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AACHENER VERFAHRENSTECHNIK

ANNUALREPORT2013.

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Content

Aachener Verfahrenstechnik

BIOCHEMICALENGINEERING (BIOVT)

ENZYMEPROCESSTECHNOLOGY (EPT)

COMPUTATIONALSYSTEMSBIOTECHNOLOGY (CSB)

MOLECULARSIMULATIONSAND TRANSFORMATIONS (MST)

CONFERENCES&WORKSHOPS

DOCTORATESANDAWARDSCHEMICALPROCESSENGINEERING (CVT)

PUBLICATIONLIST

MECHANICALPROCESSENGINEERING (MVT)

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PROLONGATION&RESULTS TMFB

SFBMICROGELS

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PROCESSSYSTEMSENGINEERING (SVT)

THERMALPROCESSENGINEERING (TVT)

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Dear Colleagues, Friends and Alumni,AVT is happy to present to you a glance back into the scientific year 2013. We continue our journey towards next generation processes and products (NGP²) with a further integration of our research, as reflected by the cross-chair projects and the short research highlights of the individual chairs. We invite you to dig deeper into our publications or to join us in the current conferences and workshops. But most of all, we are proud of our key "products", the graduated research assistants, and their achievements as reflected by the scientific awards.

Please, enjoy!Antje Spieß

PROCESSSYSTEMSENGINEERING (PT)

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PROLONGATION&RESULTS

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"Tailor-Made Fuels from Biomass"

Jörn Viell

The vision of the cluster of excellence "Tailor-Made Fuels from Biomass" at RWTH Aachen University is the development of an innovative fuel tailored to an automotive combustion engine while being sustainably produced from biomass. The objective is accomplished by an integrated product and process design jointly optimizing the fuel's molecular structure for tailored properties in combustion and for an efficient production pathway. Possible biofuel molecules are suggested by a novel molecular structure generator based on computer-aided molecular design and quantitative structure-property relationships to narrow the molecular search space (AVT.PT). In addition, the optimization-based methodology of Reaction Network Flux Analysis rapidly evaluates competing reaction pathways to identify the most promising processing route.

One of very first steps in the process is the pretreatment of biomass. Several pretreatments have been investigated (AVT.EPT & AVT.PT). Organosolv pretreatments of beech wood were carried out at the Max-Planck Institute in Mülheim in a joint effort (AVT.CVT & AVT.BioVT). Analysis of the obtained fractions is essential in order to develop an experimentally-verified mechanistic understanding. For this purpose a junior research group was installed which aims to improve the available analytical methods of chromatography for comprehensive quantitative characterization of the produced biomass fractions (AVT.EPT). The analytical methods serve to develop a better understanding of the catalytic degradation of cellulose and of the dissolution of the model-substrate cellulose in ionic liquids (AVT.EPT and AVT.PT). The experimental studies are

used for simulations of the reaction progress and of the activation energy barriers (AVT.EPT and AVT.MST).One option to convert the obtained lignin is by using fungal laccases. They have been successfully applied for an enzymatic disintegration of biomass promoting the subsequent cellulose hydrolysis of the carbohydrates (AVT.EPT). Additionally, a biocatalytic pre-oxidation of lignin by laccases, has been proven to facilitate further chemical cleaving reactions. Another means to valorize a lignin stream is the electrochemical treatment in membrane reactors with subsequent filtration steps to remove the value-added products from the process stream (AVT.CVT). Moreover, membrane separation is also employed to recycle the solvents and the enzymes (AVT.CVT) as a precondition for economic prospect of any process concept.

The viability of the concepts developed in product and process design is demonstrated in the reference process. Ongoing process optimization is applied to decrease the formation of side products, the requirement of auxiliaries and the overall energy demand from a process perspective (AVT.PT). An integrated approach with support by the Ökoinstitut e.V. is applied to analyze the global warming potential and the cumulative energy demand. The hereby revealed bottlenecks in the production of itaconic acid triggered the design of alternative separation concepts at AVT.CVT and AVT.PT and the investigation of different microorganisms (AVT.BioVT) for improved robustness against potential extraction agents and for higher yield. The conceptual process designs show the potential of the improved itaconic acid pathway towards a sustainable biofuel production process.

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Modular Biorefinery for Next Generation Processes and Products (NGP²)

Georg Wandrey

With the aim of NGP² to find and investigate new processes and products based on sustainable resources the modular biorefinery can be seen as the technical heart of our new building. A total size of 900 m² over three floors allows the realization and combination of mechanical, thermal, chemical and biochemical processes on technical scale.

In the last year a team of engineers and natural scientists started with the conceptual design of unit operations and (online) measurement techniques. The challenge is to provide infrastructure which is built up from modular units and is thus flexible enough to realize a variety of novel synthesis routes. The first route which will be established in the biorefinery is the reference process of the cluster of excellence "Tailor-Made Fuels from Biomass". Within this process, renewable plant biomass is converted to the platform chemical itaconic acid using a combination of different unit operations.

The biomass is pretreated mechanically with mills and a screw press prior to chemical fractionation via the Organocat process. Conversion of the different fractions is achieved using purpose-built reactors for enzymatic hydrolysis and fermentation. Separation processes as well as the subsequent downstream processing for purification of the final product consist of several filtration, distillation and crystallization steps. By combining and integrating all process steps on technical scale, the design of processes required for a sustainable economy will be enhanced significantly. For instance, feasibility and efficiency of recirculation can be investigated

to assess how often and under which conditions enzymes, solvents and other valuable process streams can be recycled. Ultimately, the biorefinery will focus on the overall process instead of single unit operations to determine viable parameters for an

energetically and economically efficient conversion of sustainable resources into platform chemicals. The modular biorefinery incites researchers of different disciplines to fuse their knowledge and scale up their ideas to a real-life process.

substrate(platform)chemicals

biomassproducts(e.g. fuel)

pretreatment

solventscatalystswater...

conversion separation

on-line analytics and control

INTERMEDIATES

ADDITIVES

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SFB MICROGELS

SFB 985: Functional Microgels and Microgel Systems

Said Abdu (CVT), Hans Breisig (CVT), Pompilia Buzatu (CVT), Johann Hospital (EPT), Franca Janssen (SVT), Daniel Maldonado-Parra (PT), Julian Meyer-Kirschner (SVT)

The Collaborative Research Center SFB 985 funded since Mid-2012 by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) focuses on the study of microgels and microgel systems. Microgels are defined as soft particulate polymer networks with characteristic diameters below a few micrometers, combining properties of both dissolved macromolecules and colloidal particles. Their openness and responsiveness to the environment makes them an ideal synthetic base for novel functionality. Thanks to these properties, microgels pose as promising candidates for several applications such as functionalization of surfaces, controlled uptake and release of active ingredients or their functionalization for catalysis.

By bringing together the disciplines of polymer chemistry, chemical engineering, physics and life sciences, the SFB 985 presents a comprehensive study of microgels from the synthesis of individual particles up to technical scale production and design of new applications. The Aachener Verfahrenstechnik plays a significant role with four chairs involved summing a total of 6 projects in the integrated research areas of model-based product-process design of microgels, functional microgel systems and development of microgel analysis techniques.

AVT.CVTThe chair of Chemical Process Engineering (AVT.CVT) is involved in three projects (B5, B6 and C4) within the Collaborative Research Center 985. In collaboration with the DWI – Leibniz Institute

for Interactive Materials, the AVT.CVT works within project B5 in the design of micro- and mesofluidic devices for the continuous production of monodisperse microgels in two dimensional scales: larger than 10 µm and smaller than 1 µm. Porous channels such as hollow-fiber membranes (Figure 1) and micropatterned flat sheet membranes have been used for the production of monodisperse droplets which act as templates for the synthesis of microgels. So far, continuous formation of droplets with a mean droplet size of approx. 25 µm at a rate of 320 droplets per second has been accomplished with this method. Particular focus is also given to the droplet formation in aqueous two-phase systems since the microgel synthesis in an all-aqueous environment could be

advantageous for the immobilization of biological components, such as enzymes, proteins and cells.

The principal goal of the project B6 is the reduction of the membrane fouling during microgel filtration. It is well known that fouling is a problem in every filtration process and could be even more intense during microgel separation because of their highly active surfaces (Figure 2). In this context, the project aims at understanding the interaction between the hydrodynamic conditions during microgels filtration, the properties of the membrane surface and the properties of the microgels. Isothermal titration calorimetry is used to determine the thermodynamic parameters of interaction in solution and thus the binding affinity

Figure 1: Comparison of droplet formation within a hollow-fiber membrane and the respective CFD simulation.

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between two components. With the help of a high precision, fully automated filtration unit, the microgel suspensions are filtered through virgin and modified membranes. The modification of the membrane surface can be carried out using the same device, through polyelectrolyte coating.

The aim is to reduce the membrane-microgel interaction and suppress adsorption by choosing the right polyelectrolyte for a certain microgel. An OsmoInspector can be coupled with NMR for the visualization of the layer buildup during microgels filtration in precisely controlled conditions. This step is done in collaboration with the Bluemich group (Department of Macromolecular Chemistry, ITMC). Finally, the influence of permeate flow on the microgel retention on the membrane

surface is studied using the elution-based method flow-field flow fractionation. By varying the hydrodynamic conditions within the membrane channel their influence on the microgel adsorption on the membrane surface can be assessed.

Within the C4 project (also in collaboration with the DWI), novel polyelectrolyte-microgel membranes are being developed, having their separation layers formed from patterned microgels. This opens new possibilities to understand the molecular separation phenomena as a function of the nanoscale chemical interactions and well-defined mesoscale polyelectrolyte domain patterns, which would in turn promote a rational optimization (high flux and selectivity) of the performance of electrodialysis and charged mosaic membranes. Monodisperse,

highly-charged nanogels are synthesized. For bipolar membranes, results indicate that applying highly charged nanogels to modify the interface layer of these membranes catalyzes water splitting, leaving room for further optimization – in terms of particle size, charge density and distribution.

AVT.EPTEnzyme Process Technology (AVT.EPT) explores within this SFB's, project C1 the application of responsive microgels as emulsifiers for biphasic enzyme catalyzed reaction systems. Therein, the Richtering group (Physical Chemistry II) creates a microgel tool box, which can help to obtain long term stabilized emulsions. AVT.EPT integrates online analysis and indirect hard model of mid infrared spectra for prediction of partition

Figure 3: Determination of time-resolved reactant concentrations in biphasic reaction system with defined interface using mid infrared spectra.

Figure 2: Adsorption of microgels on a porous membrane.

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coefficient and the enzymatic reaction progress on mini reactor scale. The set-up for on-line analysis of an enzymatic model reaction via attenuated total reflectance middle infrared spectroscopy (ATR-MIR) in aqueous phase is presented in Figure 3.

Linear multivariate regression methods are routinely employed to predict concentrations in the liquid phase from spectral data. Specific limitations such as signal superposition of similar components may impede the prediction quality of the calibration model. Therefore, the well-established and robust indirect hard modeling (IHM) methodology is applied.

