Freeze desalination by the integration of falling film and block freeze-concentration techniques

Abstract

Block and falling film freeze concentration are two technologies that separate water by freezing, with the potential to desalinate seawater. In this study, the integration of two freeze concentration techniques as an alternative to obtain potable water was analysed. Water with 0.5%-8% NaCl was freeze-concentrated by the falling film technique. The ice from each stage was fractionally thawed to recover the solids retained in the ice. The diluted fractions of the thawing stage were freeze-concentrated using the block technique to increase water purity. Falling film freeze concentration was effective to separate the salt from the solution, even at high salt concentrations. Block freeze concentration was effective to increase the water purity until drinkable water was obtained. A multistage process with the integration of these techniques was proposed to obtain 74% of the amount of the initial solution at 0.05% of salt, and 26% at 13.4% of salt. With this process, a salt removal efficiency of 98.5% was achieved. The energy consumption was analysed. The integration of these techniques results in water that meets the requirements for drinkable water and demonstrates the technical feasibility of the process.

Effect of Freezing Time and Shaking Speed on the Performance of Progressive Freeze Concentration via Vertical Finned Crystallizer

“…As the freezing process started, the degree of crystallinity of the formed ice layer is still low with the presence of dendrites structure. By providing longer circulation time, the ice layer grows thicker, leaving the unfrozen solution in a state approaching the saturation level [28][29][30][31]. Figure 4 shows the trends of effective partition constant (K) and solute recovery (Y) at different circulation time.…”

Influence of Cryoconcentration on Quality Attributes of Apple Juice (Malus Domestica cv. Red Fuji)

“…Actually, three CC procedures are available at industrial, semi-industrial and laboratory level: (i) suspension (SCC) [7], (ii) progressive (PCC) [8,9], and (iii) block cryoconcentration (BCC) [10]. In BCC, a liquid solution is completely freezing; then the block is thawed and, finally, the cryoconcentrate is separated from the ice fraction.…”

Effects of Centrifugal Block Freeze Crystallization on Quality Properties in Pineapple Juice

“…Different FC procedures are available today: (i) suspension , (ii) progressive , (iii) falling‐film , and (iv) block FC (BFC) . In BFC, a liquid solution is completely freezing; then the block is thawed and separated by natural gravitational methods or by adding assisted techniques to improve some process parameters .…”