Solving the Scale-Up Challenges of Biorefining

Table of contents

      1. Introduction

      Biorefining is the process of producing a wide range of bio-based products from renewable feedstocks such as agricultural crops, forestry residues, or waste materials. It offers a sustainable and cost-effective alternative to traditional refining processes, which often rely on fossil fuels as feedstocks. Biorefining can be used to produce a variety of bio-based products, including biofuels, chemicals, materials, and food and feed ingredients.

      In recent years, the biorefining industry has experienced significant growth, driven by increasing demand for sustainable and renewable products, as well as advances in biotechnology and process engineering. This trend is expected to continue in the coming years, as biorefining becomes an increasingly attractive option to meet the world's energy, chemical, and material demands.

      2. Scale up challenges in bio-based process development

      Scaling up a biorefinery process can be a complex and challenging process. Factors to consider range from selecting the right equipment and understanding how reaction kinetics will change at larger scales, to studying process robustness and process control. These challenges can affect the efficiency and consistency of the process, and it is important to consider them carefully when designing and operating a biorefinery.

      • Feedstock variability: Biorefinery processes often rely on feedstocks that can vary in quality and composition. This variability can affect the performance of the process and the quality of the products produced. As a process is scaled up, it may be necessary to develop strategies for managing feedstock variability in order to maintain consistent performance and product quality.
      • Equipment selection: A challenge when scaling up a biorefinery process is selecting the appropriate equipment. This involves choosing equipment that is suitable for the specific process and feedstocks being used, as well as ensuring that the equipment is capable of operating at the desired scale.
      • Materials compatibility: As a process is scaled up, it may be necessary to use different materials or equipment than were used at smaller scales. For instance, the choice of alloys and gasket materials can have major impact on cost and performance. Corrosion, contamination, cost, and availability need to be addressed.
      • Mixing challenges: Effective mixing is often critical to the performance of a biorefinery process, as it helps to ensure that the reactants are well-dispersed and that reaction conditions are uniform. However, scaling up a process can often result in changes in mixing characteristics, which can impact the performance of the process. It may be necessary to evaluate and optimise mixing on a larger scale to ensure that the process is efficient and effective.
      • Reaction kinetics: Another challenge is understanding how the reaction rates in the process will change as the process is scaled up. This can be influenced by factors such as temperature, pH, and the concentration of reactants, and it is important to understand how these factors will affect the overall efficiency of the process.
      • Volume/surface ratios: When a biorefinery process is scaled up, the volume-to-surface ratio of the equipment may change, which can affect heat and mass transfer in the process. It is important to consider how these changes will affect the efficiency and consistency of the process.
      • Process robustness: Ensuring that a biorefinery process is robust and can operate consistently over time can be a challenge when scaling up the process. This may involve optimising process conditions and understanding how feedstock variation affects the process.
      • Process control: As a biorefinery process is scaled up, it may become more complex and difficult to control. This can be due to the larger scale of the equipment and the increased number of variables that need to be monitored and controlled. A control strategy will typically include both in-line process control as well as off-line analysis of process samples.
      • Process optimisation: As part of a process scale up, it is normally of interest to optimise process parameters. The response surface method (RSM) is a statistical technique that can be used to identify the optimal combination of process variables that result in the desired response (e.g., maximum yield or minimum energy consumption).
      • Safety: Ensuring that a process is safe for workers and the environment is critical, and this can be particularly challenging when scaling up a process. It may be necessary to implement new safety measures or modify existing ones in order to ensure that the process is safe on a larger scale.
      • Environmental impact: It is important to carefully assess the environmental impact of a process as it is scaled up, including all effluents to air and water. The use of process water may need to be reduced. It may also be required to optimise the energy use in order to improve the sustainability.

      Besides the technical challenges the production of samples is an important step in the process of scaling up a biorefinery because it allows the manufacturer to test the product and assess its market potential. Samples are needed to evaluate the product's performance and quality. This can help determine whether the product is ready for commercial production and whether there is sufficient demand for the product in the market.

