The industry is grappling with a mounting array of energy-related challenges – ranging from escalating costs and volatile energy markets to the emergence of novel feedstocks for the protein transition and sustainability ambitions. In particular, water removal from raw material streams is highly energy-intensive, accounting for approximately 15% of Dutch industrial energy consumption. To explore opportunities for reducing this energy demand, the MilDeWat consortium investigated emerging dewatering, drying and assisting technologies. The results have given rise to further investigation of assisting technologies and research into the mechanisms behind reducing viscosity and achieving higher solids in the feed towards the spray dryer. They also provide a basis for follow-up.
In short
- Emerging dewatering methods and novel drying techniques are promising for
reducing energy with 50-80% through higher solids content prior to spray drying. - The MilDeWat consortium dived into alternative drying and assisting technologies to facilitate this shift.
- Promising research results give rise to further investigate the fundamental mechanisms
behind viscosity control before spray drying.
Pushing towards higher solids content prior to spray drying
Innovative dewatering technologies are under development, but their benefits for industry are not yet fully understood, particularly with respect to energy efficiency, sustainability, and product functionality. These benefits were now investigated by industry partners Royal Cosun, Danone and Pentair. In collaboration with ISPT, NIZO food research and TU Delft investigated the potential avenues for future integration of identified pivotal technologies, including the realm of air-free drying and assisting technologies.
The upcoming challenge lies in reducing viscosity of streams in combination with higher solids content prior to spray drying, and investigating innovative technologies and their tangible benefits to facilitate this shift. Additionally, emerging dewatering methods such as emerging membrane systems in combination with assisting technologies on reducing viscosity towards higher dry solids to a spray dryer were investigated.
The project included novel drying techniques like air-free drying and their impact on energy and CO2 reduction, while maintaining the product’s quality. Further development of emerging assisting and air-free drying technologies was taken into account with new process designs before finding practical applications.
Especially in sectors such as the food industry, the urgency surrounding energy conservation is compelling enough to warrant comprehensive evaluations, considering energy reduction potential, resilience, and product implications.
More pragmatic understanding, techno-economic analyses for a better understanding of applicability of breakthrough mild dewatering technologies was provided by the research activities in the MilDeWat project.
Results
The evaluation has resulted in process designs of new or revisited technologies within factories of the industrial partners. The new insights and designs will contribute to industry’s energy reduction goals in 2030.
The MilDeWat focused on two strategies to reduce energy consumption in dewatering and drying technologies: alternative drying technologies and assisting technologies.
Project poster
During the Drying and Dewatering program day on April 21 2026, MilDeWat presented its current status and results with this poster.
Alternative drying technologies
For alternative drying technologies practical trials were planned for the following technologies: vacuum microwave drying, pulse combustion drying, vacuum drum drying, and agitated thin film drying. During the trials, relevant products were evaluated for their dry-ability and final product quality.
With vacuum microwave a viscous sheet of material can be dried to a solid crust. Reconstitution of the mild crust into powder was possible; however, microwave drying offered very different results varying from stabile to uncontrolled and disruptive in the used set-up depending on the samples (dairy, fava bean) during the testing period and a concern is product control. However, the results were promising enough to dive deeper in the possible application of this technology in the near future to improve product control for both dairy and fava beans.
The pulse drying set-up can atomize high-viscosity feed into fine droplets at the tested scales of the samples as provided by industry. Testing was however challenging due to the set-up arrangement regarding feeding high viscous material to the nozzle and the overall dryer design. Produced powders were not promising with respect to properties like solubility and reconstitution. Scalability will have to be further investigated, as is the pulse atomization.
Test runs with fava bean concentrate on the agitated thin film dryer with a compact design continuous conductive drying and low energy consumption resulted in the targeted moisture content not fully reached, although it came close. The trial settings for powder consisting of small flakes and some larger lumps with visibly higher moisture content were not optimal for the targeted moisture content of the tested product during the testing period.
Drum drying showed promising results, both under vacuum and atmospheric pressure. However, it’s important to emphasize that the true value of these drying methods will ultimately depend on the specific functionalities and characteristics of the dried end product.
In conclusion, exploring the air free drying techniques: the agitated thin film drying and vacuum drum drying, has provided valuable insights into the drying process of fava bean protein isolate. These results show that the fava bean protein isolate can be dried effectively using both technologies. Of course, analyses of protein functionality and characteristics will provide more insight into the effect of these drying techniques. Rapid evaporation and mild dewatering can have a positive result on the protein functionalities.
Assisting technologies
Assisting processing strategies that can temporarily lower viscosity present a compelling opportunity for energy savings across multiple processing stages, including dewatering, concentration, membrane filtration, and drying. By reducing viscosity, process streams can be concentrated to a higher solids content, for example by membrane filtration rather than by more energy-intensive thermal evaporation. Similarly, reducing viscosity allows evaporation to higher solids content, which can replace more energy-intensive drying, further enhancing overall process energy efficiency.
Mechanical viscosity reducing methods – such as ultrasound, cavitation and homogenization – were studied as promising strategies. A 2-fold to 20-fold reduction in viscosity may be facilitating operation of subsequent separation and drying processes at high solids content, thereby saving energy.
Both homogenization and ultrasound showed significant viscosity decrease for different protein rich products. Though there was a decaying effect for increasing shear rates, the extrapolation to high shear processes like high concentration membrane filtration and nozzle atomization could not be evaluated in a lab setting. Consequently, more practical tests would be necessary to quantify these effects where viscosity reduction is most relevant. A first evaluation of pilot membrane filtration showed that the viscosity reducing effect of these technologies could significantly impact operational efficiency. Besides the tested technologies, the implementation of nanobubbles may provide viscosity reducing effects through a different mechanism and seems promising based on the literature available.
Overall, there are still open questions with regards to the underlying principle of mechanical viscosity reduction techniques and their effect on high shear regimes. In addition, other technologies (like nanobubbles) warrant a more thorough investigation
Conclusion
A scientific evaluation of emerging and assisting dewatering technologies, experiments for proof-of-concept and technical validation on lab-scale will have to be further extended in the follow-up project DRY4LESS on reducing energy in separation, concentration and drying operations through viscosity reduction. For this purpose, the follow-up project Reducing Energy in Separation, Concentration, and Drying Operations through Viscosity Control (DRY4LESS) has been written and aiming at a start in 2027.
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Let’s get in touch
Anne van der Zwaan
Peter de Jong
Acknowledgement & partners
This project is co-funded by TKI-Energy with the supplementary grant 'TKI- Toeslag' for Topconsortia for Knowledge and Innovation (TKI’s) of the Ministry of Economic Affairs and Climate Policy.
