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Antiscalant removal in accelerated desupersaturation of RO concentrate via chemically-enhanced seeded precipitation (CESP).
MedLine Citation:
PMID:  22673342     Owner:  NLM     Status:  Publisher    
An experimental study was carried out to demonstrate and quantify the feasibility of antiscalant (AS) removal from brackish water RO concentrate of high gypsum scaling propensity via lime treatment prior to seeded gypsum precipitation. Based on studies with model solutions, it was shown that sufficient AS removal (up to ∼90%) from RO concentrate is feasible via a lime treatment step (at a dose significantly lower than that required for conventional lime softening) to enable effective subsequent seeded gypsum precipitation. This two-step chemically-enhanced seeded precipitation (CESP) treatment of primary RO concentrate is suitable as an intermediate concentrate demineralization (ICD) stage for high recovery desalting employing secondary RO desalination. Analysis of gypsum precipitation and lime treatment kinetic data suggests that, after adequate CaCO(3) precipitation has been induced for effective AS scavenging, CaSO(4) desupersaturation can be achieved via seeded gypsum precipitation without retardation due to seed poisoning by AS. Also, the lime dose required to prevent seed poisoning during subsequent gypsum desupersaturation via seeded gypsum precipitation can be adequately assessed with a precipitation kinetics model that considers AS seed poisoning based on a Langmuir adsorption isotherm. The degree of AS removal after lime treatment increased linearly with the logarithm of the single lime dose additions. Staged lime dosing (i.e., multiple lime additions), however, removed a higher degree of AS relative to an equivalent single lime dose addition since a higher driving force for CaCO(3) precipitation could be maintained over the course of the lime treatment period.
Brian C McCool; Anditya Rahardianto; Yoram Cohen
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-5-16
Journal Detail:
Title:  Water research     Volume:  -     ISSN:  1879-2448     ISO Abbreviation:  -     Publication Date:  2012 May 
Date Detail:
Created Date:  2012-6-7     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0105072     Medline TA:  Water Res     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012 Elsevier Ltd. All rights reserved.
Water Technology Research Center, Chemical & Biomolecular Engineering Department, University of California, 5531 Boelter Hall, Los Angeles, CA 90095-1592, USA.
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