The indirect hard model prediction was successful for all reactants in the organic phase with R² > 0.96 and in the aqueous phase with R² > 0.98. The model quality was determined by the prediction of known compound mixtures and applied for process monitoring in reactive experiments. The obtained experimental concentration data will provide a detailed knowledge about e.g. partition equilibria and will serve for the identification of enzyme reaction kinetics in the biphasic and microgel stabilized emulsion system.

AVT.PT and AVT.SVTThe Chairs of Process Systems Engineering (PT and SVT) contribute two further projects to the activities of AVT within the SFB 985.

Project B4, a cooperation with DWI, addresses the kinetic mechanisms during microgel formation by precipitation polymerization of N-isopropyl-acrylamide (NIPAAm) and N-vinylcaprolactam

(VCL) in aqueous phase. In the course of exploration of the microgel synthesis, a mathematical model covering formation mechanisms that include growth of polymer chains, formation of gel particle nuclei and gel particle growth was developed. The model embraces formation mechanisms on different length and time scales: precipitation polymerization reactions are modeled in the aqueous phase, while particle growth is modeled in a singular gel particle resulting in a model regarding different time and length scales as shown in Figure 4. Model-based Experimental Analysis (MEXA) methodology will be extended to multiscale models in order to perform parameter estimation, optimal experimental design and optimal process design. Such a production-oriented modeling approach for precipitation polymerization has not yet been taken, since research on microgels has largely been focusing on the synthesis of innovative materials on lab-scale.

Within the project G2, the focus is on inline measurements of microgel polymerization processes, in collaboration with ILT. An economically viable production process requires the identification of monomer and polymer concentration and simultaneous determination of particle concentration and particle size information. For this purpose, Raman-spectroscopy is combined with light-scattering techniques. During the last year, Raman spectroscopy has been applied to VCL and NIPAAm-based microgel polymerizations at different temperatures. The Raman spectra have been processed using Indirect Hard Modeling (IHM), a nonlinear multivariate method for quantitative determination of molecular structures

from spectra. The IHM based analysis of the Raman spectra reveals the temperature dependent monomer conversion and permits a quantitative determination of the polymer fraction. This provides first quantitative insight into the polymerization of microgels in real time.

http://www.microgels.de

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PolymerizationReactor

Particlepopulation

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Light microscope image of microgels

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Ramanspectroscopy

infraredspectroscopy

Figure 4: Polymerization reactor with mounted Raman and IR probes (left), Schematic of multiscale model for reactor

simulation (right).

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MoBiDiKModular Bioproduction – Disposable and Continuous

Kristina Meier (BioVT), Tim Femmer (CVT), Markus Schmidt (TVT)

The increasing importance of biopharmaceutical drugs is characterized by a double-digit increase. The future trend is moving towards a more patient and disease oriented treatment profile. Thus, future production technologies and strategies need to be substantially faster, more flexible and cost-effective. The development of smaller production facilities is triggered by smaller recipient groups and higher product titers. Contrary to this trend, current production processes are characterized by large production batches, inflexible operations, as well as a predominantly discontinuous process

mode. Therefore, the MoBiDiK project aims at the development of an innovative, modular, flexible and continuous process technology for the biotechnological field. To accomplish this, nine industrial and academic institutions in North Rhine-Westphalia have joined together. The MoBiDiK project includes three AVT chairs: AVT.BioVT, AVT.CVT and AVT.TVT.

The project includes the investigation of an entire process chain, starting from the cell bank to the purified active ingredient. The AVT.BioVT

Figure 1: Schematic drawing of reverse-flow

diafiltration with one submerged hollow-fiber membrane. Black lines represent liquid flow, red and blue lines indicate control and

data record, respectively.

Figure 2: Application of reverse-flow diafiltration. A hollow-fiber membrane wound spirally baffels with attached hooks.

B Membrane submerged in medium. C RFD applied in a culture of Hansenula polymorpha pCoM11sc3625. Membrane is

submerged in the reactor, permeate pump extracts cell-free permeate.

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and the AVT.CVT collaborate on the development a continuously operated membrane bioreactor for insitu product recovery of (single-chain) antibodies called reverse-flow diafiltration. Harvesting and feeding is alternated over the same submerged membrane. Thus, the fouling layer on the membrane is minimized and cell retention is enabled gently. This characterizes the membrane bioreactor especially suitable for shear-sensitive cells.

On the basis of mathematical calculations and experimental data, reverse-flow diafiltration was designed to achieve maximal space-time yield, stable long-term operation conditions and to prevent substrate loss. The operation of multiple membranes sequentially achieves constant fermentation conditions as in conventional continuous fermentations.

The AVT.CVT is active in the field of protein purification with the goal of improving selective separation and product concentration. For this purpose, new disposables modules such as a membrane adsorber are developed.

The AVT.TVT is involved in the extractive purification and concentration of biological molecules from fermentation broths using aqueous two phase systems. ATPS are characterized by high amounts of water in both phases. This leads to mild environmental conditions preventing the denaturation of the proteins, but also to extreme physical properties compared to organic-aqueous system. To establish the extraction using ATPS the application in extraction columns is investigated using a combination of lab-scale experiments and simulations based on population balance models.

Figure 3: CAD module of a membrane adsorber with three separate, consecutive flow chambers.

Figure 4: 3D-Printed membrane absorber module with integrated hollow-fiber membrane for protein separation.

Figure 6: Algorithm of the simulation-tool ReDrop for the characterization and design of extraction columns.

Figure 5: Lab-scale column with agitated internals for continuous counter-current extraction.

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BIOCHEMICAL ENGINEERING

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The Shaken Repeated Batch System (ShaRBS)

Tino Schlepütz

T. Schlepütz, J. Büchs, Investigation of vinegar production using a novel shaken repeated batch culture system, Biotechnology Progress, (2013) 29 (5), 1158-1168.

Nowadays, bioprocesses are developed or optimized on small scale. For typical operation modes such as batch, fed batch or continuous culture various small scale reaction systems are available. As yet, there has been no small scale culture system for optimizing fermentation conditions for repeated batch bioprocesses. In a recent study [1], a new shaken culture system for parallel repeated batch vinegar fermentation has been proposed (Figure 1). A new operation mode – the flushing repeated batch – has been developed. Instead of partially draining and filling a conventional bioreactor at the end of a batch fermentation phase, fresh fermentation medium is flushed into special shaken vessels with overflow at a constant filling volume. Thus, a simple set-up with only one pump per

vessel could be used. The flushing repeated batch vinegar fermentation was theoretically investigated and then practically established in a completely automated operation. The ethanol concentration was on-line monitored during repeated batch vinegar fermentation by semiconductor gas sensors. Flushing repeated batch fermentations on small scale are valuable for screening fermentation conditions and, thereby, improving industrial-scale bioprocesses, such as vinegar production in terms of process robustness, stability and productivity.

Figure 1: Shaken Repeated Batch System (ShaRBS): A) Schematic sketch of the ShaRBS device for parallel vinegar fermentation. Cylindrical reaction vessels with a precise overflow at the vessel wall allow for parallel repeated batch fermentation on one shaker platform. B) Photograph of the ShaRBS device.

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Quantifying the Release of Polymer Additives from Single-Use Materials by Respiration Activity Monitoring

Kristina Meier

Disposable single-use technologies are one of the emerging trends in industrial biotechnology as it reduces costs and the effort to meet pharmaceutical quality regulations. Storage and culture bags, tubing and filtration devices are e.g. made of polymer materials. However, polymers leach out additives (like plasticizers), which are known to be toxic to some extent. At the chair of Biochemical Engineering a new method was introduced to analyze biocompatibility of single-use parts with minimal effort. The breathing behavior over time of various microorganisms is determined online with the Respiration Activity Monitoring System (RAMOS) as a function of the added amount of polymers to the culture broth. Breathing behavior comparable to a reference without added polymer indicates uncritical leaching. For instance, cable tie made from Nylon, a commonly applied material in biotechnology, is toxic to the yeast Hansenula polymorpha if more than 4 g of cable tie is used in 1 liter fermentation broth. Investigations with the RAMOS device have shown to be sensitive and time-effective to qualify materials before they are applied in microbial and cell cultures.

Figure 3: Typical polymers applied in single-use parts for biotechnology (tubing, PEEK, pipette tip, cable tie).

Figure 2: Respiration Activity MOnitoring System for online determination of biocompatibility of polymeric plastic

materials by monitoring breathing behavior.

Figure 1: Result of a biocompatibility test for the yeast Hansenula polymorpha cultured in minimal Syn6 medium: Tubing (Teflon &

polyurethane), pipette tip (polypropylene) and PEEK do not leach polymer additives in a

toxic amount, tubing (polyamide 12) leaches an amount of an additive (1,8-Diazacyclotet-radecane-2,7-dione) affecting the cells, cable

tie (Polyamide 6.6) leaches a plasticizer (N- butylbenzenesulfonamide) in a toxic

amount.

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CHEMICAL PROCESS ENGINEERING

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Membrane-Based Recovery of Glucose from Enzymatic Hydrolysis of Ionic LiquidPretreated Cellulose

Christian Abels

C. Abels, K. Thimm, H. Wulfhorst, A.C. Spiess, M. Wessling, Membrane-based recovery of glucose from enzymatic hydrolysis of ionic liquid pretreated cellulose, Bioresour. Technol. 149 (2013), 58-64.

In this work, the downstream-processing after enzymatic hydrolysis of cellulose originating from wood pretreated in ionic liquid is discussed. A complete downstream process for the recovery of glucose from ionic liquid-assisted enzymatic hydrolysis of cellulose is technically and economically evaluated. The process aims at a high product yield and purity of glucose as well as a close to complete recovery of the intermediate cellobiose and the pretreatment solvent ionic liquid. Lab-scale experiments are carried out for each unit operation to prove its technical feasibility. The cellulose is pretreated with the ionic liquid

1,3-dimethyl-imidazolium dimethylphosphate to reduce its crystallinity. After enzymatic conversion of cellulose to glucose the hydrolysate is filtered with an ultrafiltration membrane to remove residual particulates and enzymes. Nanofiltration is applied to purify the glucose from molecular intermediates, such as cellobiose originating from the hydrolysis reaction. Finally, the ionic liquid is removed from the hydrolysate via electrodialysis. Technically, these process steps are feasible. An economic analysis of the process reveals that the selling price of glucose from this production process is about 2.75 €/kg which is too high as compared to the

current market price. Cost driver of the process is the ionic liquid which accounts for 33% of the total costs. Increasing the cellulose concentration during hydrolysis would significantly reduce the costs.

