Suppression of CaCO3 scale deposition by anti-scalants

David Hasson, Raphael Semiat, Dan Bramson, Markus Busch, Bracha Limoni-Relis

Research output: Contribution to journalConference articlepeer-review

66 Scopus citations


The objective of this study was to compare the degree of CaCO3 scale suppression provided by various anti-scalants belonging to different chemical categories. The scaling system examined consisted of a freely falling film of a hot aqueous solution of Ca(HCO3)2 flowing down the outer surface of a vertical pipe. Evaporative air-cooling of the falling film released gaseous CO2 from the water, thereby creating a substantial CaCO3 scaling potential. Scale suppression effectiveness was determined by comparing the amount of scale deposited on a test pipe fed with water dosed with an anti-scalant with the amount deposited on an identical reference pipe, fed with the same water but without anti-scalant dosage. In the absence of an inhibitor, the scale layer was found to grow linearly with time, past an induction period. In the presence of an anti-scalant, the length of the induction period was extended and scale growth was arrested at an asymptotic limiting thickness. Scale suppression was more effective in the case of feed waters having a relatively higher temperature and a somewhat lower scaling potential, as compared to feed waters at a lower temperature and a somewhat higher scaling potential. No major difference could be discerned among the tested anti-scalants in the falling film system; all showed a substantially similar scale suppression effectiveness, within a narrow range of concentrations (0.2 to 0.5 ppm). Preliminary results of tests, aiming to check the applicability of the above conclusions to membrane systems, are also presented.

Original languageEnglish
Pages (from-to)285-296
Number of pages12
Issue number1-3
StatePublished - 20 Sep 1998
Externally publishedYes
EventProceedings of the 1998 Conference on Membranes in Drinking and Industrial Water Production. Part 2 (of 3) - Amsterdam, Neth
Duration: 21 Sep 199824 Sep 1998


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