Complexation Of Amino Acid With Cadmium And Its Application To Remove Cadmium From Contaminated Soil

Low molecular organic acids, such as amino acid, play an important role in cadmium (Cd) mobility. However, its complexation ability with Cd was not well studied. The complexation structure of amino and cadmium was investigated by theory calculation based on B3ly/SDD and detecting by FTIR spectrum. The conformers were found to be [COc, COc] for fatty amino-cadmium and PheCd2+, [COc, COc, COs] for GluCd2+and ThrCd2+, respectively. The complex energy of these conformers was calculated in water phase by SMD model and the order of chelation energy was; PheCd2+> AlaCd2+ > LeuCd2+ > GluCd2+ > GlyCd2+ > ThrCd2+. All the dissolving energy of complexes was below zero, indicating these complexes was easily dissolved in water. In aqueous solution experiment, the Cd2+ concentration decreased with increasing amino acid concentration. The order of logβ (Complex stability constant) was: PheCd2+> AlaCd2+ > LeuCd2+ > GluCd2+ > GlyCd2+ > ThrCd2+, consisting with the order of calculated chelation energy. The Cd removal efficiency by Thr, Glu, Gly, Ala, Leu and Phe were 38.88%, 37.47%, 35.5%, 34.72%, 34.04% and 31.99%, respectively. From soil batch experiment, the total Cd in soil was decreased in present of amino acid with the concentration of Cd in water increased from 231.97 µg/L to 652.94-793.51 µg/L. The results of BCR sequential extraction showed that the Cd in acid soluble and reducible fraction sharply decreased. From all the results, the amino acid has potential to be used as a chelation to remedy the Cd contaminated soil.

Synergistic Effects of Adding A Substrate and an Organic Reductant for Stimulating the Bioremediation of 4-Chloronitrobenzene-Contaminated Soil

Background: Soil contaminated with 4-chloronitrobenzene (4NCB) is resistant to microbial degradation due to the electron-withdrawing properties of the nitro and chloro groups in 4NCB. Currently, sufficient information is not available on how to use biostimulation strategies to enhance the bioremediation of 4NCB-contaminated soil.Results: In the present study, a novel strategy was developed by utilizing the synergistic effects of adding an organic reductant (ascorbic acid, VC) and an organic nitrogen source (peptone) to stimulate the biodegradation of 4NCB-contaminated soil. Using this strategy, the bioremediation of 1 g-4NCB/ kg-1 soil could be completed within 8 days in soil batch reactors. Furthermore, the study discovered two 4NCB cometabolic intermediates in the soil reactors added with peptone and VC, and for the first time, 4NCB was transformed to 4-chlorofromanilide.Conclusion: The proposed strategy is promising because it is highly efficient, easy to control and involves a non-toxic, environmentally friendly substrate/reductant.). Finally, this approach warrants future studies to extend its applications to soils contaminated with other nitroaromatic compounds.

Synergistic Effects of Adding a Substrate and an Organic Reductant for Stimulating the Bioremediation of 4-chloronitrobenzene-contaminated Soil

Background:Soil contaminated with 4-chloronitrobenzene (4NCB) is resistant to microbial degradation due to the electron-withdrawing properties of the nitro and chloro groups in 4NCB. Currently, sufficient information is not available on how to use biostimulation strategies to enhance the bioremediation of 4NCB-contaminated soil.Results:In the present study, a novel strategy was developed by utilizing the synergistic effects of adding an organic reductant (ascorbic acid, VC) and an organic nitrogen source (peptone) to stimulate the biodegradation of 4NCB-contaminated soil. Using this strategy, the bioremediation of 1 g-4NCB/ kg-1 soil could be completed within 8 days in soil batch reactors. Furthermore, the study discovered two 4NCB cometabolic intermediates in the soil reactors added with peptone and VC, and for the first time, 4NCB was transformed to 4-chlorofromanilide.Conclusion:The proposed strategy is promising because it is highly efficient, easy to control and involves a non-toxic, environmentally friendly substrate/reductant.). Finally, this approach warrants future studies to extend its applications to soils contaminated with other nitroaromatic compounds.

EXPERIENCE OF REMEDIATION OF SITES CONTAMINATED WITH RADIONUCLIDES ON THE EXAMPLE OF THE TERRITORY OF THE MOSRENTGEN PLANT

This study is focused on the issues of remediation of sites and territories contaminated with radionuclides as a result of the past activities of the facilities. Actions performed at the territory of the «Mosrentgen» plant, contaminated by 137Cs after the radiation accident in 1962, are evaluated as an example. This paper provides a detailed description of the actions performed in 2012–2017 and the analysis of the mistakes made during the radiation survey, leading to the detection of the large volume of the radioactive wastes during the excavation at the construction of the industrial building at the decontaminated site. The authors propose a method of preliminary assessment of the 137Cs activity concentration in soil based on the gamma-radiation exposure rate on the surface of the soil batch. The results of the study indicate a necessity of development and implementation of the legislative base regulating the structure and types of surveys for remediation of facilities and territories.

Adsorption of heavy metal by natural clayey soil

This study focused on the capability of Clayey soil to retain and release heavy metals. Batch experiment for sample of clayey soil was conducted with several concentrated solutions of heavy metals. The results show that the clayey soil sample may have a relatively high heavy metal retention capacity. This is particularly positive in the context of municipal waste disposal (landfills) in Indonesia Keywords: Adsorption, heavy metal, clayey soil, batch experiment

Evaluation of wastewater effluents for soil aquifer treatment in South Korea

Soil batch and column experiments were performed to characterize the wastewater effluents from seven different wastewater treatment plants in the Jonnam province, South Korea, with the purpose of evaluating the effluents for possible application of a soil aquifer treatment (SAT) in Korea. Batch experiments were conducted to measure the biodegradable dissolved organic carbon (BDOC) while 1 m soil columns, for simulating SAT, were employed to further analyze dissolved organic carbon (DOC) removal. The soils were collected from a river bottom in Jonnam. The BDOC fractions and the residual DOC concentrations for the effluents ranged from 19.3 to 59.9% and from 1.0 to 7.5 mg/L, respectively, depending on the reaction time. Applying the tentative criteria based on the data obtained for the BDOC and residual DOC, three effluents, from Gwangju, Hwasoon, and Jangsung, were found to be the most suitable for SAT applications. It was also concluded that the site characteristics should be also considered with regard to the retention time when evaluating the feasibility of SAT application in a certain region.