• 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.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.3
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• pp.185-193
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• 2020

There have been many studies on the calcination of oyster shells in the perspective of recycling of resources. The quicklime made by the calcination of oyster shells is used either as it is or after reacting with water to transform to liquid lime before being used. However, the liquid lime made from calcined oyster shells show slightly different properties from that of limestone. In this study, to compare these properties of oyster shell with those of limestone, the samples were calcined and reacted with water at various temperatures to transform to a liquid lime and filtered using 150 ㎛ sieves to calculate the transform rate to liquid lime. The calcined limestone was transformed to liquid lime at all temperatures, but calcined oyster shell did not show any transformation at 30℃ and 50℃ under the experimental conditions of this study, and rather increased the weight for the remaining after filtration due to the presence of Ca(OH)₂ produced by the reaction with water, Even at 90℃, the transformation rate of calcined oyster shell to liquid lime was lower than that of limestone. This difference in oyster shell can be explained partly by the preventing calcined one from reacting with water by conchiolin which is protein found in the prismatic and pearl layers of oyster shell. Conchiolin is also known to be stable and does not decompose even at high temperature. However, even the calcined chalk layer without conchiolin shows lower transformation rate than that of calcined limestone, probably due to the small amount of Na in oyster shell, which may cause additional reaction including eutectic melt during calcination process.

• Journal of Energy Engineering
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• v.26 no.2
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• pp.39-49
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• 2017

Coffee is one of the most popular and consumed beverages in the world, which leads to a high contents of solid residue known as spent coffee grounds (SCG). As is known, coffee beans contain several classes of health related chemicals, including phenolic compounds, melanoidins, diterpenes, xanthines and carotenoids. The waste water coming out of coffee industries has high concentration of organic pollutants and is very harmful for surrounding water bodies, human health and aquatic life if discharged directly into the surface waters. Hence it is essential to treat and manage the coffee waste. Oyster shells are a waste product from mariculture that creates a major disposal problem in coastal regions of southeast Korea. In the study, the oyster shell waste was used to treat the coffee waste and its effluents. Oyster shells are calcined at $1000^{\circ}C$ for 2 h, and allowed to test the calcined CaO powder ability to inhibit the growth of bacteria in different aging coffee wastes. Calcined oyster shell powder showed anti-bacterial effect that inhibited cell growth of Escherichia coli and other bacterial forms. The antimicrobial activity of calcium oxide from oyster shell waste for biological treatment and utilization as a fertilizers with economic ecofriendly in nature.

• 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.

• Resources Recycling
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• v.11 no.2
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• pp.45-51
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• 2002

This study was performed to investigate removal efficiency of wastewater by the prepared coagulant using waste oyster shell and loess. Waste oyster shell and loess contain respectively high CaO(55.43% by weight), $SiO_2$(45.30% by weight). Waste oyster shell was calcined to improve the purity of CaO at the calcination condition of $900^{\circ}C$ for 2hours, and then crushed 0.074 mm(200mesh) size by ball mill. Also, coagulant was prepared with calcined waste oyster shell and loess powder by hydration reaction. Calcined waste oyster shell and loess powder were combined with mixing ratio of 6 : 4, 7:3, 8:2 and 9:1. Though comparison experiment between prepared coagulant and chemical )$Ca(OH_2$, prepared coagulant was proved as having replaceable possibility of chemical )$Ca(OH_2$in wastewater treatment plant.

• Journal of the Korean Ceramic Society
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• v.53 no.4
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• pp.429-434
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• 2016

Here, we introduce a means of utilizing waste oyster shells which were obtained from temporary storage near coastal workplaces as $CO_2$ adsorbents. The calcined CaO can be easily dissociated to $Ca^{2+}$ cation and $CO_3{^{2-}}$ anion by hydrolysis and gas-liquid carbonation reaction and converted to precipitated calcium carbonate (PCC) in algae-containing water. The calcium hydroxide and carbonation combination in algae-containing water significantly contributed to improving water quality which is very dependent on the addition amount of calcined powders.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.25 no.2
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• pp.57-62
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• 2019

The management of oyster shell disposal is an ongoing challenge in the southern coast of Korea because of continuously dumping the oyster shell in environment. Oyster shell wastes could be a biocidal alternative after calcination using a heat treatment. Calcined oyster shell is normally obtained through thermally conversion of $CaCO_3$ (main component in oyster shell (96%)) into CaO. This study provides a brief overview of oyster shell disposal and its potential as an antimicrobial agent with a focus on calcination process, antimicrobial mechanisms, and packaging applications.

• Journal of Environmental Science International
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• v.28 no.10
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• pp.851-861
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• 2019

In this study, we performed a sediment elution experiment to evaluate water quality in terms of phosphorus, as influenced by the dissolved oxygen consumed by sediments. Three separate model column treatments, namely, raw, calcined, and sonicated oyster shell powders, were used in this experiment. Essential phosphorus fractions were examined to verify their roles in nutrient release from sediment based on correlation analyses. When treated with calcined or sonicated oyster shell powder, the sediment-water interface became "less anaerobic," thereby producing conditions conducive to partial oxidation and activities of aerobic bacteria. Sediment Oxygen Demand (SOD) was found to be closely correlated with the growth of algae, which confirmed an intermittent input of organic biomass at the sediment surface. SOD was positively correlated with exchangeable and loosely adsorbed phosphorus and organic phosphorus, owing to the accumulation of unbound algal biomass-derived phosphates in sediment, whereas it was negatively correlated with ferric iron-bound phosphorus or calcium fluorapatite-bound phosphorus, which were present in the form of "insoluble" complexes, thereby facilitating the free migration of sulfate-reducing bacteria or limiting the release from complexes, depending on applied local conditions. PCR-denaturing gradient gel electrophoresis revealed that iron-reducing bacteria were the dominant species in control and non-calcined oyster shell columns, whereas certain sulfur-oxidizing bacteria were identified in the column treated with calcined oyster powder.

• Korean Journal of Environmental Agriculture
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• v.40 no.1
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• pp.40-48
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• 2021

BACKGROUND: Although the calcined oyster shell can be used as a calcium-rich adsorbent for phosphate removal, information about it is limited. The purpose of this study was to evaluate the phosphate adsorption characteristics and its mechanism using calcined oyster shells. METHODS AND RESULTS: In this study, calcined oyster shell (C-OS600) was prepared by calcining oyster shells (P-OS) at 600℃ for 20 min. Phosphate adsorption by C-OS600 was performed under various environmental conditions. Phosphate adsorption by C-OS600 occurred rapidly at the beginning of the reaction, and the time to reach equilibrium was less than 1 h. The optimal isotherm and kinetic models for predicting the adsorption of phosphate by C-OS600 were the Langmuir isotherm and pseudo-second order kinetic model, respectively, and the maximum adsorption capacity derived from the Langmuir isotherm was 68.0 mg/g. The adsorption properties of phosphate by C-OS600 were dominantly influenced by the initial pH and C-OS600 dose. In addition, SEM-EDS and FTIR analysis clearly showed a difference in C-OS600 before and after phosphate adsorption, which proved that phosphate was adsorbed on the surface of C-OS600. CONCLUSION: Overall, the calcined oyster shell can be considered as an useful and effective adsorbent to treat wastewater containing phosphate.

• Cement Symposium
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• no.27
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• pp.6-13
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• 2000