      One of three 4000 L continuously stirred tank reactors (CSTR) in Biorefinery Demo

      3. Demo plants available for hire

      Pilot and demo scale biorefinery plants are small-scale facilities used to demonstrate the viability of a biorefinery process. These plants can be an important resource for companies that are developing new biorefinery processes, as they provide a platform for testing and optimising the process, as well as for generating data and information that can be used to assess the market potential of the bio-based products produced. A number of pilot and demo scale facilities are available for hire, providing access to equipment that otherwise could be too costly and/or time consuming to invest in.

      The largest commercial demo plant in Europe is the Bio Base Europe Pilot Plant located in Belgium. More than 140 employees are ready to help projects, consortiums and companies with their scale up challenges by offering access to a broad range of modular unit operations.

      Another example is SEKAB’s biorefinery demo plant in Örnsköldsvik, Sweden. The former ethanol pilot plant was used for the development of SEKAB’s E-technology and CelluApp, and is now available for hire.

      A comprehensive list of pilot and demo plants in available for hire can be found in the Pilots4U database compiled with support from the Bio Based Industries Joint Undertaking funded by the European Union’s 'Horizon 2020 Research and Innovation Programme'. So far, the database contains more than 450 pilot and demo plants across Europe.

      Borregaard now also offers access to our Biorefinery Demo – a state of the art demonstration facility. The Biorefinery Demo plant is well suited for process development, scale-up of biorefinery processes and manufacturing of product prototypes. Located at the Borregaard production site in Sarpsborg, Norway, it boasts a wide range of process units enabling scale-up of bio-based processes from lab scale to pilot/demo scale and further up to industrial scale. The Biorefinery Demo is described in more detail below.

      4. Introduction to Borregaard's Biorefinery Demo

      Over several decades, Borregaard has transitioned from being a traditional pulp and paper company to becoming a fully integrated biorefinery. The current product portfolio includes a wide range of bio-based performance chemicals and materials such as lignin biopolymers, speciality cellulose, cellulose fibrils, biovanillin and bioethanol.

      Inspired by this, Borregaard directed substantial resources towards development of a new biorefinery process initiated in 2007. The process was named BALI™ - short for Borregaard Advanced Lignin. The BALI™ biorefinery concept can utilise all lignocellulosic feedstocks for production of cellulosic sugars and value-added sulfonated lignin performance chemicals (also known as lignosulfonates or lignosulfonic acids). One advantage of this technology is that value is created on the lignin as well as the cellulose and hemicellulose of the feedstock. The cellulosic sugars coming out of the process are characterised by being very highly fermentable and have been branded under the name Excello.

      Construction of the Biorefinery Demo plant commenced in 2012 with generous support from Innovation Norway. The plant was inaugurated in 2013 and work on scale up of the BALI™ process continued until 2018. The BALI™ technology reached technology readiness level (TRL) 7. The BALI™ technology incorporates several unit operations that we already operate at commercial scale (i.e., TRL 9), such as sulfite cooking and handling of unbleached cellulose.

      Meanwhile the Biorefinery Demo plant has been used for other projects, both internally in Borregaard and for external customers and partners. The demo plant together with a skilled and creative staff is now available for hire on a weekly basis (Monday-Friday). The plant is well equipped for conversion of biomass and bio-based raw materials into biochemicals, biofuels, biomaterials and other bioproducts. The plant is flexible and versatile and be configured for a variety of different process schemes.

      Examples of available equipment:

      • Multipurpose stirred tank reactors 3 x 4000 L
      • Bioreactors: 30 L, 300 L and 3000 L
      • Separation equipment: decanter centrifuge, disc stack separators, various filters, screw presses, membrane filtration units, ion-exchange columns
      • Evaporators and spray dryers
      • Total storage tank capacity of about 150 m3

      Multipurpose stirred tank reactors

      These are three versatile reactors with a working volume of 2-4 m3 that are useful for many types of operations. They can operate as batch reactors as well as continuous stirred tank reactors (CSTRs), alone or in series. They are double jacketed to allow precise temperature regulation and equipped with sensors and addition lines for continuous pH regulation. Circulation loops allow for additional functions such as high shear mixing.

