• Membrane Journal
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• v.19 no.2
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• pp.136-144
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• 2009

In this study, sodium dedocyl sulfate (SDS), which was anionic surfactant, was added for forming micelles to remove ferrous ions that could be contained with a small amount in industrial water. Then aggregates were formed by adsorption or binding of ferrous ions on the surface of micelles, and then rejected by ceramic membranes to remove ferrous ions. Ferrous concentration was fixed at 1mM and SDS was changed as $0{\sim}10mM$ to investigate the effect of the anionic surfactant. As a result, rejection rate of ferrous was the highest to 88.97% at 6mM. And we used ELS (Electrophoretic Light Scattering Spectrometer) to investigate particle size distribution of micellar aggregates depending on SDS concentration. Then distribution of large aggregates was the highest at 6mM. And we investigated effects of $N_2$-back-flushing time (BT) during periodic $N_2$-back-flushing on ceramic membranes. Finally optimal $N_2$-BT for NCMT-723l (pore size $0.10{\mu}m$) membrane was 20 sec.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.2
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• pp.261-269
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• 2015

In this study, we applied a membrane distillation process to investigate a feasibility of treating a wastewater with high concentration of organic matters including nitrogen and phosphorus. The laboratory scale experiment was performed by using a hydrophobic PVDF membrane with the pore size of $0.22{\mu}m$ and porosity of 75%. The installation was direct contact type where the temperature difference between a feed and permeate side was controlled to have a range from 20 to $60^{\circ}C$. We observed a flux variation and a concentration changes of COD, $PO{_4}^{3-}$-P, $NH_4{^+}$-N and conductivity of feed side as well as permeate side with various temperature differences (20 to $60^{\circ}C$), cross flow velocities (0.09 to 0.27 m/s) through the module, and pH (6.6 to 12.0) of the feed that has the initial concentration of COD about 1,000 mg/L, total nitrogen 390 mg/L, total phosphorus 10 mg/L, conductivity of $7,000{\mu}s/cm$. The results showed that the average flux was ranged from 4 to $40L/m^2/hr$ which was almost similar with the flux of NaCl and deionized water used as a feed solution. The lowest flux was obtained at the operating condition with the temperature difference of $20^{\circ}C$ and cross flow velocity of 0.09 m/s while the highest one was measured with $60^{\circ}C$ and 0.27 m/s. Above 99% of COD and $PO{_4}^{3-}$-P in the feed could be rejected regardless of an operating condition. However, the removal rate of ammonium nitrogen was varied from 64 to 99% depending on the pH of feed solution.

• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.1
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• pp.61-70
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• 2005

In order to reduce salt(as NaCl) contents in food waste and to improve the quality of discharged wastewater produced during the recycling process of food waste for the purpose of compost and feed stuff, a salt reduction process by added water into food waste was developed. The pilot plant with a rotary type salt reduction equipment to manage continuously 0.5 ton food waste per hour was constructed and the efficiency was tested. The amount of added water was calculated by the water content and the efficiency of dewatering process of food waste. Approximately 0.8 liter water per a kilogram of food waste was injected into the reactor in which food waste was pouring simultaneously, then diluted/mixed in a rotary reactor. About 1.1 liter of leachate including added water was generated, but the leachate contained a very high content of organic particles, so most particles were recovered by two step solid-liquid separation process. The first step was a gravitational filtering process using screens with a pore diameter of 1mm, and the second separation process was centrifugal process. Organic quality of food waste which had been desalted was maintained by inputting the entirely recovered organic particles. The efficiency of salt reduction of food waste was estimated by measuring a chloride anion by titration and salinity by a probe. The results by the two different measuring methods were always over 50%, and the quality of final wastewater was improved up to $200mg/{\ell}$ as TS(total solid) by an additional settling process after the two step solid-liquid separation process.

