Improved calcium sulfate recovery from a reverse osmosis retentate using eutectic freeze crystallization
A novel low temperature crystallization process called eutectic freeze crystallization (EFC) can produce both salt(s) and ice from a reverse osmosis (RO) stream by operating at the eutectic temperature of a solution. The EFC reject stream, which is de-supersaturated with respect to the scaling compo...
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Published in | Water science and technology Vol. 67; no. 1; pp. 139 - 146 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
London
International Water Association
01.01.2013
IWA Publishing |
Subjects | |
Online Access | Get full text |
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Summary: | A novel low temperature crystallization process called eutectic freeze crystallization (EFC) can produce both salt(s) and ice from a reverse osmosis (RO) stream by operating at the eutectic temperature of a solution. The EFC reject stream, which is de-supersaturated with respect to the scaling component, can subsequently be recycled back to the RO process for increased water recovery. This paper looks at the feasibility of using EFC to remove calcium sulfate from an RO retentate stream and compares the results to recovery rates at 0 and 20 °C. The results showed that there was a greater yield of calcium sulfate obtained at 0 °C as compared with 20 °C. Operation under eutectic conditions, with only a 20% ice recovery, resulted in an even greater yield of calcium sulfate (48%) when compared with yields obtained at operating temperatures of 0 and 20 °C (15% at 0 °C and 13% at 20 °C). The theoretical calcium recoveries were found to be 75 and 70% at 0 and 20 °C respectively which was higher than the experimentally determined values. The EFC process has the added advantage of producing water along with a salt. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0273-1223 1996-9732 |
DOI: | 10.2166/wst.2012.540 |