• Economic and Environmental Geology
• /
• v.39 no.1 s.176
• /
• pp.75-82
• /
• 2006

Acid drainage occurs when sulfide minerals are exposed to an oxidizing environment. The objective of this study was to examine the optimum condition for creating a phosphate coating on standard pyrite surfaces for reduction of pyrite oxidation. The solution of $10^{-2}M\;KH_2PO_4,\;10^{-2}M\;H_2O_2$ was identified as the best phosphate coating agent for the reduction of pyrite oxidation. The formation of an iron phosphate coating on pyrite surfaces was confirmed with ore microscope and scanning electron microscope equipped with energy dispersive spectroscopy. The temperature did not significantly affect the formation of phosphate coating on the surface of pyrite. However, the phosphate coating was less stable at higher temperature than at lower temperature. The phosphate coating was quitely stable at wide range of pH and $H_2O_2$ concentration. The less than $3.4\%$ of phosphate was dissolved at pH 2.79 and 10.64 and less than $1.0\%$ of phosphate was dissolved at 0.1M $H_2O_2$. On the basis of these results, the phosphate coating can effectively reduce the negative environmental impact of acid rock drainage.

• Economic and Environmental Geology
• /
• v.50 no.3
• /
• pp.251-256
• /
• 2017

This study presents measures to enhance the efficiency of Successive Alkalinity Producing Systems(SAPS), a natural biological purification method that prevents environmental pollution arising from the release of Acid Mine Drainage(AMD) from abandoned mines into rivers and groundwater. The treatment of AMD using SAPS is based on biological processing technology that mostly involves sulfate reducing bacteria(SRB). It has been proven effective in real-world applications, and has been employed in various projects on the purification of AMD. However, seasonal decrease in temperature leads to a deterioration in the efficiency of the process because sulfate-reducing activity is almost non-existent during cold winters and early spring even if SRB is able to survive. Against this backdrop, this study presents measures to enhance the activity of the SRB of the organic layer by integrating light emitting diode(LED)s in SAPS and to maintain the active temperature using LEDs in cold winters. Given that mine drainage facilities are located in areas where power cannot be easily supplied, solar cell modules are proposed as the main power source for LEDs. By conducting further research based on the present study, it will be possible to enhance the efficiency of AMD treatment under extreme cold weather using solar energy and LEDs, which will serve as an environmentally-friendly solution in line with the era of green growth.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.39 no.5
• /
• pp.569-577
• /
• 2019

Urban flooding has been a frequent phenomenon in recent years caused by the increase in maximum stormwater runoff arising from abnormal rainfall due to global warming, urban development, and development of lowlands according to population inflows. In order to respond positively against abnormal precipition in the city, it is necessary to check the GWI (Green Water Infra) effect and effectively utilize the existing stormwater detention tanks and treat stormwater to prevent local flooding. In this study, Overflow Type stormwater drainage methods are evaluated as a method of preventing urban flooding in abnormal precipitation using the Dynamic Wave Analysis SWMM (Storm Water Management Model) provided by the United States Environmental Protection Agency. Comparing and analyzing the Upward Watergate Type and Overflow Type, it was analyzed that the Overflow Type reduces the maximum flood discharge by 61 % and the total flood volume by 56 % in the rainfall of Typhoon Kong-rey. The application of the Overflow Type and the natural-pneumatic drainage method to the rainfall of Typhoon Soulik resulted in a 20 % reduction in maximum flood runoff and a 67 % reduction in total flood quantity. Therefore, as a solution to the abnormal rain fall, it is possible to improve the existing stormwater detection tank and install additional facilities. It is expected to be economically possible to strom drainage under limited conditions.

