Application Note: Role of EBA and SMB in organic/amino acid production

#Application Note: Role of EBA and SMB in organic/amino acid production

Several organic and amino acids have found applications as specialty molecules in food, consumer goods and pharmaceutical industries. Itaconic Acid (IA) is a 5 carbon dicarboxylic acid produced through bacterial fermentation and used as an important building block for biopolymers. In case of IA production, downstream processing can account to 30-50 % of the overall cost of goods (COGs). Therefore, it requires effective and efficient operations to improve sustainability and cost competitiveness. In the current article, we will briefly discuss the role of expanded bed adsorption (EBA) and simulated moving bed (SMB) technologies in production of IA.

Figure 1: Purification of IA requires a downstream process to separate IA from suspended and dissolved impurities

The basis for selecting a specific unit-operation is defined by desired separation. Typical fermentation output stream contains 5-10 % IA, 5-10 % impurities and 80-90 % water. Impurities include both suspended solids like biomass and dissolved compounds that are produced as co-metabolites. Though precipitation is an easy method for IA purification, it results in formation of by-products and limits product purity. Therefore, instead of precipitation, adsorption using a chromatography resin is a preferred alternative. However, feed for packed bed chromatography columns need to be free of suspended solids and this require additional unit operations for clarification, resulting in yield losses and higher costs. To overcome these limitations, Expanded Bed Adsorption (EBA) can be applied. EBA is an integrated adsorption process, where the product is selectively captured by fluidized adsorbent beads from unclarified fermentation broth. Thereby, enabling removal of both suspended and soluble impurities in 1 step.

Successful EBA process can achieve desired product purity with high recovery yields using 30-60 % less number of unit-operations. In addition, it is easier to scale EBA for large-scale production processes with several kilotons annual capacity, due to no pressure drop limitations. However, it is important to note that application of EBA on large scale can lead to large side streams, which require processing before recycling or release into the environment. Additionally, fluid distribution and hydrodynamic performance of EBA may result in reduced dynamic binding capacity compared to packed bed. A prudent approach to overcome these limitations is by operating EBA in SMB mode.

In conclusion, EBA in combination with SMB mode enables continuous operation, reduced number of downstream steps, improved resin + buffer utilization and enhanced productivity, which makes it a techno-economically viable technology for IA production process. For more information on the EBA and SMB technologies please have a look at or you can contact us via Dit e-mailadres wordt beveiligd tegen spambots. JavaScript dient ingeschakeld te zijn om het te bekijken..

Target Ingredients for Adsorption Chromatography in Whey and Milk

#Target Ingredients for Adsorption Chromatography in Whey and Milk

This blog focusses on useful and valuable proteins in both milk and whey that can be recovered with chromatographic separation.

Milk and its derivatives contain various proteins that are useful as human nutrition. Milk proteins are especially rich in amino acids that stimulate muscle synthesis. In addition, some proteins and peptides in milk have positive health effect e.g. on blood pressure, inflammation, oxidation and tissue development [1]. Some people suffer from deficiency of specific proteins, In order to to find a solution for this, manufacturers produce balanced, composed (semi-)synthetic milk products, e.g. baby food, by adding those proteins in the manufacturing process.

This blog describes a few examples where adsorption chromatography can serve as a separation technology to isolate useful milk and whey proteins.

Minor Milk Proteins

Figure 1. Human versus bovine minor milk protein composition [2], [3], [4].

Above Figure 1 represents the average milk protein composition in both human and bovine milk (note that only  the “high-value” minor proteins are represented in this figure, because the majority (i.e. > 80%) of cow milk proteins consists of different types of casein. For human milk approximately 40% of total protein consists of casein).

Total bovine milk proteins content amounts to 30-34 g/l.


Protein adsorption has been applied on batch scale utilising dedicated functionalised resins, e.g. agarose-based cation exchange resin [5].

In expanded bed mode, suited to direct the fermentation broth to the adsorption process, without having to clarify the crude broth first, it has been found that the feed flow rate can be substantially higher (~10 m/h or even higher) without significant backpressure [6].

Before loading milk on a chromatography column the fat (components) need to be skimmed first in order to prevent blockage of the adsorption phase, and reduce viscosity to attain higher bed flow rates.

Dairy Characteristics

Milk is a complex medium; in addition the composition of milk is subject to seasonal influences. and further pooling prior to processing is quite common in dairy industry. Volumes to be processed lie in the range up to 100’s of m3’s per day.

Since the proteins are utilised in food supplements, regulatory and hygiene rules apply.

Pasteurisation is a common step in milk processing, temperature largely affects the adsorption characteristics and may also pose additional demands on the adsorption materials in terms of thermosensitivity.

Adsorption Technology

Figure 2. Part of flow scheme to recover milk proteins, including chromatographic adsorption

Figure 2 conveys part of a typical milk process where fat and protein are separated.

The Adsorption step comprises the capture of specific proteins to a specific, selective resin, and the elution with a proper salt buffer.

Depending on the magnitude of the process, as well as process control requirements, the adsorption step may be operated in a continuous mode. A well established continuous chromatography mode is based on simulated moving bed technology (SMB). This technology features a multiple (typically 4-16) column process that smartly accommodates all distinct process steps –running simultaneously- that are part of the bind and elute process, including wash/rinse/equilibration and regeneration.

XPure has developed a SMB system that can be operated both in fixed and expanded bed mode, so called Expanded Bed Adsorption (EBA). This EBA mode features all individual steps of the SMB process cycle, operated in upflow / expanded bed mode, refer to Figure 3.

Figure 3. Typical SMB flow scheme for protein isolation/purification from dairy

Note: Regeneration has not been included, every column can be read as a zone consisting multiple columns,, either in series or parallel

Process cycle time and specific residence time in certain zones may be adapted to changing input parameters, e.g. protein content and composition.

Case studies have been done both for lacto-peroxidase and lactoferrin. Based on packed bed mode for a daily milk production of 70 m3 a continuos process for lactoferrin would result in significant cost reduction in cost of goods, refer to Figure 4. A significant part of the cost reduction in SMB-mode in relation to batch-mode chromatography, can be related t0 consumables. It has further been found that skimming is necessary to reduce the residual fat content below 0.1 w-%, prior to applicable chromatography processes.

Figure 4: Cost of Goods for bovine-Lactoferrin from milk, batch versus SMB operation

XPure EBA-SMB has been successfully run on amino-acid containing fermentation broth without prior clarification or filtration. This process design can directly be translated to the milk protein application and could flexibly be fit in any process step that the skimmed milk goes through.


For large-scale dairy processes cost reduction can be attained by a continuous operating mode. For the adsorption process, simulated moving bed chromatography (SMB) is a state-of-the-art technology that contributes to a high level of process automation, product quality and yield.

The XPure SMB-EBA offers the additional feature to process the unclarified (skimmed) milk directly, and so reducing operational and capital costs. For further information you are invited to contact us at Dit e-mailadres wordt beveiligd tegen spambots. JavaScript dient ingeschakeld te zijn om het te bekijken.. You will find more information about XPure’s product portfolio and services on


[1] A. Haug, “Bovine milk in human nutrition – a review,” Lipids in Health and Disease, vol. 6, no. 25, 2007.
[2] M. Malacarne, F. Martuzzi, A. Summer and P. Mariani, “Protein and fat composition of mare's milk,” International Dairy Journal, vol. 12, no. 11, pp. 869-877, 2002.
[3] J. Billakanti, “Extraction of high-value minor proteins from milk,” University of Canterbury, Christchurch, 2016.
[4] S. Séverin and W. Xia, “Milk Biologically Active Components,” Critical Reviews in Food Science and Nutrition, vol. 45, pp. 645-656, 2007.
[5] General Electric Health Care - Pharmaceuticals, “GE Health Care - Pharmaceuticals,” 2019. [Online]. Available:
[6] R. Noël, “Industrial processing and biotherapeutics,” Filtration+Separation, vol. 44, no. 3, pp. 26-28, 2007.


Application Note: Vit C production and purification

#Application Note: Vit C production and purification

Ascorbic acid was discovered in 1928 by Szent-Györgi. Commercially, ascorbic acid is mainly produced by a combination of synthetic organic steps and biotransformation. A well-known intermediate product is 2-keto-L-gulonic acid. This is produced from the sodium salt of the L-gulonic acid and has been acidified according to exact the same Ion Exchange route, as presented below for vitamin C.

In order to obtain the pure product, ion exchange is an attractive method for removing the salts.

The objective of this application note is to demonstrate the feasibility of the continuous ion exchange for removing Na+ from the sodium ascorbate. The feed flow consists of an aqueous solution containing Na-ascorbate. The sodium is exchanged by H+ on a strong cation resin in the H+ form. The resin is regenerated with HCl.



2-keto-L-gulonic acid (precursor to vit. C or ascorbic acid)

Ascorbic acid (vitamin C)


Design Considerations

The sodium form associated with the Asc (ascorbic acid) would be exchanged for a H+ thus forming ascorbic acid on a strong acid cation resin with 1,8 eq/l (expressed in terms of equivalents per unit volume of packed bed) maximum capacity.

