Earticle

수산물 처리과정중에서 다량으로 발생하는 폐굴껍질을 흡착제로 활용하는 방안을 모색하고자 이의 물성을 분석하였다. 폐기되는 굴껍질의 조성은 대부분 CaCO3 인 것으로 나타났으며 온도를 증가시키면서 굴껍질을 열분해를 시키면 온도에 따라 수분과 CO2에 의한 분해가 일어나 약 46% 의 무게 감량을 보인다. pH 가 증가할수록 흡착되는 불소 이온의 양은 크게 감소했다. 또한 산성 불소 폐수가 흡착 반응의 평형에 도달하였을 경우 굴껍질에서 용해된 CO23-의해 중화되는 경향이 관찰되었다.

The material properties of waste oyster shell, which is largely generated from the treatment of marine products, have been investigated for its possible utilization as an adsorbent for fluoride ion-containing wastewater. The major composition of waste oyster shell was analyzed to be CaCO3 and loss of 46% in weight reduction occurred during its thermal treatment by the emission of moisture and CO2. The surface structure of oyster shell was decomposed by the heating and its surface potential was negatively increased with pH. As the pH of wastewater was increased, the adsorbed amount of fluoride ion onto oyster shell was decreased and the wastewater was found to be neutralized during adsorption process by CO32- which generated from the partial dissolution of oyster shell

Oyster shells, a major by-product of the shellfish industry (37~70% of an oyster’s mass), generate substantial waste. This study investigates their use in synthesizing calcium sulfoaluminate (CSA) cement, a sustainable alternative to ordinary Portland cement (OPC) with lower environmental impact. Oyster shells decompose at lower temperatures than limestone due to their porous microstructure, facilitating CO₂ release. Alunite undergoes two decomposition stages: dihydroxylation (500~580℃) and desulfurization (580~780℃). CSA was successfully synthesized using alunite and oyster shells at 1,100~1,250℃, with an optimal molar ratio of 1/10. Ye’elimite(Ca4(AlO2)·6SO4) formation occurred at 800℃ when oyster shells are used, significantly lower than 950℃ for limestone, improving energy efficiency. The clinker exhibited reduced chloride content due to the volatilization of calcium and sodium chlorides. Compressive strength tests demonstrated that OPC mixed with 10% CSA exhibited significantly higher compressive strength, achieving 73.55 MPa at 28 days, thereby confirming its potential as a viable and sustanible alternative in cement.

본연구는수산폐기물인폐굴껍질과우리나라에넓게분포되어있는황토를이용하여응집제를제조하기위한것으로서응집제원료의성분조사결과, 폐굴껍질은 CaO 성분이 55.43(wt%) 로가장많이함유되어있었고, 황토는 SiO2가 45.30(wt%) 로주성분임을알수있었다. 폐굴껍질내의 CaO 순도를높이기위해 900oC에서 2시간동안소성하였으며, ball mill 을사용하여 0.074 mm(200 mesh) 로분쇄하였다. 소성된폐굴껍질분말과황토분말을각각 6 : 4, 7 : 3, 8 : 2, 9 : 1 의비율로혼합하여응집제를제조하였다. 또한제조된응집제와화학소석회와의비교실험을통해화학소석회의대체가능성을확인하였다.

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), SiO2(45.30% by weight). Waste oyster shell was calcined to improve the purity of CaO at the calcination condition of 900oC for 2hours, and then crushed 0.074 mm(200 mesh) 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

