• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.245-253
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• 2014

BACKGROUND: Oyster shell(OS) is alkaline with pH 9.8, porous, and has high concentration of $CaCO_3$. It could be used as an alternative of lime fertilizer to immobilize cadmium(Cd) in heavy metal contaminated arable soil. Therefore, this study has been conducted to compare effects of calcium(Ca) materials [OS and $Ca(OH)_2$] on Cd extractability in contaminated soil and determined mechanisms of Cd immobilization with OS. METHODS AND RESULTS: Both Ca materials were added at the rates of 0, 0.1, 0.2, 0.4, and 0.8% (wt Ca wt-1) in Cd contaminated soil and the mixtures were incubated at $25^{\circ}C$ for 4 weeks. Both Ca materials increased pH and negative charge of soil with increasing Ca addition and decreased 1N $NH_4OAc$ extractable Cd concentration. 0.1 N HCl extractable Cd concentration markedly decreased with addition of OS. 1 N $NH_4OAc$ extractable Cd concentration was related with pH and net negative charge of soil, but not with 0.1 N HCl extractable Cd concentration. We assumed that Cd immobilization with $Ca(OH)_2$ was mainly attributed to Cd adsorption resulted from increase in pH-induced negative charge of soil. Scanning electron microscope (SEM) images and energy dispersive spectroscopy(EDS) analyses were conducted to determine mechanism of Cd immobilization with OS. There was no visible precipitation on surface of both Ca materials. However, Cd was detected in innerlayer of OS by EDS analyses but not in that of $Ca(OH)_2$. CONCLUSION: We concluded that Cd immobilization with OS was different from that with $Ca(OH)_2$. OS might adsorbed interlayer of oyster shell or have other chemical reactions.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.3
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• pp.302-308
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• 2005

Nitrate is one of common contaminants frequently found in the bank filtrate. Biological autotrophic denitrification into permeable reactive barrier(PRB) system to reduce nitrate concentration in bank filtrate was implanted. The objectives of research are to investigate effect of inoculation, to evaluate alternative alkalinity sources, and to determine effect of hydraulic characteristics, such as retention time, flow rate on the performance of semi-pilot PRB system. Semi-pilot scale biological PRB system was installed using elemental sulfur and limestone/oyster shell as reactive materials near Nakdong River in Kyoungnam province, Korea. Nitrate concentration in bank filtrate was reduced by indigenous microorganisms in oyster shell as welt as by inoculating microorganisms isolated from the sludge of an anaerobic digester in a wastewater treatment plant. Oyster shell as well as limestone can be used as an alkalinity source. However, oyster shell resulted in suspended solids of effluent. As the flow rate in the system increased from 66 to 132 mL/min and accordingly the residence time decreased from 15 to 7.5 hours, nitrate concentration in effluent increased and nitrate removal efficiencies decreased from 75 to 58% at the fixed thickness of 80 cm of PRB.

• Korean Journal of Pharmacognosy
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• v.4 no.1
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• pp.9-17
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• 1973

A score and more kinds of molluscan shells have been used as drugs in oriental medicine. The Korean Pharmacopoeia (K.P.) contains a monograph on oyster shell "Ostreae Testa" as an official drug. A huge deposit of the fossil shell Crassostrea gravitesta eoilensis has been recently excavated in the region of Wolsung, Kyong-Sang-Buk-Do. This study was conducted to determine the applicability of the fossil shell as a substiute for Ostreae Testa, K.P. The fossil shell not only met the K.P. requirements, but also exhibited an appropriate antacid activity. Amino acid survivals were also determined quantitatively with amino acid autoanalyzer.

• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.79-85
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• 2005

An experimental study was carried out to investigate the recycling possibility of waste oyster shells, which induce environmental pollutions by piling up out at the open or the temporary reclamation. The purpose of this study is to develope eco-friendly binder using waste oyster shells, and to reinforce dredged soils fur soft soil improvement. In this paper, a series of laboratory tests including compressive strength tests were performed to evaluate strength characteristics of soils treated by developed binder with different water content of dredged soils, mixing rates of binder, curing days. Based on test results, eco-friendly binders manufactured from waste oyster shells were estimated as good resource materials for soft soil improvements.

• Environmental Engineering Research
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• v.10 no.5
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• pp.247-256
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• 2005

A combination of the submerged membrane activated-sludge bioreactor(SMABR) equipped with non-woven fabric filter and oyster-zeolite (OZ) packed-bed adsorption column was studied to evaluate the advanced tertiary treatment of nitrogen and phosphorous. The non-woven filter module was submerged in the MBR and aeration was operated intermittently for an optimal wastewater treatment performance. Artificial wastewater with $COD_{Cr}$ of 220 mg/L, total nitrogen (T-N) of 45 mg/L, and total phosphorous (T-P) of 6 mg/L was used in this study. MLSS was maintained about $4,000\;{\sim}\;5,000\;mg/L$ throughout the experiments. The experiments were performed for 100-day with periodic non-woven filter washing. The results showed that $COD_{Cr}$ could be effectively removed in SMABR alone with over 94% removal efficiency. However, T-N and T-P removal efficiency was slightly lower than expected with SMABR alone. The permeate from SMABR was then passed through the OZ column for tertiary nutrients removal. The final effluent analysis confirmed that nutrients could be additionally removed resulting in over 87% and 46% removal efficiencies for T-N and T-P, respectively. The results of this study suggest that the waste oyster-shell can be effectively reclaimed as an adsorbent in advanced tertiary wastewater treatment processes in combination with SMABR equipped with non-woven fabric filter.