The entire operation is executed in a XPure carousel system with 20 to 30 columns.

Process description

The overall manufacturing process is schematically summarised in the next diagram Figure 1:


Figure 1. Flow diagram for vitamin C manufacturing


For the Ion Exchange step we focus on the acidification step to vitamin C. This is in fact a purification step, see below Figure 2.

Figure 2. Conceptual design of continuous IX purification for (Product) vitamin C. Each block may contain multiple columns. Total number of columns typically 20-30.
Note: yellow lines indicate water flows within the system

The regenerant involves hydrochloric acid implying that NaCl is the target compound to remove in the subsequent wash steps. Caustic is applied for intermittent regeneration and protein removal.

In an experimental study it has been found that residual Na-ascorbate is more difficult to remove (ads wash) than NaCl (regen rinse), the ascorbate obviously shows affinity to the resin surface.

Water consumption is an important process parameter. In order to save on water, a counter current contact concept has been applied. This can be accomplished by assigning multiple columns to the wash&rinse zones. The next Figure 3 shows the effect on water consumption –expressed in BedVolumes- for 4 different configurations. Please note ideally 0.3-0.5 BV (“interstitial volume” or void fraction) would be sufficient for 1 column displacement.

Figure 3. Wash efficiency with growing number of counter-current connected columns

A multi-column carousel system can easily, and relatively cost-effectively accommodate a counter-current contact zone.

The dilution in the vitamin C process typically is 20%-35%. This is significantly lower than fixed bed processes in which 2-fold dilutions are not exceptional.

The conversion of Na-ascorbate is at least 99.5%. . The water consumption, without using the possibilities to re-use water in the process is about 15 liter per kg Vitamin C. The hydrochloric acid (7 wt%) consumption is 5.4 liter per kg vitamin C, taking into account an excessive use of 20%. The caustic consumption should be fine-tuned to the protein content of the feed solution and can be minimised by optimising the intermittent caustic wash. Losses of product in the caustic wash and contamination of the product stream with chloride are minimised by carefully designing the adsorption wash and elution wash sections. Product dilution is minimised by applying an entrainment rejection zone.

One of the dominant factors in the operating expenses for ascorbate (and Na-2-KLG) acidification is related to the costs of the ion exchange resin. This can be related to the specific productivity of the system, which expresses the annual amount of product that can be purified per unit volume of resin. The productivity of a carousel system for the purification of KGA and vitamin C typically is higher than 800 tpa/m3. Productivities in fixed bed processes may be a factor 5-10 lower.

Application Note: Lactic Acid

#Application Note: Lactic Acid

Platform molecules form the basis for several formulations in chemical, food and pharmaceutical industries. Lactic acid (LA), a 3 carbon carboxylic acid is one such platform molecule. LA has a broad application field ranging from food industry to polymer production. Complying with the traditional philosophy of demand vs scale vs cost, a cumulative annual growth rate > 20 % for LA drives the need for cost effective and efficient production processes to meet the demand.

Figure 1: Fundamental aspects involved in industrial production of products (Orange: Involves XPure Technologies)

LA is produced by both chemical synthesis and fermentation, where fermentation has been the preferred choice due to enantio-selectivity and environmental sustainability factor. However, fermentation based processes require highly efficient downstream processing (DSP) for removal of impurities and to enable the claimed environmental benefits. Because, if DSP is energy intensive, then sustainability can become questionable. Further, DSP also contributes to > 50 % of overall cost of goods (COGs) which can define the business model. In this application note, we will discuss how use of simulated moving bed (SMB) mode of ion exchange adsorption (IEX) steps can influence the overall COGs.

Figure 2: Major sub-processes integrated to produce lactic acid

LA production process involves both cation and anion exchangers to remove positively-charged cationic impurities and to capture LA, respectively. These two steps use industrial resins, which are known for their robustness, high exchange capacity and long process life. However, operating these resins in batch mode result in partial utilization of the resin capacity and requires larger columns, high amount of buffers and waste streams.

Figure 3: Different separation principles applied in downstream processing of lactic acid

This scenario leads to low productivity, less sustainable process and increase in process costs. Therefore, the SMB technology can successfully be applied in this scenario, to develop a more sustainable process with reduced costs. This is due to the fact that SMB results in better resin utilization and lower buffer usage leading to reduced operating costs. Additionally, improved product titers in case of SMB can reduce the scale of unit operations used post SMB.

In the traditional scenario of switching from batch to SMB, the IEX costs can be reduced by 30-50 %. For example, in a lactic acid purification process, where IEX step can contribute to about 20 % of overall DSP COGs, the SMB technology can reduce the DSP COGs by 5-10 %. This improvement in process economics can be critical for fermentation based products like LA, which competes with petrochemical products. An estimated cash flow analysis for LA production process with batch and SMB IEX systems is depicted below. Here, a 32 kt/a plant capacity is assumed, with an OPEX of about 915 €/t, CAPEX of about 21 M€ and a sales price of 1500 €/t. Shifting from batch to SMB in such a scenario can reduce the breakeven period from 3.25 to 2.75 years. Thereby enhancing efficiency, sustainability and profitability.

Figure 4: Cash flow analysis with batch and SMB IEX steps for LA purification

Application Note: Fractionating Chromatography for sweeteners

#Application Note: Fractionating Chromatography for sweeteners

Sugar is produced in many countries all over the world. The term “sugar production” relates to various products, primarily mono- and disaccharides.

There are two widely applied large-scale chromatographic carbohydrate (sugar) separations: the isolation of the disaccharide sucrose from molasses and the separation of the two monosaccharides fructose and glucose (figure 1).

Figure 1: The structure of fructose (left) and of glucose (right)

Sugar refining

Monosaccharides like fructose and glucose are produced mainly from beet, cane or corn. After several refinery steps including milling, filtration and hydrolysis, a mixture containing glucose is obtained. Glucose is isomerized using immobilized enzymes, to the much sweeter component fructose. The composition of this equilibrium mixture ranges from 50/50 to 45/55 (fructose/glucose), and often contains up to about 8% of oligosaccharides.

This mixture is separated by chromatographic separation into a fructose-rich and a glucose-rich component. The dry matter content of the feed flow varies up to 60%w/w.

The resin material used in fructose/glucose fractionation is a gel-type sulfonated polystyrene-DVB strong acid exchange resin in the calcium form. The separation is based on the preferential adsorption of fructose, which forms a complex with the calcium ions. This chromatographic method is called Ligand Exchange Chromatography (LEC). There are several commercially available resins for this application.

A secondary phenomenon is that larger molecules, i.e. higher oligosaccharides are not able to physically fit into the resin pores. The mechanism of separating large molecules from small molecules by preventing some of the large molecules from getting inside the stationary packing is called size exclusion chromatography. Size exclusion chromatography takes place simultaneously with ligand exchange chromatography in the purification of fructose. This results into larger oligosaccharide concentration to leave in the raffinate phase. Size exclusion can also be exploited in the separation of higher saccharides from monosaccharides.

Both components are recovered for over 90% and the purity of the product flows is above 90% as well. Glucose is recycled and re-isomerized; fructose is sold as a pure product or mixed with the equilibrium mixture mentioned above to yield high-fructose syrup. The fractionation process takes place at 60°C, to reduce microbial contamination and to reduce the pressure drop by lowering the dynamic viscosity of the liquid.

SMB Chromatographys

The chromatographic separation of fructose and glucose can be efficiently done in a simulated moving bed (SMB). Figure 2 shows experimental data from a glucose-fructose fractionation in a SMB system. It also shows the predicted performance from our process design software.

Figure 2.Comparison of production data of fructose/glucose fractionation on a 12-column system with calculations according to our process design model

The same fractionation mechanism applies for lots of other applications,

  • often directly related to sugar processes where C5/C6 sugars are involved,
  • or indirect sugar processes where sugar lies at the basis of a fermentative route to produce biomaterials like organic acids, (residual) saccharides and amino-acids.

Figure 3. Representation of a 4-zone SMB system to separate Fructose (strongest chelating) in Extract Phase (yellow exit) from Glucose (weakest chelating) in Raffinate Phase (blue exit). Green input flow represents the feed mixture. The white influent represents the desorbant buffer, often water.

Figure 3 conveys a generic projection of a 4 zone / 8 column fractionating SMB system., it is stereotype for any binary fractionation system.

Application areas

The fractionating principle evidently can be applied in a large field of applications.

  • Fractionate out undesirable side-components from natural sweetener, for example steviolglycoside
  • Separation of betaine from cell culture supernatant
  • Separation of organic acids from inorganic solution
  • Upgrading C5- and C6 from cellulose hydrolysates, idem for organic acids

In conclusion, Fractionating Chromatography is a strong separation tool that perfectly suits continuous SMB operation.

EBA-SMB: Single Step Purification Of Amino Acids From Bacterial Broth

#EBA-SMB: Single Step Purification Of Amino Acids From Bacterial Broth

This blog will present a new development regarding the application of Expanded Bed Adsorption (EBA) technology for small molecules.

