• Journal of Korean Society of Environmental Engineers
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• v.35 no.3
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• pp.226-232
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• 2013

Several pretreatment processes such as softening, coagulation and precipitation, activated carbon adsorption, ion-exchange and neutralization processes were studied to remove organics and inorganics for selection of the RO based reusing system of metal industry wastewater. The effects of the hydrophobic/hydrophilic fractions of the organics on DOC removal were tested and used to optimize the combination process. Among various pretreatment processes, softening could reduce 93.4% of hardness and could remove all hydrophobic organics from the effluent of metal industry wastewater. Softening followed by coagulation process could reduce DOC (Dissolved Organic Carbon) from 5.1 mg/L to 1.6 mg/L. In addition, as a result of physiochemical pretreatment to raw wastewater of metal industry, neutralization with NaOH showed an efficient removal of iron and TDS (Total Dissolved Solids) without increase in the hardness.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.627-636
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• 2022

In nuclear power plants and other nuclear facilities the removal of cobalt from radioactive liquid waste is needed to reduce the radioactivity concentration in effluents. In liquid wastes containing strong organic complexing agents such as EDTA cobalt removal can be problematic due to the high stability of the Co-EDTA complex. In this study, the removal of cobalt from NaNO₃ solutions using antimony oxide (Sb₂O₃) synthesized from potassium hexahydroxoantimonate was investigated in the absence and presence of EDTA. The uptake studies on the ion exchange material were conducted both in the dark (absence of UV-light) and under UV-C irradiation. Ca²⁺ or Ni²⁺ were included in the experiments as competing cations to test the selectivity of the ion exchanger. Results show that UV-C irradiation noticeably enhances the cobalt sorption efficiency on the antimony oxide. It was shown that nickel decreased the sorption of cobalt to a higher extent than calcium. Finally, the sorption data collected for Co²⁺ on antimony oxide was modeled using six different isotherm models. The Sips model was found to be the most suitable model to describe the sorption process. The Dubinin-Radushkevich model was further used to calculate the adsorption energy, which was found to be 6.2 kJ mol^-1.

• Journal of Korea Soil Environment Society
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• v.3 no.2
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• pp.89-99
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• 1998

Sorption of the aqueous cyanide onto steel mill sludge and steel mill slag, both of which are the by-products from the converter furnace, was studied. In the study, the influence of temperature, activation energy, concentration and pH on sorption of cyanide was investigated. Three different temperature($25^{\circ}C$ > $37^{\circ}C$> $50^{\circ}C$) was chosen to represent that of landfill leachate. Initial concentration was 1 mg/$\ell$ 5 mg/$\ell$, 10 mg/$\ell$, and 20 mg/$\ell$. In addition, pH was set to three different level, that is, 3, 7, and 11 respectively. As the result of batch mode experiment for cyanide adsorption, the removal rate was found to be proportional to the initial concentration of cyanide. The order of removal rate was 20 mg/$\ell$> 10 mg/$\ell$> 5 mg/$\ell$> 1 mg/$\ell$. Similarly the influence of pH was proportional because of the change in solubility of cyanide. The order of removal rate was pH 11 > pH 7 > pH 3. As the temperature increased, so did the removal rate. The reaction was endothermic and the value of activation energy(Ea) was 127.93 J/mole and 59.44 J/mole respectively at 1 mg/ιand 20 mg/ιof initial concentration. From the experiment, it can be postulated that the capability of steel mill by-products to attenuate aqueous cyanide is enough to be used as substitute for clay liner of landfill site in the aspect of pollutant removal.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.3
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• pp.265-276
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• 2007

The primary objective of this study is to investigate the effect of media on the performance of biofilters. Two types of experiments were carried out in this study. The first type of experiment used a biofilter with the media composed of three different packing materials of compost, peatmoss and GAC(granular activated carbon), whereas the second type used a biofilter with the media composed of compost only. It was found from the two experiments that the biofilter composed of compost, peatmoss and GAC showed better performance than the one composed of compost only with the higher toluene removal efficiency, lower pressure drop, and more uniform media moisture content. In particular, no appreciable media compression occurred for the biofilter composed of compost, peatmoss and GAC, whereas significant media compression took place in the biofilter composed of compost only. As suggested by the other researchers, it is likely that GAC may be responsible for the higher toluene removal efficiency in the case of the biofilter composed of mixed media especially for the early stage of biofiltration due to its adsorption capability of toluene of such high concentration as 300 ppm. It was also regarded that GAC may playa major role in maintaining lower media pressure drop in the case of the mixed media than the media with compost only because of its mechanical strength resisting to the compression. Nonetheless, further refined experiments may need to draw more accurate conclusion. The results of the additional test run using the same mixed media showed that the biofilter system using the mixed media can be consistently operated for more than 100 days very stably despite sudden change in operating conditions of temperature and flow rate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.4055-4068
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• 2010

