A continuous freeze crystallization process for separating organics from water

Researchers from Wageningen University and Research, Wetsus – European centre of excellence for sustainable water technology, and Cool Separations BV have just published a new technique for separating lactose from whey permeate by partly freezing it in Food Research International magazine. This highly efficient method can recover a continuous stream of organic material from a liquid solution. And it does so at a fraction of the energy cost, preserving flavours, and with little chance of biological activity and fouling, scaling, and corrosion issues.

With this publication, the scientists have proven the workings of the pilot-scale application of eutectic freeze crystallization (EFC) for separating organics from a watery solution. With this method a solution is simultaneously converted in crystals and ice. Lactose is industrially recovered by first concentrating it by evaporation and then slowly cooling this solution to produce the crystals. This is a very energy intense process; a state-of-the-art evaporator costs 30 to 80% more energy to run than than EFC. And EFC can continuously produce 60 kilograms of highly pure ice and 16 kg of lactose per hour. Building from this conceptual design, yields of at least 80% and up to 95% of the input lactose can be achieved.

Though previously EFC was mainly used on brines, this study makes a strong point for its use in the food and agricultural industry for compounds such as sugars. Because it works by freezing water while crystallizing the desired compounds, it is ideal for food application – heat-sensitive compounds are unaffected and preserve taste and quality. Another big plus: biological activity is low, and fouling, scaling, and corrosion issues will be less prominent at temperatures below zero.

The mechanic is the result of an exemplary PhD study. “It is a great case of how close collaboration can lead to actual innovation,” says Wetsus’ theme coordinator Dr. Henk Miedema. The main author and PhD candidate Ruben Halfwerk showed that there is certainly potential for EFC in the food industry. In four years’ time Wetsus developed the EFC process for lactose from lab to pilot scale. The next step would be to further develop and optimize the process and to look into other streams in the agro- and food industry. 

For more information:
please contact Wetsus’ science communication specialist Rouèl Gnodde;; +058 284 3158 /+31 6 51 879 000

Read more:

Halfwerk, R., L. Verdonk, D. Yntema, J. van Spronsen, A. van der Padt. 2023. “Scaling up Continuous Eutectic Freeze Crystallization of Lactose from Whey Permeate: A Pilot Plant Study at Sub-Zero Temperatures.” Food Research International (Ottawa, Ont.) 168 (112764): 112764.

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