• Economic and Environmental Geology
• /
• v.54 no.6
• /
• pp.709-716
• /
• 2021

In this study, an adsorbent prepared by natural drying of iron hydroxide-based sludge collected from settling basin at a mine drainage treatment facility located in Gangneung, Gangwon-do was used to remove fluoride in an artificial fluoride solution and mine drainage, and the adsorption characteristics of the adsorbent were investigated. As a result of analyzing the chemical composition, mineralogical properties, and specific surface area of the adsorbent used in the experiment, iron oxide (Fe₂O₃) occupies 79.2 wt.% as the main constituent, and a peak related to calcite (CaCO₃) in the crystal structure analysis was analyzed. It was also identified that an irregular surface and a specific surface area of 216.78 m²·g^-1. In the indoor batch-type experiment, the effect of changes in reaction time, pH, initial fluoride concentration and temperature on the change in adsorption amount was analyzed. The adsorption of fluoride showed an adsorption amount of 3.85 mg·g^-1 16 hours after the start of the reaction, and the increase rate of the adsorption amount gradually decreased. Also, as the pH increased, the amount of fluoride adsorption decreased, and in particular, the amount of fluoride adsorption decreased rapidly around pH 5.5, the point of zero charge at which the surface charge of the adsorbent changes. Meanwhile, the results of the isotherm adsorption experiment were applied to the Langmuir and Freundlich isotherm adsorption models to infer the fluoride adsorption mechanism of the used adsorbent. To understand the thermodynamic properties of the adsorbent using the Van't Hoff equation, thermodynamic constants 𝚫H° and 𝚫G° were calculated using the adsorption amount information obtained by increasing the temperature from 25℃ to 65℃ to determine the adsorption characteristics of the adsorbent. Finally, the adsorbent was applied to the mine drainage having a fluoride concentration of about 12.8 mg·L^-1, and the fluoride removal rate was about 50%.

• Journal of Environmental Science International
• /
• v.19 no.11
• /
• pp.1315-1322
• /
• 2010

A membrane bioreactor (MBR) was designed using polyvinylidene fluoride(PVDF)-type hollow fiber membrane modules with a treatment capacity of 10 ton/day. A pilot plant was installed in a sewage treatment plant and was operated with an intermittent aeration method which avoids any concentration gradient of suspended solids (SS) in the MBR. For continuous operation, the pilot plant was first tested with influent (mixed liquor suspended solid:MLSS of 1000-2000 mg/L) of aeration tanks in the sewage treatment plant. The MBR was pre-treated with washing water, 10% ethanol solution, 5% NaOCl solution and finally washing water, one after another. To demonstrate the effect of the MBR on sewage treatment, compared with conventional activated sludge processes, we investigated the relationships among permeate amount (LMH), change in operation conditions, influent MLSS level and sludge production. It was found that the optimum aeration rate and suction pressure were $0.3\;m^3$/min and 30~31 cmHg, respectively. Under stable conditions in aeration, suction pressure, influent flow rate and drainage, the SS removal efficiency was more than 99.99% even when the MLSS loading rate changes. Compared with conventional activated sludge processes, the MBR was more effective in cost reduction by 27% based on permeate amount and by 51.5% on sludge production.

• Geomechanics and Engineering
• /
• v.35 no.4
• /
• pp.385-393
• /
• 2023

To analyze the consolidation with horizontal sand drains, the plane strain consolidation model under multi-ramp loading is established, and its corresponding analytical solution is derived by using the separation of variables method. The proposed solution is verified by the field measurement data and finite element results. Then, the effects of the loading mode and stress distribution on consolidation and dissipation of pore pressure are investigated. At the same time, the influence of hydraulic conductivity and thickness of sand blankets on soil consolidation are also analyzed. The results show that the loading mode has a significant effect on both the soil consolidation rate and generation-dissipation process of pore water pressure. In contrast, the influence of stress distribution on pore pressure dissipation is obvious, while its influence on soil consolidation rate is negligible. To guarantee the fully drained condition of the sand blanket, the ratio of hydraulic conductivity of the sand blanket to that of clay layer k_d/k_v should range from 1.0×10⁴ to 1.0×10⁶ with soil width varying from 100 m to 1000 m. A larger soil width correspondingly needs a greater value of kd/kv to make sure that the pore water can flow through the sand blanket smoothly with little resistance. When the soil width is relatively small (e.g., less than 100 m), the effect of thickness of the sand blanket on soil consolidation is insignificant. And its influence appears obvious gradually with the increase of the soil width.