      There are several systems for dosing chemicals, substrates can be added as dewatered biomass by screw press, and other reactants can be added in liquid form. The agitator impellers are designed for combined mixing requirements such as suspension, homogenisation, and heat transfer at both high and low viscosity. These reactors have mainly been used to produce sugars from lignocellulosic biomass by enzymatic hydrolysis, but also in a wide range of other applications.


      The fermentation facility has 3 multipurpose bioreactors, all approved for GMO fermentations, sizes 30 L, 300 L and 3000 L (working volumes 20 L, 200 L and 2000 L). The bioreactors provide control over pH, temperature, oxygen, foam, pressure, and level. The vessels are equipped for gassing with air or nitrogen. The bioreactors can run in batch, fed batch and continuous mode. Each reactor has separate feed lines, which provides flexibility. The vessels are connected to Clean-in-Place (CIP) and Sterilise-in-Place (SIP) systems for automated cleaning and disinfection. A seed train from agar plates to 2 litre scale in the laboratory is part of the service.

      Separation of solids and liquids 

      In a biorefinery it is often necessary to separate solids from liquids. Two common technologies are centrifugal separation and filtration. Decanters and disc stack separators (also referred to as centrifuges) are both centrifugal separators. In many processes, both decanters, discs stack separators and filters are used, at different stages of the process to achieve the required result.

      The decanter centrifuge continuously separates solid materials from liquids in the slurry, and therefore plays an important role in the biorefinery. Decanter centrifuges are suitable for processing slurries or liquids with high concentrations of solids, resulting in extracted/clarified products.

      The disc stack separator also uses centrifugal force to separate solid materials from liquids. Compared to the decanter centrifuge, the disc stack separator operates at higher g-forces and handles slurries with lower solids concentrations and relatively small particle sizes. A disc stack separator can also be configured for liquid-liquid separation of two immiscible liquids of different densities.

      Membrane filters typically handle low solids concentrations and capture the smallest particles. Membrane filters usually remove particles of up to 1 micron is size, in liquids where the solids content is less than 5%. The Biorefinery Demo has a rod filter, a bag filter, and a disc filter, with different capacities and pore sizes.

      In addition, Biorefinery Demo has 4 screw presses for dewatering slurries with large solid particles. The screw press separates liquids from solids by pressing the material with a conical screw shaft against a cylindrical screen. Screw presses are often used for materials that are difficult to press, such as those that tend to pack together.

      Membrane filtration

      The Biorefinery Demo plant has two membrane filtration systems that may be used to process a wide variety of aqueous solutions using microfiltration (MF), ultrafiltration (UF) and nanofiltration (NF). Both systems utilise tubular crossflow membranes with a wide range of membranes available to suit the required application. There is a pilot unit for membrane testing and smaller scale filtrations, with a membrane area of ~1 m2. The other is a larger filtration plant with membrane areas of up to 132 m2. The systems allow for monitoring of pH, temperature, and conductivity, as well as both retentate and permeate flow.

      Ion exchange resins

      A manual ion exchange rig with two 40 L columns is available for testing of various ion exchange resins. Salts can be removed from a solution by first passing it through a cation-exchange resin to remove ions of alkali metals and alkaline earth metals. The acidic solution is then passed through an anion exchange resin to remove ions such as chloride or sulphate.


      In a biorefinery, aqueous solutions can sometime be quite dilute. To concentrate these solutions, there are two options for removing water in Biorefinery Demo. There is one vacuum evaporator operating at 60-100°C and 80-950 mBar with a water removal capacity of up to 400 kg/h. The second option is a flash evaporator typically operated at 60-100°C and 40-950 mBar with a water removal capacity of up to 100 kg/h.

      Storage tanks

      There is a total tank storage capacity of 150 m3 in Biorefinery Demo, distributed over a multitude of tanks:

      • 2 x 50 m3 pulp tanks with MC pumps
      • 2 x 10 m3 storage tanks
      • 2 x 8 m3 storage tanks
      • 3 x 6 m3 storage tanks

      The storage tanks are insulated and fitted with agitators, circulation pumps, temperature sensors, jacket heating/cooling and level sensors.

