• Journal of Korean Society of Environmental Engineers
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• v.39 no.2
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• pp.51-58
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• 2017

We investigated the efficiency of natural zeolite with different cation exchange capacity (CEC) as capping material for the remediation of marine sediments contaminated with heavy metals. Three different zeolite with high CEC (HCzeo, 163.74 cmolc/kg), medium CEC (MCzeo, 127.20 cmolc/kg), and low CEC (LCzeo, 70.62 cmolc/kg) were used. The surface area of the zeolite was in decreasing order: HCzeo ($59.43m^2/g$) > MCzeo ($52.10m^2/g$) > LCzeo ($10.12m^2/g$). The results of mineralogical composition obtained from X-ray diffraction (XRD) show that LCzeo was mainly composed of quartz and albite. In the XRD result of MCzeo and HCzeo, the peaks of clinoptilolite, heulandite, and mordenite were also observed along with that of quartz and albite. Sorption equilibrium onto the HCzeo, MCzeo, and LCzeo was reached in 6 h at initial concentration of 10 mg/L and 100 mg/L. Higher adsorption of Cd and Zn onto the zeolite with higher CEC were achieved but adsorption of Cu and Ni were not dependent on the CEC of zeolite. It can be concluded that the zeolite with high cation exchange ability is recommended for the contaminated sediments with Cd and Zn but the inexpensive zeolite with low CEC for Cu and Ni.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.3
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• pp.135-143
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• 2016

We investigated the effectiveness of natural zeolite (NZ) and sand (SD) as a capping material to block the release of heavy metals (Cd, Cr, Cu, and Zn) from heavily contaminated marine sediments and stabilize these heavy metals in the sediments. The efficiency of NZ and SD for blocking trace metals was evaluated in a flat flow tank attached with an impeller to generate wave. 0, 10, 30, and 50 mm depth of NZ or SD were capped on the contaminated marine sediments and the metal concentration in seawater was monitored. After completion of flow tank experiments, sequential extractions of the metals in the sediment below the capping material were performed. The difference of pH, EC, and DO concentration between uncapped and capped condition was not significant. The release of cations including Cd, Cu, and Zn were effectively blocked by NZ and SD capping but the interruption of Cr release was observed only in 50 mm depth of SD capped condition. However, the stabilization of Cr in 50 mm depth of SD capped condition was not achieved when compared to uncapped condition. NZ and SD capping were effective for stabilizing Cd, Cu, and Zn in marine sediments. It is concluded that the use of NZ with SD as a capping material is recommended for blocking Cd, Cr, Cu, and Zn release and stabilizing them in contaminated marine sediments.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.8
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• pp.470-477
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• 2017

In this study, the applicability of calcite, sand, and zeolite for the remediation of sediments contaminated with organics and nutrients were investigated. Sediments and seawater for water tank experiments were sampled from Pyeongtaek harbor, and 1 cm or 3 cm of calcite, sand, and zeolite were capped on the sampled sediments. pH, electric conductivity (EC), dissolved oxygen (DO), chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) were monitored for 63 days. The sampled sediments were highly contaminated with organic matter and total nitrogen. DO in uncapped condition was exhausted within 10 days but DO in capping condition except 3 cm of zeolite capping was prolonged above 2 mg/L. Capping efficiency for interrupting COD release from sediments was in the following order: zeolite 1 cm > calcite 1 cm > calcite 3 cm > sand 3 cm ${\cong}$ zeolite 3 cm ${\cong}$ sand 1 cm. Zeolite was found to be effective for interrupting nitrogen release. T-P was not observed in both uncapped and capped sediment, i.e., all experimental conditions. It can be concluded that zeolite can be effectively used for the remediation of sediments highly contaminated with organic matter and nitrogen.

• Journal of Navigation and Port Research
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• v.39 no.4
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• pp.335-344
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• 2015

This study aims to assess the effectiveness of zeolite, montmorillonite, and steel slag as capping materials to block the release of heavy metals from marine sediment depending on their depths. The results showed that all capping materials used this study were not effective in interrupting release of As. Zeolite had negative effect on the block of Cr release but it was significantly reduced to 5 cm by montmorillonite capping. In contrast to As and Cr, Cd, Ni, and Pb were not released even from uncapped sediments. Cu and Zn were the heavy metals those were most significantly influenced by the capping conditions. Cu release from marine sediments were effectively blocked by more than 1 cm depth of montmorillonite and more than 3 cm depth of zeolite. All capping materials were found to be effective in interrupting release of Zn from marine sediments. It was concluded that the zeolite, montmorillonite, and steel slag could be used as a potential capping material for interrupting the release of Cr, Cu, and Zn from the contaminated marine sediments.

• Journal of Navigation and Port Research
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• v.41 no.4
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• pp.195-206
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• 2017

In situ capping technology for marine sediment pollution control has never been applied in South Korea. In this study a pilot project for the capping was carried out in Busan N Harbor. Pipeline and clamshell capping technologies were implemented for the pollution control. Changes of capping shapes, sediment contamination, and the time and costs required for the two constructions were compared. Both the pipeline and clamshell technologies were found to satisfy the target thickness of 50 cm on average. However, the pipeline method did not operate sensitively in terms of change of the sea floor topography, resulting in an uneven shape and a thickness. Organic carbon and ignition loss quite decreased after the pipeline or the clamshell capping while pH showed no significant change. Organic and residual fraction of Cd, Ni, and Zn in the sediments appeared to decrease after all cappings. The pipeline method took a construction time four times as much as the clamshell method. The clamshell method was demonstrated to reduce the construction cost by about 40% compared with the pipeline method. However, a monitoring for all the parameters needs to be conducted at least two years in order to better evaluate an efficiency of the pollution control by these capping constructions.

• Journal of Soil and Groundwater Environment
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• v.27 no.1
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• pp.60-70
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• 2022

We evaluated the performance of in-situ capping to prevent the release of phenol, one of hazardous chemicals of concern for their impact on sediment. Sediment near the estuary of Hyeongsan River, Korea, and commercially-available sand were collected to evaluate their physical properties and phenol sorption characteristics. Biodegradation kinetics of phenol spiked into the sediment was evaluated under freshwater and estuarine salinity conditions. These experimental measurements were parameterized and used as input parameters for executing CapSim, a software predicting the performance of in-situ capping. The CapSim simulation demonstrated that capping with 50-cm sand reduced the phenol release by several orders of magnitude over 0.25- and 1-year duration for almost all simulation scenarios. The variables tested, i.e., cap thickness, pore-water movement, and biodegradation rate, showed high correlation to each other to influence the extent of phenol release from sediment to the water column. The findings and the framework employed to evaluate the performance of in-situ capping in this study can be adopted to determine whether in-situ capping is appropriate remedial approach at sediment sites impacted by hazardous chemicals due to accidental spills.