• 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.

• Geomechanics and Engineering
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• v.25 no.3
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• pp.207-219
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• 2021

Several additives are used to enhance the geotechnical properties (e.g., shear wave velocity, shear modulus) of soils to provide sustainable, economical and eco-friendly solutions in geotechnical and geo-environmental engineering. In this study, piezoelectric ring actuators are used to measure the shear wave velocity of unreinforced, fiber, cemented, and fiber reinforced cemented Toyoura sand. One dimensional oedometer tests are performed on medium dense specimens of Toyoura sand-cement-fiber-silica flour mixtures with different percentages of silica flour (0-42%), fiber and cement (e.g., 0-3%) additives. The experimental results indicate that behavior of the mixtures is significantly affected by the concentration of silica flour, fiber and cement additives. Results show that with the addition of 1-3% of PVA fibers, the shear wave velocity increases by only 1-3%. However, the addition of 1-4% of cement increases the shear wave velocity by 8-35%. 10.5-21% increase of silica flour reduces the shear wave velocity by 2-5% but adding 28-42% silica flour significantly reduces the shear wave velocity by 12-31%. In addition, the combined effect of cement and fibers was also found and with only 2% cement and 1% fiber, the shear wave velocity increase was found to be approximately 24% and with only 3% cement and 3% fibers this increased to 35%. The results from this study for the normalized shear modulus and normalized mean effective stress agree well with previous findings on pure Toyoura sand, Toyoura silty sand, fiber reinforced, fiber reinforced cemented Toyoura sand. Any variations are likely due to the difference in stress history (i.e., isotropic versus anisotropic consolidation) and the measurement method. In addition, these small discrepancies could be attributed to several other factors. The potential factors include the difference in specimen sizes, test devices, methods of analysis for the measurement of arrival time, the use of an appropriate Ko to convert the vertical stresses into mean effective stress, and sample preparation techniques. Lastly, it was investigated that there is a robust inverse relationship between α factor and 𝞫₀ exponent. It was found that less compressible soils exhibit higher 𝜶 factors and lower 𝞫₀ exponents.

• Clean Technology
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• v.29 no.2
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• pp.118-125
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• 2023

Once a site is contaminated with polychlorinated biphenyls (PCBs), serious environmental and human health risks are inevitable. Therefore, innovative but economical in situ remediation technologies must be immediately applied to the contaminated site. Recently, nanoscale zero-valent iron (nano-ZVI) particles have successfully been applied for the dechlorination of various chlorinated organic compounds like TCE, PCE and DDT, and they are considered to be environmentally safe due to the high abundance of iron in the earth's crust. Nano-ZVIs are much more reactive than granular ones, but tend to agglomerate due to their high surface energy and magnetic properties. In order to prevent them from being agglomerated toward larger particles, TiO₂ was used as a support to immobilize the nano-ZVI particles as much as possible. 10wt% ZVI/TiO₂ was prepared by adding NaBH₄ slowly into an FeSO₄/TiO₂ aqueous slurry. In spite of their non-uniformity in size, the nano-ZVI particles were quite successfully dispersed onto the exterior surface of a non-porous TiO₂ powder. The ZVI/TiO₂ was then employed to degrade Aroclor 1242, a kind of PCBs standard, in spiked soil, and its reactivity towards the degradation of Aroclor 1242 was investigated. The fabricated ZVI/TiO₂ degraded Aroclor 1242 in soil quite effectively, but the creation of remaining dechlorinated compounds, possibly high molecular weight hydrocarbons, in the soil was unavoidable.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.1008-1012
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• 2008

