• Journal of Korea Water Resources Association
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• v.49 no.9
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• pp.741-748
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• 2016

Laboratory scale model was constructed for open-cut riverbed infiltration experiment and four kinds of media were selected, medium sand, sand, volcanic rock, and gravel, for the experiment. Hydraulic conductivity for each medium and flow rate from the collecting pipe with functional screen were estimated from the experiment. Modified hydraulic conductivity scenarios considering turbid water (30~50 NTU) were applied in Visual MODFLOW modeling to analyze the effects of turbid water on the flow rate. Twenty-two scenarios were generated considering prticles in turbid water and applied to each medium cases in MODFLOW modeling. The minimum error was occurred when the gravel medium had 20% less hydraulic conductivities for the third layer-depth from the top and clay particles in turbid water might play a role in adsorption process to the surface of volcanic rock (2~5 mm). For medium sand case the error was also quite small when the mediumhas 5% less hydraulic conductivities for the second layer-depth from the top.

• Clean Technology
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• v.23 no.1
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• pp.34-41
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• 2017

The scrubber wastewater should be replaced frequently to maintain efficiency. Most chemical companies consign scrubber wastewater, because there are no wastewater treatment facilities. So scrubber wastewater is not frequently replaced because of high treatment cost. For this reason, the most scrubber exhaust gas exceeds the odor emission limit or has a phenomenon that the odor intensity of exhaust gas becomes higher. Therefore we have developed a scrubber wastewater cleaning system consisting of filtration and adsorption processes. The scrubber wastewater cleaning system was applied two chemical companies. We evaluated the water quality and odor reduction effect before and after system application. As a result, scrubber wastewater quality improved by 50% or more, odor reduction efficiency of scrubber exhaust gas improved by 20% or more. And the total operating costs of the scrubber could be reduced by 40% or more.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.4
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• pp.191-195
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• 2017

The microstructures of nonwoven fabric with and without nanofibers used as a filter for air purification type mask were investigated using scanning electron microscope. Moreover, we proposed a new mask design which is effective in the improvement of the fine dust blocking property. When comparing to nonwoven fabrics of which an average diameter was $25{\mu}m$, the nanofibers formed by the electrospinning process had a tight mesh structure arranged irregularly with a relatively large specific surface area, which could be associated with their much smaller diameter ranging from 25 to 120 nm. Such a prominent structural feature at nanofibers led to mechanical adsorption of fine particles, resulting in enhancement of filtering behavior maintaining high permeability. In addition to the excellent performance of the mask filter, wearing the mask properly is expected to maximize the blocking property of fine dust. To meet such a requirement, a new mask design that can be closely attached to the face in order to effectively block fine dust entering the gap between the face and the mask.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.2027-2036
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• 2013

Comparison of removal performance between reverse osmosis(RO), nanofiltration(NF), electrocoagulation(EC) and electroadsorption(EA) for removal of nitrate and fluoride often exceeded the limits of water quality in small water treatment plants. Removals of nitrate and fluoride were 72-92% and 74-85% in RO, 5-15% and 1% in NF, 99% and 44% in EA equipped with MWCNT coated electrodes, 82% and 77% in EA equipped with Cu-MWCNT electrodes, and 11-46% and 69-99% in EC. Consequently, high removals of both ions were anticipated in RO. Effective removal of both ions are possible for EC, but great production of sludge is a big burden. EA equipped with the MWCNT electrodes showed a great fluctuation in removal efficiency, and electrode stability should be upgraded.

• International Journal of Highway Engineering
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• v.14 no.1
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• pp.55-61
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• 2012

The ability of clay mineral to remove non-point sources such as SS, COD, T-N. T-P in the urban runoff has been tested to develop the porous filter material. The diameter of 3mm ball type filters were made of clay minerals for the tests. The experiments were carried out to measure the concentration of non-point sources of contaminants with flow rate of effluents. The test results show that clay filter has good response to remove SS, COD comparing to those of activated carbon filter. Also the performance of the clay filter to remove T-N and T-P is almost the same when using the activated carbon filter.

• 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.

