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Chen Z, Zhang P, Brown KG, van der Sloot HA, Meeussen JCL, Garrabrants AC, Delapp RC, Um W, Kosson DS. Evaluating the impact of drying on leaching from a solidified/stabilized waste using a monolithic diffusion model. WASTE MANAGEMENT (NEW YORK, N.Y.) 2023; 165:27-39. [PMID: 37080015 DOI: 10.1016/j.wasman.2023.04.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 03/06/2023] [Accepted: 04/04/2023] [Indexed: 05/03/2023]
Abstract
The release rates of constituents of potential concern from solidified/stabilized cementitious waste forms are potentially impacted by drying, which, however, is not well understood. This study aimed to identify the impacts of drying on subsequent leaching from Cast Stone as an example of a solidified cementitious waste form. The release fluxes of constituents from monoliths after aging under 100, 68, 40, and 15 % relative humidity for 16, 32, and 48 weeks, respectively, were derived from mass transfer tank leaching tests following EPA Method 1315. A monolithic diffusion model was calibrated based on the leaching test results to simulate the leaching of major and redox-sensitive constituents from monoliths after drying. The reduction in physical retention of constituents (tortuosity-factor) in the unsaturated zone was identified as the primary impact from drying on subsequent leaching. Fluxes of both major (i.e., OH-, Na, K, Ca, Si, and Al) and redox-sensitive constituents (i.e., Tc, Cr, Fe, and S) from monoliths during leaching were well described by the model. The drying-induced reduction of tortuosity-factor and concomitant changes in porewater pH and redox conditions can significantly change the subsequent release fluxes of pH- and redox- sensitive constituents.
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Affiliation(s)
- Zhiliang Chen
- Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, TN 37235, United States
| | - Peng Zhang
- Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, TN 37235, United States; Shanghai Shaanxi Coal Hi-tech Research Institute Co., Ltd., Shanghai 201613, China
| | - Kevin G Brown
- Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, TN 37235, United States
| | - Hans A van der Sloot
- Hans van der Sloot Consultancy, Glenn Millerhof 29, 1628 TS Hoorn, the Netherlands
| | | | - Andrew C Garrabrants
- Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, TN 37235, United States
| | - Rossane C Delapp
- Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, TN 37235, United States
| | - Wooyong Um
- Pacific Northwest National Lab., Richland, WA, United States; Pohang University of Science and Technology (POSTECH), Pohang, Korea
| | - David S Kosson
- Department of Civil and Environmental Engineering, Vanderbilt University, Nashville, TN 37235, United States.
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