Nanoscale zero-valent iron(nZVI) is famous for its high reactivity originated from its high surface area and it has received considerable attentions as one of the latest innovative technologies for treating contaminated groundwater. Due to its fine powdery form, nZVI has limited filed applications. The efforts to overcome this shortcoming by immobilizing nZVI on a supporting material have been made. This study investigated the differences of resin-supported nZVI's characteristics by changing the preparation methods and evaluated its reactivity. The borohydride reduction of an iron salt was proceeded in ethanol/water solvent containing a dispersant and the synthesis was conducted in the presence of ion-exchange resin. The resulting material was compared to that prepared in a conventional way of using de-ionized water by measuring the phyrical and chemical characteristics. BET surface area and Fe content of nZVI-attached resin was increased from $31.63m^2/g$ and 18.19 mg Fe/g to $38.10m^2/g$ and 22.44 mg Fe/g, respectively, by switching the solution medium from water to ethanol/water with a dispersant. The reactivity of each material was tested using nitrate solution without pH control. The pseudo first-order constant of $0.462h^{-1}$ suggested the reactivity of resin-supported nZVI prepared in ethanol/water was increased 61 % compared to that of the conventional type of supported nZVI. The specific reaction rate constant based on surface area was also increased. The results suggest that this new supported nZVI can be used successfully in on-site remediation for contaminated groundwater.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.8
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• pp.554-560
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• 2014

To investigate the applicability of montmorillonite to capping material for the remediation of contaminated marine sediment, adsorption characteristics of $PO{_4}{^{3-}}$ onto montmorillonite were studied in a batch system with respect to changes in contact time, initial concentration, pH, adsorbent dose amount, competing anions, adsorbent mixture, and seawater. Sorption equilibrium reached in 1 h at 50 mg/L but 3 h was required to reach sorption equilibrium at 300 mg/L. Freundlich model was more suitable to describe equilibrium sorption data than Langmuir model. The $PO{_4}{^{3-}}$ adsorption decreased as pH increased, due to the $PO{_4}{^{3-}}$ competition for favorable adsorption site with OH- at higher pH. The presence of anions such as nitrate, sulfate, and bicarbonate had no significant effect on the $PO{_4}{^{3-}}$ adsorption onto the montmorillonite. The use of the montmorillonite alone was more effective for the removal of the $PO{_4}{^{3-}}$ than mixing the montmorillonite with red mud and steel slag. The $PO{_4}{^{3-}}$ adsorption capacity of the montmorillonite was higher in seawater than deionized water, resulting from the presence of calcium ion in seawater. The water tank elution experiments showed that montmorillonite capping blocked well the elution of $PO{_4}{^{3-}}$, which was not measured up to 14 days. It was concluded that the montmirillonite has a potential capping material for the removal of the $PO{_4}{^{3-}}$ from the aqueous solutions.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.949-957
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• 2000

This study investigates the remediation of the phenol or PNP(p-Nitrophenol) contaminated soils in a slurry reactor by a pure culture, P-99. The application of a pure culture for the phenol decontamination make the degradation rate three times faster than that of the mixed activated sludge. The destruction of 300 mg/L phenol was completed in 26 hours. As 1 mg of phenol was added, 0.1457 mg of microorganism was grown in the medium. The pure culture could not utilizes PNP, one of the xenobiotics, as a growth substrate. When the bacteria was induced by phenol enrichment medium. PNP could be effectively transformed with cometabolic process. The induction of the bacteria requires 1 mg of phenol for the destruction of 0.027 mg PNP. When PNP concentration in the medium contained phenol and PNP increased. the degradation rate of phenol was decreased. The degradation rate of phenol and PNP in the slurry reactor was about two times faster than in the reactor without slurry because of higher dissolved oxygen supply in the aqueous phase and adsorption on the surface of the soil.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.11-16
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• 2005

Humic substances(HS) from raw and process waters at a conventional water treatment plant were isolated and extracted by physicochemical fractionation methods to investigate their characteristics. They are characterized for their functionality, chemical composition, and spectroscopic characteristics using FT-IR(Fourier transform infrared) and $^1H-NMR$(proton nuclear magnetic resonance) spectroscopy. Humic fraction gradually decreased from 47.2% to 26.4%(from 0.97 to 0.54 mgC/L) through conventional water treatment processes. Concentration of phenolic groups in the HS fraction gradually decreased from 60.5% to 21.8%(from 12.2 to $6.0\;{\mu}M/L$ as phenolic-OH) through water treatment. In the case of carboxylic groups, the concentration increased from 39.5% to 46.9%(from 7.9 to $10.6\;{\mu}M/L$ as COOH) by pre-chlorination, but gradually decreased to 34.2%($9.4\;{\mu}M/L$ as COOH) through sedimentation and sand filtration. From the results of the FT-IR and $^1H-NMR$ spectra of HS, the content of carboxylic groups increased and ratio of aliphatic protons to aromatic protons($P_{Al}/P_{Ar}$) also increased through water treatment, which indicated the increase of aliphatic compounds.

