Recovery of Na2SO4·10H2O from a reverse osmosis retentate by eutectic freeze crystallisation technology.
Journal Article
2010
Permanent link to this Item
Authors
Journal Title
Chemical Engineering Research and Design
Journal ISSN
Volume Title
Publisher
Elsevier
Publisher
University of Cape Town
License
Series
Abstract
The increasing amount of waste water and effluent from South Africa’s mining industry forms a growing problem, which processing requires sustainable solutions in which both the water and the dissolved component can be reused. Eutectic freeze crystallisation (EFC) has been identified as a key technology that is not only energy efficient, but also produces ice and salt products of high quality. Unlike reverse osmosis membrane systems, EFC can treat both dilute and concentrated systems minimising waste water volumes. In this paper it is shown that freeze and eutectic freeze crystallisation can be used for the processing of a reverse osmosis retentate stream containing 4% NaSO4 and a number of impurities (F, Cl, K, Li, Mg, Ca, NO3 and NH4), producing both pure water and NaSO4•10H2O crystals. The influence of the impurities on the eutectic point and on the crystal structure of mirabilite was investigated using EFC technology investigated for a pure binary system, for a synthetic reverse osmosis retentate as well as for a concentrated NaCl system. In addition, investigations into the recovery and purity of mirabilite for these streams were conducted.
Description
Reference:
Reddy, S. T., Lewis, A. E., Witkamp, G. J., Kramer, H. J. M., & Van Spronsen, J. (2010). Recovery of Na 2 SO 4· 10H 2 O from a reverse osmosis retentate by eutectic freeze crystallisation technology. Chemical engineering research and design, 88(9), 1153-1157.