Amino acid – Gamma-aminobutyric Acid (GABA)

Biotechnological fermentation processes are nowadays common in the industry to produce a broad range of biological molecules. Obviously, the bio-based industries need efficient, cost effective, downstream solutions to process these complex streams. 

The topic for this blog is the purification of small molecules like amino acids from unclarified bacterial broth using a combination of different technologies. To date the use of Expanded Bed Adsorption (EBA) for processing unclarified broth is state-of-the-art technology and its description can adequately be found in literature. In an EBA column, the resin bed is expanded by upward feed flow and the (then actuate) bed void allows particulate biomass to flow through the resin bed and selectively capture target molecules. This makes dedicated clarification steps such as centrifugation and filtration redundant. However, a further improvement of the technology that has been regarded feasible, is integration of EBA with the simulated moving bed (SMB) technology (Ref. 1). To address this challenge the purification of a model compound, ɣ-aminobutyric acid (GABA) was investigated.

What is new: use of geltype adsorbent in Eba mode processing

Resin selection is one of the critical aspects of developing an EBA process. Relevant resin hydrodynamic properties include particle diameter and density. Typically, these beads are agarose-based and have a heavy core. Only a few specific EBA resin types are available, which are also quite expensive. These aspects are major hurdles for the application of the EBA technology in manufacturing of bulk chemicals where low production costs are key.

The current study focusses on the purification of ɣ-amino butyric acid (GABA) from a bacterial, E. coli, fermentation broth. It is known that strong acid cation exchange (SAC) resins exhibit selective binding of GABA (Ref. 2). The resin screening for current investigation was not limited to specific, porous EBA resins. Surprisingly, it has been discovered that gel-type (non-porous) resin(s) could also be used for EBA applications; although the density is at the low end (e.g. 1.2 g/mL) linear flow rate up to 600 cm/h were attained. In this case,  industrially available resin type (Finex, CS16GC) is furthermore characterized by high ion exchange capacity (e.g. 1.6 eq/L). In Fig. 1 pictures of gel-type and macroporous-type polystyrene resins are shown.

Fig. 1 Text see last page

GABA purification and eba-mode processing

First, the GABA purification process using the gel-type strong acid cation exchange (SAC) resin was defined for a “single EBA column process”. The following process steps were identified:

  • Adsorption (loading GABA-containing unclarified broth)
  • Wash (H2O)
  • Elution (NaOH)
  • Wash (H2O)
  • Regeneration (H2SO4),
  • Wash (H2O)

Obviously, critical process requirement for EBA processing (e.g. maintaining the target bed expansion) should be fulfilled. Important parameters incl. buffer concentrations, target buffer volumes and flow rates were established. Flow rate ranges for individual process buffers and unclarified broth were studied and optimized to prevent the occurrence of unwanted changes in the expanded resin bed. Detrimental for EBA process in SMB mode is the overflow of resin from the column top resulting in loss of resin or even clogging of valves.

Technology integration: EBA in SMB mode

For the integration of EBA and SMB process, a state-of-the-art 8-column lab scale system has been designed and built (see Figure 2). Important feature is the flexibility to define the operating conditions per column.
Within the software, recipes can be generated that address

  • the total number of columns in a SMB cycle
  • number of column positions
  • inlet and outlet valve configuration per position
  • pump flow rate
  • sensor control and
  • switch time per position.

As mentioned, a critical aspect is to ensure optimal bed expansion. For this purpose, ultrasound sensors were installed at each column outlet that measured the expanded bed level. By this measurement, the software controlled the pump flow rate to maintain the desired bed expansion for the individual columns. The pH profile of the product stream exiting the different SMB columns passing through the elution zone was assessed to represent consistent product quality at a cyclic steady state of operation. The quality was defined by removal of biomass and other soluble impurities (Ref. 3).

Fig. 2. Text see last page


The promise of reduction of unit operations, increased product yield and productivity and reduced buffer consumption using EBA technology for complex feed streams has been recognized for many years. It has now been demonstrated that further process improvement by integration of the EBA and SMB technology for purification of an amino acid, GABA, from unclarified bacterial broth was successful. A relevant factor is the use of gel-type resin (CS16GC) exhibiting a higher binding capacity as compared to that of macroporous resin. The integrated one-step EBA-SMB process resulted in a GABA purity of ≥ 92% and > 98% removal of biomass. The results show that integrated EBA-SMB technology enhances process efficiency and economics of bioprocesses. It is anticipated that further improvement can be realized by increasing the number of columns.


Ref. 1. Ping Li, Pedro Ferreira Gomes, José M. Loureiro and Alirio E. Rodrigues. Proteins Separation and Purification by Expanded Bed Adsorption and Simulated Moving Bed Technology. In Continuous Processing in Pharmaceutical Manufacturing (2014). Editor Ganapathy Subramanian.

Ref. 2. Trinath Pathapati, Dennis N. Rutze, Piet den Boer, Pieter de Wit and Menne Zaalberg. Expanded Bed Adsorption of ɣ-Aminobutyric Acid from E. coli broth by CS16GC and IRC747 Resins. Chem. Eng. Technol. 2018, 41, No.12, 2427-2434..

Ref. 3. Trinath Pathapati, Dennis N. Rutze, Pieter de Wit, Piet den Boer and Menne Zaalberg. Innovation of Expanded-Bed Adsorption by Integrating Simulated Moving-Bed Technology. Chem. Eng. Technol. 2018, 41, No.12, 2393-2401.

Development Strategy For EBA-SMB Processes

#Development Strategy For EBA-SMB Processes

EBA-SMB: one unit operation

The use of Expanded Bed Adsorption (EBA) for the purification of biological molecules from unclarified harvest is well described for many applications in literature. The advantages are obvious; including shorter process time, higher yield, low buffer consumption, and no additional clarification step.

The next step to further increase the productivity within e.g. bio-based industries is integration of EBA with Simulated Moving Bed (SMB) technology in one single unit. For this application, multiple EBA columns need to be connected to each other in order to obtain the full advantage of processing in SMB mode. Important differences as compared to packed bed column chromatography are that

  1. the resin particles in the EBA columns can move freely and
  2. the resin particle movement and behaviour in the EBA column is highly dependent on resin properties, inlet flow rate.

The Challenge

The main challenge is to prevent collapse of the expanded resin bed or a sudden increase of the resin bed level resulting in loss of resin particles at the column top outlet.The latter may happen when the density and/or viscosity of unclarified broth is significantly higher than aqueous process buffers. It is evident that processing of high viscous (feed) solutions result in a (much) higher resin bed expansion as compared to aqueous solutions at the same flow rate. Both occasions; a too low bed expansion or too high expansion are potential obstructions to properly execute EBA processes in SMB mode.

A very tight control of the expanded bed level is therefore mandatory for EBA executed in SMB mode


Expanded bed level control is crucial

A number of strategies can be applied to keep the level of the expanded resin bed constant during processing of unclarified broth.

  • Full automatic feedback on the feed flow rate using a target expanded bed level.
  • Automation using
    a) expected flow rates for the individual steps in the process combined with
    b) target expanded bed level.
  • , In case of well defined process characteristics regarding target expansion and expected flow rates, . no or only limited feedback on the feed flow rate maybe applied

The third option requires profound process knowledge. The behaviour of the resin bed expansion as a result of change in flow rates and consecutively applied different feed streams and buffers need to be known in order to develop a proper strategy for controlling the EBA process. Furthermore, it should be taken into consideration that time and volume required to achieve both the required expansion and an effective process step may constrain each other.


Development of EBA-Smb process

Using well-characterized feed streams, it is worthwhile to anticipate on the expected changes of expansion brought about by the consecutive processing of unclarified broth and different process buffers. Three parameters are relevant a) required volume per step, b) flow rate and c) viscosity/density.

(a)   Make an assessment of the number of settled resin bed volumes (BV) needed for the execution of the EBA process. This can be done based on a regular packed bed chromatography process. It must be recognized that the displacement of particulate containing material does take more rinse volume in EBA mode.

(b)   Establish the flow/expansion behaviour of the unclarified broth and all process buffers. This will give a reliable indication of the flow rates that need to obtained for each process step.

(c)   Establish the behaviour of the expanded bed during the transitions between unclarified broth and process liquids.

Crucial is to know how the expanded bed responds to the change to a feed stream with a higher viscosity (for instance unclarified broth). Loss of resin from the column top may occur if the flow rates remain too high. This is particularly relevant in case the EBA process runs in SMB mode. At a worst case scenario the resin particles may block valves and tubing and damage the system.

Below, an example is given how the expanded bed level can be kept in a narrow range during the transition from an aqueous solution to a high viscosity solution just by changing flow rates in a smart manner.

Easy control of expansion feasible?

Polyvinyl alcohol (PVA) is used as a model compound to mimic a high viscosity feed stream (i.e. “unclarified broth”).