      Flexible configuration

      Initially, when an innovative process is taken from the laboratory to industrial scale, a number of scalable unit operations are selected for testing. The Biorefinery Demo is designed to be a flexible multi-purpose facility. The equipment and unit operations listed above can be easily configured in various sequences using flexible hoses. The selected unit operations are tested, and the settings are optimised. Then the first prototype batches of the innovative product are produced to test the quality and applications and enter the market before taking the financial risk of building a commercial-scale production line.


      Biorefinery Demo services include process follow-up and preparation of samples for example by centrifugation and filtration. Samples can be prepared for storage and later analysis, for example the quantification of sugars, organic acids, or other intermediates or compounds of interest. Analytical capabilities in the Biorefinery Demo laboratory cover measurements of dry matter, pH, density, conductivity, refractive index, and optical density. The generated data can be used directly for feedback process control.

      Operating staff

      Equipment is useless without trained staff and we have an excellent team that ensures a quick and efficient scale-up. The team consists of 1 plant manager, 1 assistant plant manager and 3 operators who are all creative problem solvers with extensive technological know-how. The team has many years of experience and in-depth knowledge of the operation of many different types of process units. All operations are executed by members of the Biorefinery Demo team, to ensure solid documentation of trials. Samples are taken for process control as well as for advanced external analysis as required.

      5. What outputs can be expected?

      In a demo run the scale is often too small to be of commercial relevance (with an exception being high value products for embryonic markets). Thus, the real value lies in the various outputs generated:

      • Report: Reports summarising the test results and providing recommendations for next steps are of great value. These reports can be used to inform decision-making and guide the development of the biorefinery process.
      • Process description: Prior to an experimental run we will work closely together with tenants to create a highly detailed process description where each individual step is described. This document is then used by the Biorefinery Demo operators, but also serves as a documentation of the process for later use and scale up.
      • Process data: This may include information about the process conditions (e.g. temperature, pressure, flow rate), process variables (e.g. feedstock composition, catalyst type), and process performance (e.g. yield, efficiency). Process data may be provided as an appendix in a report or in digital format.
      • Product samples: Samples in kilogram or even tonne scale will normally be produced. These samples can be used to evaluate the product's quality, performance, and market potential.
      • Process models: Depending on the specific biorefinery process being tested, it may be possible to generate process models that predict the performance of the process under different conditions. These models can be used to optimise the process and design a full-scale biorefinery.
      • Intellectual property: The test run may generate new ideas or innovations that could be protected as intellectual property (e.g. patents, trademarks). As a rule of thumb, the company paying for the demo run owns the results.
      • Data for sustainability assessment: The test run may generate samples and data that can be used to assess the sustainability of the biorefinery process, including environmental impacts, resource efficiency, and social impact.

      6. Rental of Biorefinery Demo

      With the Biorefinery Demo plant, Borregaard offers access to a state-of-the-art pilot facility handled by a skilled staff that is ready to help you develop and upscale your innovation. Rental of Borregaard's Biorefinery Demo requires a rental agreement including a non-disclosure agreement and a minimum rental period of one week (= 5 working days from Monday 07:00 to Friday 15:00 with operation day and night). The rental includes staff and utilities such as water, steam, and power.

      The tenants are responsible for raw materials, chemicals, experimental protocols, test procedures, handling of products and analysing results. To maximise the learning and to ensure efficient use of the time available we recommend that tenants are present during experiments. This allows first hand observations of the scale up and the materials produced.

      Biorefinery Demo is located on Borregaard's industrial site in Sarpsborg, Norway.

      7. Reference customers

      Alginor is a Norwegian marine biotech company developing a transparent, traceable, and integrated value chain for commercial harvesting and biorefining of Laminaria hyperborea for production of ingredients for pharmaceutical and nutraceutical applications. Since 2020 Alginor has conducted several 2-4 week campaigns. The purpose of the runs has been process development, testing of equipment, and prototype production.

