Brine Treatment by a Membrane Distillation-crystallization (MDC) Process

Advances in Membrane Distillation for Water Desalination and Purification Applications

“…Recently, the crystallisation of near saturated NaCl solution was explored, finding that at a certain concentration of the feed, sudden flux decline occurred. This was due to crystal formation at the membrane surface which in turn had detrimental effects to the membrane as salts can penetrate into the pores compromising salt rejection [152]. Further applications for MD crystallisers have also been explored in other industries, for example in drug development [153].…”

Water recovery from brines and salt‐saturated solutions: operability and thermodynamic efficiency considerations for desalination technologies

“…Several recent publications and reports have focused on brine concentrate management in terms of additional water recovery with some including salt recovery and/or ZLD, including general reviews/overviews of brine treatment technologies, reviews of ZLD options, an analysis of ED for salt recovery, and MD paired with a crystallization process (termed ‘membrane distillation crystallizer’ or ‘MDC’) . In one, a 2006 report prepared for the US Department of the Interior Bureau of Reclamation (BoR), Mickley and Associates identified the six most frequently practiced disposal methods for RO brine concentrate streams .…”

“…As a thermal process, the ME‐MVC system cannot operate effectively at low temperatures, so it cannot meet the fifth desirable technology characteristic of small temperature changes, although it will be better than evaporative processes operating at temperatures over 100 °C. Whether ME‐MVC meets the sixth characteristic, recovery of salable salts, remains to be demonstrated although previous work on salt recovery from brines suggests it is possible . As a result, an ME‐MVC system possesses many of the desired characteristics for a brine concentrate treatment technology, although several aspects require further development and demonstration.…”

Membrane Distillation Crystallization Applied to Brine Desalination: Additional Design Criteria

“…The above-described behavior for the concentration at the retentate–membrane interface can be attributed to the almost invariable solubility with respect to temperature (“flat” solubility curve) and to the very narrow metastable zone width of sodium chloride aqueous solutions. Some authors recommend keeping the saline solution under subsaturated conditions inside the membrane module, in a modus operandi where supersaturation is achieved only inside the crystallizer by application of cooling. For salts with a flat solubility–temperature curve such as that exhibited by sodium chloride, such recommendation is not effective for two reasons: (a) This recommendation refers to the bulk conditions, and the analysis of Figure indicates that even when the bulk concentration is below saturation the interface region is already supersaturated.…”