separation efficiency. These limitations can be overcome by the novel Tunable Aqueous Polymer Phase Impregnated Resins (TAPPIR) technology which immobilizes one phase out of a biphasic aqueous extraction system in porous material (Figure 1) [3]. By immobilizing these impregnated resins in columns continuous operation similar to Simulated Moving Bed systems become possible. TAPPIR provides high separation efficiency along with high capacity, avoids long phase separation times (especially for highly viscous polymer phases) and offers an answer to the non-ecological image of ATPE through immobilizing and re-using phase forming material. The application of the TAPPIR technology has been shown for the separation of lysozyme and myoglobin using a polyethylene glycol 4000/citrate aqueous two-phase system in batch experiments [4]. In addition, the influence on protein partitioning of the porous solids\u27 properties like solid material, particle and pore size has been investigated. It could be demonstrated that the same partitioning levels can be reached for the TAPPIR as for classical ATPE mixer/settler experiments and that the leaching of the immobilized phase is negligible [5]. The presentation will introduce the TAPPIR technology, describe the advantages over chromatography and present a process concept for continuous operation with zero waste

Progress towards continuous aqueous two-phase extraction via TAPPIR

At ICB II, we presented Aqueous Two-Phase Extraction (ATPE) as a non-chromatographic alternative for protein purification. We had developed an aqueous two-phase system with inexpensive and biocompatible PEG 1500 or 4000 and ammonium citrate. We purified several enzymes, more specifically a series of dehydrogenases [1], to near homogeneity after forward extraction into a PEG-heavy top phase at pH \u3e 9 and back extraction into a bottom phase at pH 4-6; in selected cases, we were able to obtain pure protein in the bottom phase without forward extraction into the top phase. Scale-up of the PEG 1500/4000-ammonium citrate to 5-10 L scale still often gave phase separation times of less than five minutes.[2] However, ATPE technology is characterized by complex phase separation and very limited number of separation stages not offering enough separation efficiency. Furthermore, conventional ATPE does not lend itself to continuous operation. Please click Additional Files below to see the full abstract

Tailor-made aqueous two-phase systems for application in continuous separation of potent biomolecules

Aqueous Two-Phase Extraction (ATPE) using Aqueous Two-Phase Systems (ATPS) has long been shown to be a viable and promising alternative in the work-up of potent biomolecules (e.g. enzymes, proteins, therapeutics) from fermentation broth. Although ATPE has significant advantages over common separation strategies, such as a high biocompatibility, gentle separation profile due to low interfacial tension, good scalability and high efficiencies, industrial applications have not yet been realized. Reasons typically given are based on the ATPS “physiochemical” properties such as viscosities and low density differences between the phases, which lead to long phase separation times. However, these challenges can be addressed using advanced technology such as the “Tunable Aqueous Polymer-Phase Impregnated Resins” (TAPPIR)-Technology immobilizing one phase of an ATPS inside porous solids, which are then transferred into a chromatography column. The second aqueous phase serves as mobile phase. The main advantage of this technique is the simple and efficient emulsification and liquid–liquid phase separation through the packed-bed column design. In addition, the extraction phases, i.e. both the back extraction phase and the immobilized phase, can be reused enabling a low-waste production process. The remaining bottleneck for an industrial application is the identification of the “base” ATPS, which enables the desired extraction of the biomolecule with the required yield and purity to be competitive to existing processes. State-of-the-art ATPS design so far is based on a “trial-and-error” based approach identifying ATPS that work for a given task but often perform in suboptimal fashion. In the present work, we will present a novel thermodynamics-based strategy for the identification and characterization of tailor-made ATPS for the continuous separation of highly potent industrial enzymes by ATPE. By consideration of the molecular interactions in solution, we are able to define potentially suitable ATPS based on a predictive modeling approach using ePC-SAFT, a state-of-the-art equation of state. The objective of this step is to supply a thermodynamically optimized combination of ATPS-phase formers that lead to optimal water condition (low concentration of phase formers, large process window), in principal enabling optimal separation. This initial selection is refined by taking into account molecular interactions of the biomolecule (enzyme), by measuring and modeling biomolecule-biomolecule and biomolecule-phase former interactions. These interactions are experimentally captured using advanced light scattering techniques that are both time and cost efficient. It will be shown that, based on the description of molecular interactions through osmotic virial coefficients (B22 and B23) as well as the diffusion interaction parameter (kD) between the molecules in solution, the phase behavior of the biomolecule in an ATPS can be made accessible, but was previously inaccessible with other phase diagram estimation strategies One major advantage of our predictive modeling approach is the estimation of the partition coefficient of the biomolecule between the two aqueous phases based on a minimal set of experimental data, i.e. B22, B23, kD, and phase composition data. Furthermore, the influence of the ATPS phase-formers on protein solubility and stability can be judged qualitatively, an ideal complement in the development of ATPS. Lastly, we applied the thermodynamics-based strategy to the separation of an industrially relevant dehydrogenase from fermentation broth. The design-driven process development led to the identification of a tailor made ATPS that outperformed the reference ATPS from previous works in terms of solubility and stability of the biomolecule enabling a cost-efficient use of the TAPPIR technology

Research on industrial biotechnology within the CLIB-Graduate Cluster - Part I

Pietruszka J, Pühler A, Schembecker G. Research on industrial biotechnology within the CLIB-Graduate Cluster - Part I. Journal of Biotechnology. 2012;159(3):121-122