• Korean Journal of Materials Research
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• v.12 no.9
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• pp.747-749
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• 2002

Hydroxyapatite powders were prepared after heating at $1250^{\circ}C$ by the direct reaction using oyster shells and $H_3$$PO_4$. Properties of hydroxyapatite powders were investigated as XRF, XRD, DTA, FT-IR, SEM. Only hydroxyapatite was observed in XRD powders which was heated at $1250^{\circ}C$ for 2 hours and there was no remained CaO in that sample. And the results of FT-IR of sample was confirmed hydroxyapatite. Sample was agglomerated together, but needle shape morphology was observed in powders heated at $1250^{\circ}C$.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.75-76
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• 2022

In the event of a fire in the lower space, a high temperature of 1000℃ or more and an explosive fire may occur due to the closed structural features and combustible materials. On the other hand, more than 90% of oyster shells are made of CaCO₃, and when heated to about 700℃ or higher, CaO and CO₂ is generated due to decarboxylation reaction. In this study, we try to infer the amount generated by CO₂ changing the weight of mortar using oyster shells as fine aggregates after heating. in conclusion It is considered that the smaller the particle, the greater the decarboxylation reaction and the greater the weight change.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.37-38
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• 2023

The purpose of this study is to manufacture mortars incorporating oyster shells and install them in the form of shaped, shaped butt joints, and flat boards to see what difference there is in the back temperature depending on the joint method and the type of installation. Based on the fact that similar backside temperatures were measured regardless of the presence or absence of a joint It is judged that the joint will not affect the backside temperature if it is constructed closely, In the case of ㄱ shaped, it is believed that the backside temperature higher than the backside temperature of the flat board was measured because heat accumulates on the backside during heating.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.7
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• pp.873-880
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• 2020

After pre-treatment of oyster shells according to particle size (0 ~ 1, 1 ~ 2, 2 ~ 5 mm) and pyrolysis temperature (400(P400), 500(P500), 600(P600), 800(P800)℃), changes in the properties of sediments mixed with pre-treated oyster shells were investigated. The primary component of the oyster shell was changed from CaCO3 to CaO at temperatures above 700℃. The Ca2+ concentration in P800 was 790 mg/L, which was 2 ~ 3 times higher than those in the control and other experimental samples. Ca2+ elution significantly increased at the pyrolysis temperature over than 600℃. In oyster shells pyrolyzed over 600℃, the pH of the pore water increased by 0.1 ~ 0.5, due the hydrolysis of CaO formed by the pyrolysis of CaCO3. The PO4-P of the overlying and pore water in P600 and P800 were 0.1 ~ 0.2 mg/L lower than those of the control. The increased pH and elution of Ca2+ from oyster shells should suppress the upwelling of PO4-P from the sediment. Based on the above results, it was confirmed that the pyrolysis temperature of oyster shells influenced NH3-N and PO4-P concentrations in the sediment; however, the particle size of oyster shells had little effect. The results of this study can be used as a foundation for research on the use of pyrolyzed oyster shells to improve low-contamination coastal benthic environments.

• Korean Journal of Environmental Agriculture
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• v.28 no.4
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• pp.378-385
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• 2009

Arsenic (As) is known to be very toxic and carcinogenic to human beings. Arsenic contaminated soil was collected from a timber mill site at Busan Metropolitan City, Korea, where chromated copper arsenate (CCA) had been used to protect wood from rotting caused by insects and microbial agents. The soil was stabilized using both natural oyster shells (NOS) and calcinated oyster shells (POS). The calcination of natural oyster shells was accomplished at a high temperature in order to activate quicklime from calcite. Two different oyster shell particle sizes (-#10 mesh and -#20 mesh) and curing periods of up to 28 days were investigated. The stabilization effectiveness was evaluated based on the Korean Standard Test (KST) method (1N HCl extraction). The stabilization results showed that the POS treatment was more effective than the NOS treatment at immobilizing the As in the contaminated soils. A significant As reduction (96%) was attained upon a POS treatment at 20 wt% and passed the Korean warning standard of 20 mg/kg ('Na' area). However, an As reduction of only 47% (169 mg/kg) was achieved upon a NOS treatment at 20 wt%. The -#20 mesh oyster shells seem to perform better than the -#10 materials. The scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDX) results showed that As immobilization was strongly associated with Ca and O in the presence of Al and Si.