Cr(VI) concentration from batch contact/tank leaching and column percolation test using fly ash with additives

Chai, Jinchun; Onitsuk, Katsutada; Hayashi, Shigenori

doi:10.1016/j.jhazmat.2008.11.010

Cited by 24 publications

(6 citation statements)

References 3 publications

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“…Large discrepancies have been documented for sorption dynamics in well-mixed batch reactors and those in the natural subsurface. ,− Sorption occurs fast in well-mixed batch reactors, often reaching equilibrium within seconds to hours. ,, Sorption “microkinetics” or microrates in these systems have been observed to undergo multiple stages, with early fast sorption reflecting chemical kinetics followed by later slower rates limited by intragrain diffusion. ,− Sorption “macrokinetics” or macrorates observed in natural systems at large scales, however, have been documented to be much slower with temporal scales between days and weeks. ,− Stochastic analysis indicated that macrorates depend on flow and mass transport limitation imposed by natural system characteristics. − …”

Section: Introductionmentioning

confidence: 99%

Illite Spatial Distribution Patterns Dictate Cr(VI) Sorption Macrocapacity and Macrokinetics

Wang

2015

Environ. Sci. Technol.

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This work examines the largely unexplored role of illite spatial distribution patterns in dictating the sorption of Cr(VI), a ubiquitously occurring contaminant. Flow-through experiments were carried out at 0.6, 3.0, and 15.0 m/day using columns packed with the same illite and quartz mass however with different spatial patterns and permeability contrasts. Column-scale sorption macrocapacity and macrorates were found to decrease with transport connectivity, a quantitative measure of heterogeneity characteristics. At 0.6 and 3.0 m/day, well-connected low permeability illite zones oriented in the flow-parallel direction lead to diffusion-controlled mass transport limitation for accessing sorption sites. This results in up to 1.4 order of magnitude lower macrocapacity and macrorates compared to those in minimally connected columns with well-mixed illite and quartz. At 15.0 m/day, effects of spatial heterogeneities are less significant (up to a factor of 2.8) owing to the close to chemical kinetics-controlled condition. Although the column-scale macrocapacity can reach full sorption capacity under low flow conditions, the macrorates are 10(-1) to 10(-3) of the microrates measured in well-mixed reactors. Insights gained here bridge gaps between laboratory observations and field applications and advance predictive understanding of reactive transport processes in the naturally heterogeneous subsurface.

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Section: Introductionmentioning

confidence: 99%

Illite Spatial Distribution Patterns Dictate Cr(VI) Sorption Macrocapacity and Macrokinetics

Wang

2015

Environ. Sci. Technol.

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“…The contact time of 24 h is too short for some metals to reach equilibrium, resulting in an underestimation of metal(loid) solubility [32]. The batch test represents the process of mixing a solid mass into groundwater so as to confirm the effect of this process of groundwater [34]. Nevertheless, the main disadvantage of the batch test is that the provided information is limited, as it only offers a single result in terms of L/S ratio, which does not reflect real-world conditions [31].…”

Section: Methodsmentioning

confidence: 99%

“…On the other hand, percolation column tests better simulate the field conditions and are appropriate to assess the long-term release of chemical constituents from the soil into water and groundwater. The percolation column tests resemble the process of the percolation/seepage of water into a soil structure to examine the effect of leachate on the environment [34]. Besides, the column percolation leaching tests simulate the time-dependent percolation behavior of solids in surface waters and groundwater.…”

Section: Methodsmentioning

confidence: 99%

Granular Material Development Applied in an Experimental Section for Civil Engineering Purposes

2020

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In this study, a granular material (GM) derived from wastes generated in waste-to-energy plants was developed. Weathered bottom ash (WBA) and air pollution control (APC) ashes obtained from municipal solid waste incineration (MSWI) were used as raw materials. A mortar (M) with 50 wt. % of APC and 50 wt. % of Ordinary Portland Cement (OPC) CEM-I was prepared. The GM formulation was 20 wt. % M and 80 wt. % WBA. At the laboratory scale, WBA, APC, M, and crushed GM were evaluated by means of dynamic leaching (EN 12457-4) tests, and WBA, M, and crushed GM by percolation column (CEN/TS 16637) tests. The metal(loid)s analyzed were below the non-hazardous limits, regarding the requirement of the metal(loid)s released for waste revalorization. In order to simulate a road subbase real scenario, the crushed GM was tested in an experimental section (10 × 20 × 0.2 m). During a 600-day period, the leachates generated by the percolation of rainwater were collected. This research shows outstanding results regarding the metal(loid)s released for both the “accumulated” and “punctual” leachates collected. An accomplishment in the immobilization of metal(loid)s from APC residues was achieved because of the encapsulation effect of the cement. The GM formulation from both MSWI wastes can be considered an environmentally safe procedure for revalorizing APC residues.

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“…The tank leaching test (TLT) is commonly used to study the release properties of minor compounds and to predict the number of released ions in the hardened backfill [24][25][26]. The potential hazards related to the leachable impurities from hardened backfill samples were measured by conducting compliance leaching test according to EA NEN 7375.…”

Section: Tank Leaching Testmentioning

confidence: 99%

Slurry Preparation Effects on the Cemented Phosphogypsum Backfill through an Orthogonal Experiment

Zhou

Zhu

et al. 2019

Minerals

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The cemented phosphogypsum (PG) backfill technique provides a new method for massive consumption of PG, and therefore alleviating the environmental pollution of PG. This study considered the effects of slurry preparation on the performance of cemented PG backfill. A L 16 (4 4 ) orthogonal experiment was designed to analyze four factors, namely the solid content, phosphogypsum-to-binder ratio (PG/B ratio), stirring time and stirring speed, with each factor having four levels. According to the range analysis, the solid content played the dominant role in controlling the bleeding rate, while the setting times strongly depended on the PG/B ratio. In terms of strength development of the backfill, the PG/B ratio was shown to be the most significant factor determining the unconfined compressive strength (UCS), followed by the solid content, stirring time and stirring speed. Furthermore, the results showed that the slurry preparation affected the environmental behavior of impurities that originated in PG. By analyzing the concentrations of impurities in the bleeding water of the slurry as well as the leachates of the tank leaching test, the results showed that the release of F − and SO 4 2− was aggravated clearly with the increase in the PG/B ratio, while the release of PO 4 3− always remained at relatively low levels.

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Cr(VI) concentration from batch contact/tank leaching and column percolation test using fly ash with additives

Cited by 24 publications

References 3 publications

Illite Spatial Distribution Patterns Dictate Cr(VI) Sorption Macrocapacity and Macrokinetics

Illite Spatial Distribution Patterns Dictate Cr(VI) Sorption Macrocapacity and Macrokinetics

Granular Material Development Applied in an Experimental Section for Civil Engineering Purposes

Slurry Preparation Effects on the Cemented Phosphogypsum Backfill through an Orthogonal Experiment

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