• Resources Recycling
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• v.7 no.3
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• pp.36-41
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• 1998

Objective of the research is to deteonine the praeLic따 running parameters for neutralization and removal of heavy metals from plating wastewater with waste-oyster shells by the Bohart$.$Adams equation. Waste-oyster shells discharged from the d domestic oyster cultnring fields cause a serious ocean environmental pollution. However, it is expected that those are able to b be recycled for removal of heavy metals through neutralization of plating wastewater because the shells contain approximate 93% $CaCO_3$, and have multi-pore voids. By applying the results of the continuous experiments to Bohart-Adams equation, s service time decreases in the order of Cr>Fe>Cu while removal efficiencies of metals become less in the order of Fe>Cr>Cu.

• Journal of Environmental Health Sciences
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• v.26 no.3
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• pp.43-49
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• 2000

A laboratory experiments were performed to investigate the effects of several factors on the phosphorus removal by waste oyster shells. The waste oyster shells used in this experiments were crushed particle, calcined particle and extracted solution. A higher efficiencies of phosphorus removal were observed, when a particle size of crushed and calcined particle were smaller. The effluent concentration of phosphorus was around 1.6mg/ι in continuous column experiment which packed with crushed particle of waste oyster shell at the influent concentration of PO4-P of 10 mg/ι. But the clogging of column occurred with increasing of throughput volume of influent. The efficiency of phosphorus removal increased with increasing of dosage amount of crushed, calcined particle and extracted solution. When the calcined particle which contained only about 1/10~1/100 of crushed particle was used, the efficiency of phosphorus removal was correspondingly equivalent to the removal efficiency obtained from crushed particle. The efficiency of phosphorus removal by calcined particle after 9 runs repeated use was decreased about 21.5% as that of the first run. The removal efficiency of 100% could have been achieved at the HRT of 18 hours during the continuous treatment of phosphorus by the solution extracted from calcined particle.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.553-560
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• 2005

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

• Economic and Environmental Geology
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• v.52 no.2
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• pp.119-128
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• 2019

About 300,000 tones of oyster shell are annually produced in Korea and, thus, a massive recycling plan is required. Many desulfurizing studies using oyster shells with chemical composition of $CaCO_3$ have been performed so far; however, most of them have focused on dry desulfurization. This study investigates the possibility of using oyster shells for wet desulfurization after calcination. For this, a simulated wet desulfurization facility of spray type was devised and compared the SOx-stripping characteristics of calcined oyster shell with those of limestone. The calcined oyster shell slurry indicate a better desulfurizability than the slurries of raw shell or limestone because the oyster shell transformed to a more reactive phase ($Ca(OH)_2$) by the calcination and hydration. Because of this reason, when the calcined oyster shell slurries were used, the reaction residue showed the higher gypsum ($CaSO_4{\cdot}2H_2O$) contents than any other cases. In the continuous desulfurization experiments, calcined oyster shell slurry showed a wider pH variation than limestone or raw oyster shell slurries, another clear indication of high reactivity of calcined oyster shells for $SO_2$ absorption. Our study also shows that the efficiency of wet desulfurization can be improved by the use of calcined oyster shells.

• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.1-6
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• 2016

In this year, Koreans have a shortage in agricultural and drinking water due to severe algal blooms generated in major lakes. Waste oyster shells were obtained from temporary storage near the workplace at which oysters were separated from their shells. Heating ($1000^{\circ}C$ for 1 h in air) was employed to convert raw oyster shell powders into calcium oxide powders that reacted efficiently with phosphorus and nitrogen to remove algal blooms from eutrophicated wastewater. As the dispersed amount of heated oyster shell powders was increased, water clarity and visual light penetration were improved. Coagulation, precipitation and carbonation process of the heated oyster shell powders in a water purifier facilitated removal of eutrophication nutrient such as phosphorus and nitrogen, which is both beneficial and economically viable. $CO_2$ implantation by carbonation treatment not only produced thermodynamically stable CaO in oyster shells to derive precipitated calcium carbonate (PCC) but also accelerated algal removal by activation of coagulation and precipitation process. The use of oyster shell powders led to a mean reduction of 97% in total phosphate (T-P), a mean reduction of 91% in total nitrogen (T-N) and a maximum reduction of 51% in chemical oxygen demand (COD), compared with the total pollutant load of raw algal solution. Remarkable water quality improvement of algal removal by heated oyster shell powders and PCC carbonation treatment will allow utilization as water resources to agricultural or industrial use.