Ionic liquid pretreatment

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Cellobiose /Ionic liquid /

WaterEnzymes / Cellulose residuals

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Membrane Processes in Biorefinery Applications

C. Abels, F. Carstensen, M. Wessling, Membrane processes in biorefinery applications, J. Mem. Sci., 444 (2013), 285–317.

The 1st generation of biofuels stemming from sugar cane, rape or corn is commercially established today and holds a considerable market share as a drop-in fuel. However, due to interference with the food chain, the ethical discussion on fuel or food has originated. Therefore, current research focuses on the utilization of lignocellulosic materials as a bio-renewable feedstock. Simultaneously several biomass-based processes were developed over the past decade suggesting scenarios from a classic biofuel plant to a new biorefinery concept which produces for instance polymers which were previous fossil resources based. The growth of bio-

resource based chemicals, functional monomers as well as fuels leads to an increased demand for new separation processes. This review highlights the role of membrane separations within current and future biofuel and biorefinery scenarios. Membrane processes reviewed are for instance pervaporation for alcohol recovery and ultrafiltration of canola oil, as well as new developments such as the ultrafiltration/nanofiltration of lignin in a solvent-based lignocellulose conversion process or the recovery of amino acids via electrodialysis.The membrane processes are classically categorized as concentration-driven membrane

processes, pressure-driven membrane processes, electrical-driven membrane processes and prospective membrane processes. It follows the transition of a classic biofuel production plant to a new sophisticated biorefinery. The review closes with a reflection of membrane-based downstream processes required in a biorefinery transforming cellulose into an itaconic acid.

Biorefinery application Potential membrane process

Pervaporation

Ultrafiltration

Nanofiltration, Reverse osmosis

Micro-, Ultrafiltration

Ethanol production

Biodiesel productionSugar production

Lactic acid production

Nutrient production

Amino acid purification

Solvent recovery

Micro-, Ultrafiltration

ElectrodialysisElectrophoresis

Lignin recovery Ultra-, Nanofiltration

Bio-chemical production Membrane extraction

Nanofiltration, Reverse osmosisSolvent / Product desalination

Fractions

• Cellulose• Hemi-Cellulose• Lignin

Intermediates

• 5-HMF• Levulinic Acid• Itaconic Acid• Furfural

Ligno-cellulose Fuels

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Transforming Biogas into Biomethane Using Membrane Technology

Marco Scholz

M. Scholz, T. Melin, M. Wessling, Transforming biogas into biomethane using membrane technology, Renewable and Sustainable Energy Reviews, 17 (2013), 199-212.

The transition to renewable energy supply is one major challenge to be solved in the near future. Biogas is an important source of renewable energy since in contrast to solar and wind power it is generated continuously. Biogas, which mainly consists of methane and carbon dioxide, can either be converted into electrical energy in combined heat and power cycles (CHP) or it can be upgraded serving as a natural gas substitute. While CHPs generate heat which is often unused, biogas upgrading is more efficient. The upgraded gas can be injected into the natural gas grid, where it can be converted into electrical energy in large and efficient combined heat and power plants. In addition, natural gas is used as a feedstock for chemical processes and it is applied as a vehicle fuel.

Gas permeation membranes are well known for separating methane and carbon dioxide. Due to their robustness and energy efficiency membranes are an ideal technology to be applied in biogas upgrading. Single stage gas permeation processes are not meeting the challenging demands for gas purity and product gas recovery at the same time. Hence, multistage gas permeation processes have to be installed. Compared to conventional upgrading processes such as pressure swing adsorption and amine absorption, gas permeation membranes offer outstanding advantages.

The paper gives a comprehensive overview on gas permeation materials, modules and processes for biogas upgrading developed during the last two decades including process data from operating biogas upgrading plants. Furthermore, a detailed outlook on current and future developments is presented.

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COMPUTATIONAL SYSTEMS BIOTECHNOLOGY

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Parallelized Micro-Bioreactor for Rapid Screening of Biocatalysts

Daniel Jussen, Martina Pohl, Prof. Wolfgang Wiechert

The identification of optimal reaction conditions for a biocatalytic process is of utmost importance for efficient process development, since almost all enzymatic parameters, such as stability, activity and selectivity are influenced by the reaction conditions.

Screening for optimal reaction conditions is a multi-parameter problem and should ideally be performed in a continuous reaction system in order

to adjust constant reaction conditions with respect to substrate - and product concentrations. Such studies require usually lab-scale processes at a 10 -100 mL scale to obtain reliable data e.g. in a continuous stirred tank reactor. Such processes are difficult to parallelize and require large amounts of enzyme. In order to allow the screening of optimal reaction condition at the microscale we have recently developed a parallelized micro-bioreactor

(µMORE: mycrofluidic magnetic oscillation reactor for enzymes), which is operated with immobilized enzyme on magnetic beads. The immobilization process can easily be performed using a terminal hexahistidine tag, which was attached to the enzyme sequence via molecular cloning. The magnetic beads are retained and agitated by two permanent magnets situated at both sites of the reaction chamber in a glass microchip (Figure 1).

Figure 1 (left): Principle of the magnetic array for the micro-bioreactor. Two cylinders with magnets staggered by 180° in antiparallel orientation are placed on both sides of the chip (only the cylinder on the left side is shown).

1) In position 1 magnetic beads will move to the right side, 2) in position 2 they will move to the left side. Switching between the positions is realized by a 180° turn of the cylinders and enables mixing of two fluids

injected in parallel into the microfluidic channel. Right: µMORE with three bioreactor chips.

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Model-Based Analysis and Scale-Up of Membrane Chromatography

Pranay Ghosh, Eric von Lieres, Prof. Wolfgang Wiechert

Membrane chromatography (MC) is increasingly being used as a purification platform for large biomolecules due to higher operational flow rates. The zonal rate model (ZRM) has previously been applied to accurately characterize the hydrodynamic behavior in commercial MC capsules at different configurations and scales. Explorations of capsule size, geometry and operating conditions using the model and experiment were used to identify possible causes of inhomogeneous flow and their contributions to band broadening. Recently, the hydrodynamics within membrane chromatography capsules are more rigorously investigated by computational fluid dynamics (CFD). The CFD models are defined according to precisely measured capsule geometries in order to avoid the

estimation of geometry related model parameters. In addition to validating the assumptions and hypotheses regarding non-ideal flow mechanisms encoded in the ZRM, CFD simulations can be used to mechanistically understand and predict non-binding breakthrough curves without need for estimation of any parameters.

When applied to a small-scale axial flow MC capsule (Pall Mustang XT5), CFD simulations identify non-ideal flows in the distribution (hold-up) volumes upstream and downstream of the membrane stack as the major source of band broadening. For a large-scale radial flow capsule (Pall Mustang XT140), the CFD model quantitatively predicts breakthrough data using binding parameters independently

determined using the small-scale axial flow capsule, identifying structural irregularities within the membrane pleats as an important source of band broadening. The proposed modeling and parameter determination scheme therefore facilitates a holistic mechanistic-based method for model based scale-up, obviating the need of performing expensive large-scale experiments under binding conditions. The CFD model provides a rich mechanistic analysis of membrane chromatography systems and the ability to explore operational space, but requires detailed knowledge of internal capsule geometries and has much greater computational requirements, it is complementary to the previously described strengths and uses of the ZRM for process analysis and design.

Figure 2: MRI image, axial cross section of a Pall Mustang XT140 membrane chromatography capsule (left) and CFD simulation of the stationary flow profile, velocity magnitude

(right).

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BACKTOCONTENT

Disposable Picolitre Bioreactor for Cultivation and Investigation of Industrially Relevant Bacteria on the Single-Cell Level

Alexander Grünberger, Dietrich Kohlheyer, Prof. Wolfgang Wiechert

In the continuously growing field of Industrial Biotechnology the scale-up from lab to industrial scale is still a major hurdle to develop competitive bioprocesses. During scale-up the productivity of single cells might be affected by bioreactor inhomogeneity and population heterogeneity. Currently, these complex interactions are difficult to investigate. At the microscale bioengineering group we have developed a disposable picoliter cultivation system (Figure 1), in which environmental conditions can be well controlled on a short time scale and bacterial microcolony growth experiments can be observed by time-lapse microscopy.

Growth and analysis of industrially relevant bacteria with single cell resolution (in particular Escherichia coli and Corynebacterium glutamicum) starting from one single mother cell to densely packed cultures was successfully performed. Applying our picoliter bioreactor, 1.5-fold increased growth rates of C. glutamicum wild type cells were observed compared to typical 1l lab-scale batch cultivation. Moreover, the device was used to analyze and quantify the morphological changes of an industrially relevant L-lysine producer C. glutamicum after artificially inducing starvation conditions. Instead of a one week lab-scale experiment, only 1 hour was sufficient to reveal the same information. Furthermore, time-lapse microscopy during 24 hours picoliter cultivation of an arginine producing strain containing a genetically encoded fluorescence sensor disclosed time dependent single cell productivity and growth, which was not possible with conventional methods (Grünberger et al. 2012).

Figure 3: Illustration of the picoliter bioreactor (PLBR) for cultivation of bacteria. The shallow circular PLBR has radially arranged channels and is placed inside a deeper supply channel. A) During the "seeding phase" single cells are seeded into the PLBR.

B) Once a single cell is seeded, growth medium is infused initiating the "growth phase". C) As soon as the reactor is fully packed, cells are pushed out of the overflow channels during the "overflow phase". Illustration is not to scale.

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ENZYME PROCESS TECHNOLOGY

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Microgel-Stabilized Smart Emulsions for Biocatalysis

Johann Hospital

Wiese S., Spiess A. C., Richtering W., Angewandte Chemie, (2013) 125(2), 604-607.

Poor solubility of organic substrate and product in aqueous solutions is a major drawback for enzyme catalyzed production of e.g. fine chemicals. In order to circumvent this issue a biphasic system can be used where the organic phase serves as a substrate and product reservoir while the enzymatic reaction takes place in the aqueous phase. Furthermore, mass transfer efficiency is improved by increasing the area between organic-aqueous phases by formation of an emulsion.

Figure 1 shows a two-phase system (A) with poly(N-isopropylacrylamide) (PNIPAM)-based microgels in aqueous phase. These thermo-responsive microgels enable stabilization of a two-phase system (B) and destabilization of emulsions (C) by exceeding the volume phase transition temperature. The (PNIPAM)-based microgel collapses and the emulsion breaks. Thereby, a simple product recovery from the organic phase and a recycling of the biocatalyst becomes possible. As proof-of-concept for a biocatalytic reaction the substrates acetophenone and 2-propanol were supplied in MTBE whereas the enzyme alcohol dehydrogenase from Lactobacillus brevis (LbADH) performed the conversion in continuous TEA buffer phase. A particular challenge lies in the mutual adaptation of optimal reaction conditions for the biocatalyst and the microgel switching behavior, which may be achieved by tailoring the microgel to the particular application. To this end, the microgel influence on mass transfer between oil and water phase and on the reaction or deactivation kinetics of a model biocatalyst and the microgel effect on emulsification and reaction processing is investigated using both physico-chemical and reaction engineering methods.

Figure 1: Microgel-stabilized smart emulsions for biocatalysis: MtBE/TEA(MG), 1/1, 1 wt% MG in TEA; Ultra Turrax: 1 min, 8000 rpm, RT; Thermomixer: 10 min, 300 rpm, 50 °C.

