• Economic and Environmental Geology
• /
• v.53 no.5
• /
• pp.529-542
• /
• 2020

The cesium (Cs) sorption characteristics of a bead-type polysulfone carrier contained HNO₃-treated bamboo charcoal (3 - 5 mm in diameter) in water system were investigated and its Cs removal efficiency as an adsorbent from water was also identified by various laboratory experiments. From the results of batch sorption experiments, the bead-type polysulfone carrier with only 5% HNO₃-treated bamboo charcoal (P-5NBC) represented the high Cs removal efficiency of 57.8% for 1 hour sorption time. The Cs removal efficiency of P-5NBC in water after 24 hours reaction maintained > 69% at a wide range of pH and temperature conditions, attesting to its applicability under various water systems. Batch sorption experiments were repeated for P-5NBC coated with two cultivated microorganisms (Pseudomonas fluorescens and Bacillus drentensis), which were typical indigenous species inhabited in soil and groundwater. The Cs removal efficiency for two microorganisms coated polysulfone carrier (BP-5NBC) additionally increased by 19% and 18%, respectively, compared to that of only P-5NBC without microorganisms coated. The average Cs desorption rate of P-5NBC for 24 h was lower than 16%, showing the Cs was stably attached on HNO₃-treated bamboo charcoal in so much as its long-term use. The maximum Cs sorption capacity (q_m) of P-5NBC calculated from the Langmuir isotherm model study was 60.9 mg/g, which was much higher than those of other adsorbents from previous studies for 1 h sorption time. The results of continuous column experiments showed that the P-5NBC coated with microorganisms packed in the column maintained > 80% of the Cs removal efficiency during 100 pore volumes flushing. It suggested that only 14.7 g of P-5NBC (only 0.75 g of HNO₃ treated bamboo charcoal included) can successfully clean-up 7.2 L of Cs contaminated water (the initial Cs concentration: 1 mg/L; the effluent concentration: < 0.2 mg/L). The present results suggested that the Cs contaminated water can be successfully cleaned up by using a small amount of the polysulfone carrier with HNO₃-treated bamboo charcoal.

• Journal of Wetlands Research
• /
• v.18 no.3
• /
• pp.301-312
• /
• 2016

This study has performed comparative analysis on characteristics of contaminated 35 tributaries on seasonal variation/point discharge load/pollutant distribution of water quality factors(8) in order to understand the effect of the watershed in Nakdong River Basin. As a results, the water quality of $BOD_5$(Biochemical Oxygen Demand), Chl-a(Chlorophyll a) and Fecal E. Coli shows II grade at tributaries of more than 50% without COD(Chemical Oxygen Demand), TP(Total Phosphate), TOC(Total Oxygen Carbon) and TN(Total Nitrogen) factors. The specific discharge(Q) were occupied about 54.4% (19 sites) as $0.05m^3/sec/km^2$ value. Among these results, the contaminant level of Dalseocheon, Hyeonjicheon, Seokkyocheon 1, Uriyeongcheon and Dasancheon was also high, which has to consider a discharged pollutant load(kg/day). The 35 major tributaries of Nakdong River were included in 7 mid-watershed, such as Nakdong Waegwan, Geumho River, Nakdong Goryung, Nakdong Changnyung, Nam River, Nakdong Milyang, Nakdong River Hagueon. Especially, the discharged pollutant load of Nam River and Geumho River also was high according to the amount of discharge such as Kachang dam, Gongsan dam and Nam river dam. Seasonal difference of the water quality factors such as $BOD_5$, TN, SS and Q was observed largely, on the other hand the TP and Chl-a was not. This is guessed due to the precipitation effect of site, biological and physicochemical degradation properties of pollutant and etc. The co-relationship between the seasonal difference and water quality factors was observed using a Pearson correlation coefficients. Besides, the Multiple Regression analysis using a Stepwise Regression method was conducted to understand the effect between seasonal difference and water quality factors/regression equations. As a result, the Multiple Regression analysis was adapted in the spring, summer and autumn without the winter, which was observed high at spring, summer and autumn in the order COD/TP, Chl-a/TOC, TOC/COD/$BOD_5$ water quality factors, respectively.