• Journal of Environmental Impact Assessment
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• v.32 no.6
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• pp.431-436
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• 2023

As the industry develops, the amount of heavy metals flowing into the ecosystem is increasing. Heavy metals are difficult to decompose and remain in the ecosystem for a long time and cause toxicity, which is removed by physicochemical methods such as adsorption, filtration, and chemical precipitation during water treatment. In this study, Alginate bead was selected as a chelating resin for adsorbing and removing heavy metals, and the Jellyfish Extract at Immunity reaction (JEI) were mixed to evaluate the adsorption efficiency of heavy metals accordingly. beads mixed with JEI showed high adsorption efficiency in lead (79-99%) and copper (64-70%) according to the characteristics of Alginate, and low adsorption efficiency in cadmium (25-37%) and zinc (5-6%). Although heavy metal adsorption did not increase in proportion to the content of JEI, 50% and 100% JEI beads showed significant increases. As a result of applying the reaction rate equation, it was found that it was more suitable for the pseudo-secondary reaction equation than the pseudo-first reaction equation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.4
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• pp.857-864
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• 2009

This study aimed at developing the two stage and dual filtration system. It has a sand + activated carbon layer above the underdrain system and a sand layer above the middledrain system for pretreatment. When retrofitting an old filter bed or designing a new one, this technology can substitute the existing sand filter bed without requiring a new site. In order to extend the filtering duration, the upper layer of the filter bed consists of the rapid sand filtration with large particles which pre-treats and removes coarse particles and turbidity matters. The middle layer has biological activated carbon(BAC) and granular activated carbon(GAC) to eliminate dissolved organic matters, disinfection by-products precursors etc. The lower layer consists of the sand filtration for the post filtering mode. In this study, a pilot plant of two stage and dual filtration system was operated for 4 months in the S water treatment plant in Kyounggi-Do. The stability of turbidity was maintained below 1NTU. The TOC, THMFP and HAAFP were removed about 90% by two stage and dual filtration system, which is almost 2 times higher than S WTP. From analysis result of HPC along the depth of activated carbon + sand layer at 2nd stage, microorganism was mostly not detected, however, increment of HPC was shown as it becomes deeper. It indicates that growth of microorganism is occurred at activated carbon layer.

• Clean Technology
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• v.23 no.1
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• pp.1-14
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• 2017

At high nitrate concentrations, water must be treated to meet regulated concentrations because it results in threat to human health and eutrophication of natural water. However, it is almost impossible to remove nitrate by conventional water treatment methods such as coagulation, filtration and precipitation, due to its high water solubility. Therefore, other technologies including adsorption, ion exchange, reverse osmosis, denitrification, and electrodialysis are required to effectively remove nitrate. Each of these technologies has their own strengths and drawbacks and their feasibility is weighted against factors such as cost, water quality improvement, residuals handling, and pre-treatment requirements. An adsorption technique is the most popular and common process because of its cost effectiveness, ease of operation, and simplicity of design. Surface modifications of adsorbents have been enhanced their adsorption of nitrate. The nitrate-selective membrane process of electrodialysis reversal and reverse osmosis have proven over time and at many locations to be highly effective in removing nitrate contaminating problems in aqueous solutions. Both electrodiaysis and reverse osmosis methods generate highly concentrated wastes and need careful consideration with respect to disposal.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1180-1185
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• 2005

Iron sand, having iron as a major component, was applied in the treatment of synthetic wastewater containing Cu(II) or Pb(II). To investigate the stability of iron sand at acidic condition, dissolution of Fe and Al was studied with variation of solution pH ranging from 2 to 4.5. Iron concentration in the extracted solution was below the emission regulation of wastewater even at a strong acidic condition, pH 2. Although an important concentration of aluminum was extracted at pH 2, the dissolution greatly decreased above pH 3. This stability test suggests that application of iron sand has little problem in the treatment of wastewater above pH 3. Adsorption capacity of Cu(II) and Pb(II) onto iron sand was investigated in a batch and a column test. In case of Cu(II), rapid adsorption was noted, showing 50% removal within 2 hrs, and then reached a near complete equilibrium after 24 hrs. Adsorption was favorable at higher pH in each metal ion and showed a near complete removal above pH 6, indicating a typical cationic-type adsorption. From the adsorption isotherm obtained with variation of the concentration of each metal ion, the maximum adsorption capacity of Cu(II) and Pb(II) was identified as 2,170 mg/kg 및 3,450 mg/kg, respectively.