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S&T Project 7120 Final Report: Measuring sparingly-soluble, aqueous salt crystallization kinetics using CSTRs-in-series: methodology development and CaCO3 studies

We present a methodology and results for measuring crystallization kinetics of sparingly-soluble salt mixtures typical of reject/concentrate streams from membrane-based, inland water supply processes. More usable water can be recovered (and lower disposal costs incurred) from these concentrate streams through efficient crystallization. In this work, we present a steady state, continuous stirred tank reactors (CSTRs)-in-series approach to study crystallization kinetics of a model solution mixture that is supersaturated in CaCO3. We have used pH, conductivity and turbidity changes in the system to monitor crystallization. We examined how mixing energy dissipation affects the induction times for crystallization. Notably, discernible crystallization could only be advanced to the 1st CSTR by using a recirculation loop to "fine-tune" the effect of surface area exposure-to-volume ratio, as well as, mixing energy dissipation. A rudimentary, semi-empirical model was used to capture the parametric trends of our experimental results, using the Kolmogorov mixing lengths, surface area-to-volume ratios, flow rates, and nominal diffusion coefficients. This parameterization may be tested further for design scale-up guidance.
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Generation Effort S&T Project 7120: Measuring sparingly-soluble, aqueous salt crystallization kinetics using CSTRs-in-series: methodology development and CaCO3 studies
Location Name Worldwide
Type Uploaded file(s)
File Type PDF
Publisher Bureau of Reclamation
Publication Date Thursday, September 17th, 2020
Update Frequency not planned
Last Update Monday, August 23rd, 2021

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The findings and conclusions of this work are those of the author(s) and do not necessarily represent the views of the Bureau of Reclamation.