First, the flow rates have been determined to obtain the target expansion of 1.85-fold for water and the viscous PVA solution (i.e. 610 and 344 cm/h, respectively). Thereafter, it has been investigated how the expanded bed responds to the transition from water to the PVA solution. Figure 1 shows what will happen when the flow rate is directly switched from 610 cm/h to 344 cm/h upon changing to PVA: a sudden sharp decrease of the expansion is observed within 0.5 BV. Not earlier than after 3 BV the expanded bed reaches the target 1.85-fold expansion. This is an undesirable situation. An unstable bed may result in suboptimal flow distribution and mixing of the supernatant.

Fig.1 (see text last page)

This is prevented by initially doing nothing i.e. just keep the flow rate unchanged upon the switch to PVA. As shown in Figure 2 there is a substantial delay of the bed expansion to respond to the PVA solution. By keeping the flow rate unchanged for 0.5 BV the collapse of the expanded resin bed has been prevented. Interestingly, a first change in flow rate (i.e. 400 cm/h), followed by a second change to the final flowrate of 344 cm/h during the transition has a major effect on the resin bed expansion: undesirable changes in the resin bed expansion have been prevented.

Fig.2 (see text last page) 


A development strategy for processing unclarified harvest in EBA-SMB mode has been presented. By taking the delay of the expanded bed to respond to changes in viscosity into account, simple programming of flow rates and volumes for the individual process steps prevent significant changes in resin bed expansion. As a result, the resin bed expansion remains within a 90% – 110% range of the target bed expansion and enables the successful processing of complicated feed streams in EBA-SMB mode.

Figure 1

Impact of a 1-step decrease of flow rate on the resin bed expansion in case the flow rate is changed directly upon switching to the PVA solution (“unclarified broth”).

Figure 2. . 

Impact of a 2-step decrease of flow rate on the resin bed expansion in case the flow rate is changed after 0.5 BV after switching to the PVA solution (“unclarified broth”).

XPure in conversation with ESBES winner Victor Koppejan

#XPure in conversation with ESBES winner Victor Koppejan

XPure in conversation with Victor Koppejan, winner, ESBES award 2018, thoughts on EBA Technology

At XPure, we believe that the application of efficient downstream technologies like EBA leads to sustainable and profitable process industries. Here, we would like to share the thoughts of a young scientist from TU Delft, about his work on EBA Technology and award-winning talk at ESBES 2018.

How do you feel about winning ESBES (European Society of Biochemical Engineering Sciences) award for 2018

I’m really happy as a Ph.D. candidate in Bioprocess Engineering at Delft University of Technology, that I was able to participate and selected as one of the winners. At the previous ESBES in Dublin two years ago I saw two of my colleagues present during the award ceremony. Since then I’ve been looking forward to a change to participate and be able to share my story with a bigger audience.

What do you think made you stand out among the high-quality research presentations from different streams of biochemical engineering?

In the group of Dr. Marcel Ottens, I strongly feel that our approach in which we applied traditional chemical engineering techniques together with mathematical modelling to a high potential technology like expanded bed adsorption (EBA) helped me to stand out.

How do you see the future of EBA?

Here I must say that I’m really excited about the approach to EBA Xendo has within the European PRODIAS  (PROcessing Diluted Aqueous Systems) project. So far the application of EBA in biopharma has been challenging, as investments on technologies which can have a small level of discrepancy can lead big risk factor. Also, cleanability (and with it the validation and compliance challenges) is a very critical aspect for pharma and one of the fundamental challenges. The fields of non-pharma proteins and small molecules have different drivers for process development and CAPEX/OPEX optimizations are more dominant. I think here EBA can be a competing separation technology. In turn, successful business cases based on EBA will help convince industries that might have become reluctant to implement it.

What do you see as challenges to be addressed that can prepare the technology for future?

In our research (which is part multi-disciplinary consortium) we focus on the fundamentals of fluidization in EBA columns. We try to approach it as a liquid-solid fluidized bed rather than a packed bed column “in disguise”. Since experimental research on hydrodynamics for such a system is highly challenging, we use advanced computer simulations. These allow us to investigate local resin particle environment as well as extract statistics for the overall expanded resin bed. Developing these models has proven to be a tough challenge but are now at a point where we can generate reliable data. Our aim is to use insights we get from the simulation data for the better design of column hardware and to provide a benchmark for ideal fluidization behavior. These benchmarks can then be used to detect early deviations in the process. We hope that this increases the rationale in process control, leading to a more robust equipment operation.

Brief motivation for researchers out there.

Development of EBA systems is a field dealing with multi-phase, multi-scale and multi-physics challenges. Typically, processes at various length and time scales will interact with each other in ways that may not seem obvious at first. These are challenges which, on a more abstract level, are not unique to EBA and I think lessons learned here can be applicable to a broader range of technologies. Continuing that line of thought I’d like to end with a quote from Sir Stanley Eddington I recently came across.

“we often think that we have completed our study of one we know all about two, because ‘two’ is ‘one and one’. We forget that we still have to make a study of ‘and’ ”



Learn how our XPure Systems reduce chromatography costs in downstream processing by using Simulated Moving Bed technology and turn your batch processes into continuous processes. Find out which system fits your needs in this explanimation!

Simulated Moving Bed Reactors

#Simulated Moving Bed Reactors

Innovation through hybridization/integration of technologies is a well-known approach. This approach has been effectively applied to achieve specific process objectives in chemical, biochemical, food and pharmaceutical industries. The approach can include either two separate units operating in tandem or as a single integrated unit. Membrane operations are usually found in tandem with other unit-operations for recycling cells during fermentation or buffers in case of downstream processing. In integrated operations, the overall efficiency is achieved by using two or more operating principles in parallel. Reactive distillation, pervaporation, fermentation with in-situ product removal through stripping etc. are some examples of integrated unit-operations. The current article briefly discusses one such integrated unit-operation called Simulated Moving Bed Reactors (SMBR).

SMB technology has proven to enhance the efficiency of chromatography/adsorption separation through continuous counter-current operation. This principle can have a similar impact on heterogeneous catalytic reactors with catalysts immobilized on support beads or adsorbent and packed as a fixed bed or fluidized bed. The countercurrent effect of SMB is known to enhance the performance of equilibrium driven reactions and mass transfer kinetics, whereas the continuous mode of operation helps in achieving improved productivity. Therefore, SMBR can find its application as a techno-economically viable process solution.

Fundamental phenomena during heterogeneous catalysis are mass transfer (MT), reaction and inhibition kinetics. MT is more critical in case of a catalyst on solid support and substrate dissolved in a liquid system. However, the difference in MT kinetics of a substrate and inhibitor can also be applied as a separation principle to maintain or improve catalytic efficiency. For example, consider a catalyst exhibits product inhibition at a specific product concentration and it is identified that the substrate and product have different characteristic times at which they flow through the column. If the characteristic time difference in a batch reactor is not sufficient to minimize product inhibition, an SMBR can help in increasing the difference through the countercurrent effect. Thereby enhancing step efficiency and process economics.

Schematic representation of modular fluid distribution system involving valves that enable SMB operation of catalysis columns/reactors

Blog by: Trinath Pathapati



Resin is an integral part of any chromatographic process and often a big cost factor. Over time, the resin will deteriorate until it reaches the point where it needs to be replaced in order to maintain an economically viable process. As resin can be costly, you don’t want to replace it too early but predicting exactly when you should this can prove to be difficult when you're developing new processes. When the resin gets exposed to new combinations of products and chemicals, its lifetime may vary and you might need to replace it after 250 production cycles. Or maybe after 500? Or can the resin still deliver after 2000 cycles?

Without experimental data to back up the resin costs, it's quite difficult to write a robust business case for chromatography; the XPure-R is our answer to this challenge. The system enables you to age up to 10ml resin under your process conditions in a fully automated and time-efficient manner and can be tested in both fixed and expanded bed (EBA) mode.

XPure-R allows you to focus on your other research and will age your resin because it was designed to operate without attendance. All you need to do is prepare the XPure-R by supplying all the required process liquids, programming the recipe, and press run. 

It is also possible to outsource your resin aging studies to XPure, saving you even more time.


The cycle time for an investigated process was reduced from 1 hour and 33 minutes to 7,5 minutes;  a 92% reduction.

For a resin aging experiment of 1000 cycles, the XPure-R reduced the experimental time from 64 days to only slightly over 5 days.


5 Levels of Process Control for SMB Systems

#5 Levels of Process Control for SMB Systems

A shift from batch production to continuous production requires a different approach in terms of process control. Especially when the continuous chromatography is, in essence, a rapid sequence of “batch” operations with specific conditions for each process step. Combine this with integration of the unit operation in a production chain, process control quickly becomes critical. With several real-life examples of how control within an SMB can be applied, this blog will look into the different levels of process control for continuous chromatography and how they work together to ensure an efficient process. These examples cover the impact of the impact of variation in processes due to flow rate control or sensor based progression on cycle times and how to mitigate this impact and ensure steady state.