본 연구는 폐금속광산 산성토양에서 탄소흡수량 증가를 위해 폐석회와 굴패각을 혼합한 토양중화제가 소나무 묘목 근원경 생장과 주변 산림으로부터의 초본 유입 및 토양특성에 미치는 영향을 평가하여 토양중화제의 적정 혼합비율을 선정하기 위해 수행되었다. 토양중화제 혼합비율은 토양중량대비 0.6%, 1.0%, 1.2%, 1.6%였다. 모든 중화제 처리구의 혼합비율에서 소나무 묘목의 근원경 생장과 초본 유입이 촉진되었다. 또한, 토양 pH가 중화제 처리에 따라 개선되었다. 1.6% 처리구가 소나무 묘목 근원경 생장량과 주변 산림에서 유입된 초본의 총개체수, 토양내 TOC와 총질소 함량이 다른 처리구에 비해 높았다. 본 연구에서 중화제 혼합비율은 소나무 묘목의 근원경 생장량과 생존률, 주변 산림으로부터 초본 유입과 토양 pH, TOC 함량과 정의 상관관계를 보였다. 이러한 결과로 폐금속광산에서 소나무 묘목과 초본 생육, 토양 화학적 특성, 중화제 비율에 따른 경제성 등을 고려할 때, 본 연구 대상지인 폐금속광산에서 산림복구를 위해 1.6% 처리가 적합하다. 하지만 다른 폐금속광산에 토양 중화제를 적용하기 위해서는 현장실험을 통해 적정 중화제 혼합비율을 선정해야 한다.

The objective of this study was to select a proper mixing ratio of soil neutralizer (waste-lime and oyster mix) by assessing treatment effect on the root collar diameter (RCD) growth of Pinus densiflora seedlings, the inflow of herbaceous vegetation from the forest edge, and soil characteristics in the acid soil of abandoned metal mines to increase carbon uptake. The mixing ratios of the soil neutralizer were 0.6%, 1.0%, 1.2%, and 1.6% in comparison with the soil weight. All soil neutralizer treatments promoted RCD growth and survival of P. densiflora seedlings and the inflow of herbaceous vegetation from the forest edge. In addition, soil pH was improved by the soil neutralizer treatment. Treatment with 1.6% soil neutralizer resulted in increased RCD growth of P. densiflora seedlings, total population of herbaceous plants from around the forest, TOC, and total N. In this study, the mixing ratio showed a positive correlation with RCD growth and survival of P. densiflora seedlings, the inflow of herbaceous vegetation, soil pH, and TOC. The results of this study indicated that treatment with soil neutralizer at a ratio of 1.6% is applicable for rehabilitation in this abandoned metal mine considering the growth of P. densiflora seedlings and herbaceous vegetation, soil chemical characteristics, and economic feasibility. However, it is necessary to conduct field experiments to select a proper mixing ratio of soil neutralizers to apply in other abandoned metal mines.

The objective of this study is to develop the sorbent of oyster shell, which can remove gaseous acid pollutants emitted from the incinerator and power plants. The physicochemical properties of prepared absorbents have been measured using ICP and BET Also, this study is to investigate the Hydration/calcination reaction in the fixed bed reactor. Thus, the results could be summarized as follows. Oyster shell can be used in powder type without former processing. It should be also noted that sulfation reactivity of oyster sample increases to about 5 times by calcination/hydration reaction due to the increase of specific surface area and pore volume. From these experiments, we have found that both $SO_2$ and $NO_x$ in simulated flue gas can be effectively removed by use of oyster absorbent.

Dry grinding of a mixture of CaCO$_3$ and Ca(H$_2$PO$_4$)$_2$.$H_2O$ was conducted using a planetary ball mill in order to investigate solid state reaction for a synthesis of hydroxyapatite(Ca$_{10}$(PO$_4$)$_{6}$(OH)$_2$, HAp) through mechanochemical treatment method. The raw materials, which are composed of waste oyster and calcium biphosphate Ca(H$_2$PO$_4$)$_2$.$H_2O$, were mixed and then treated mechanochemically. The synthesis of hydroxyapatite(Ca$_{10}$(PO$_4$)$_{6}$(OH)$_2$, HAp) from the mixture was almost completed by about 60 minute grinding. The formation of HAp monophase in the ground mixture was characterized through X-ray diffraction (XRD) analysis. Moreover, the formation of HAp monophase depending on the grinding time was improved by increasing the grinding time.ime.ime.

