In situ field application of electrokinetic remediation for an As-, Cu-, and Pb-contaminated rice paddy site using parallel electrode configuration

The operational variables of electrokinetic remediation have not been cleared yet, because this method is relatively new and is an innovative technique in the aquifer remediation. In order to investigate the operational variables of the electrokinetic remediation, a mathematical model has been constructed based on the physico chemical mass transport process of heavy metals in pore water of contaminated aquifer. The transport of the heavy metals is driven not only by the hydraulic flow due to the injection of the purge water but also by the electromigration due to the application of the electric potential gradient. The electric potential between anode and cathode is the important operational variable for the electrokinetic remediation. From the numerical simulations with use of this model it is confirmed that the remediation starts from the up stream anode and gradually the heavy metal is transported to the down stream cathode and drawn out through the purge water.

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Application of UV radiation for in-situ Cr(VI) reduction from contaminated soil with electrokinetic remediation

Journal of Hazardous Materials ◽

10.1016/j.jhazmat.2021.125806 ◽

2021 ◽

Vol 416 ◽

pp. 125806

Author(s):

Yi Zheng ◽

Huilin Li ◽

Qiu Yu ◽

Lin Yu ◽

Binquan Jiao ◽

...

Keyword(s):

Uv Radiation ◽

Contaminated Soil ◽

Electrokinetic Remediation

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Mercury methylation in paddy soil: source and distribution of mercury species at a Hg mining area, Guizhou Province, China

Biogeosciences ◽

10.5194/bg-13-2429-2016 ◽

2016 ◽

Vol 13 (8) ◽

pp. 2429-2440 ◽

Cited By ~ 34

Author(s):

Lei Zhao ◽

Christopher W. N Anderson ◽

Guangle Qiu ◽

Bo Meng ◽

Dingyong Wang ◽

...

Keyword(s):

Paddy Soil ◽

Surface Soil ◽

Ambient Air ◽

Rice Paddy ◽

Guizhou Province ◽

Mercury Species ◽

Low Concentration ◽

Paddy Water ◽

Hg Mining

Abstract. Rice paddy plantation is the dominant agricultural land use throughout Asia. Rice paddy fields have been identified as important sites for methylmercury (MeHg) production in the terrestrial ecosystem and a primary pathway of MeHg exposure to humans in mercury (Hg) mining areas. We compared the source and distribution of Hg species in different compartments of the rice paddy during a complete rice-growing season at two different typical Hg-contaminated mining sites in Guizhou province, China: an abandoned site with a high Hg concentration in soil but a low concentration in the atmosphere and a current-day artisanal site with a low concentration in soil but a high concentration in the atmosphere. Our results showed that the flux of new Hg to the ecosystem from irrigation and atmospheric deposition was insignificant relative to the pool of old Hg in soil; the dominant source of MeHg to paddy soil is in situ methylation of inorganic Hg (IHg). Elevated MeHg concentrations and the high proportion of Hg as MeHg in paddy water and the surface soil layer at the artisanal site demonstrated active Hg methylation at this site only. We propose that the in situ production of MeHg in paddy water and surface soil is dependent on elevated Hg in the atmosphere and the consequential deposition of new Hg into a low-pH anoxic geochemical system. The absence of depth-dependent variability in the MeHg concentration in soil cores collected from the abandoned Hg mining site, consistent with the low concentration of Hg in the atmosphere and high pH of the paddy water and irrigation water, suggested that net production of MeHg at this site was limited. We propose that the concentration of Hg in ambient air is an indicator for the risk of MeHg accumulation in paddy rice.

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Potential Electrokinetic Remediation Technologies of Laboratory Scale into Field Application- Methodology Overview

Journal of Physics Conference Series ◽

10.1088/1742-6596/995/1/012083 ◽

2018 ◽

Vol 995 ◽

pp. 012083

Author(s):

Anis Ayuni Suied ◽

Saiful Azhar Ahmad Tajudin ◽

Muhammad Nizam Zakaria ◽

Aziman Madun

Keyword(s):

Electrokinetic Remediation ◽

Field Application ◽

Laboratory Scale

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Live-Scale Testing of Granular Materials Stabilized with Alkali-Activated Waste Glass and Carbide Lime

Applied Sciences ◽

10.3390/app112311286 ◽

2021 ◽

Vol 11 (23) ◽

pp. 11286

Author(s):

Marina Paula Secco ◽

Débora Thaís Mesavilla ◽

Márcio Felipe Floss ◽

Nilo Cesar Consoli ◽

Tiago Miranda ◽

...