• Korean Chemical Engineering Research
• /
• v.46 no.5
• /
• pp.1008-1012
• /
• 2008

Nanoscale zero-valent iron(nZVI) is famous for its high reactivity originated from its high surface area and it has received considerable attentions as one of the latest innovative technologies for treating contaminated groundwater. Due to its fine powdery form, nZVI has limited filed applications. The efforts to overcome this shortcoming by immobilizing nZVI on a supporting material have been made. This study investigated the differences of resin-supported nZVI's characteristics by changing the preparation methods and evaluated its reactivity. The borohydride reduction of an iron salt was proceeded in ethanol/water solvent containing a dispersant and the synthesis was conducted in the presence of ion-exchange resin. The resulting material was compared to that prepared in a conventional way of using de-ionized water by measuring the phyrical and chemical characteristics. BET surface area and Fe content of nZVI-attached resin was increased from $31.63m^2/g$ and 18.19 mg Fe/g to $38.10m^2/g$ and 22.44 mg Fe/g, respectively, by switching the solution medium from water to ethanol/water with a dispersant. The reactivity of each material was tested using nitrate solution without pH control. The pseudo first-order constant of $0.462h^{-1}$ suggested the reactivity of resin-supported nZVI prepared in ethanol/water was increased 61 % compared to that of the conventional type of supported nZVI. The specific reaction rate constant based on surface area was also increased. The results suggest that this new supported nZVI can be used successfully in on-site remediation for contaminated groundwater.

• Clean Technology
• /
• v.26 no.1
• /
• pp.13-21
• /
• 2020

Air pollutants in a subway are complexly caused by outdoor factors such as ventilating opening and indoor factors such as the movement of passengers on the subway. According to recent research results, most of the air pollutants generated in subway tunnels and stations are caused by indoor variables such as train movement. To control air pollutants such as particulate matter (PM), a prevention facility such as the electrostatic precipitator (EP) or bag filter collector was required in a subway station. In particular, the PM removed by the EP must be kept clean continuously to manage PM effectively. Therefore, a nano-bubbling washing system was developed in this study to clean a contaminated collecting plate in an EP at the main subway tunnel in Seoul. Removal efficiency compared with normal water and nano-bubbling water was likewise studied. As a result, the washing efficiency of collective PM increased in accordance with the increasing of injection pressure, with nano bubbling washing being 130.8% higher than tap water. According to increase in washing times, the maximum washing efficiency was 143.1% higher than tap water, but suitable washing times were less than 3 times. According to the results of the washing efficiency by variation of residence time, it was confirmed that the maximum residence time of nano-bubble water was maintained within 5 minutes.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.24 no.6
• /
• pp.726-734
• /
• 2018

The total number of Sea Area Utilization Consultation in the environment management sea areas reviewed from 2015 to 2017 were 60. The number of development projects in the environment conservation sea areas decreased steadily, but special management sea areas increased. Development types in environment management sea areas showed that artificial structure installation was the highest ratio, followed by fishery port development and construction of habor and coastal maintenance and sea water intake and draining. By comparing the trend of water quality changes using marine environment information system (MEIS) data in the environment management areas from 2006 to 2017, COD showed no significant changes but the environment conservation sea areas increased slightly, and the concentration of TN and TP decreased. Gwangyang and Masan bays in the special management sea areas and Gamak bay in the environment conservation sea areas displayed oxygen deficient mass in the summer. As the use of development projects of the environment management sea areas are performed continuously, an analysis of the status of sufficient water quality changes is necessary for environmental impact assessment (Sea Area Utilization Consultation) in the marine environment and should be evaluated mainly for management of contamination by diagnosing thoroughly water quality effects and the pollution of sediment. Especially, the water quality goal for the purpose of designation in each of the environment management sea areas is set clearly, connection with pollution source control and the total pollution load management system (TPLMS) should be proposed and measured to reduce the amount of contaminated water.