In this study, validity of wastewater treatment system with advanced treatment processes was evaluated by studying its operational conditions by applying the advanced treatment to the wastewater treatment system which was operating for last several years. Study indicated a fair result for the removal efficiencies of BOD, T-P, and T-N for each unit operation. BOD removal efficiencies for primary clarifier, bioreactor, final effluent are 35, 87, and 48 % respectively. T-P(T-N) removal efficiencies for primary clarifier, bioreactor, final effluent are 18(23), 40(38), and 25(25) % respectively. Further investigation of bioreactor showed that various microorganism such as bacteria, protozoa, and metazoa is present in the bioreactor, and the main function of the media, adhesion (adsorption) of microorganism onto the media, is stabilized. Final effluent quality was lower than the regulation, and BOD, COD, SS, T-N, T-P were 5.5, 9.9, 4.6, 11.8, 0.99 mg/L respectively.

• 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.

• Microbiology and Biotechnology Letters
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• v.30 no.1
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• pp.73-78
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• 2002

Four inorganic packing materials (zeocarbon, porous celite, porous glass, zeolite) and a earthworm cast were compared with regard to the removal of ammonia in a biofilter inoculated with earthworm cast. Physical adsorption of ammonia on packing materials were negligible except zeocarbon (23.5 g-$NH_3$/kg), and cell immobilization capacity have similar values irrespective of packing materials. Pressure drops of the packed bed were in order of earthworm cast zeocarbon zeolite porous glass porous. The maximum elimination capacity ($g-Nkg^{-1}$ $d^{-1}$ ) of ammonia, which were based on a unit volume of packing material, were in order of zeocarbon (526) earthworm cast (220) porous celite (93) > zeolite (68) > porous glass (53). By using kinetic analysis, the maximum removal rates ($V_{m}$ ) and the saturation constant ($K_{s}$ ) for ammonia were determined, and zeocarbon showed superior performance among the five materials.

• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.39-42
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• 2019

We report on the design of oil-water separators and the selection of materials for the effective application of highly selective membranes fabricated by commercial PET (polyester) fabrics. The waterproof ability of PET fabrics was optimized to improve the separation selectivity. The density of individual PET fabrics should be over $60g/m^2$, and the multi-layered structure is more favorable for the waterproof ability together with maintaining the removal efficiency. For the continuous adsorption and removal process, the rotating perforated cylinder was selected, and covered with membranes. Furthermore, more improved and stable removal efficiency was obtained by installing floating baffles which forces the oil content to move toward membranes.

• Membrane Journal
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• v.30 no.5
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• pp.342-349
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• 2020

In this study, we suggest conditions to reduce fouling in capacitive deionization (CDI) caused by alginic acid sodium salt, one of the most common fouling-causing substances in natural water and wastewater management. First, NaCl is used as feed material, which is selected as the control of the experiment. As expected, fouling phenomena is not observed from NaCl. On the other hand, when alginic acid sodium salt is added to the inlet, the fouling phenomena can be observed. In order to minimize the fouling phenomena, the feed concentration of alginic acid sodium salt, applied potential during desorption process, and duration of applied potential to our CDI cell are controlled. With 7 mg/L of feed stream concentration, CDI performed using 1.2 V for 1 min during adsorption followed by desorption with -2 V for 1 min exhibited the highest alginic acid salt removal efficiency reaching 50.07%.

• Membrane Journal
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• v.27 no.1
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• pp.77-83
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• 2017

Transient behavior of fouling resistance was observed with a laboratory-scaled, submerged microfiltration membrane system treating high-turbidity source water consisting of inorganic silica particles and humic acid. Fouling mitigation efficiency with inorganic silica particles caused by aeration was reduced significantly as both humic acid and calcium ion existed together. Scanning electron microscopic observations showed that humic acid was adsorbed onto the surface of inorganic silica particles in the presence of calcium. Turbidity removal was achieved almost completely by submerged MF system regardless of feed compositions. However, the $UV_{254}$ removal of humic acid was improved in the presence of both calcium and inorganic silica particles. Additionally, increasing air-flow rate tended to increase $UV_{254}$ removal efficiency higher than 80%. This may be caused by back-transport of humic acid enhanced by inorganic silica particles providing surface for organic adsorption in the presence of calcium.