• Economic and Environmental Geology
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• v.51 no.6
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• pp.485-492
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• 2018

About 300 thousand tones of oyster shells are produced annually and, thus, their massive recycling methods are required. Recently, a method, utilizing them as wet desulfurization materials after removal of organic matters and changing $CaCO_3$ phase into CaO through calcination, is under consideration. This study investigates the mineralogical changes (specific surface area, phase changes, surface state, etc.) of oyster shells by calcination and their characteristics were compared with those of limestone. Uncalcined oyster shells showed the higher specific surface area than limestone because the former are composed of platy and columnar structures. In contrast, investigated limestone showed a dense structure. The phase change of oyster shells occurred at lower temperature than that of limestone. The specific surface area of oyster shell decreased significantly after calcination while limestone depicted a drastic increase. Small amount of Na contained in oyster shell was suggested as the cause of this phenomenon; in that, it acted as a flux causing melting and sintering of oyster materials at lower temperature. Because of this, an additional phenomenon was observed that a part of shell materials remained untransformed even at higher calcination temperature and after longer treatment period due to the sintered surface, which covers the rest parts. Further studies investigating the effect of this phenomena from the perspective of desulfurization is required.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.43-44
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• 2017

In this study, mortar strength was measured by grinding oyster shell and changing the particle size distribution. For the experiment, the oyster shells were processed to a fine aggregate size of 10mm or less. In this experiment, seven particle size distribution conditions were selected and tested. Because oyster shells are different in density from sand, their volume ratios were calculated and converted to mass ratios of 1: 3. The strength test was carried out one day after the steam curing.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.33-34
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• 2022

The purpose of this study was to provide basic data for applying oyster shells and egg shells as fireproof cladding materials by substituting fine aggregates for oyster shell powder and egg shell powder, and comparing strength and fire resistance performance. The reason for the high strength was thought to be that the oyster shell had higher strength than the egg shell itself, and both ESP and OSP were measured at a backside temperature of less than 500℃, so it was judged that it could be used as a fireproof coating for steel structures.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.281-290
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• 2003

In order to investigate recycling possibility as a construction material of oyster-shells, the geotechnical characteristics including permeability, confined compression and shear strength of crushed oyster shell were quantitatively examined in terms of fineness modulus and relative density of crushed oyster-shell. Experimental results show that the crushed oyster-shells are lighter than sand in weight, and have similar characteristics on permeability and shear strength to sandy soils. The oyster-shell can be considered as highly crushable material but not much crushable with existing high loads. Based on the laboratory test results, it is highly fudged that the crushed oyster-shell can be a substitute of sand as SCP materials.

• Korean Journal of Environmental Agriculture
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• v.18 no.1
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• pp.48-53
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• 1999

In this study, various batch tests were performed to examine the utilization of waste oyster shells for removal of $PO_4^{3-}-P$ in livestock wastewater, because waste oyster shells have been known to be very porous and to have alkaline minerals such as calcium and mangnesium. $PO_4^{3-}-P$ removal rate were increased by waste oyster shells, as specific surface area and contact efficiency per unit area of their were increased. Generally, it could be showed that $PO_4^{3-}-P$ removal rate were very influenced by particle size, dosage and temperature. At low pH of initial reactions, it would be showed that $PO_4^{3-}-P$ removals were directly influenced by adsorption but crystallization process were dominated with passed time and pH increasing. The SEM observed that the variations were hardly seen, but particle sizes of waste oyster shell were relatively big after reactions and showed forms of smaller plate than before reactions.