Limestone is an important commodity in Philippines. Limestone has numerous uses that range from agricultural applications to building materials to medicines. Many limestone products require rock with specific physical and chemical characteristics. Most limestone is biochemical in origin meaning the calcium carbonate in the stone originated from shelled oceanic creatures. In this paper, we reported the natural sources of limestone, geological formation of limestone and the oyster shell waste in Cebu, Bantayan, Philippines were reported. Due to the mining or quarrying in Cebu, Bantayan, in a limestone area poses the threat of groundwater pollution (since limestone is a porous geologic formation with a high transmissivity). The other environmental issue is oyster shell waste. The oyster shell waste is the major source of limestone. We developed and applied appropriate technologies for the extraction of limestone from oyster shell waste and utilizes as high value added material.

To evaluate the remediation performance of recycled oyster shell powders to control nutrients release from polluted sediments. Different types of recycled oyster shell powder were applied on separated bottom sediments. The first type of oyster shell powder is Calcined Oyster Shell Powder (COSP) and another consist of ultrasonicated oyster shell powder (SOSP) which were composed of calcium peroxide. The recycled oyster shell powders were improving the water quality as slow oxygen releasing compound. The experimental results indicated that the Dissolved Oxygen (DO) in the treated columns were higher than the control column. pH was increased in the both experimental columns due to the hydrolysis of CaO₂. Meanwhile, recycled oyster shell powders could prevent the nutrients (nitrogen and phosphorus) release from sediments into the overlying water. In addition, the total nitrogen and total phosphorus concentrations of the COSP applied column were decreased 27% and 20% compared to the control column respectively and the SOSP applied column were decreased 33% and 27% compared to control in the overlying water. It was proved that, COSP and SOSP can effectively adsorb phosphorus from sediments and prevent phosphorus release into overlying water from bottom sediments. In conclusion, COSP and SOSP applications was increased DO in the overlying water and nutrient released controlled effectively from the sediment.

To evaluate the practical application of oyster shells as construction materials, an experimental study was performed. More specifically, the long-term mechanical properties and durability of concrete blended with oyster shells were investigated. Test results indicate that long-term strength of concrete blended with 10% oyster shells is almost identical to that of normal concrete. However, the long-term strength of concrete blended with 20% oyster shells Is appreciably lower than that of normal concrete. 1'hereby, concrete with higher oyster shell has the possibility giving a bad influence on the concrete long-term strength. Elastic modulus of concrete blended with crushed oyster shells decreases as the blending mixture ratio increases. Namely, the modulus is reduced by approximately 10∼15% when oyster shells are blended up to 20% replacing the fine aggregate. The drying shrinkage strain increases as the blending ratio increases. In addition, the existing model code of drying shrinkage does not coincide with the test results of this study. An adequate prediction equation needs to be developed. The utilization of oyster shells as the fine aggregate in concrete has an insignificant effect on freezing and thawing resistance, carbonation and sulfuric acid attack of concrete recycling. However, water permeability is considerably improved.

The objective of this research paper is to discuss the waste coffee residue disposal and its environmental effects on the environment. As we know, coffee is one of the most demand and swallowed beverages in the world, which leads to large quantities of solid waste. Which can be toxic and a lot of environmental problems occur. In developing countries, there is a lack of proper coffee waste residue management. The coffee beans and residues contain several organic compounds. The wastewater from coffee industry emitted several pollutants (highly concentrated) and it contaminates the soil, ground waters, aquatic life, and also human health. Hence it is essential to treat the coffee waste residues. Mean while, oyster shell waste and its disposal also a big environmental challenge in the coastal regions of southeast Korea. In this paper, we focused the treatment of coffee waste residue with oyster shell waste powder. Primarily, oyster shells are calcinated at higher temperatures and investigated the calcined CaO powder as an anti microbic agent to the bacteria presented in coffee waste residues. We successfully applied calcium oxide from oyster shell waste, as an antimicrobic agent.