Simulated Moving Bed (SMB) Chromatography is a continuous form of chromatography that seeks to enhance the separation efficiency of chromatography while reducing operating expenses such as resin inventory and buffer consumption. There are 2 different types of SMB system available; the carrousel SMB and a valve matrix-based or static SMB. This blog is mostly aimed at valve matrix-based SMBs, but parts of this blog can also be applicable to carrousel SMBs.

Before running an SMB you have to decide how you want to control it: synchronously or asynchronously.

As the name implies, in a synchronous process all columns move through the process at the same pace. A carrousel SMB is a great example of a synchronous SMB as all columns move to a new position after a predetermined switch time.

An asynchronous process gives a lot more opportunity to control the process. It is possible to break down the process into a series of positions, where each position has a detailed set of instructions and conditions. A column can only progress through the process as soon as it has completed these set conditions. This approach places more control and responsibility in the hands of the process engineer and the control strategy.

As with any continuous process, it is important that the process is controlled in such a way that the desired steady state is obtained and maintained. At steady state, the continuous process is performing at the intended efficiency and any deviation from this will impact overall process efficiency and economics. The process control and strategy should, therefore, be able to handle deviations that could disturb the cyclic steady state of an SMB.

For an SMB process, the progression of columns through the various positions within the process is conducive to the steady state of the process. The condition for a column to progress can be based on time but also on different parameters such as pH or conductivity. An example of such a step is an elution step. In the elution zone, it can be economically attractive to stop collecting liquid to the elution stream when the product concentration in the eluent becomes too low and would cause dilution of the product stream. When letting an inline parameter control the progression of columns, time becomes a secondary progression condition and thus variation in switch times could occur. The control strategy should be able to ensure steady state when this occurs.

Control strategy becomes even more important when SMB technology is hybridized with other technologies such as Expanded Bed Adsorption (EBA). As both technologies in a hybridization have their own specific set of requirements, the control strategy will need to be able to handle both technologies. To expand slightly on the EBA technology, this is a chromatography technique where the liquid flows in an upward fashion. This allows particulate matters (e.g. cells, cell debris) to flow through the bed without clogging. As the adsorbent is pushed up by the liquid flow, care needs to be taken that the bed level of the resin is monitored or controlled and that the adsorbent does not wash out of the column. An example of such a system can be seen in this article.


Figure A: the 5 levels of control within an asynchronous switching, optimised SMB setup


Figure B: example chromatographic process describing the various steps potentially

Level 5: individual columns

In processes where a certain set of conditions within a single column are needed to ensure the desired process efficiency, it is important that the control system can react to potentially detrimental effects down on a single column level.

Control of conditions within the column use sensors directly connected to a column to control a parameter within the column. To illustrate this, in an EBA setup a bed level sensor can be used to ensure that the resin bed expands appropriately but does not expand too much and overflow out of the column. The sensor would control the bed level by controlling the involved pump(s).

Level 4: Zone level control

It is possible for an SMB to have multiple columns located in a zone. The column configuration can be both parallel and/or serial. In parallel the liquid stream is divided over the columns in parallel, effectively dividing the flow rate and increasing contact time. When the columns are in a serial configuration, the liquid is fed from the outlet of one column to the next.

When a zone has been configured with a parallel or serial configuration, the control strategy should ensure that the columns in the zone are only receiving fluid when the zone is populated with the required amount of columns. Therefore, it could be possible that two columns are “waiting” for a third in a zone requiring three columns. “Waiting” in this context would be that there is no liquid flow through the columns until the run condition of three columns is fulfilled.

Within a zone containing multiple columns, it should also be possible for a sensor to be able to influence the process. An example of this could be a zone with three columns linked in series. When product dilution in the product stream is undesirable, you would want to stop elution collection once a certain product concentration is reached. This means that a sensor connected to column three controls the outlet valve of column three, effectively controlling on a zone level.

Level 3: Inter-zone control

Little control is required in zones where time is the main controlling parameter. As discussed previously, it is possible for a zone to be controlled by different parameters such as time, pH, conductivity, bed expansion and UV absorption. In zones where other variables are the controlling parameter, time becomes a variable that could potentially affect system steady state if inappropriately controlled.

As the cycle time for the columns needs to be equal, the variation in position timing needs to be compensated. To compensate in a fixed bed SMB, a column can be parked in a waiting position. This means that the valves to the column are closed and that there is no liquid flow through the column. In an EBA-SMB, there is the added complication of having the expanded bed which potentially cannot recover if it collapses after, for example, the feed zone. In this case, the compensation positions are used to keep the bed expanded and are a prelude to the next zone.

Process optimization for both SMB and EBA-SMB systems is done in such a way to minimize the duration of any waiting position. The aim of these waiting positions is purely to ensure a cyclic steady state.

Level 2: SMB level control

The SMB as a singular entity also requires control. For a carousel SMB, this control is simple as only pump speeds and switch times need to be controlled.

As discussed above, a valve-based SMB allows for many more degrees of control enabling potentially higher levels of efficiency but requiring more rigorous process design. Depending on the requirements of control at column, intra-zone and inter-zone conditions, the SMB control can be simple time-based switching or integration of several levels of control.

Level 1: Inter-unit operation control

As the SMB is dependent on upstream and downstream unit operations to receive and discharge liquids, it is important that it is clear how the SMB should react to changes in the process. When upstream unit operations produce faster, the SMB may need to speed up its production speeds. The same holds true that it may be necessary to slow down the SMB production speed if downstream unit operations are disrupted. However, the range of flexibility to speed-up and slow-down the SMB process is defined by the permissible deviations in efficiency, purity and yield requirements.

A comprehensive and holistic approach should be taken when designing an SMB control strategy. Single column experiments can yield significant information on how to control on a single column level and provide enough input for an initial SMB design. For further steps however SMB experiments would be required, to allow for fine tuning on higher levels of control.

Scenarios for inter-unit operation control for an SMB need to be determined from a good process understanding and then be tested to confirm appropriate SMB performance.

Blog by: Dennis Rütze

ACHEMA 2018 - Congratulations to our bike winner!

#ACHEMA 2018 - Congratulations to our bike winner!

Recently, we brought one of our customized VANMOOF bikes to this year’s ACHEMA. As always, the bike attracted a large crowd and we wish to congratulate this years' winner and Wim Vermeire, Director Production DSP at Citrique Belge! We hope that you enjoy it! If you’d like to see where you can win the next XPure bike and learn about SMB and EBA technologies subscribe to our newsletter!

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Designing a chromatography process

#Designing a chromatography process

There are quite a few excellent textbooks that cover the design of separation processes, this also applies to adsorption chromatography processes, the subject of this blog. The majority of these books, however, deal with the design process from a rather academic approach. Most of the time, too little attention is paid to the specific product requirements and market or client specifications to be complied with.

Moreover, most often the design information is not readily available.

The reality is a bit more complicated and the majority of information required for designing an SMB operation has to be derived from column tests, estimated or correlated.


Any design procedure is an iterative process, it starts with some essential considerations

  1. Can the (target) product be purified
  2. Is it feasible and thus easier, to design an adsorption process for removal of impurities
  3. Is fractionation a better alternative when dealing with poor binding properties of either the target molecule or impurities
  4. Is conversion of the target molecule the case, for example dealing with acidification of organic acid conjugates.

Next items to thoroughly think about are feed properties, process capacity, and product requirements.

  1. Plant factor. A continuous adsorption process should be designed as full continuous 24h/day. If the upstream process is a (semi-)batch process, one should base the design capacity on a time-average feed production rate
  2. Maximum feed capacity, it is noted that a continuous adsorption process can be easily be downrated by simply slowing down the cycle time and related feed, wash and buffer consumption rates. So it’s best to design and configure a system based on the maximum (future) expected feed capacity
  3. Feed properties, like density, viscosity, stability, particulates, and temperature. Mass transfer kinetics are influenced by temperature and viscosity, and also by flow velocity in the resin bed. Particulates may disturb the bed stability and flow distribution and should, therefore, be avoided
  4. Last but certainly not least, requirements like product purity, yield and concentration are of tremendous influence on the design. Concentration has a substantial effect on further downstream process costs, e.g. evaporation/crystallisation and drying.
    In general, in case it is required to attain purity levels beyond 98% the costs of processing will exponentially grow


Iterating to an optimal process design, it is important to look at:

  1. Process chemistry, this is the resultant of combining feed and buffer (eluent) properties, with an appropriate resin, having the best adsorption performance
  2. Process parameters are resin adsorption capacity and other resin manufacturer data, flow velocity, pressure drop (in particular the packed resin bed), equilibrium behaviour between the target molecule and the resin particle.
  3. Kinetic parameters, these can be derived from literature or column tests. In the process model calculations, a 2-film model featuring diffusion from bulk to film, respectively from liquid film to stationary phase film has been applied. The model also contains correlations from published experimental data

For 2 and 3 most of the time good and reliable information can be obtained by column tests. Often an industrial scale batch chromatography process already is in place which data could be of tremendous value when it is considered to change to a continuous process.