• Journal of Soil and Groundwater Environment
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• v.15 no.1
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• pp.50-56
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• 2010

Oil contamination soil has been one of the most environmental social issues for decades in the inside and outside of country. The law of soil environmental preservation was carried out in the 1990s and the government controlled not only soil environment management and the remediation of contaminated soil but also promoted the development of remedial technology and cleanup business of contaminated soil by national policy. In addition to agriculture areas, the main oil contaminated sites are a gas station, oil reservoir, petro-chemical complex, site of railway carriage base and military camp. The contamination-frequency of agriculture area and effect sites are low but it has significantly important area on account of producing food for human beings. Therefore, we should be concerned about oil contamination damage of agriculture area. The oil contamination damage of agriculture area influenced drop of birth and breeding since the oil directly adheres to seeds and farm products even diffusion of contaminated soil to cultivation area. The studies of the crops and the food vegetation has not enough detailed data caused by the incident of oil contamination. This study investigated the effect of oil in germination and growth of selected plant seeds. In this study, we try to verify whether the oil contamination by accidents on farmland influenced the damage of farm produce and the mutual relation both oil contaminated soil or the vegetation of crops. The impact of oil on plant development was followed by phytotoxicity assessments. The plants exhibited visual symptoms of stress, growth reduction and perturbations in developmental parameters. The increase of the degree of pollution induced more marked effects in plants, likely because of the physical effects of oil. The relationships between the phytotoxicity contents of plants and growth reduction suggest a chemical toxicity of fuel oil. In addition, while cleaned up the contaminated soil under the standard of contaminated soil we examined it was suitable for region standard and it may have practical possibility for fill material of construction of afforestation and molding soil of landfill.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.8
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• pp.938-943
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• 2007

Anaerobic degradation of petroleum hydrocarbons in a soil artificially contaminated with 10,000 mg/kg soil of diesel fuel was tested by adding an anaerobic sludge taken from a sludge digestion tank. Treatments of soil(50 g) with 15 mL/kg soil and 30 mL/kg soil of the digestion sludge(2,000 mg/L of vss(volatile suspended solids)) showed 37.2% and 58.0% of total petroleum hydrocarbons(TPH) removal during 90 days incubation, respectively. In evaluation of several anaerobic conditions including nitrate reducing, sulfate reducing, methanogenic, and mixed electron accepters condition, treatments with the digested sludge showed significant degradation of diesel fuel under all anaerobic conditions compare to a control treatment of soil without the sludge and a treatment of autoclaved soil treatment with autoclaved digestion sludge. The rate of diesel fuel degradation was the highest in the treatment with the sludge and mixed electron accepters (75% removal of TPH) for 120 days incubation followed in order by sulfate reducing, nitrate reducing, methanogenic condition as 67%, 53%, 43%, respectively. However, the removal rate of non-biodegradable isoprenoid was the highest in the sulfate reducing condition. These results suggest that anaerobic degradation of diesel fuel in soil with digested sludge is effective for practical remediation of soil contaminated with petroleum hydrocarbons.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.12
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• pp.1305-1310
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• 2005

As a way to the optimum design of the collector well lateral in riverbed filtration, experiments were performed using sand tanks which were connected to form a model lateral system. Measured were the residual hydraulic heads along the laterals, the discharge rates at each sand tank and the production rates at the collector well while the model laterals were operated with various scenarios of changing parameters including water level of the collector well, the lateral diameter and length, and the hydraulic conductivity of the sand. Results showed that riverbed filtration could be more efficient when the resistance in the lateral was weak compared with the resistance in the sand, which was indicated by the more flattened distribution of the residual hydraulic heads along the lateral. Results also showed that the discharge rate increased exponentially with the approach to the collector well, and that the exponent increased as the lateral diameter decreased and/or the hydraulic conductivity of the sand increased. It was also seen that the well production increased with the increase in the lateral length and diameter although the marginal productivity decreased. It could be concluded that the axial flow velocity in the lateral was an important factor governing the efficiency of a lateral in riverbed filtration and that the maximum entrance velocity to the collector well, over which the efficiency decreased drastically, was about 1 m/sec under the conditions of this study.