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.

In this paper, we investigated the alternative sources of limestone. Oyster shell waste originated from aquaculture that causes a major disposal landfill problem in coastal sectors in southeast Korea. Their inadequate disposal causes a significant environmental problems araised. Bio mineralization leads to the formation of oyster shells and consists $CaCO_3$ as a major phase with a small amount of organic matter. It is a good alternative material source instead of natural lime stone. The utilization of oyster shell waste for industrial applications instead of natural limestone is major advantage for conservation of natural limestone. The present work describes the limestone and oyster shells hydraulic activity and chemical composition and characteristics are most similar for utilization of oyster shell waste instead of natural limestone.

A water treatment agent with antimicrobial activity(Ag-Os) was created by exchanging silver ion($Ag^{+}$) on calcined oyster shell powder. The desorption of the exchanged silver ion was negligible, thereby indicating a stable antimicrobial water treatment agent. The sterilization effect of Ag-Os on underwater microorganisms was then investigated. An MIC (Minimum Inhibitory Concentration) test result indicated that Ag-Os had an excellent sterilization effect on G-germs, such as Escherichia coli and Pseudomonas aeruginosa. Most germs were annihilated with an Ag-Os concentration of 200 ppm and contact time of 60 minutes. The sterilization effect was mainly dependent on the contact time. The zeta potential of the Ag-Os powder adsorbed on sand was measured relative to the concentration of exchanged silver ion. As the concentration of the exchanged silver ion increased, the surface charge density of the anions on the surface of the Ag-Os powder adsorbed on sand also increased. Accordingly, this result indicated that a higher silver ion than ion exchange capacity was present on the particle surface due to adsorption. Consequently, this increased concentration of exchanged silver ion would appear to significantly enhance the sterilization power.

In this paper, we reported that the influence of advanced functional mineral filler calcium carbonate ($CaCO_3$) extracted from oyster shell waste, which are rich mineral sources of $CaCO_3$. Oyster Shells, available in abundance, have no eminent use and are commonly regarded as waste. Their improper disposal causes a significant level of environmental concern and also results in a waste of natural resources. Recycling shell waste could potentially eliminate the disposal problem, and also turn an otherwise useless waste into high value added products. Oyster shell waste calcination process to produce pure lime (CaO) which have good anti-microbial property for waste water treatment and then focuses on its current applications to treat the coffee waste and its effluents for biological treatment and utilization as a fertilizers.

Humic acids react with chlorine to produce Trihalomethanes(THMs), known as carcinogens, during disinfection, the last stage in water purification. Currently, the removal of organic humic acids is considered the best approach to solve the problem of THM formation. Accordingly, the current study examined the adsorption of organic compounds of humic acids onto an inorganic carrier prepared from oyster shell waste. The adsorbent used was activated oyster shell powder(HAP) and silver ion-exchanged oyster shell powder(HAP-Ag), with CaCO$_3$ as the control. The adsorbates were phthalic acid, chelidamic acid, catechol, dodecylpyridinium chloride(DP), and 2-ethyl phenol(2-EP). The adsorption experiments were carried out in a batch shaker at $25^{\circ}C$ for 15 hours. The equilibrium concentration of the adsorbate solution was analyzed using a UV spectrophotometer and the data fitted to the Langmuir isotherm model. Since the solution pH values were found to be greater than the pKa values of the organic compounds used as adsorbates, the compounds apparently existed in ionic form. The adsorptive affinities of the organic acid and phenolic compounds varied depending on the interaction of electrostatic forces, ion exchange, and chelation. More carboxylic acids and catechol, rather than DP and 2-EP, were adsorbed onto HAP and HAP-Ag. HAP and HAP-Ag exhibited a greater adsorptive affinity for the organic compounds than CaCO$_3$, used as the control.