• Journal of Korean Society on Water Environment
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• v.35 no.5
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• pp.418-424
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• 2019

In this study, $TiO_2$ nanotubes with different morphologies were prepared in the electrolyte consisting of ethylene glycol, ammonium fluoride($NH_4F$), and deionized water($H_2O$) by controlling the voltage and time in the anodization method. Thicknesses and pore sizes of these $TiO_2$ nanotubes were measured to interpret the relationship between anodization conditions and $TiO_2$ nanotube morphologies. Element contents in the $TiO_2$ nanotubes were detected for further analysis of $TiO_2$ nanotube characteristics. Photoelectrolyticdecolorization efficiencies of the $TiO_2$ nanotube plates with various morphologies were tested to clarify the morphology that a highly active $TiO_2$ nanotube plate should have. Influences of applied voltage in photoelectrolysis processes and sodium sulfate($Na_2SO_4$) concentration in wastewater on the decolorization efficiency were also studied. To save the equipment investment cost in photoelectrolysis methods, a two-photoelectrode system that uses the $TiO_2$ nanotube plates as photoanode and photocathode instead of adding other counter electrodes was studied. Compared with single-photoelectrode system that uses the $TiO_2$ nanotube plate as photoanode and titanium plate as cathode on the view of the treatment of dye wastewater containing different amounts of salt. As a result, a considerably suitable voltage was strictly needed for enhancing the photoelectrolyticdecolorization effect of the two-photoelectrode system but if salts exist in wastewater, an excellent increase in the decolorization efficiency can be obtained.

• Journal of the Korean GEO-environmental Society
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• v.11 no.6
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• pp.77-83
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• 2010

In this study, we tried to determine any detrimental effects on water quality when bottom ash obtained from a coal-fired power plant intended to be used as a fill material in construction sites. Physical-chemical properties of bottom ash were determined using proximate analysis, elemental analysis, XRD, and XRF. Classification of bottom ash as a waste material and soil contamination due to the use of bottom ash were performed by Korea waste standard leaching test and soil toxicity test, respectively. Results of leaching tests were compared to the regulations for water quality and groundwater quality and no harmful effects on water quality were found. Most of heavy metals in leachate were below detection limits but trace amount of $Cr^{6+}$ was found. However, concentration of $Cr^{6+}$ was below the regulation criteria. Column leaching tests indicated that concentrations of Pb and Zn were slightly higher than regulations but below regulations within 1 PVE, but concentrations of sulfate were 10 times higher than regulation and thus, the required time to reach regulation was almost 8 PVE.

• Korean Journal of Environmental Agriculture
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• v.18 no.4
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• pp.321-326
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• 1999

This study was performed to evaluate the quality of produced compost and to analyse the change of a component during the reduction compost according to the input volume. The volume of pilot scale used in this study was about 300㎥. The pile of 2m width, 20m length and 1.2m height was constructed. Woodchip was used as bulking agent to enhance pore volume of composting bay and to control water content of food waste in starting time. Food waste was turned using a mechanical tumer twice a day. The result are as follows : In these cases of input volume of $2m^3$ and $3.5m^3$, temperature of composting pile was maintained over $60^{\circ}C$ and water content was 43.6% and 47.2%, respectively. It was proved that microorganisms activity was maintained high in each input volume. After operation of step 1 and step 2, pH and organic matter in the final compost were 6.2, 6.6 and 84.3%, 79.6%, respectively. Cation concentration such as $K_2O,$ CaO and NaCl was accumulated in the compost during the composting period. NaCl concentration in the final compost was 4.62%, 4.92%, respectively. Hence, If was recommended that this compost should be applied to others expect agricultural area or mixed with a low concentration other compost. In the steps 1, input volume of $2m^3$, heavy metal concentration of Pb, Cu, Cr, Ni. Cd were 37.82㎎/㎏, 56.87㎎/㎏, 9.8㎎/㎏. 22.21㎎/㎏ and 3.69㎎/㎏, and 44.55㎎/㎏, 95.54㎎/㎏, 12.22㎎/㎏, 24.94㎎/㎏, and 3.86㎎/㎏ in the step 2.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.78-84
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• 2019

The Marine concrete that located at immersion zone receives an hydrostatic pressure of 1 atm as depth of the water increased by 10 m. And it could accelerate chloride ion penetration. In this study, to evaluate the influence of hydrostatic pressure on chloride ion penetration, concrete mixed by ordinary Portland cement and Portland blast-furnace slag cement was exposed to 1 and 6 atm and substitute ocean water. As a result, the surface chloride ion concentration of the concrete under 6 atm of hydrostatic pressure increased rapidly and the water-soluble chloride ion contents was increased by depth. In addition, the concrete under 6 atm of hydrostatic pressure showed the increase of capillary pores corresponding to 5~100 nm.