A conceptual SMB configuration contains a number of zones. A zone is defined as a part of the overall process flow diagram in which the flows through all applicable columns are equal.
The conceptual configuration displays these zones in terms of a block diagram with the interconnections between the zones.
The figure below shows an elementary conceptual design for the most simple bind & elute chromatography system. It contains 4 zones:

  1. Adsorption
  2. Elution
  3. Adsorption wash
  4. Elution rinse

In the conceptual design phase, the following zone may be considered

  • To apply diluted adsorption section (same applies to elution zone). The advantage of adsorption wash recycle is that entrained feed liquor will be recovered and moreover it saves an additional side-stream. It should be noted that the sorption isotherm must show adequate binding capacity in the lower feed concentration regime to make diluted adsorption advantageous.
  • Entrainment rejection (upstream) adjacent to either adsorption or elution zone. This enhances the depleted feed or the elute (often containing the product) effluent concentration
  • Regeneration zone. This may be necessary to bring back the IX resin into the adsorption condition. Or, in other cases, to remove residual impurities after the elution.
  • Equilibration zone. After a regeneration or elution, the equilibration buffer brings the chromatography resin into the right condition to resume adsorption
  • Upflow wash zone in case the feed solution contains particulates. An upflow wash should, therefore, be considered after the adsorption wash step.

An SMB configuration displays how the sequence of process steps is included in the SMB process cycle. The concept doesn’t specify the number of columns (per zone) yet. This is one of the essential parameters that needs to be iterated in the detailed design process further on.

This iterative process concludes with a detailed design featuring:

  • Performance indicators: yield, purity, and recovery
  • Hydraulic indicators like pressure drop and flow velocities in both resin vessels and connecting piping.

To conclude the figure below shows a typical process flow diagram for a bind and elute IX-chromatography system. It features a diluted regeneration zone as well as additional upwash to remove any particulates that may be trapped in the feed adsorption zone.

Blog by: Pieter de Wit




(E.g. proteins from plant extract)

Expanded bed adsorption systems (EBA):

EBA chromatography effectively addresses the critical challenges of packed bed chromatography. It reduces e.g. clarification operations prior to the columns resulting in lower costs and improved yield. Minimal back pressure enables to achieve optimal scale of operation and productivity. The XPure-E system has been designed and built to perform EBA chromatography operation in a smooth and controlled fashion enabling:

  • Process development with enhanced scalability and operability
  • Handling viscous and turbid feed streams which are difficult to process through membranes or packed beds
  • Removal of clarifications steps prior to adsorption
  • 5-15 % increase in product yield
  • 2-4 x increase in productivity
  • 10-20 % reduction in waste
  • In-situ product removal and cell recycling (fermentation based streams)


Intensification of Process Development using a Design Based Turnkey Solution: a case from SMB Chromatography

#Intensification of Process Development using a Design Based Turnkey Solution: a case from SMB Chromatography

Intensification of Process Development using a Design Based Turnkey Solution: a case from SMB Chromatography.

Rapid technology development and an increasing number of technologies entering the market are setting the bar high for their successful application. This is no different for separation technologies. How does a design based turnkey solution help in successful application of novel technologies? A case presented, based on SMB (simulated moving bed) technologies and intensification of SMB process development.


SMB is an industrially proven technology, which can improve the efficiency of adsorption/ chromatography based processes by enabling continuous processing, better resin utilization, reduced buffer requirement, improved yield, purity and productivity with a compact footprint of equipment. However, these benefits do not proportionally indicate the extent to which SMB technologies are currently applied or even being investigated at a process development stage. Major factors leading to this situation include limited availability of:

  1. SMB specific design tools aiding SMB process development for broad range of input streams
  2. Flexible SMB lab equipment that can validate the design outcome
  3. System that can represent an appropriate scale-down model for an existing or to be developed industrial scale operation
  4. System which is easy to set-up, CIP, maintain and modify in short time
  5. Process control which is flexible to process integration and enhances operability

These limitations not only inhibit successful application of SMBs but also reduce the efficiency during process development stage.


It is clear from the problem background that it is essential to provide a turnkey solution that enables investigation of SMB technology under diverse process development scenarios overcoming the current limitations.

Stages of technology investigation and optimization during process development

Technology investigation and optimization as shown above consists of four major stages. Therefore,  proposed turnkey solution needs to be flexible to aid at any of these stages.

The  solution contains 4 parts, which form a package that can aid in SMB technology testing and implementation during process development:

  1. A design-based approach is proven to improve the efficiency of a development process. A regular design tool for process technologies involves input from the user, iteration of design equations and provides an output. Therefore, it is essential to define the appropriate input parameters and fundamentals that allows the tool to provide a representative output taking into account all the process performance attributes. To obtain such a design tool for SMB, we propose a parameter sensitivity based approach. In this approach, the design tool involves a sensitivity analysis prior to the design iteration, where you can identify the critical process parameters for the specific process scenario. Based on the outcome of sensitivity analysis, the design tool provides the flexibility to enable additional input parameters and iterations or eliminate redundant parameters and functions for a specific process scenario. This way, the tool can filter the SMB designs for a broad range of applications and at the same time guide design-based optimization. This can potentially enhance the freedom for process developers from different fields of application to investigate SMB as a potential alternative before deciding on further
  2. The design outcome is used to build an appropriate scale-down model which not only takes into account all the critical process parameters but also provides an operating window for further investigation and optimization.
  3. Stage 3 is highly critical in case of SMB, mainly because an SMB operating window can involve a range of column numbers and operating conditions to be experimentally investigated using a lab scale system for determining the optimum. Therefore, it is important to design and build lab systems, which are flexible to mechanical modifications. The desired mechanical flexibility directly translates into the requirement for automation software that is highly flexible to implement additional changes and features based on process demand.Along with the process concerns, the practical concerns to set-up and maintain the system with minimal effort need to be addressed during system design stage. This can be done by dividing the system design and construction into several layers with corresponding options for customization at each layer and detailed outcomes related to both process and practical concerns. As a result, a system that can be readily deployed to determine the optimal operation and automation strategy can be
  4. When all the above stages are integrated, a scale-up design can be obtained with relatively high accuracy as the above 3 stages give clear indication on critical aspects for large scale implementation


All the four stages discussed, when integrated, can provide a turnkey DSP solution for SMB process development as it will allow you to design, validate and scale-up SMB systems for diverse process scenarios. Thereby enabling successful investigation and application of SMB technologies. This design-based approach, when implemented for other process technologies, can enhance the overall efficiency of process development in terms of time, process detailing and performance, without requiring major additional investments.

Blog by Trinath Pathapati



#Expanded Bed Adsorption and Biological molecules

This blog will present a new development regarding Expanded Bed Adsorption (EBA) technology. A turnkey solution is presented that makes feasibility studies using EBA easy.

Biological molecules  

Biotechnological fermentation processes are widely used in industry to produce an abundant range of biological molecules (small molecules as well as large molecules,   from amino acids to complicated monoclonal antibodies) which often need to be purified in order to meet high-quality standards. Examples of these fermentation feed streams include mammalian cell cultures, yeast and bacterial suspensions. Next to that plants like Tobacco are genetically engineered to produce recombinant proteins. These feed streams have in common that they contain particulates (e.g. cells, cell debris) and are hard to clarify.

In the diagram, the initial phase of the purification of a biological molecule is depicted. Several technologies (or combination of technologies) are commonly used to remove particulate material and isolate the molecule from the biological fermentation broth. For clarification the following technologies are widely used:

  • Centrifugation
  • Depth Filtration
  • Flocculation and depth filtration
  • Precipitation and filtration
  • Cross-flow filtration.

In general, a packed bed chromatography step is applied after clarification of the broth. Different chromatography resins can be used (including cation exchange resins and affinity-type resins) for a typical bind (adsorption) and elute process.

XPURE-E: Expanded Bed Adsorption

This purification process can be significantly improved using the Expanded Bed Adsorption (EBA) technology as can be observed on the right-hand side of the diagram. Whereas traditional column chromatography uses a packed resin bed, EBA uses an expanded bed. Particles such as whole cells or cell debris, which would quickly clog a packed bed column, easily pass through the expanded bed. Therefore, EBA columns can be used directly on crude harvests or slurries of broken cells, thereby bypassing initial clarification steps such as centrifugation and filtration.

Xendo developed the XPURE-E system. A fully automated stand-alone Expanded Bed Adsorption device capable of running these type of purification processes (see picture).

The XPURE-E system operates with a closed-top column and therefore only one pump is needed to operate the EBA column. The system can be equipped with analytics including in- and outlet pressure, pH, conductivity, bed height and UV. 

What is new: Active bed level control

The XPure-E system has been designed and built to perform EBA chromatography operation in a smooth and controlled fashion.

The most important feature of the XPURE-E system is the capability to monitor and control of the expanded bed level (bed expansion). This is important since an EBA process is run preferably at a predefined resin bed expansion. The level detector is integrated in the  top adapter of the EBA column and continuously monitors the resin bed level..