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Embedding Enzymatic Hydrolysis of Cellulose into the Biorefinery Route

Simon Roth

C. Abels, K. Thimm, H. Wulfhorst, A. C. Spiess, M. Wessling, Membrane-based recovery of glucose from enzymatic hydrolysis of ionic liquid pretreated cellulose, Bioresource Technology, 149 (2013), 58–64.J. Viell, H. Wulfhorst, T. Schmidt, U. Commandeur, R. Fischer, A. C. Spiess, W. Marquardt, An efficient process for the saccharification of wood chips by combined ionic liquid pretreatment and enzymatic hydrolysis, Bioresource Technology, 146 (2013), 144–151.

Modern biorefinery concepts focus on the utilization of biomass feedstocks non-competitive with food production. Those approaches shift the scope of suitable raw materials towards more complex lignocellulosic substrates, whose carbohydrate fraction is manly packed into cellulose fibers. Thus, a major challenge for biorefinery processes is accessing the fermentable monomeric carbohydrates. The depolymerisation of cellulose to glucose can be efficiently realized by enzymatic hydrolysis, but requires a preliminary disintegration of the biomass and a subsequent downstream processing of the glucose stream. Hence, the enzymatic hydrolysis of cellulose has to be compatible with the neighboring process steps. The pretreatment of wooden biomass with the

ionic liquid [EMIM][Ac] is an outstanding way to disintegrate lignocellulose but entails residual [EMIM][Ac] in the resulting process streams. The process conditions for the enzymatic cellulose hydrolysis were adapted to deal with the presence of [EMIM][Ac]. A smart connection with further membrane-driven purification steps (Figure 1) allows an economic recycling of enzymes, ionic liquid and water. Removal and dosed feedback of residual cellulose and inhibitory cellobiose to early process stages enhances the process efficiency. The described concept enables a reasonable, cost-efficient embedding of the enzymatic cellulose hydrolysis into the biorefinery process route.

Figure 1: The enzymatic hydrolysis of cellulose as essential process step is reasonably embedded into the biorefinery concept [Abels et al., 2013].

BACKTOCONTENT 26.

BACKTOCONTENT

MECHANICAL PROCESS ENGINEERING

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Integrated Mechanical Pretreatment of Biomass

Qingqi Yan

Within the Cluster of Excellence "Tailor-Made Fuels from Biomass" the selective conversion process from biomass into the third generation of biofuels is explored. At the chair of Mechanical Process Engineering the mechanical pretreatment process for lignocellulosic biomass by using a screw press is investigated. Since pretreatment makes biomass accessible to any further solution and chemical or enzymatic transformation, it is a step which is necessary and essential for the entire downstream process.

The main subject focuses on the improvement of the screw press. The high compression and shear forces of the screw press cause defibration and disruption of the biomass (Figure 1). The results of

our study show that the screw press pretreatment can significantly enhance the available surface area of the materials and improve the chemical hydrolysis from biomass. Furthermore, a synergetic effect of the screw press and the OrganoCat process was observed, leading to a more efficient hydrolysis of the cellulose pulp.

However, the mechanisms involved in this process are complex and little is known about the design and operation of this machine. The operating conditions and construction of the screw press are usually based on empirical data. In order to understand the solids conveying in the screw press and develop suitable mathematical model for this process, formulas and balances for describing

the throughput, pressure generation, power consumption and dissipation in the comparable screw extruders are investigated. An additional objective of this project is to develop a novel pretreatment process for biomass which integrates mechanical and chemical decomposition of its structure and allows for efficient depolymerisation of the biomass. First results show that by combining with alkali (delignification agent) soaking and screw press/reactor, the sugar recovery from the straw biomass is significantly improved, in comparison to only screw pressed or with alkali soaked materials. The design of a novel pretreatment apparatus based on a screw press will allow for direct utilization in the reference and NGP2 demonstration process (Figure 2).

Figure 1: SEM micrographs of wood particle before (left) and after (right) screw press pretreatment. Figure 2: A possible screw press design for the process integration of mechanical and chemical pretreatment.

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Rheological Properties of Metals in the Semi-Solid State

Christoph Zang

M. Modigell, A. Pola, M. Suéry and C. Zang, Investigation of correlations between shear history and microstructure of semi-solid alloys, Solid State Phenomena Vols., 192-193 (2013), pp 251-256.M. Modigell, T. Volkmann and C. Zang, A High-Precision Rotational Rheometer for Temperatures up to 1700 °C, Solid State Phenomena Vols., 192-193 (2013), pp 359-364.

The processing of metals in the semi-solid state bears various advantages compared to the classical forming processes casting and forging. The process route however is more complex than the classical techniques. One major reason for this is the flow behavior of the semi-solid material. Semi-solid metal alloys are non-Newtonian fluids with pseudo-plasticity, thixotropy and yield stresses.

AVT.MVT has been researching for several years on the flow properties of tin and aluminum alloys. The recent development of a high temperature rheometer (Figure 1) made it possible to quantify the rheological properties of steel at temperatures up to 1700°C and to investigate the microstructure after the rheological experiments.

Microstructural parameters such as particle size and shape need to be determined in order to model the flow properties on a physical foundation. These are commonly determined by 2D cross section analysis. The determination of mechanisms such as particle agglomeration with decreasing shear rate however, requires information on the 3D spatial distribution.

These have been gathered by utilizing synchrotron radiation tomography on aluminum-copper samples. Mechanisms such as particle ripening over time can be observed and quantified (Figure 2). Also the agglomeration of particles with decreasing shear-rate has been validated experimentally.

Figure 1 (left): Schematic of the proprietary furnace rheometer, (right): Photograph of the device with parts of

the peripheral components.

Figure 2 (left): 3D-Structure of semi-solid AlCu Sample (diameter = 2mm), (right): Growing particles with increasing shear duration.

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MOLECULAR SIMULATIONS AND TRANSFORMATIONS

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Molecular Modeling of Biomass Dissolution

Brooks Rabideau, Prof. Ahmed E. Ismail

The goal of this project is to develop full working models for the dissolution of biomass in solvent media, from the atomistic level up to the level of complete "bundles".

Our recent work has moved beyond the study of cellulose dissolution in ionic liquids, to include additional solvents, such as NMMO and so-called "organocat" and "organosolv" media, as well as examining hemicellulosic components in these mixtures.

In collaboration with the group of Prof. Roberto Rinaldi at the MPI for Coal Research, we are also conducting molecular dynamics simulations of the solvation of cellobiose in aqueous solutions of lithium bromide and lithium chloride, while efforts with AVT.PT and the Institute for Technical Thermodynamics look to make sense of various experimental, molecular modeling, and group contribution theories of cellulose dissolution.

Finally, our most recent work has developed a kinetic Monte Carlo model for dissolution of complete bundles, with results showing dissolution times on the order of 10 to 100 microseconds for complete separation of strands in cellulose bundles comparable to those in Avicel 60 (a commercially available cellulose source).

Small bundles (8-10 glucose units) dissociate completely in ionic liquid in 100 ns, but a cellulose bundle with 60 glucose units per chain shows only minimal dissolution in the same period of time. Multiscale

modeling is required for observation of complete dissolution in such large bundles.

A kinetic Monte Carlo model used to study dissolution of the cellulose bundle shown atomistically above. Because dissolution takes on the order of a millisecond, detailed atomistic modeling is impossible.

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Probing the Structure and Dynamics of Interfaces

Rolf Isele-Holder, Prof. Ahmed E. Ismail

In this area we focus on contact applications of interfaces, such as measuring the dynamics of contact problems, in the form of terraced wetting and superspreading (fluid droplets) or stresses and responses in nanoindentation problems (solids). The materials being studied include solid substrates, polymeric liquids, and self-assembled monolayers.

The mechanism for terraced wetting, the formation of multiple layers of molecular thickness as a precursor ahead of the macroscopic contact line of a spreading droplet, remains unknown after many years. The molecular length scales inherent to the problem make molecular dynamics (MD) simulations a natural choice to study this problem. Using large-scale MD simulations of atomistic and chain molecules on crystalline substrates with varying substrate energies, we have observed clear evidence that goes

beyond showing images of the simulation snapshots for the formation of multiple layers that spread ahead of the droplet for the first time, showing the correct expected time-dependence of the spreading.

Superspreading, the vastly enhanced spreading of water caused by a reduction in surface tension through the addition of small amounts of trisiloxane-based surfactants, is another major phenomenon associated with droplet spreading whose onset mechanisms have not been well understood. Using advanced treatments of long-range dispersion interactions developed within our research group, we have been able to explore these phenomena with much greater fidelity than previously available, demonstrating that there is a sudden change in the early growth of droplets with regular surfactants and trisiloxane surfactants.

Simulations of terraced wetting, showing layer-by-layer precursor formation at the droplet edge. Each layer is of molecular thickness: as shown, two layers

extend from each side of the droplet.

Surfactant-laden droplets spreading on a polymer surface. The droplet at left, with an alkane-based surfactant, spreads like a normal water droplet. The droplet at right contains a trisiloxane-based surfactant. Because its

contact with the surface is smooth rather than sharp, the droplet exhibits greatly enhanced spreading, a phenomenon called "superspreading".

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Improved Methodologies for Molecular Simulations

Carl Simon Adorf, Prof. Ahmed E. Ismail

In addition to applications, we are also interested in providing simulation tools that allow us to obtain results more accurately and efficiently than is possible with existing tools.

While much of the work in the group has been focused on how to solve interfaces more accurately, we also realize that in many problems, such as biomass dissolution, the relevant processes happen on length and time scales that are impractical for all-atom methods. For instance, dissolution of a small cellulose bundle can last on the order of 10 to 1000 microseconds, which would effectively require massive computational resources to simulate successfully on an atomistic scale. Therefore, we are

currently using methodology inspired from the signal processing community – including wavelets, graph Laplacians, dictionary learning, and optimization – to derive new tools for coarse-graining systems both spatially and temporally.

In particular, we are developing a systematic coarse-graining and reverse-mapping technique which can achieve user-specified levels of coarse-graining, enabling tens or even hundreds of monomers at the atomistic scale to be represented by a single coarse-grained particle, while still retaining the basic physical properties of the system, even in the semi-dilute and concentrated range. This method is coupled with a reverse-mapping strategy that allows for the

restoration of the eliminated degrees of freedom, either along the backbone or off the main chain.

Using an intelligent "learning-based" approach, the reverse-mapping approach achieves a smoother path to equilibrium states than existing reverse-mapping approaches.

The coarse-graining work is being performed in collaboration with Dr. Chris Rinderspacher of the US Army Research Laboratory and Dr. Jay Bardhan of Northeastern University, while collaborators on the reverse-mapping work are Dr. Chris Iacovella and Prof. Peter Cummings of Vanderbilt University.

Reconstruction of a dodecane chain represented by a united-atom model (left), showing the

original positions of the hydrogen atoms (white) and the positions predicted by the reverse-

mapping algorithm (pink). Backbone reconstruction is also possible.