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.902-907
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• 1998

In this study the anaerobic degradation of nitrate by in GFM (gel and foam matrix) and bead gel immobilized Paracoccus denitrificans DSM 65 in continous culture was conducted. A novel GFM immobilization system was developed in order to improve conventional system (bead). With increasing nitrate concentration in water, the nitrate reduction rate was increased. The observed maximum denitrification rate by in GFM immobilized cells was 177 mg/L h in buffered water, while that was 33 mg/L h in tap water. In comparison with bead system the reduction activity by GFM system showed $1.2{\sim}2.1$ times better. The denitrification activity was not changed after 16 days storage at $5^{\circ}C$ and also showed better activity than that of free cells or even bead immobilized cells.

• Economic and Environmental Geology
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• v.54 no.1
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• pp.105-115
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• 2021

The geological CO2 sequestration in underground geological formation such as deep saline aquifers and depleted hydrocarbon reservoirs is one of the most promising options for reducing the atmospheric CO2 emissions. The process in geological CO2 sequestration involves injection of supercritical CO2 (scCO2) into porous media saturated with pore water and initiates CO2 flooding with immiscible displacement. The CO2 migration and distribution, and, consequently, the displacement efficiency is governed by the interaction of fluids. Especially, the viscous force and capillary force are controlled by geological formation conditions and injection conditions. This study aimed to estimate the effects of surfactant on interfacial tension between the immiscible fluids, scCO2 and porewater, under high pressure and high temperature conditions by using a pair of proxy fluids under standard conditions through pendant drop method. It also aimed to observe migration and distribution patterns of the immiscible fluids and estimate the effects of surfactant concentrations on the displacement efficiency of scCO2. Micromodel experiments were conducted by applying n-hexane and deionized water as proxy fluids for scCO2 and porewater. In order to quantitatively analyze the immiscible displacement phenomena by n-hexane injection in pore network, the images of migration and distribution pattern of the two fluids are acquired through a imaging system. The experimental results revealed that the addition of surfactants sharply reduces the interfacial tension between hexane and deionized water at low concentrations and approaches a constant value as the concentration increases. Also it was found that, by directly affecting the flow path of the flooding fluid at the pore scale in the porous medium, the surfactant showed the identical effect on the displacement efficiency of n-hexane at equilibrium state. The experimental observation results could provide important fundamental information on immiscible displacement of fluids in porous media and suggest the potential to improve the displacement efficiency of scCO2 by using surfactants.

• Carbon letters
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• v.7 no.3
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• pp.188-195
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• 2006

Phosphoric acid-activated carbon WP's and zinc chloride-activated carbons WZ's were developed from wild cherry stones. The textural properties of the activated carbons were determined from nitrogen adsorption data at 77 K and the chemistry of the carbon surface, i.e. the surface carbon-oxygen groups (type and amount) was determined from the base and acid neutralization capacities (Boehm method). The adsorption of phenol, p-nitrophenol, p-chlorophenol, dinitrophenol and dichlorophenol was followed at 298 K. The activated carbons obtained were characterized by high surface area and large pore volumes as well as by high surface concentration of C-O groups. The investigated carbons exhibited high adsorption capacities towards phenols with these capacities increased with the increase of molecular weight and the decrease of the solubility of phenol in water. However, no general relationship could be observed between the adsorption capacities of carbons and any of their textural parameters or their surface chemistry. This may be attributed to the many factors controlling phenol adsorption and the different types and mechanisms of adsorption involved.