Electrokinetic-enhanced phytoremediation of uranium-contaminated soil using sunflower and Indian mustard

Abstract

Electrokinetic-enhanced phytoremediation is an effective technology to decontaminate heavy metal contaminated soil. In this study, we examined the effects of electrokinetic treatments on plant uptake and bioaccumulation of U from soils with various U sources. Redistribution of uranium in soils as affected by planting and electrokinetic treatments was investigated. The soil was spiked with 100mg kg -1 UO2, UO3, and UO2(NO3)2. After sunflower and Indian mustard grew for 60 days, 1 voltage of directcurrent was applied across the soils for 9 days. The results indicated that U uptake in both plants were significantly enhanced by electrokinetic treatments from soil with UO3 and UO2(NO3)2. U was more accumulated in roots than in shoots. Electrokinetic treatments were effective on lowering soil pH near the anode region. Overall, uranium (U) removal efficiency reached 3.4-4.3% from soils with UO3 and uranyl with both plants while that from soil with UO2 was 0.7-0.8%. Electrokinetic remediation treatment significantly enhanced the U removal efficiency (5-6%) from soils with UO3 and uranyl but it was 0.8-1.3% from soil with UO2, indicating significant effects of U species and electrokinetic enhancement on U bioaccumulation. This study implies the potential feasibility of electrokineticenhanced phytoremediation of U soils with sunflower and Indian mustard. DISCLAIMER:The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents.DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR.

Coupling Electrokinetics and Phytoremediation to Remove Uranium from Contaminated Soil: A Laboratory Pilot-Scale Study

“…Lowering the soil pH often increases the bioavailability of most metals in soil. Our results were consistent with our previous pot study …”

“…The shoot U concentrations in the anode region were higher than those in the cathode region, which was ascribed to soil acidification (pH = 2.7) and the activation of soil U in the anode region. These results were consistent with our previous pot study and were similar to the results by O’Connor et al The results also indicated that more U was accumulated in shoots than that in roots with the initial EKF. The grass showed different tolerances to various U species in soils.…”

“…The sum of SOL and EXC fractions in soils with U species had the following order: UO 2 (NO 3 ) 2 > UO 3 > UO 2 , especially with the EKF in both the initial and reversal stages (Figure ). The current observations were in agreement with our previous pot studies with the electrokinetic treatment (EKT) and without the EKT. , Thus, this indicates the relatively higher solubility of U in UO 2 (NO 3 ) 2 -contaminated soils than that in UO 3 - and UO 2 -contaminated soils. , …”

“…The translocation factor (TF), the ratio of the contaminant concentration in shoots to that in roots, describes the extraction efficiency of contaminants from plants . Plants commonly used for phytoremediation combine rapid growth rates with large biomass production, high tolerance to contaminants, and great accumulation and translocation ability, for instance, oat (Avena sativa), barley (Hordeum vulgare), Indian mustard (Brassica juncea), sunflower, and ryegrass. − Our previous studies reported that both the Indian mustard and sunflower plants were potential candidate plants for the phytoremediation of U-contaminated soil. , On the other hand, for large contaminated areas, perennial grasses possess great advantages in the potential phytoremediation of contaminated soils. Ryegrasses are easily cultivated and fast-growing and have good growth adaptability in degraded contaminated soils. − Ryegrass has high tolerance to pollutants such as uranium. , …”

Hazardous wastes treatment technologies

“…Bioaugmentation with Paracoccus MAL 1HM19 enhanced the oxidation of the accumulated S 0 to sulfate in the anoxic BTF. Li, Zhang, Larson, et al (2019) coupled an EK process with phytoremediation to remove uranium from soils containing different uranium compounds, UO 2 , UO 3 , and UO 2 (NO 3 ) 2 . EK process could enhance the removal efficiency at different levels (e.g., UO 3 was the most and UO 2 was not significantly removed).…”