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PROCESS SYSTEMS ENGINEERING

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Innovative Synthesis in Continuous-Flow Processes for Sustainable Chemical Production

Sebastian Recker, Olga Walz, Prof. Wolfgang Marquardt

S.Recker, N. Kerimoglu, A. Harwardt, O. Tkacheva, W. Marquardt, On the integration of model identification and process optimization, In: Proceedings of the 23rd European Symposium on Computer Aided Process Engineering, (2013) 1021-1026.

Depleting natural resources, increased international competition, and the desire for sustainability foster the chemical and pharmaceutical industries to pursue more efficient processes. Therefore, the EU-project SYNFLOW aims to shift the paradigm from batchwise large volume processing to highly integrated and yet flexible catalytic continuous-flow processing. To achieve this goal, SYNFLOW integrates SYNthetic methodologies for catalytic molecular transformation with FLOW chemistry in continuously operated reactor systems.

SYNFLOW is a four-year project funded under the EU's Seventh Framework Programme. It involves 19 consortium partners embracing industry and academia from 8 EU countries working together across industrial and scientific boundaries. In addition to leading European academic institutions, major industrial partners involved in the project include AstraZeneca, Bayer Technology Services, Evonik Oxeno, Johnson Matthey and Britest. DECHEMA - Society for Chemical Engineering and Biotechnology e.V. - is responsible for the overall project organization.

The aim of the Aachener Verfahrenstechnik – Process Systems Engineering is the transfer of the developed model identification and process synthesis strategies into industrial processes. By integrating model-based experimental analysis and novel optimization-based design methods for integrated reaction and separation processes, innovative process concepts can be developed in close cooperation between chemists and engineers. In addition to the development of these novel methods, the project also focuses on their application and implementation to case studies on a laboratory scale.

CatalystDevelopment Lab Experiments Process

Demonstration

35.

The economically and ecologically reasonable application of state-of-the-art processes for the desalination of seawater is strongly limited by their high energy demand. To lower the energy demand, current research activities focus on the development of new promising concepts on the basis of electrodialysis (ED) and membrane distillation (MD) processes.

In the ED process, ion-selective properties of ion-exchange membranes are used to separate ions of opposite charges in an electric field. The efficiency of the process is determined by the intensity of the mass transfer in the electrolyte-membrane system. The underlying coupled physico-chemical phenomena (cf. Figure 1) characterizing the mass transport in the membrane-electrolyte system are not completely understood. In the HISEEM project [1], a detailed model for the local transport processes in an ED stack is developed. An ED pilot plant has been constructed to investigate the process behavior and conduct dedicated experiments for model validation.

Membrane distillation is a hybrid desalination process. It is a process driven by a difference in temperature which leads to a vapor pressure difference that causes water to evaporate, transport through the hydrophobic membrane and condensate in the cold side of the membrane (Figure 2). The hydrophobic membrane allows the water vapor to pass

but not water liquid. A two-dimensional dynamic mathematical model of a direct contact MD (DCMD) has been developed in this work to predict the salt concentration and temperature profiles. A DCMD pilot plant using a flat-sheet of polyethylene membrane with a pore size of 0.31 µm (see Figure 2) is used to perform experimental studies and model validation.

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Rigorous Dynamic Modeling of Membrane Processes for Water Desalination

Matthias Johannink, Badr Bin Ashoor

Figure 1: Interacting phenomena in an electrodialysis module: a) complex hydrodynamics and transport in a spacer filled channel, b) diffusive transport in ion-ex-

change membranes, and c) polarization at the membrane-electrolyte interphase.

Figure 2: The DCMD pilot plant with a scheme of the phenomena at the membrane interface.

BACKTOCONTENThttp://www.hiseem.de/, rev. 17.03.2014; M. Johannink, A. Mhamdi, W. Marquardt, Towards a modeling methodology for mass transport phenomena in liquid electrolytes, 9th World Congress of Chemical Engineering, 18-23.08.2013 in Seoul, Korea.B. B. Ashoor, A. Mhamdi, W. Marquardt, Numerical Modeling of Direct Contact Membrane Distillation (DCMD), 11th International Symposium on Process Systems Engineering, 15-19 July 2012, Singapore.

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PROCESS SYSTEMS ENGINEERING

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SusChemSys: CO2 as Resource for Combustibles and Raw Chemicals

Luisa Schulze-Langenhorst

The research cluster "Sustainable Chemical Synthesis – A Systems Approach" (SusChemSys) in North Rhine-Westphalia is aiming at innovative methods and technologies for sustainable synthesis of chemical products by academic and industrial research partners.

As one academic research partner, the AVT contributes to the identification of alternative sources of raw materials for chemical products, by analyzing the use of carbon dioxide as a possible resource for combustibles and raw chemicals. By this means, the development of a resource and environmentally friendly synthesis for a

sustainable future is supported. AVT.SVT works together with AVT.CVT, in the development of an electrochemical reaction in which gaseous carbon dioxide is electrochemically converted into hydrocarbons. On the experimental side, the AVT.CVT engineers, manufactures and characterizes the reactor. The AVT.SVT is approaching from the theoretical perspective and focuses on the identification of predictive models for the description of the underlying coupled kinetic phenomena on a mesoskopic scale. On the basis of these modular models, a dynamic process model of the whole system is developed, which predicts the performance of the ecMR on a macroscopic scale.

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Project "AUFWIND". Algae Cultivation and Conversion to Aviation Fuels:Economic Efficiency, Sustainability and Demonstration

Christian Abels (CVT), Philipp Grande (ITMC), Qingqi Yan (MVT), Moll Glass (SVT)

Depleting fossil resources and the need for reducing carbon dioxide emissions raise the question of how to provide sustainable jet fuels in the long-term. As the first airline worldwide, in 2011, Lufthansa started blending conventional kerosene with biokerosene for Airbus A321 for flights between Hamburg and Frankfurt.

Both a sustainable and economic production of bio jet fuel is targeted by the project "AUFWIND", as well as the exploitation of the potentials of microalgae biomass. Which conditions are appropriate in terms of light and nutrients is examined in several photo bio reactor set-ups in Jülich. Subsequent harvesting and in particular, dewatering are crucial issues when it comes to algae as a raw material for fuel production.

Having extracted the lipids of the microalgae, in particular Chlorella vulgaris (approx. 20 wt% lipids), hydrogena-tion and refining are the next steps to bio jet fuel synthesis. The goal is to realize this process in a pilot plant in Jülich, with a capacity of approx. 4 kg kerosene per day. Construction has started, envisaging the launch in April 2014.

Apart from the lipids, algae biomass contains many more valuable fractions, such as proteins and carbohydrates. It is the algae biomass residuals' economic potential which is considered one of the key issues for an overall profitable process. The carbohydrate fractions, in particular, are in the focus of the RWTH group in AUFWIND. The team

is working both experimentally and theoretically covering pulping and fractionation of the algae biomass. A significant content of proteins needs to be separated before subsequently analyzing the various carbohydrates. Further processing the carbohydrate fractions, such as cellulose, glucose and xylose to valuable secondary products, is investigated in terms of economics via conceptual process design.

Finally, the market potential of these products shall allow for a biokerosene selling price of less than 1 € per liter.

Funded by:

Microalga Chlorella vulgaris before (left) and after (right) screw pressing as mechanical pulping.

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COOPOL

Jennifer Puschke, Preet Joy

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COOPOL (Control and Real-Time Optimization of Intensive Polymerization Processes) is an EU collaborative research project (www.coopol.eu), in which AVT.SVT and AVT.PT are jointly participating.

It's goal is to achieve a significant increase in the product quality of polymerization reactions by employing novel process control approaches for intensified semi-batch and 'smart-scale' continuous polymerization processes.

To achieve these goals significant progress is aimed via specific science and technology objectives

• Developing intensified 'smart-scale' reactor technology with real-time feed-back control for emulsion polymerization applications• Developing a novel sensor–fusion approach for off-line inference of process parameters and state information in the polymerization processes• Developing advanced models of polymerization processes, utilizing new types of sensors and the model-based experimental analysis methodology accounting for emulsion stability and rheology• Developing realistic optimization models and economic objectives• Explicit consideration of uncertainty in the optimization problem formulation for increased robustness

The new processes developed will be benchmarked against current industrial processes, including technological, economic, risk and environmental factors.

Parameter and state estimation in polymerization systems is particularly challenging due to limited amount of sensors available which can provide quick and reliable measurements of polymer property. AVT.SVT focuses on issues of observability and identifiability of polymerization systems and contributes towards development of sensor fusion and soft sensing algorithms for state and parameter estimation.

AVT.PT develops novel approaches to robust model-based dynamic real-time optimization and implements these in a modular environment for on-line operation and control. One approach for more robustness is the so called two-model approach, where model uncertainties are considered in a way that two models are optimized simultaneously. One model is the nominal model, where the parameter values correspond to estimated values, and the second model is the so called "worst-case" model, where the parameter values drive the model more aggressively to its path constraints. This approach will be tested in an industrial setting during the project and is expected to improve both upon process safety and profit.

BACKTOCONTENTProposal of Control and Real-Time Optimisation of Intensive Polymerisation Processes COOPOL, European Union's Seventh Framework Programme (FP7/2012-2014) under Grant Agreement 280827 (www.coopol.eu), 2012. 40.

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Simulation Based Design of Extraction Columns for Aqueous Two-Phase Systems

Markus Schmidt

For the downstream processing of biological products such as proteins extraction using aqueous two-phase systems (ATPS) provides a viable alternative to established but expensive separation processes such as chromatography. Due to high water amounts in both phases, gentle environmental conditions for fragile components are provided. Additionally, the low interfacial tension inherent to aqueous two phase systems reduces the mechanical stress during mass transfer, preventing the denaturation of the molecules. To establish extraction with ATPS as standard procedure in downstream processing, the continuous operation of extraction columns for ATPS is investigated at AVT-TVT. The aim is to provide a method for column characterization and design using a combination of lab-scale experiments and simulations based on population-balance models.

For organic-aqueous systems, this procedure has already been successfully applied. However, ATPS strongly differ in their physical properties from organic-aqueous systems for which these methods were developed, which motivates the extension of the simulation tool ReDrop.To this end, the fluid dynamics of ATPS were investigated both in single-drop and in column experiments in order to adapt the implemented correlations in ReDrop. The methods designed for organic-aqueous systems were extended for ATPS, such that the sedimentation behaviour of single droplets could be characterized experimentally. Based on the experimental results system-specific model parameters for the description of the sedimentation were determined. Including the experimental results on hold-up and flooding of a lab scale extraction column the predictions with ReDrop on fluid dynamics could be verified.

Droplet distribution of an aqueous two-phase system in a lab-scale extraction column with slow rotating internals.

