• Journal of Korean Society of Environmental Engineers
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• v.29 no.1
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• pp.82-88
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• 2007

The objective of this study is to examine the effect of the waste oyster shell powder as the addition agent in bulking sludge thickening of paper manufacturing plant using DAF(Dissolved Air Flotation) and gravitational sedimentation. The effect of parameters such as dosage and size distribution of oyster shell were examined. The results showed that the optimum dosage of mixed oyster shell(size range : $\sim250{\mu}m$) was 0.8 g/L. The oyster shell addition of 5.0 g/L in sedimentation process was increased thickening concentration of 3.25 times. When 5.0 g/L of oyster shell was added in DAF process, water content of sludge was decreased from 95.5% to 82.7% in dewatering process using Buchner funnel test device. When size of oyster shell was divided four ranges($\sim53{\mu}m$, $53\sim106{\mu}m$, $106\sim150{\mu}m$, $150\sim250{\mu}m$), optimum size range for the flotation and dewatering was $53\sim106{\mu}m$.

• Clean Technology
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• v.21 no.4
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• pp.241-247
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• 2015

Oyster shells are a waste product from mariculture that creates a major disposal problem in coastal regions of southeast Korea. To make practical use of unused oyster shells, calcined oyster shell (COS) collected from a local company was allowed to adsorb AITC (allyl isothiocyanate), and then tested the powder's ability to inhibit the growth of some potential food borne disease-causing bacteria. COS powder showed bacteriostatic effect that inhibited cell growth of Escherichia coli, Staphylococcus aureus and Salmonella typhimurium from 3 to 5 log10 CFU/mL at concentrations around 1%. The MIC of pure AITC was found as 1 mg/mL, 0.8 mg/mL and 0.7 mg/mL for Escherichia coli, Staphylococcus aureus and Salmonella typhimurium, respectively. The calcined powder adsorbed about 225 mg of AITC per gram of shell, indicating porous material was created by calcination. FTIR data confirmed the adsorption of AITC by COS. Characterization of particle data showed very fine particle size and highly convoluted surface. AITC adsorbed calcined oyster shell (ACOS) completely inhibited bacterial cell at 1% concentration. ACOS showed better antibacterial effect than COS, indicating synergistic effect of AITC and calcined oyster shell powder on bacteria.

• Clean Technology
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• v.19 no.2
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• pp.90-94
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• 2013

We investigated one-dimensional thermal conduction for gypsum objects incorporating oyster shell powder. We presumed that according to the portion of oyster shell in the hybrid structure conductive characteristics of that would also change as some physicochemical properties such as volatile organic compound (VOC) adsorption were found to be changed considerably. Based on Fourier's 2nd law of heat conduction an analytical analysis in a flat slab (one axis perpendicular to an infinite plane) was performed. We found that composition of oyster shell and conduction-related coefficients and parameters could greatly influence on the thermal profile of that conduction, and some model experiments also served for it in the affirmative.

• Preventive Nutrition and Food Science
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• v.15 no.1
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• pp.78-82
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• 2010

This study investigated the effects of water-soluble calcium supplements manufactured with eggshells and oyster shells on growing rats. The aim was to review the potential use of food wastes as materials for water-soluble calcium supplements as compared to water-soluble calcium supplements made from imported seaweed powder. When experimental animals were administered three types of water-soluble calcium supplements orally for six weeks, the serum calcium level of the seaweed calcium supplement group were significantly higher than that of eggshell or oyster shell-derived calcium, but blood alkali phosphatase activity, osteocalcin and urine crosslink levels were not different in the three types of calcium supplements. Bone mineral density and bone mineral content in spine, femur and tibia also were not significantly different among the groups. However, when considering body weight of each group, bone mineral density and bone mineral content of the femur were significantly higher in the oyster shell calcium supplement group. These results suggest that at least on a short-term basis, the effect of calcium supplements prepared from eggshell and oyster shell are similar to the effects of seaweed calcium supplements.

• Journal of Conservation Science
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• v.32 no.2
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• pp.261-271
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• 2016

We have investigated relationship between particle characteristics of oyster shell powder pigments and their performance such as workability and durability. Three types of the powder which have different particle size and shape(spherical, elliptical, columnar and irregular) distributions were made for this study and we evaluated spreadability and uniformity for workability, and adhesion and surface hardness for durability of painted films by each powder paints. As a result, we found out that the workability and durability of the paints were influenced by the particle shape distribution more than the particle size distribution. The durability, especially, was enhanced as the ratio of columnar particles in the powders was increased. This result verifying the important factor affecting the durability can be base data for selecting oyster shell white paint and assessing its quality for conservation and restoration of Dancheong, as well as to produce high quality traditional paints.

