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Investigating Freeze Crystallization as Promising Next-generation Water Purification Technology for the Brewing Industry
L. Erlbeck, D. Wssner, T. Kunz, M. Rdle and F.-J. Methner

Water purification is important in the brewing industry, even more so when the possibility of water scarcity in the immediate future is considered. The current water purification technologies have the disadvantage that they require many chemicals and are not easily paired with renewable energies. Freeze crystallization can potentially be an alternative for which no chemicals are necessary. A multi-step process, consisting of a commercial scraped surface crystallizer, in combination with a self-made pressing mold, were used to investigate the possibility of purifying water with this technology. Results show that it is feasible to reduce the residual alkalinity significantly. A pressing force of 7.7 kN (20.6 bar), and a holding time of 300 s, were found to be sufficient. A seawater desalination-based design was then used to investigate water purification using a single-step process, which consisted of a screw conveyor as scratcher, and a perforated, tapering cone for ice pressing. The results showed good removal efficiencies for manganese, total organic carbon, residual alkalinity, and nitrate depending on the rotational speed and coolant temperature. Heat flows, heat transition coefficients, and ice crystal areas underpinned assumptions. Finally, one correlation was found to best reflect experimental and calculated results.

Descriptors: brewing water, freeze crystallization and ice pressing, water purification, water treatment

BrewingScience, 71 (July/August 2018), pp. 56-67