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Rapid Evaluation of Bio-Based Synthesis Pathways Based on Exergy Balances

Philipp Frenzel

P. Frenzel, S. Fayyaz, R. Hillerbrand & A. Pfennig, Biomass as Feedstock in the Chemical Industry – An Examination from an Exergetic Point of View, Chemical Engineering & Technology, (2013) 36(2), 233-240.P. Frenzel, R. Hillerbrand & A. Pfennig, Increase in energy and land use by a bio-based chemical industry, Chemical Engineering Research and Design, in Press. (2014)P. Frenzel, R. Hillerbrand & A. Pfennig, Exergetical Evaluation of Biobased Synthesis Pathways, Polymers, (2014) 6(2), 327-345.

While today about 80% of the chemical products are based on crude oil, bio-based materials will gain increasing importance in the future. As the amount of oxygen is normally higher in biomass as compared to crude-oil, new synthesis pathways and separation processes will have to be developed. In order to compare the different pathways quantitatively and to evaluate which process is most efficient a combination of mass and exergy balances can be applied. Exergy balances compare the quality of different forms of energy is possible, and it has been shown in the past that exergy losses correlate well with cost in the corresponding steps.

The chemical processes of the considered synthesis pathways are partly in an early stage of development and therefore, knowledge about the processes is limited. Thus, a method is developed which allows an exergy-based evaluation of the potential of synthesis pathways with less knowledge about the individual process steps. The exergy analysis takes into account the losses which arise due to the reaction and stoichiometry, the unit operations for separation of the product mixture, and the recycle flows.

The exergy analysis starts with a characterization of the synthesis pathway by evaluation the chemical exergy of the involved compounds depicted in Figure 1. The examinations have shown that the exergy losses of processes can be low if the chemical exergy of the reactants, intermediates and products is relatively similar. Especially for bio-based synthesis pathways starting from glucose whose chemical exergy is low it means that intermediates and products should be preferred whose chemical exergy is low as well. Regarding to Figure 1 synthesis pathways with a horizontal course should be preferred. Because the chemical exergy increases with decreasing oxygen content of a compound bio-based products should have a high oxygen content in order to avoid high exergy losses. An example for such a synthesis pathway is the production of polylactic acid via lactic acid by fermentation of glucose.

Figure 1: Characterization of synthesis pathways by the chemical exergy of the compounds involved.

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CONFERENCES AND WORKSHOPS

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OSN 2013

Stefanie Hoffmann

The 4th International Conference on Organic Solvent Nanofiltration (OSN 2013) aimed to facilitate the exchange of current research results as well as new ideas on Organic Solvent Nanofiltration (OSN) and to connect with the success of preceding conferences in Leuven and London. The conference took place at the exceptional SuperC in Aachen.

Requirements of OSN in the areas of food, pharmaceutical, fine chemical and petrochemical industries were to be distinguished during this event by about 60 participants.

Well-known experts provided an extensive program containing lectures about current technologies and products in the field of OSN

from industry and academia, leaving OSN 2013 as an excellent platform for collaboration and networking. Besides the lectures given during the conference, poster presentations and an evening programme including a gala dinner and a lab tour gave the opportunity to vividly discuss numerous topics and to get in touch with fellow researchers on a personal level.

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10th Aachen Conference Water and Membranes

Axel Böcking

The 10th AWM took place end of October 2013 organized by the Chair of Chemical Process Engineering at AVT and the Institute for Water and Waste Management (ISA). More than 300 participants from industry, research facilities and administration met at Eurogress Aachen for two days.

The Conference focused on the application of membrane technology in the drinking and waste water sector. 48 talks informed the interested audience about new science and technology in this field. Latest developments and operational experiences of successful process configurations were presented.The industrial exhibition with 29 exhibitors enabled various networking opportunities and comprehensive discussions about the role of membranes in integrated water resources management. The exhibition was accompanied by posters of recent developments and projects by research institutions and universities. In the future, the conference title will change to "Aachener Tagung Wassertechnologie (ATW)" in order to align the conference to a wider variety of topics. We are looking forward to the 11th ATW, taking place in Aachen 27 to 28 October 2014.

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BIONOCO SUMMER SCHOOL 2013„BIOCATALYSIS USING NON-CONVENTIONAL MEDIA“

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BioNoCo Summer School 2013

Jan-Hendrik Grosch

The 2nd international summer school "Biocatalysis Using Non-Conventional Media" from September 9th to September 11th 2013, took place in Aachen. It was organized in the context of the interdisciplinary DFG research training group BioNoCo which combines researcher teams from RWTH Aachen University, FZ Jülich and HHU Düsseldorf. More than 40 experts, young scientists and students discussed key issues, novel aspects and process potentials using non-aqueous or non-conventional reaction media for biocatalysis in synthetic application. The emphasis of this summer school was on various aspects of non-conventional media with respect to specified enzyme classes. Several non-conventional media have been investigated for the first time using lipases as enzymatic model reaction system. Besides presenting state-of-the-art experiments with lipases, the summer school also covered the application possibilities of other enzyme classes such as hydroxynitrile lyases (HNL) and alcohol, dehydrogenases (ADH) in non-conventional media. The key note lectures were given by Prof. Udo Kragl from Universität Rostock, Prof. Ulf Hanefeld from TU Delft and Dr. Frank Hollmann from TU Delft.

The participants could gain insight to the strong collaborative research within AVT during their visit of the laboratories of AVT and DWI – Leibniz Institute for Interactive Materials and the Biotechnology Department. Fruitful discussion between participants aroused during the poster session of 30 posters. The social program, including a visit of an original "Aachen Printen" bakery, a barbecue party and a gala dinner, offered the possibility to even deepen these discussions and to form new collaborations.

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"Look closer" – A Successful First "Symposium on Advanced Imaging in Cell- and Microbiology"

Second "Jülich Biotech Day"

Prof. Wolfgang Wiechert

The first Symposium on "Advanced Imaging in Cell- and Microbiology" with about 100 registrations from researchers all around Germany and the Netherlands was a great success. The symposium was organized by Dietrich Kohlheyer and Julia Frunzke from the Biotechnology institute IBG-1 at Forschungszentrum Jülich and sponsored by Nikon. At October 10 several internationally renowned researchers presented their work on the topics superresolution microscopy, live cell imaging and their application in cell- and microbiological research. The next day (October 11) a "Hands-on session" allowed interested participants a practical glimpse into superresolution microscopy.

With 250 participants the second "Jülich Biotech Day" was organized by the Biotechnology institute IBG-1 at Forschungszentrum Jülich. The symposium on 11th October 2013 offered scientists and representatives from industry the opportunity to gain insights into the current state of research and development in industrial biotechnology. The first keynote lecture was given by Prof. Jones Prather from MIT, Boston (USA) talking about "Exploiting the synthetic capacity of microbes for the production of novel value-added biochemicals". Dr. Marcel Wubbolts from DSM, Delft (NL) gave an overview about "Building biobased business at DSM: a journey from Jülich to Emmetsburg". Prof. Michael Müller from the University Freiburg presented new trends in chemical diversity through biotransformations and, finally, Prof. Andreas Weber from the University Düsseldorf talked about "From complex traits to synthetic modules: evolutionary genomics meets synthetic biology".

Organizers and speakers of the first Jülich Biotech Day. From left to right: Dr. Kohlheyer, Prof. Bott, Prof. Weber, Prof. Jaeger, Prof. Prather, Prof. Pietruszka, Prof. Müller,

Dr. Wubbolts, Prof. Wiechert.

Poster award to Christina Krämer (second from the left) at meeting “Advanced

Imaging in Cell- and Microbiology” in Jülich, 10.

October 2013.

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BACKTOCONTENT

GRADUATION AND AWARDS

Doctorates

Sara Fayyaz, TVTFlorian Buchbender, TVT Nicole Kopriwa, TVT

Christian Abels, CVT

Cornelia Bähr, BioVT Thomas Harlacher, CVTTobias Klement, BioVTTino Schlepütz, BioVT

Frederike Carstensen, CVT Franz Beggel, MVT Anna Voll, PT

Evangelos Bertakis, TVTKatharina Tarnacki, CVT

Marco Scholz, CVT

Claudia Niewersch, CVT

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Doctorates

BioVT (Univ.-Prof. J. Büchs)

• Dr.rer.nat. Tino Schlepütz, 27.08.2013: "Submerged Vinegar Fermentation in Small Scale Culture Systems" • Dr.rer.nat. Tobias Klement, 04.09.2013: "Itaconic Acid Fermentation with Ustilago maydis and its Integration into a Next Generation

Bio-based Process"

• Dr.rer.nat. Cornelia Bähr, 22.10.2013: "Small-Scale Bioreactors for Efficient Screening in Bioprocess Development"

CVT (Univ.-Prof. M. Wessling)

• Dr.-Ing. Claudia Niewersch, 28.01.2013: "Nanofiltration for Phosphorus Recycling from Sewage Sludge" • Dr.-Ing. Katharina Tarnacki, 17.05.2013: "Evaluating Industrial Water Saving and Water Management Options in Order to Mitigate

Water Stress" • Dr.-Ing. Thomas Harlacher, 04.07.2013: "Membrane Separation Processes for Argon Plasma Gas Recovery" • Dr.-Ing. Frederike Carstensen, 20.09.2013: "In-situ Product Recovery from Fermentation Processes Using Reverse-Flow Diafiltration" • Dr.-Ing. Marco Scholz, 11.10.2013: "Membrane Based Biogas Upgrading Processes" • Dr.-Ing. Christian Abel, 12.12.2013: "Membrane Separations in Ionic Liquid Assisted Processing of Lignocellulosic Biomass"

MVT (Univ.-Prof. M. Modigell)

• Dr.-Ing. Franz Beggel, 23.05.2013: "Modellierung von Membrankontaktoren zur CO2-Abscheidung"

PT (Univ.-Prof. W. Marquardt)

• Dr.-Ing.AnnaVoll,21.10.2013 "Model-Based Screening of Reaction Pathways for Biorenewables Processing"

TVT (Univ.-Prof. A. Pfennig)

• Dr.-Ing. Nicole Kopriwa, 17.06.2013: "Quantitative Beschreibung von Koaleszenzvorgängen in Extraktionskolonnen" • Dr.-Ing. Florian Buchbender, 17.06.2013: "Single-Drop-Based Modelling of Drop Residence Times in Kühni Columns" • Dr.-Ing. Evangelos Bertakis, 17.06.2013: "Interfaces in Fluid-Dynamic Simulations of Single Droplets in Liquid-Liquid Systems" • Dr.-Ing. Sara Fayyaz, 25.11.2013: "Herleitung von Gitterzustandsgleichungen aus der Zustandsgleichung für harte Kugeln"

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BACKTOCONTENT

Awards

BioVT:Gernot Jäger Borchers BadgeMatthias Funke Borchers Badge

CSB:Nina Pfelzer Poster Award at DECHEMA meeting May 2013, Bad WildungenChristina Krämer Poster Award at AICMB2013 October 2013, Jülich Poster Award at VAAM Meeting June 2013, BerlinJochen Wachtmeister Poster Award at BioTrans July 2013, ManchesterTorsten Sehl Poster Award at BioTrans July 2013, ManchesterDr. Dietrich Kohlheyer Granting the Helmholtz Junior Research Group, "Microscale Bioengineering Group", September 2013

CVT:Fee Pitsch LANXESS Talent AwardClemens Fritzmann Borchers Badge

EPT:Philip Engel Friedrich-Wilhelm-Award

MVT:Stefan Engels Borchers Badge

PT:Andreas Wiesner Borchers BadgeLynn Würth, Inga Wolf Best Presentation Award at 10th DYCOPS Internationaland Wolfgang Marquardt Symposium December 2013, Mumbai

SVT:Alexander Mitsos Internal Faculty Teaching Award

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BioVT

• F. Carstensen, T. Klement, J. Büchs, T. Melin, M. Wessling, Continuous production and recovery of itaconic acid in a membrane bioreactor, Bioresource Technology, 137 (2013), 179–187.