Keyword(s):

Portland Cement ◽

Mechanical Performance ◽

Raw Materials ◽

Sodium Hydroxide Solution ◽

Fine Sand ◽

Field Application ◽

Natural Soil ◽

In Situ Tests ◽

Alkali Activated

The increasingly strong search for alternative materials to Portland cement has resulted in the development of alkali-activated cements (AAC) that are very effective at using industrial by-products as raw materials, which also contributes to the volume reduction in landfilled waste. Several studies targeting the development of AAC—based on wastes containing silicon and calcium—for chemical stabilization of soils have demonstrated their excellent performance in terms of durability and mechanical performance. However, most of these studies are confined to a laboratory characterization, ignoring the influence and viability of the in situ construction process and, also important, of the in situ curing conditions. The present work investigated the field application of an AAC based on carbide lime and glass wastes to stabilize fine sand acting as a superficial foundation. The assessment was supported on the unconfined compressive strength (UCS) and initial shear modulus (G0) of the developed material, and the field results were compared with those prepared in the laboratory, up to 120 days curing. In situ tests were also developed on the field layers (with diameters of 450 and 900 mm and thickness of 300 mm) after different curing times. To establish a reference, the mentioned precursors were either activated with a sodium hydroxide solution or hydrated with water (given the reactivity of the lime). The results showed that the AAC-based mixtures developed greater strength and stiffness at a faster rate than the water-based mixtures. Specimens cured under controlled laboratory conditions showed better results than the samples collected in the field. The inclusion of the stabilized layers clearly increased the load-bearing capacity of the natural soil, while the different diameters produced different failure mechanisms, similar to those found in Portland cement stabilization.

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Optimizing Preloading Pressure of Precharged Gas for Isobaric Gas-Tight Hydrothermal Samplers

Journal of Pressure Vessel Technology ◽

10.1115/1.4038901 ◽

2018 ◽

Vol 140 (2) ◽

Cited By ~ 1

Author(s):

Haocai Huang ◽

Liang Huang ◽

Wei Ye ◽

Shijun Wu ◽

Canjun Yang ◽

...

Keyword(s):

Volume Change ◽

Theoretical Models ◽

Sample Volume ◽

Field Application ◽

Laboratory Simulation ◽

Application Process ◽

Sampling Depth ◽

Ambient Temperatures ◽

Gas Tight

Isobaric gas-tight hydrothermal samplers, with the ability to maintain pressure, can be used to keep in situ chemical and biological sample properties stable. The preloading pressure of the precharged gas is a major concern for isobaric gas-tight hydrothermal samplers, especially when the samplers are used at different sampling depths, where the in situ pressures and ambient temperatures vary greatly. The most commonly adopted solution is to set the preloading pressure for gas-tight samplers as 10% of the hydrostatic pressure at the sampling depth, which might emphasize too much on pressure retention; thereby, the sample volume may be unnecessarily reduced. The pressure transition of the precharged gas was analyzed theoretically and modeled at each sampling stage of the entire field application process. Additionally, theoretical models were built to represent the pressure and volume of hydrothermal fluid samples as a function of the preloading pressure of the precharged gas. Further, laboratory simulation and examination approaches were also adopted and compared, in order to obtain the volume change of the sample and accumulator chambers. By using theoretical models and the volume change of the two chambers, the optimized preloading pressure for the precharged gas was obtained. Under the optimized preloading pressure, the in situ pressure of the fluid samples could be maintained, and their volume was maximized. The optimized preloading pressure obtained in this study should also be applicable to other isobaric gas-tight hydrothermal samplers, by adopting a similar approach to pressure maintenance.

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