• Journal of Korean Society on Water Environment
• /
• v.21 no.4
• /
• pp.347-352
• /
• 2005

The isolated microorganisms, Pseudomonas stutzeri, Raoultella planticola (Klebsiella), Serratia fonticola from petroleum contaminated soil were enriched on benzene, toluene, ethylbenzene, o-xylene as carbon and energy sources, respectively. And the degradation characteristics of BTEX was observed in the mixed BTEX substrates. We found that the BTEX in mixed substrates were degraded more than 50% by three isolated microorganisms. Among three isolated microorganisms, the highest degradation rate was observed in Pseudomonas stutzeri, but the degradation rate was different according to microorganisms. In order to increase the degradation efficiency, we applied the co-culture of isolated three microorganisms. The mixture rate of pseudomonas stutzeri : Raoultella planticola (Klebsiella) : Serratia fonticola was follows ; 1:2:1, 1:1:2, and 2:1:1, respectively. In two co-culture of 1:2:1 and 1:1:2, degradation rate was lower than isolated microorganisms. However, degradation rate became higher than isolated microorganisms and the degradation rate of benzene, toluene, and ethylene was more than 95% in co-culture of 2:1:1. The degradation rate increased through the co-culture of isolated microorganisms, however, the growth rate decreased. This was resulted from the substrate competition between microorganisms. The co-culture of microorganisms is a effective method to increase the degradation efficiency of BTEX and the co-culture mixing rate is a important factor for determination of degradation efficiency.

• Journal of environmental and Sanitary engineering
• /
• v.7 no.2
• /
• pp.111-128
• /
• 1992

According to the increase of population and industrialization, the quality of our drinking water are becoming worse by the contamination of resources, production of THM and other halogenated hydrocarbons during the purifying process, the problem of corroded water supplying pipeline, and the water reservoir tanks, Many people choose groundwater to drink instead of city tap water, but sometimes we get report about groundwater contamination by wastes, swage, septic tank, etc. It is reported that in U. S. over 20% of population are drinking groundwater, but U. S EPA reported the groundwater contamination by pesticides, herbicides, fungicides, fertilizer, and various chemical substances. Craun, et at announced the groundwater contamination by bacteria which are related with poor installation of septic tank. Johnson and Kross mentioned aboutmethemoglobinemia by NO3-N originated from human and animal feces, organic chemicals, and fertilizer, and as the results the infant mortality could be risen. Some scientist also reported the high concentration of metals in groundwaters and some cation and anions, and volatile organic compou nds. Authors investigated 80 groundwaters in urban, agricultural, and industrial area during last 3 month(June - August) to check any drinking water quality parameters are exceeding the standards. The results were as follow. 1, The average value of ammonia nitrate were within the standard, but 11.76% of urban area were exceeded the 10 rpm standard, in agricultural area 42.3175 were exceeded, and in industrial area 20.2% were exceeded the drinking water standard of 10 ppm. the highest concentration was 29.37 ppd in industrial area. 2. The mean value of metals is not exceeded the standard, but there were some groundwater whose Mn value was 0.424 ppm(standard is 0,3 ppm) in urban area, 0.737 rpm in agricultural area, and 5.188 ppm in industrial area. The highest Zn value was 1.221 ppm (standard is 1.0 ppm)was found in industrial area. 3. The percentage of contamination by general bacteria was 8.82% in urban area, 15.38% in agricultural area, and 15.00% in industrial area. Escherichia coil group was also contaminated by 35.29% in urban area, 30.76% in agricultural area, and 30.00% in industrial area. 4, The pH value was within the standard which means there was no influence by acid or alkali chemicals, nor acid rain Through the above results, all the groundwater should be tested to check the safety for drinking water and should make some alternative methods suitable for drink.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.24 no.2
• /
• pp.9-14
• /
• 2020