• A. Daub, M. Böhm, S. Delueg, J. Büchs, Measurement of maximum stable drop size in aerated dilute liquid–liquid dispersions in stirred tanks, Chemical Engineering Science, 104 (2013), 147–155.

• A. Hibino, R. Petri, J. Büchs, H. Ohtake, Production of uroporphyrinogen III, which is the common precursor of all tetrapyrrole cofactors, from 5-aminolevulinic acid by Escherichia coli expressing thermostable enzymes, Applied Microbiology and Biotechnology, 97 (2013), 7337–7344.

• W. Klöckner, R. Gacem, T. Anderlei, N. Raven, S. Schillberg, C. Lattermann, J. Büchs, Correlation between mass transfer coefficient kLa and relevant operating parameters in cylindrical disposable shaken bioreactors on a bench-to-pilot scale, Journal of Biological Engineering, 7 (2013).

• T. Klement, J. Büchs, Itaconic acid – A biotechnological process in change, Bioresource Technology, 135 (2013), 422–431.

• K. Meier, E. Herweg, B. Schmidt, T. Klement, L. Regestein, J. Büchs, Quantifying the release of polymer additives from single-use materials by respiration activity monitoring, Polymer Testing, 32 (2013), 1064–1071.

• C. Núñez, C. Peña, W. Klöckner, A. Hernández-Eligio, A. V. Bogachev, S. Moreno, J. Guzmán, J. Büchs, G. Espín, Alginate synthesis in Azotobacter vinelandii is increased by reducing the intracellular production of ubiquinone, Applied Microbiology and Biotechnology, 97 (2013), 2503–2512.

• T. G. Palmen, M. Scheidle, R. Huber, C. Kamerke, A. Wilming, B. Dittrich, D. Klee, J. Büchs, Influence of Initial pH Values on the Lag Phase of Escherichia coli and Bacillus licheniformis Batch Cultures, Chemie Ingenieur Technik, 85 (2013), 863–871.

• L. Regestein, H. Giese, M. Zavrel, J. Büchs, Comparison of two methods for designing calorimeters using stirred tank reactors, Journal of Biotechnology and Bioengineering, 110 (2013), 180–190.

• L. Regestein, T. Maskow, A. Tack, I. Knabben, M. Wunderlich, J. Lerchner, J. Büchs, Non-invasive online detection of microbial lysine formation in stirred tank bioreactors by using calorespirometry, Journal of Biotechnology and Bioengineering, 110 (2013), 1386–1395.

Peer-reviewed publications

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• J. Richhardt, B. Luchterhand, S. Bringer, J. Büchs, M. Bott, Evidence for a Key Role of Cytochrome bo3 Oxidase in Respiratory Energy Metabolism of Gluconobacter oxydans, Journal of Bacteriology, 195 (2013), 4210–4220.

• M. Scheidle, B. Dittrich, C. Bähr, J. Büchs, Freisetzungssysteme zur Prozessentwicklung in Kleinkulturen, BIOSpektrum, 19 (2013), 96-98.

• T. Schlepütz, J. Büchs, Investigation of vinegar production using a novel shaken repeated batch culture system, Biotechnology Progress, 29 (2013), 1158–1168.

• T. Schlepütz, J. P. Gerhards, J. Büchs, Ensuring constant oxygen supply during inoculation is essential to obtain reproducible results with obligatory aerobic acetic acid bacteria in vinegar production, Process Biochemistry, 48 (2013), 398–405.

• A. Wilming, J. Begemann, S. Kuhne, L. Regestein, J. Bongaerts, S. Evers, K. Maurer, J. Büchs, Metabolic studies of γ-polyglutamic acid production in Bacillus licheniformis by small-scale continuous cultivations, Biochemical Engineering Journal, 73 (2013), 29–37.

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Peer-reviewed publications

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• S. Abdu, K. Sricharoen, J. E. Wong, E. S. Muljadi, T. Melin, M. Wessling, Catalytic Polyelectrolyte Multilayers at the Bipolar Membrane Interface, ACS Applied Materials and Interfaces, 5 (2013), 10445–10455.

• C. Abels, F. Carstensen, M. Wessling, Membrane processes in biorefinery applications, Journal of Membrane Science, 444 (2013), 285–317.

• C. Abels, K. Thimm, H. Wulfhorst, A. C. Spiess, M. Wessling, Membrane-based recovery of glucose from enzymatic hydrolysis of ionic liquid pretreated cellulose, Bioresource Technology, 149 (2013), 58–64.

• A. Alhadidi, B. Blankert, A. Kemperman, R. Schurer, J. Schippers, M. Wessling, W. van der Meer, Limitations, improvements and alternatives of the silt density index, Desalination and Water Treatment, 51 (2013), 1104–1113.

• J. André, Z. Borneman, M. Wessling, Enzymatic Conversion in Ion-Exchange Mixed Matrix Hollow Fiber Membranes, Industrial and Engineering Chemistry Research, 52 (2013), 8635–8644.

• C. Bayer, M. Follmann, H. Breisig, I. M. Wienk, F. P. Cuperus, M. Wessling, T. Melin, On the Design of a 4-End Spiral-Wound L/L Extraction Membrane Module, Industrial and Engineering Chemistry Research, 52 (2013), 1004–1014.

• N. Bettahalli, I. Arkesteijn, M. Wessling, A. Poot, D. Stamatialis, Corrugated round fibers to improve cell adhesion and proliferation in tissue engineering scaffolds, Acta Biomaterialia, 9 (2013), 6928–6935.

• F. Carstensen, T. Kasperidus, M. Wessling, Overcoming the drawbacks of microsieves with micromeshes for in-situ product recovery, Journal of Membrane Science, 436 (2013), 16–27.

• F. Carstensen, T. Klement, J. Büchs, T. Melin, M. Wessling, Continuous production and recovery of itaconic acid in a membrane bioreactor, Bioresource Technology, 137 (2013), 179–187.

• S. Dutczak, F. Cuperus, M. Wessling, D. Stamatialis, New crosslinking method of polyamide–imide membranes for potential application in harsh polar aprotic solvents, Separation and Purification Technology, 102 (2013), 142–146.

Peer-reviewed publications

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• C. Fritzmann, M. Hausmann, M. Wiese, M. Wessling, T. Melin, Microstructured spacers for submerged membrane filtration systems, Journal of Membrane Science, 446 (2013), 189–200.

• T. Harlacher, T. Melin, M. Wessling, Techno-economic Analysis of Membrane-Based Argon Recovery in a Silicon Carbide Process, Industrial and Engineering Chemistry Research, 52 (2013), 10460–10466.

• P. J van Rijn, M. Tutus, C. Kathrein, L. Zhu, M. Wessling, U. Schwaneberg, A. Böker, Challenges and advances in the field of self-assembled membranes, Chemical Society Reviews, 42 ( 2013), 6579-6592.

• A. J. C. Kuehne, T. Luelf, M. Wessling, J. Sprakel, F. So, C. Adachi, Conjugated polymer particles: towards self-assembling organic photonics, 88290A.

• K. Lorenz, M. Wessling, How to determine the correct sample volume by gravimetric sorption measurements, Adsorption, 19 (2013), 1117–1125.

• W. Ogieglo, J. de Grooth, H. Wormeester, M. Wessling, K. Nijmeijer, N. E. Benes, Relaxation induced optical anisotropy during dynamic overshoot swelling of zwitterionic polymer films, Thin solid films, 545 (2013), 320-326.

• W. Ogieglo, H. van der Werf, K. Tempelman, H. Wormeester, M. Wessling, A. Nijmeijer, N. E. Benes, n-Hexane induced swelling of thin PDMS films under non-equilibrium nanofiltration permeation conditions, resolved by spectroscopic ellipsometry, Journal of Membrane Science, 437 (2013), 313–323.

• W. Ogieglo, H. Wormeester, M. Wessling, N. E. Benes, Probing the Surface Swelling in Ultra-Thin Supported Polystyrene Films During Case II Difusion of n-Hexane, Molecular Chemistry and Physics, 214 (2013), 2480-2488.

• W. Ogieglo, H. Wormeester, M. Wessling, N. E. Benes, Temperature-induced transition of the diffusion mechanism of n-hexane in ultra-thin polystyrene films, resolved by in-situ Spectroscopic Ellipsometry, Polymer, 54 (2013), 341–348.

Peer-reviewed publications

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• S. Postel, G. Spalding, M. Chirnside, M. Wessling, On negative retentions in organic solvent nanofiltration, Journal of Membrane Science, 447 (2013), 57–65.

• M. Scholz, B. Frank, F. Stockmeier, S. Falß, M. Wessling, Techno-economic Analysis of Hybrid Processes for Biogas Upgrading, Industrial and Engineering Chemistry Research, 52 (2013), 16929–16938.

• M. Scholz, T. Harlacher, T. Melin, M. Wessling, Modeling Gas Permeation by Linking Nonideal Effects, Industrial and Engineering Chemistry Research, 52 (2013), 1079–1088.

• M. Scholz, T. Melin, M. Wessling, Transforming biogas into biomethane using membrane technology, Renewable and Sustainable Energy Reviews, 17 (2013), 199–212.

• M. S. Tijink, M. Wester, G. Glorieux, K. G. Gerritsen, J. Sun, P. C. Swart, Z. Borneman, M. Wessling, R. Vanholder, J. Joles, D. Stamatialis, Mixed matrix hollow fiber membranes for removal of protein-bound toxins from human plasma, Biomaterials, 34 (2013), 7819–7828.

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Peer-reviewed publications

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• D. J. Beste, K. Nöh, Niedenführ, T. A. Mendum, N. D. Hawkins, J. L. Ward et al., 13C-Flux Spectral Analysis of Host-Pathogen Metabolism Reveals a Mixed Diet for Intracellular Mycobacterium tuberculosis, Chemistry and Biology, 20 (2013), 1012–1021.

• T. Dalman, T. Dörnemann, E. Juhnke, M. Weitzel, W. Wiechert, K. Nöh, B. Freisleben, Cloud MapReduce for Monte Carlo bootstrap applied to Metabolic Flux Analysis, Future Generation Computer Systems, 29 (2013), 582–590.