In the figure below is illustrated how the expansion of the resin bed (orange line) is monitored when the flow rate is stepwise increased from approximately 500 up to 850 cm/h (gray horizontal lines). The bed expansion factor is calculated by the software from the expanded bed height and the settled bed height.

As mentioned the XPURE-E is also designed to control the expanded bed level during operation. This is brought about via a feedback loop on the pump. The density and viscosity of different feed streams (incl. buffers) within one process may be different and may lead to changes of the resin bed expansion in case the flow rate remains the same. Therefore, the resin bed expansion needs to be controlled actively and kept constant within (narrow) ranges during the entire EBA process.

Active control of  the expanded level during the process can be established in 2 ways:

  1. Use of a setpoint value for the target bed expansion in combination with expected flow rate. This is especially useful when you are familiar with the process.
  2. If not, you just need to fill in the target bed expansion and the system will increase the flow until the target bed expansion is reached.

In addition, it is also possible to operate the system without active level control. This feature can be used in case all feed streams are well defined and result in a predictable resin bed expansion at target flow rate.

The software platform allows the user to perform experiments in an easy and automated manner.

Easy programming

The XPURE-E is controlled by a comprehensive software package which runs using Windows operating system. Manual and recipe-based operation is possible all via a 10” touchscreen. The recipe is introduced into the system through a recipe editor (see the figure below).  

It allows the user to define the process recipe including:

  • Up to 8 different zones in the process (equilibration, wash, adsorption, wash, etc.)
  • Flow rate, buffer volume and target bed expansion per zone
  • Different inlets and outlets
  • Active bed level control

The software calculates the expected process time per step and for the whole process. The intuitive graphic user interface gives the analyst an insight into the current state of the EBA process through various overviews.  The data generated can easily be processed in spreadsheets such as Excell.


Performing EBA feasibility studies with the XPURE-E makes life easy:

  • It is the preferred technology to perform product capture and recovery step from complex feed streams, without requiring clarification or any intensive preprocessing steps
  • The use of EBA technology will result in increased product yield and productivity and reduced buffer consumption.
  • The XPURE-E system is easy to install and has high flexibility for lab scale operations
  • It is equipped with innovative automation and control with flexibility to evaluate design parameters and perform process optimization

If you’d like to investigate what EBA could mean for your processes don’t hesitate to contact us. 

Blog by: Piet den Boer

A comprehensive outlook on Industrial Biotechnology

#A comprehensive outlook on Industrial Biotechnology

A comprehensive outlook on Industrial Biotechnology and its importance in
Fourth Industrial Revolution (Expoquimia 2017, Barcelona)

The XPure systems team was recently present at Expoquimia 2017, in the beautiful city of Barcelona. We presented our new product XPure-E, which has been specifically designed for expanded bed adsorption (EBA) as part of the EU subsidized horizon 2020 project PRODIAS. This exhibition was organized in collaboration with WCCE (World congress for chemical engineering) and ECAB (European congress for applied biotechnology). At the expo, we had the opportunity to interact with experts in the field of bioprocessing from different industrial sectors, both upstream and downstream processing. In the current blog, we present an overview of discussions on major challenges industrial biotechnology is targeting to address, state of the art developments and implementation status and a conclusion on how XPure systems can aid in addressing the challenges.

Challenge groups vs Industrial sectors

  1. Circular economy is one of the major challenges of the 4th industrial revolution which is involving breakthrough technologies developed from combination of physical, digital and biological advancements, in order to achieve the PPP (people, planet and profit) targets of several industrial sectors. Biorefineries and innovative bio-based solutions are contributing to circular economy both as a separate industrial sector and in synergy with traditional industries.
  2. Healthcare and nutrition demands are continuously increasing with growing population, and changing environmental conditions are further posing new problems to solve. Quality and regulatory requirements add another dimension to technology development and implementation.

State of the art developments and implementation status

  1. The role of large-scale industries is quite crucial to achieve circular economy due to the shear amount of mass and energy flows. At Expoquimia, key note speakers from several multi-national companies discussed their state of the art developments and approaches to fulfil the demands of circular economy with PPP solutions, it includes
    1. Increase the number of novel biomolecules that can replace traditional chemicals
    2. Along with capital, time is critical and therefore it is important to make quick decisions. For example, curves representing profitability vs value of compounds when produced using existing traditional vs biobased processes represent that low value molecules result in decreased profitability using biobased processes, which aids in business decision making. However, research should focus on changing this scenario (XPure systems is a potential technology in such a scenario with its ability to enhance profitability of low value molecules)
    3. Gas fermentation which has been considered a farfetched fruit is now being implemented at a scale of 10,0000-120,000 m3/year, both in Europe and the US in synergy with steel plants, to treat waste streams in the form of syngas and produce ethanol.
    4. Polylactic acid (PLA) and polyhydroxyalkanoates (PHA) from biobased lactic acid and polyhydroxy butyrate are growing to become platform molecules for several polymer industries. This reduces the carbon footprint generated by the traditional petrochemical based polymers like PET and PC etc.
    5. Breakthrough technologies like electricity from photosynthetic energy shines light on brighter future
  2. Healthcare and nutrition challenges are identified to have more dimensions, some of the points include that
    1. Existing process platforms are of major concern compared to capacities and therefore product and process development need to be simultaneous
    2. Bridge between regulatory requirements and technology development is critical throughout the development process
    3. Novel technologies like plant stem cells for cosmetics, nutraceuticals and API are being implemented at production scale. This method not only allows in selective production of target compounds, but also reduces the carbon footprint and water consumption considering that it requires fewer processing steps.


The PRODIAS horizon 2020 EU subsidized project is developing technologies targeted at the above. Xendo is taking part in this project which is aimed at reducing the processing costs of compounds from renewable sources in diluted aqueous systems. PRODIAS  targets on a holistic approach to develop upstream and downstream technologies meeting people, planet and profit demands. Xendo’s XPure systems (XPure-C/E/S) developed as a result can flexibly fit into the cost and regulatory model to achieve circular economy and meet demands of health and nutrition industry due to the following reasons:

  1. Reduced number of process units by implementing technologies like EBA, in Simulated Moving Bed (SMB) mode (planet, profit)
  2. Reduced waste (people, planet)
  3. Reduced demand of resources by 100 % utilization of buffers and resins (profit)
  4. Easy scalability and flexibility to adapt to changing process conditions (people, profit)


In view of the talks by professionals from various fields of Industrial Biotech and diverse organizational roles, it is concluded that the strong demand to balance sustainable products and processes with desired profitability makes it essential to simultaneously develop efficient upstream and downstream technologies. PRODIAS is working on these aspects and Xendo is happy to contribute to this with our XPure Systems.  

Blog by: Trinath Pathapati

Pilot study - Organic Acid

#Pilot study - Organic Acid

Ketogluconic, lactic, citric, succinic and many other organic acids are products that rely on a platform manufacturing technology. This means that most modern manufacturing facilities apply – to a large degree – the same processes. In both cases, the key step in the production process involves a fermentation followed by purification of products using at least one ion exchange step.

Application of a continuous countercurrent ion exchange technology for purification of these products result in significant advantages. In this memorandum, the effect of continuous ion exchange technology on purification of ascorbic acid will be elucidated.

Read more about Organic Acid and SMB.

Pilot study - Lysine

#Pilot study - Lysine

L-Lysine is one of the essential amino acids, which cannot be synthesized in the body. The main application of Lysine is animal feed. The global market for food-grade L-Lysine is estimated at over 800,000 ton (2007 figure). The market price for bulk Lysine has dropped significantly over the past decade(s), forcing suppliers to apply more efficient manufacturing technologies.

Read more about our pilot study with Lysine and SMB.

Learn how SMB reduces downstream processing costs

#Learn how SMB reduces downstream processing costs

Simulated Moving Bed Adsorption significantly reduces downstream processing costs

This paper gives an overview of industrial SMB chromatography and focusses on the strategy how to develop a purification system either in the early development phase of a product or to assess whether a batch process can be optimised and scaled into a continuous process.

Biotechnological fermentation processes are widely used in industry to produce an abundant range of organic products which often need to be purified in order to meet high-quality standards. 
Typical bioprocesses comprise:

  • upstream (USP, e.g. prior to, and including fermentation
  • downstream (DSP following the fermentation-harvesting, e.g. purification and crystallisation)

Industrial Bioprocesses can be characterised by a few common rules of thumb:

  • Typical fermentation broth contains many compounds (product, sugars, proteins and biomass residuals)
  • Downstream processing is necessary for purification and accountable for the highest process costs

Reducing downstream process steps can reduce capital investment and operational costs and reduce the overall energy consumption of an industrial process.

Downstream processing: the basics

Conventional downstream processing involves biomass separation from the soluble fractions of the fermentation broth as a first step (e.g. filtration, centrifugation). Hereafter, other downstream process steps follow, depending on the required product purity and concentration. Decolorization is often necessary to remove the brownish colour of a fermentation broth, caused by degenerated sugar and proteins. Adsorption chromatography is widely used to bind the product of interest or the impurities to a specific resin (sorbens), packed in a column (packed bed). The bound product is then eluted and can be used in further processing like crystallisation. After elution, the resin/column is regenerated and cleaned (CIP-Cleaning In Place).