      Previwo is a Norwegian based biotechnology company with biological health products for aquaculture. By exposing fish to probiotic bacteria in the water, they get assistance to create a microflora of beneficial bacteria. This way of fortifying the microbiome makes for a more robust fish, reduces the risk of various microbial infections, including lice and generally promotes better health and growth. Since 2020 Previwo has conducted several campaigns for development and production of the probiotic bacteria in our state-of-the art fermentation facility which is part of Biorefinery Demo.

      Foods of Norway is a Centre for Research-based Innovation that links academia and industry at the Norwegian University of Life Sciences. It develops novel feed ingredients from forestry, agriculture, and animal and marine by-products through research on bioprocessing and technology. The goal is to improve feed efficiency of farm animals and farmed fish, to produce more fish and meat with less feed. Biorefinery Demo has been used for production of lignocellulosic sugars on a multi tonne scale that subsequently have been fermented to single cell protein (SCP) used in the project.

      8. Reference projects

      Below is a selection of projects with external financing where a significant part of the experimental work in Borregaard’s part of the project was done in Biorefinery Demo.

      9. Scientific publications of results from Biorefinery Demo

      Most of the experimental results from Biorefinery Demo are documented in internal reports and thus remain trade secrets. Some results, especially when done in collaboration with external academic partners, are published in peer reviewed journals.

      • Costa, T. H. F., Kadic, A.Chylenski, P., Várnai A.Bengtsson, B., Lidén, G., Eijsink, V. G. H.Horn, S. J. "Demonstration‐scale enzymatic saccharification of sulfite‐pulped spruce with addition of hydrogen peroxide for LPMO activation." Biofuels, Bioproducts and Biorefining 4 (2020), 734-745. DOI: 10.1002/bbb.2103
      • Sahlmann C., Djordjevic, B., Lagos, L., Mydland, L. T., Morales-Lange, B., Hansen, J. Ø., Ånestad, R., Mercado, L., Bjelanovic, M., Press, C. M., Øverland, M. "Yeast as a protein source during smoltification of Atlantic salmon (Salmo salar L.), enhances performance and modulates health." Aquaculture 513 (2019), 734396. DOI: 1016/j.aquaculture.2019.734396
      • Sharma, S., Hansen, L. D., Hansen, J. Ø., Mydland, L. T., Horn, S. J., Øverland, M., Eijsink, V. G. H., Vuoristo, K. S. "Microbial protein produced from brown seaweed and spruce wood as a feed ingredient." Journal of agricultural and food chemistry 31 (2018), 8328-8335. DOI: 10.1021/acs.jafc.8b01835
      • Rødsrud, G., Lersch, M., Sjöde, A. "History and future of world's most advanced biorefinery in operation." Biomass and bioenergy 46 (2012), 46-59. DOI: 1016/j.biombioe.2012.03.028

      10. Further reading

      Below is a list of books that may be useful when scaling up a biorefinery process:

      • Jamal Chaouki and Rahmat Sotudeh-Gharebagh, “Scale-up Processes: Iterative Methods for the Chemical, Mineral and Biological Industries”, 1st ed. 2021, De Gruyter.
      • Jan Harmsen, “Industrial Process Scale-up – A practical Innovation Guide from Idea to Commercial Implementation”, 2nd ed. 2019, Elsevier.
      • Joe M. Bonem, “Chemical Projects Scale Up: How to go from Laboratory to Commercial”, 1st ed. 2018, Elsevier Science.
      • Stephen Hall, “Rules of Thumb for Chemical Engineers”, 6th ed. 2017, Elsevier.
      • Jack Hipple, “Chemical Engineering for Non-Chemical Engineers”, 1st ed. 2017, Wiley-AIChE.
      • Jonathan Worstell, “Scaling Chemical Processes: Practical Guides in Chemical Engineering”, 1st ed. 2016, Butterworth-Heinemann.
      • Marko Zlokarnik, “Scale-up in Chemical Engineering”, 2nd ed. 2006, Wiley-VCH.
      • Attilio Bisio and Robert L. Kabel, “Scaleup of Chemical Processes: Conversion from Laboratory Scale Tests to Successful Commercial Size Design”, 1st ed. 1985, Wiley-Interscience.