Four developed patents have applied for a new type of Composite Cyclone Scrubber followed by the previous research (Cho and Kim, 2017), including dust reducing fan with filters. Regarding target installation and maintenance cost, 64% reduction for investment costs (6.2 billion won vs. 17 billion won) compared to existing road pollution reduction system, while social benefit costs increase by 43% compared to existing road pollution reduction measures (72.6 billion won vs. 50.8 billion won). The composition of the device is an air blower type spiral guide vane, and an injection pressure collecting dust efficiency. A nozzle varies Injection angle and contact range, spray liquid species (waterworks, salty water). The proposed patent tests are circulation water Time-by-Time Spray and collected 41.4% more increased micro dust since the sprayed water meets contaminated gas due to the 45° degree colliding, which is 141% increased conventional dust collector. (Ratio of collection over 85%). As regards the source of collection liquid, circulated rainwater and well water, we expect a huge amount of energy and economically saved eco-friendly system in our patent. Finally, the guided vane and metal filter reduced over 90% micro-dust, while sprayed water cleans the vane and filters, resultantly minimizing the maintenance budget. The preliminary evaluations of the developed design make it possible to reduce not only cheaper maintenance budget due to the characteristic water spraying but the cost of water comes from mainly rain and underground.

• Korean Journal of Materials Research
• /
• v.8 no.6
• /
• pp.532-537
• /
• 1998

The purpose of this study was to investigate the behavior of ozone in DI water and the reaction with wafers during the semiconductor wet cleaning process. The solubility of ozone in DI water was not only dependent on the temperature but also directly proportional to the input concentration of ozone. The lower the initial ozone concentration and the temperature, the longer the half-life time of ozone. The reaction order of ozone in DI water was calculated to be around 1.5. The redox potential reached a saturation value in 5min and slightly increased as the input ozone concentrations increased. The completely hydrophilic surface was created in Imin when HF etched silicon wafer was cleaned in ozonized DI water containing higher ozone concentrations than 2ppm. Spectroscopic ellipsometry measurements showed that the chemical oxide formed by ozonized DI water was measured to be thicker than that by piranha solution. The wafers contaminated with a non-ionic surfactant were more effectively cleaned in ozonized DI water than in piranha and ozonized piranha solutions.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.47 no.1
• /
• pp.79-91
• /
• 2005

Wetland systems are widely accepted natural water purification systems around the world in nonpoint sources pollution control. Constructed wetlands have become a popular technology for treating contaminated surface and wastewater. In this study, the field experiment to reduce nonpoint source pollution loadings from polluted stream waters using wetland system was performed from June 2002 to March 2004, including winter performance using four newly constructed wetlands. The Dangjin stream water flowing into Seokmun estuarine lake was pumped into wetlands, and inflow and hydraulic residence time of the system was $500m^{3}{\~}1500m^{3}/day\;and\;2{\~}5$ days respectively. After 3 years operation plant-coverage was about $80~90\%$ from zero at initial stage even with no plantation. Average water quality of the influent in growing season was BOD_{5}\;3.96mg/L$, TSS 22.98 mg/L, T-N 3.29 mg/L, T-P 0.30 mg/L. The average removal rate of four wetlands for $BOD_{5},\;TSS,\;T-N\;and\;T-P$ in growing season was $24\%$, $62\%$, $54\%$, and $51\%$, respectively. And average water quality of the influent in winter season was $BOD_{5}$ 4.92 mg/L, TSS 12.47 mg/L, T-N 5.54 mg/L, and T-P 0.32 mg/L, respectively. The average removal rate of four wetlands for them was $-21\%$. $23\%$, $33\%$, and $53\%$, respectively. The reason of higher BOD_{5} effluent concentration in winter season might be that low temperature restrained microorganism activity and a organic body from the withered plant and algae was flown out. Except the result of $BOD_{5}$, the effectiveness of water quality improvement in winter season was satisfactory for treating polluted stream waters, and $BOD_{5}$ variation was within the range of background concentration. Performance of the experimental system was compared with existing data base (NADB), and it was within the range of general system performance. Overall, the wetland system was found to be satisfactory for NPS control such as improvement of polluted stream water.