A typical process flow diagram is shown in the figure below.

Conventional bioprocesses can be summarised by the following steps:

  • Biomass removal (e.g. flocculation, filtration, centrifugation)
  • Decolorization
  • Adsorption Chromatography
  • Concentration and Crystallisation

Simulated Moving Bed Chromatography

In adsorption processes, the adsorbent is held in a (pressure) vessel, most often called a resin vessel. The stationary phase is referred to as a packed resin bed. As the process fluid flows through the vessel, the resin attains an equilibrium with the process fluid, resulting in a mass transfer zone that gradually moves through the bed. If the mass transfer zone has reached the exit of the resin bed, the bed is saturated and “breaks through”. The resin needs to be washed and regenerated before it can be loaded again. As a consequence, continuous processing of the liquid requires at least two fixed beds, but usually, three beds are installed.

In the previous century, the advantages of continuous countercurrent processing have been recognised for adsorption processes, as well as for other mass transfer processes.
In SMB technology, the chromatography material is kept inside columns or vessels. The transport of the chromatography material is obtained by periodically switching in- and outlet positions.
In the 1980’s, the SMB concept was originally developed for binary fractionation processes, where a stronger and weaker binding component are present in the feed solution and are separated into two product streams:

  1. Extract phase, which contains the stronger binding component.
  2. Raffinate phase, which contains the weaker binding component.

A state of the art example of such fractionating system is the production of High Fructose syrup fractions in the sugar industry. Here the Fructose is the monosaccharide with a stronger affinity towards the resin compared to Glucose.

At a somewhat later stage, the same concept has also been developed for bind and elute systems. Bind and elute systems typically comprise –at least- the following zones:

  1. Adsorption of the active ingredient or, in some case, impurities
  2. Adsorption wash, to replace the mother liquor (from fermentation broth) by water. This is to prevent contamination between elution and adsorption zone
  3. Elution, to desorb the active ingredient that has been adsorbed in zone I
  4. Elution rinse, to prevent contamination between product- and feed stream (zone I)

This zone distribution is not restricted to the four as mentioned, for instance, regeneration and cleaning in place have been frequently applied.
Bind and elute SMB systems are designed in carrousel configuration, featuring a central rotating fluid distribution valve, and a static vessel configuration featuring a valve block for each individual resin vessel. Each valve block is identical and comprises a number of valves accommodating all in- and outlet flows that have been defined for the chromatographic cycle.

The below figure represents a typical conceptual flow diagram for a bind and elute system.

Bind and elute IX chromatography systems based on the SMB principle has opened a huge field of applications where valuable products are recovered or purified on a continuous basis thereby saving substantial water consumption as well as elute and regenerant agent.
Xendo has the experience and capability to design and build custom-made SMB continuous Ion Exchange and Chromatography systems under the product name XPure™.

Development studies

In general, a process development study can be approached from different angles and started or initialised in different stages of the study.
When developing a production process first the target objectives should be defined; what is the required yield and purity of the target compound; what is the composition of the starting material (feed); which recovery or purification process is most beneficial in terms of energy (including clean water) and material consumption and gives the least waste production; what is the scale of continuous operation.
If industrial (IX) chromatography could be a (or one of) potential route, we then start surveying the literature on the presence of similar or equivalent applications for the particular compound or molecule under study.
If literature cannot elucidate the case, based on the molecular structural or other adsorption relevant characterisation, a resin screening study can be conducted. The outcome would be one or several resin functionalities that are preferably commercially available.
A lab scale column test on a representative feed sample – a so-called pulse-response test- repeated for a few different resin species will obtain a strong indication of the effectiveness of a specific adsorption system.
Depending on the specific adsorption capacity of the target molecule onto the resin, further column tests – so-called breakthrough tests- will produce data on the resin capacity and information on how to elute (buffer composition, treatment ratio) the target molecule.

In the case, that potential resin candidates can be identified for the purification job the column tests can be elaborated with further break-through or pulse-tests at variable process conditions that cover the window of operation in a full-scale industrial setting. Typically this is conducted on one or two best performing resin candidates from the previous stage.
Here a Design of Experiment approach combined with the rationale of experienced chromatography engineering practice is used to define how many column tests will be conducted and what parameters will be varied at different levels.

Based on the data from the extended tests a preliminary process design and CAPEX/OPEX estimate can be made. Here we have developed our design tool where all relevant parameters can be put in and the outcome shows a full-scale SMB configuration and equipment dimensions. Dimensional data refer to a number of individual resin cells, dimensions of resin cells, line and valve sizing and pressure drop per distinct zone.

The design tool is based on the 2-film mass transfer kinetics model which is the principle for which we have created an algorithm. The design tool further features the (universal) Kremser equation for counter-current contacting.
A set of physical and mass flow-related variables have been accounted for. The most important parameters are:
Resin porosity, particle size (specific area) and evidently the most important -- specific adsorption capacity; diffusivity in both liquid and stationary phase; void fraction of resin bed; bed velocity; fluid viscosity and temperature.

The design tool could also be deployed if the adsorption system is a state of the art process, or close to this. In that case lab scale column tests could be skipped, and the specific feed characteristics need to be combined with the (specific) resin type that could do the purification/recovery job.

The output of the design tool can be used to do preliminary cost and value engineering. The outcome is essential to evaluate the purification/recovery process.
In the case of a positive decision, i.e. a (IX) chromatography process is the most beneficial and cost-effective route, the process can be optimised on a (slightly) larger scale.
Here we can enter two different scales for piloting.A mini pilot or lab-SMB system featuring small resin cells up to 1-inch column diameter and on average 200-500 mm bed height that still can be operated on a lab scale.

1. A mini pilot or lab-SMB system featuring small resin cells up to 1-inch column diameter and on average 200-500 mm bed height that still can be operated on a lab scale.

2. A large pilot SMB system featuring a bit larger resin cells from 1-4 inch column diameter on average 400-1000 mm bed height.

The selection merely depends on the availability of adequate feed and buffer volumes, any uncertainties that may not adequately be identified on an industrial scale, for example, impurities presence and identification, the presence of suspended solids or temperature variations.
The large scale pilot system typically works on site, close to the operating plant or at a pilot facility.

The outcome of a pilot study will be a robust design of the industrial scale process also featuring chemical consumption figures, product yield and purity. From the design data, the basic engineering of auxiliary equipment –like pumps, inter-stage tanks, piping, instrumentation etc.- can commence. Ideally, a commercial design proposal is the final delivery of a pilot study. The client/end user can now make a final assessment of the chromatographic process, possibly comparing this –if any- with alternative purification processes (e.g. batch wise adsorption, crystallisation, evaporation, distillation et cetera)


Simulated Moving Bed has distinct benefits over classical single column systems with significantly higher yields / productivity and lower consumption of chemicals, water, and energy.  Also, it lowers production cost due to the lowered column volume and diminished use of chromatographic separation medium (resin) and, of course, less labour.

This continuous production system is increasingly used on industry scale and also becoming more popular in the pharmaceutical, fine chemicals and food sectors due to its capability to be integrated into production plants, where it contributes by delivering high concentrations of product under the beneficial circumstances mentioned before. Because of these advantages, we see a bright future for this technology for separation, purification and recovery, turning simplistic batch separation operations into profitable continuous processes. Next to these advantages, SMB fits seamlessly into the developing trend of sustainable solutions and the realisation of a bio based economy.

If you’d like to investigate what SMB could mean for your production processes don’t hesitate to contact us or have a look at our currently available systems: XPure-C & XPure-S. We also have a wide variety of pilot studies available for those interested.

XPure General info

#XPure General info

The static SMB system XPure-S that represents the by XPure patented valve system with a zero dead leg concept.
The carrousel SMB system XPure-C featuring a turn table that carries the sorption containers going through the distinct process steps of a typical IXchromatography cycle.

XPure offers SMB technology for product recovery and purification, comprising of

  • Feasibility studies
  • Developed simulation modelling software
  • Full-scale design
  • Start-up, validation, maintenance and (process) service


  • Is not related to any manufacturer of resins
  • Applies originally manufactured components or and fabricates that are consistent with clients material standards
  • Optional elements
  • vessels and liquid distributors
  • (inter)connecting piping and auxiliary equipment

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  • It is the preferred technology to perform a continuous separation, purification and recovery with any feed solution
  • It is a reliable continuous system due to the use of high-quality components and materials
  • Bench-scale carrousel system with a powerful tool to evaluate design parameters and perform process simulation





The XPure-S SMB system offers a system for ion exchange processes with virtually unlimited scalability. The columns are not mounted on a carrousel and the valve manifolds can be designed to allow very large hydraulic throughputs. This makes the system suitable for any scale of operation.

In addition to this, the modular design of the fluid distribution system allows extension in a later stage without significant extra investments, by connecting additional valve manifolds and extra columns (and resin volume). This allows a stage-wise capacity extension of the plant without having to build an entirely new system.