• Journal of Bio-Environment Control
• /
• v.26 no.4
• /
• pp.418-423
• /
• 2017

In hydroponics, the nutrient solution is supplied considering the water and nutrient uptake characteristics of crops. However, as the ionic uptake characteristics are changed as a result of the weather conditions or the growth response of the crops, the root zone can not be maintained in optimal condition. In addition, the coir substrate has been used mainly for the tomato cultivation in place of the inorganic substrate, there are few studies on long-term cultivation using coir substrate. Therefore, this study was conducted to investigate the effect of EC level of irrigation solution on tomato growth and inorganic ions of root zone in soilless culture using coir. Coir substrate mixed with 5 : 5 chip and dust was used. EC level of irrigation solution was 1.0, 1.5, 2.0, and $3.0dS{\cdot}m^{-1}$. At the initial stage, $NO_3-N$, P, Ca and Mg in the drainage were lower than the irrigation level at 1.0 and $1.5dS{\cdot}m^{-1}$. However, EC $2.0dS{\cdot}m^{-1}$ or higher, all the ions except P were highly concentrated in the drainage. The average fruit weight was not significantly different between 1.0 and $1.5dS{\cdot}m^{-1}$ until 3th cluster, but from the next cluster, the higher the EC level, the smaller the weight. The number of fruit and yield to 6th cluster was the highest at $1.5dS{\cdot}m^{-1}$. From the next cluster, The yield was decreased with the higher EC level. At the early stage of growth, BER occurred only in EC $3.0dS{\cdot}m^{-1}$, but increased in all treatments with increasing irradiation. The incidence rate of EC $3.0dS{\cdot}m^{-1}$ was higher than that of the lower EC level treatment.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.48 no.2
• /
• pp.99-105
• /
• 2016

The increase of wet web solid content after wet press and dry compressive strength were observed in lab study by judicious application of wood flour and starch for the old corrugated container (OCC). Pearl starch was better than cationic starch in strength development, but cationic starch was better for drainage. Application of vacuum on the mixed solution of wood flour and starch helped strength development further without loss of other properties. The effect of wood flour addition on wet web solid content improved as the wet pressing pressure increased. The use of wood flour and starch mixture improved wet web solid contents further.

• KCID journal
• /
• v.21 no.1
• /
• pp.64-77
• /
• 2014

This study evaluated the soil loss considering the R-Factor value following the climate change. To calculate the soil loss of the basin in Jaun-ri, Hongcheon-gun which is the study area, the future climate change scenario and convenience revision were used to build the past 30 years, future 30 years R-Factor and it was applied to USLE model. As a result, as the R-Factor value declined a little in the future, the soil loss was also reduced but it corresponds to the 'very high' according to the OECD soil loss grade so the solution to reduce the soil loss is necessary and it can be used for another study material.

• Archives of Reconstructive Microsurgery
• /
• v.17 no.1
• /
• pp.51-54
• /
• 2008

We experienced a case of 49-year-old male patient with amputated two fingers preserved in Soju (Korean traditional liquor, a kind of alcoholic beverages). The amputation level of the two fingers was at the distal interphalangeal joint. The Soju was not an adequate physiologic solution for preserving the amputated tissues. Even though arterial anastomosis was successful, there was no venous drainage visible in the operative field. On the first day after the initial operation, we succeeded in the anastomosis of one vein in one of the two amputated fingers. This was 12 hours after arterial anastomosis was carried out. But no venous dranage was visible in the other finger. In spite of a salvage procedure sustained with external bleeding for 7 days, this replanted fingertip eventually fell into necrosis.