CCD series no-21: illustration of high recovery (93.8%) of a silica containing (57 ppm) source by a powerful technology of volume reduction prospects

Abstract

The Fabbri farm well-water source (TDS: 1,304 ppm; SiO₂: 57 ppm) in the California Central Valley was desalinated with up to 93.8% recovery under extreme silica supersaturation (930 ppm) conditions using a closed-circuit desalination (CCD) pilot with a single module (8″) of three elements at pH 5.5 in the presence of an antiscalant (FLOCON-260). Experimental trials of the Fabbri source at 17.2 and at 19.6 lmh 7.2 are described in this study with complete online data provided for an extended 8-h trial at 17.2 lmh of 92.8% recovery with consecutive sequential pressure variation of 6–14 bar and electric conductivity (EC) of average permeates (230 μS/cm) and of brine (23,450 μS/cm) cited in parentheses and specific energy consumption of 0.918 kWh/m³ with high-pressure pump efficiency of 55%. Analysis of the consecutive sequential online data during the extended and all other trials revealed unchanged module pressure difference and minor variations of maximum and minimum applied pressures, EC of permeates and recycled concentrates, and a sequential period which ruled out any scaling and/or fouling effects. The findings of this study clearly suggest the viability of the CCD as a powerful technology of considerable prospects for volume reduction applications on route to zero liquid discharge.

Keywords:

• RO
• Closed-circuit desalination (CCD)
• High recovery
• Low energy
• Silica removal
• Silica supersaturation
• Volume reduction

Acknowledgments

Funds to Desalitech Ltd. by Aquagro Fund L.P. (Israel) and by Liberation Capital LLC (USA) and Spring Creek Investments (USA) are gratefully acknowledged.