• P. Droste, K. Nöh, W. Wiechert, Omix - A Visualization Tool for Metabolic Networks with Highest Usability and Customizability in Focus, Chemie Ingenieur Technik, 85 (2013), 849–862.

• A. Grünberger, C. Probst, A. * Heyer, W. Wiechert, J.* Frunzke, D. Kohlheyer, Microfluidic Picoliter Bioreactor for Microbial Single-cell Analysis: Fabrication, System Setup, and Operation, Journal of Visualized Experiments 82 (2013), 50560.

• A. Grünberger, J. van Ooyen, N. Paczia, P. Rohe, G. Schiendzielorz, L. Eggeling et al., Beyond growth rate 0.6: Corynebacterium glutamicum cultivated in highly diluted environments, Journal of Biotechnology and Bioengineering, 110 (2013), 220–228.

• T. Hanke, K. Noh, Noack, T. Polen, Bringer, H. Sahm et al., Combined Fluxomics and Transcriptomics Analysis of Glucose Catabolism via a Partially Cyclic Pentose Phosphate Pathway in Gluconobacter oxydans 621H, Applied and Environmental Microbiology, 79 (2013), 2336–2348.

• C. Probst, A. Grünberger, W. Wiechert, D. Kohlheyer, Microfluidic growth chambers with optical tweezers for full spatial single-cell control and analysis of evolving microbes, Journal of Microbiological Methods, 95 (2013), 470–476.

• C. Probst, A. Grünberger, W. Wiechert, D. Kohlheyer, Polydimethylsiloxane (PDMS) Sub-Micron Traps for Single-Cell Analysis of Bacteria, Micromachines, 4 (2013), 357–369.

• K. Schmitz, V. Peter, Meinert, G. Kornfeld, T. Hardiman, W. Wiechert, Noack, Simultaneous utilization of glucose and gluconate in Penicillium chrysogenum during overflow metabolism, Journal of Biotechnology and Bioengineering, 110 (2013), 3235–3243.

• M. Weitzel, K. Nöh, T. Dalman, Niedenfuhr, B. Stute, W. Wiechert, 13CFLUX2--high-performance software suite for 13C-metabolic flux analysis, Bioinformatics, 29 (2013), 143–145.

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• W. Wiechert, K. Nöh, Isotopically non-stationary metabolic flux analysis: complex yet highly informative, Current Opinion in Biotechnology, 24 (2013), 979–986.

• W. Wiechert, K. Nöh, M. Weitzel, Metabolic isotopomer labeling systems. Part III: Path tracing. Mathematical Biosciences 244 (2013), 1–12.

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• C. Abels, K. Thimm, H. Wulfhorst, A. C. Spiess, M. Wessling, Membrane-based recovery of glucose from enzymatic hydrolysis of ionic liquid pretreated cellulose, Bioresource Technology, 149 (2013), 58–64.

• B. Bonhage, B. Seiferheld, A. C. Spiess, Kinetics of the enzymatic hydrolysis by the endoglucanase from the extremophile S. solfataricus. In Kraslawski A, Turunen I (eds.). Proceedings of the 23rd European Symposium on Computer Aided Process Engineering – ESCAPE 23, (2013), 85-90.

• H. F. Liu, L. L. Zhu, M. Bocola, N. Chen, A. C. Spiess, U. Schwaneberg, Directed laccase evolution for improved ionic liquid resistance. Green Chemistry 15 (2013), 1348-1355.

• W. Richtering, K. Geisel, S. Wiese, A. C. Spiess, Smart microgel-stabilized emulsions: Fundamental properties and applications in biocatalysis, 245th National Meeting of the American-Chemical-Society (ACS), APR 07-11, 2013, American Chemical Society, (2013).

• J. Viell, H. Wulfhorst, T. Schmidt, U. Commandeur, R. Fischer, A. C. Spiess, W. Marquardt, An efficient process for the saccharification of wood chips by combined ionic liquid pretreatment and enzymatic hydrolysis, Bioresource Technology, 146 (2013), 144–151.

• S. Wiese, A. C. Spiess, W. Richtering, Microgel-Stabilized Smart Emulsions for Biocatalysis, Angewandte Chemie International Edition, 52 (2013), 576–579.

Peer-reviewed publications

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• S. Diez de Medina, H. Silva, W. Jeblick, I. Nowik, M. Modigell, H. E. Neuhaus, U. Conrath, Profiling carbohydrate composition, biohydrogen capacity, and disease resistance in potato, Electronic Journal of Biotechnology, 16 (2013).

• S. Harboe, M. Modigell, Yield Stress in Semi-Solid Alloys – The Dependency on Time and Deformation History, Key Engineering Materials, 554-557 (2013), 523–535.

• S. Harboe, M. Modigell, A. Pola, Wall Slip Effect in Couette Rheometers, Solid State Phenomena, 192-193 (2013), 353-358.

• M. Modigell, A. Pola, M. Suéry, C. Zang, Investigation of Correlations between Shear History and Microstructure of Semi-Solid Alloys, Solid State Phenomena, 192-193 (2013), 251-256.

• M. Modigell, T. Volkmann, C. Zang, A High-Precision Rotational Rheometer for Temperatures up to 1700 °C, Solid State Phenomena, 192-193 (2013), 359-364.

• Rogal, J. Dutkiewicz, H. Atkinson, L. Litynska-Dobrzynska, T. Czeppe, M. Modigell, Characterization of semi-solid processing of aluminium alloy 7075 with Sc and Zr additions, Materials Science and Engineering, A 580 (2013), 362–373.

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MVT

Peer-reviewed publications

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• R. E. Isele-Holder, W. Mitchell, J. R. Hammond, A. Kohlmeyer, A. E. Ismail, Reconsidering Dispersion Potentials: Reduced Cutoffs in Mesh-Based Ewald Solvers Can Be Faster Than Truncation, Journal of Chemical Theory and Computation, 9 (2013), 5412–5420.

• A. A. Niazi, B. D. Rabideau, A. E. Ismail, Effects of Water Concentration on the Structural and Diffusion Properties of Imidazolium-Based Ionic Liquid–Water Mixtures, Journal of Physical Chemistry, 117 (2013), 1378–1388.

• B. D. Rabideau, A. Agarwal, A. E. Ismail, Observed Mechanism for the Breakup of Small Bundles of Cellulose Iα and Iβ in Ionic Liquids from Molecular Dynamics Simulations, Journal of Physical Chemistry, 117 (2013), 3469–3479.

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Peer-reviewed publications

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• J. Busch, D. Elixmann, P. Kühl, C. Gerkens, J. P. Schlöder, H. G. Bock, W. Marquardt, State estimation for large-scale wastewater treatment plants, Water Research, 47 (2013), 4774–4787.

• D. A. Munoz, W. Marquardt, Robust control design of a class of nonlinear input- and state-constrained systems, Annual Reviews in Control, 37 (2013), 232–245.

• M. Skiborowski, A. Harwardt, W. Marquardt, Conceptual Design of Distillation-Based Hybrid Separation Processes, Annual Review of Chemical and Biomolecular Engineering, 4 (2013), 45–68.

• J. Viell, A. Harwardt, J. Seiler, W. Marquardt, Is biomass fractionation by Organosolv-like processes economically viable? A conceptual design study, Bioresource Technology, 150 (2013), 89–97.

• J. Viell, H. Wulfhorst, T. Schmidt, U. Commandeur, R. Fischer, A. Spiess, W. Marquardt, An efficient process for the saccharification of wood chips by combined ionic liquid pretreatment and enzymatic hydrolysis, Bioresource Technology, 146 (2013), 144–151.

• R. Schneider, C. Georgakis, How to NOT make the extended Kalman filter fail, Industrial and Engineering Chemistry Research, 52 (2013), 3354-3362.

• W. Marquardt, Urheberrecht und Open Access: Angemessene Rahmenbedingungen für die Wissenschaft, Bibliothek, Forschung und Praxis, 37 (2013), 9-15.

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Peer-reviewed publications

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• A. Bompadre, A. Mitsos, B. Chachuat, Convergence analysis of Taylor models and McCormick-Taylor models, Journal of Global Optimization, 57 (2013), 75–114.

• H. Ghasemi, M. Paci, A. Tizzanini, A. Mitsos, Modeling and optimization of a binary geothermal power plant, Energy, 50 (2013), 412–428.

• E. Lizarraga-Garcia, A. Ghobeity, M. Totten, A. Mitsos, Optimal operation of a solar-thermal power plant with energy storage and electricity buy-back from grid, Energy, 51 (2013), 61–70.

• E. J. Sheu, A. Mitsos, Optimization of a hybrid solar-fossil fuel plant: Solar steam reforming of methane in a combined cycle, Energy, 51 (2013), 193–202.

• G. M. Zak, A. Ghobeity, M. H. Sharqawy, A. Mitsos, A review of hybrid desalination systems for co-production of power and water: analyses, methods, and considerations, Desalination and Water Treatment, 51 (2013), 5381–5401.

• G. M. Zak, N. D. Mancini, A. Mitsos, Integration of thermal desalination methods with membrane-based oxy-combustion power cycles, Desalination, 311 (2013), 137–149.

• H. Zebian, A. Mitsos, Pressurized oxy-coal combustion: Ideally flexible to uncertainties, Energy, 57 (2013), 513–526.

• H. Zebian, N. Rossi, M. Gazzino, D. Cumbo, A. Mitsos, Optimal design and operation of pressurized oxy-coal combustion with a direct contact separation column, Energy, 49 (2013), 268–278.

• G. M. Zak, A. Mitsos, Hybrid thermal-thermal desalination structures, Desalination and Water Treatment, 52 (2013), 2905-2919.

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Peer-reviewed publications

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TVT

• F. Buchbender, A. Fischer, A. Pfennig, Influence of compartment geometry on the residence time of single drops in Kühni extraction columns, Chemical Engineering Science, 104 (2013), 701–716

• P. Frenzel, S. Fayyaz, R. Hillerbrand, A. Pfennig, Biomass as Feedstock in the Chemical Industry – An Examination from an Exergetic Point of View. Chemical Engineering & Technology, (2013) 36(2), 1-9.

• R. Bronneberg, A. Pfennig, MOQUAC, a new expression for the excess Gibbs energy based on molecular orientations, Fluid phase equilibria, 338 (2013), 63-77.

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Aachener VerfahrenstechnikRWTH Aachen UniversityAachener Verfahrenstechnik, Templergraben 55, 52056 Aachen+49 (0) 241 80-95470+49 (0) 241 80-92252www.avt.rwth-aachen.deSecretary.CVT@avt.rwth-aachen.deNicolas NauelsAntje SpiessSimone Joschko, Julian LaschetVolker Stevens(p. 3, 6, 9, 10, 11, 12, 13, 14, 15, 16, 24, 27, 29, 34, 36, 37, 41, 42, 44, 45)RWTH Aachen (p. 52, www.prorwth.de)

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