• Environmental Engineering Research
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• v.25 no.2
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• pp.230-237
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• 2020

Nitrogen flux release from organically enriched sediments into overlying water, which may have significantly influence on water quality and increasing continuous eutrophication. The purpose of this study is to evaluate the remediation efficiency of oyster shell powder and its treated product into organically enriched sediment in terms of nitrogen flux, organic matter, chlorophyll-a, pH and dissolved oxygen (DO). The TOSP was mainly composed of CaO2. The application of TOSP into the sediment has increased the pH, DO and significantly decreased the concentrations of NH₄⁺-N and T-N compared to other basins. On the other hand, nitrate was enriched with the addition of treated oyster powder, an oxygen releasing compound on both phases. Furthermore, chlorophyll-a was found to be increasing with time in the control basin meanwhile it dropped drastically with the addition of TOSP, which implied on the repression of algal growth owing to blockage of nitrogen source migrating from the sediment. This study has shown that the TOSP was effective to improve sediment-water quality, diminish eutrophication and control harmful algae blooms in a marine environment. Therefore, it is a good reference as an effective environmental remediation agent.

• Clean Technology
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• v.19 no.2
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• pp.134-139
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• 2013

VOCs such as formaldehyde and benzene in a control chamber were adsorbed onto gypsum incorporating oyster shell powder, which was solidified and dried. VOC was first exposed in air and then gypsum mortar was placed in the chamber for 180 min for adsorption. The mortar was prepared with 0, 10, 30, and 50% of oyster shell powder. Two initial concentrations of VOCs including formaldehyde were $27.7{\sim}28.5mg/m^3$ or $175{\sim}150{\mu}g/m^3$. We found out that the initial concentrations did not seem to make any difference in adsorption performance but higher oyster content strongly led to higher adsorption. We used a convection-diffusion-adsorption model to compare the experiment. The model which considers diffusion coefficients of adsorbates and affinity of the adsorbents well represented the experimental data with a fair agreement.

• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.17-21
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• 2001

The object of this study is to find out the characteristics of waste oyster shells and determine the proper dosage of powdered waster oyster shells as the conditioning agent for water treatment sludge dewatering process. The large amount of waste oyster shells which discharges from the oyster farming, occurs serious environmental hazards. However, oysters shell contain large amount(about 38% by weight) of alkaline minerals, such as calcium and magnesium and so on, this natural material is thought to have the petential ability as a good conditioning agent. The results of this study are as follows. The optimum condition for improvement of the water treatment sludge dewaterability is when 6 g of waste oyster shell powder added to 200$m\ell$ of water treatment sludge. At optimum condition, the solid contents can reach to 31.78% and the specific resistance of conditioned sludge is 0.16$\times$10$^{8}$ sec$^2$/g. However, exceeding the of powdered waste oyster shell is needed to get the effective result. Consequently, the waste oyster shell can be a recyclable material to improve the dewaterability of water treatment sludges.

• 보존과학연구
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• s.29
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• pp.199-220
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• 2008

Hobun(Oyster shell White) is a traditional material used as extender and white pigment from ancient times. The production method of it, however, has been discontinued. We have studied the traditional production method of Hobun by weathering oyster shell, which is one of the traditional ways for preparing Hobun. Reproduction study of manufacturing method of the discontinued traditional material is an important accomplishment of our research. Also this study provides solid background knowledge to stabilize the production and supply of Hobun for the cultural asset repairing materials. The result can be summarized as follows: The production process of Hobun by weathering method takes 5 steps - (1) weathering shells ${\rightarrow}$ (2) washing ${\rightarrow}$ (3) pulverization ${\rightarrow}$ (4) separating fine powder by submerging in water ${\rightarrow}$ (5) drying. The major aim in step (1) is to eliminate organic impurities. In the step (4), the fine particles smaller than $25{\mu}m$ are separated by extracting the supernatant from stirred suspension after heavy particles are submerged. Also, the soluble inorganic impurities can be eliminated through the powder submerge in 15 times water and stirring the suspension 6 hours and changing the water 3~4 times. The final products have high quality with 94.03, 0.52, 2.05 for L, a, b, less than $25{\mu}m$ particle size, fine resistance for discoloration by light and environmental pollution and good workability.

• Composites Research
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• v.27 no.5
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• pp.201-206
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• 2014

Utilizing waste materials in making useful products is a globally increasing trend. This can reduce the cost and environmental issues. In this study, oyster shell powder (OSP) is reinforced as a filler in polypropylene (PP) matrix to make a new composite. The purpose is to improve fire retardant properties of PP as a result of OSP reinforcement. Mechanical, fire retardant and water absorption properties of the new composite have been studied in this research. Concentration of OSP reinforcement in PP has been varied by wt% and its effect on the above mentioned properties has been observed. SEM (scanning electron microscopy) images of tensile and bending fractured surfaces have been taken to observe the failure mechanism during mechanical tests. An increase in the fire retardancy has been observed as a result of the OSP reinforcement while tensile strength decreased. Stiffness also increased with the addition of OSP in PP.