• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.2
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• pp.91-98
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• 1991

In this paper, the microscopic results of granular sludge from the two-phase UASB reactors are presented, particularly on the acidogenic phase where the distillery waste water is directly delivered. Distillery wastewater as a feed contained SS of 3.6~10.6 g/l and COD of 17.3~30.4 g/l. A 12.5 l and a 4.7 l UASB reactors were used for acidogenic and methanogenic phases, repectively. Morphological studies on the granular sludge consortia were made with both scanning and transmission electron microscopies. It was interesting enough to find the different colored and shaped granules at the acidogenic on the 90th day and at the methanogenic phase on the 120th day. The acidogenic granular sludge mainly consisted of acidogenic bacteria, such as long chains of large rods, short plump rods, and various size of cocci. Whereas the filamentous bacteria of Methanothrix spp. prevail in the methanogenic granule, with dirverse bacteria entrapped therein.

• Geophysics and Geophysical Exploration
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• v.18 no.1
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• pp.21-30
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• 2015

Induced seismicity has been observed in the relation with lots of anthropogenic influence and at variety of geological conditions over the last several decades. This paper reviews those induced earthquakes and compares with each other as well as with natural tectonic earthquakes. Hydraulic fracturing is commonly used to enhance the permeability through new cracks in the rock formation. The process triggers the induced seismicity, which can give crucial information on the fracture network and oil/gas migration. In the similar way, unintentionally induced events during the production procedure of the field, dam reservoir, minig activity, or wastewater injection can be used to give insight into various hydrodynamic processes and changes of reservoir properties at a various scales. The general conclusion summarizes the uncertainty or limitations of knowledge up to date and presents some issues to be dealt with in the future research.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.11 no.2
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• pp.116-126
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• 1999

In this paper, we have studied the seasonal vanatIons of near-field dilutions of wastewater discharged from the submerged mutiport-diffuser in Masan Bay. Seasonal changes of temperature and salinity, and tidal currents were measured at 16 stations in Masan Bay. Based on the observed ambient field data, the seasonal changes of near-field dilutions due to ambient current and density fields were calculated by CORMIX model. Because of the shallow ambient water depth of 15 m, the density profiles are isopycnal in autumn and winter seasons, in which the dilution factors were the highest, 168 with the strong spring-tidal current and 110-120 with the weak neap-tidal current. As the season changes from spring to summer, the dilution factors are considerably reduced by the factor of 2 as the thermocline is getting deepened up to Sm in depth in summer. In the case of a weak ambient current, the dilution factor in summer was reduced to 1/4 of the dilution in winter. However, with strong ambient current the difference between summer and winter dilutions becomes relatively small by 30%. The results indicate that the seasonal variation of near-field dilution is very large up to 4 times with a weak neap-tidal current, but its variations become small under a strong ambient current of spring tide in MasanBay.

• Journal of Environmental Health Sciences
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• v.37 no.3
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• pp.218-225
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• 2011

Objectives: In this paper, a dielectric barrier discharge (DBD) plasma reactor was investigated for degrading the dye Rhodamine B (RhB) in aqueous solutions. Methods: The DBD plasma reactor system in this study consisted of a plasma component [titanium discharge (inner), ground (outer) electrode and quartz dielectric tube], power source, and gas supply. The effects of various parameters such as first voltage (input power), gas flow rate, second voltage (output power), conductivity and pH were investigated. Results: Experimental results showed that a 99% aqueous solution of 20 mg/l Rhodamine B is decolorized following an eleven minute plasma treatment. When comparing the performance of electrolysis and plasma treatment, the RhB degradation of the plasma process was higher that of the electrolysis. The optimum first voltage and air flow rate were 160 V (voltage of trans is 15 kV) and 3 l/min, respectively. With increased second voltage (4 kV to 15 kV), RhB degradation was increased. The higher the pH and the lower conductivity, the more Rhodamine B degradation was observed. Conclusions: OH radical generation of dielectric plasma process was identified by degradation of N, N-dimethyl-4-nitrosoaniline (RNO, indicator of OH radical generation). It was observed that the effect of UV light, which was generated as streamer discharge, on Rhodamine B degradation was not high. Rhodamine B removal was influenced by real second voltage regardless of initial first and second voltage. The effects of pH and conductivity were not high on the Rhodamine B degradation.

• Journal of radiological science and technology
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• v.41 no.1
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• pp.67-73
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• 2018

In this paper, risk assessment was conducted to verify self - disposal requirements by landfill for exempted incineration ash by using Resrad Ver.6.5 computer code. The result of risk assessment by landfill for the incineration by-product is that individual dose is $6.91{\times}10^{-2}{\mu}Sv\;y-1$ and collective dose is $3.475{\times}10^{-7}man-Sv\;y-1$. It proved that the result meets reference dose of individual dose $10{\mu}Sv\;y-1$ and collective dose 1 man-Sv y-1 for general public. According to the current 'Nuclear Safety Commission Notice [No. 2014-3]', it states that the exempted wastes can be disposed of by incineration, landfill and recycling. However, most of recently documents and papers related to exempted wastes are disposed of by landfill and recyling and it could not confirm the case of exempt by incineration. If the national consensus is derived and treating the waste by using process of incineration is activated, it could be considered to treat low level of radiation wastewater and activated carbon excluded from exempted waste because of nuclide $^3H$ and $^{14}C$.

• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.180-186
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• 2005

This paper discusses the development of mixtures for silica fume as a stabilization/solidification agent and a binder for industrial wastewater residue containing organic and heavy metal contaminants. The UCS (unconfined compressive strength) gradually increased to 66.7% as the silica fume content increased to 15%. The leaching of TOC (total organic carbon) and chromium decreased as more OPC (Ordinary Portland Cement) was substituted with the silica fume. When a mixture had 5% silica fume, it retained about 85% TOC, and chromium leached out 0.76 mg-Cr/g-Cr in acidic solution. Also, microstructural studies of the solidified analysis showed that the silica fume caused an inhibition to the ettringite formation which did not contrilbute to setting but coated the cement particles and retarded the setting reactions. The results indicated that the incorporation of silica fume into the cement matrix minimized the detrimental effects of organic materials on the cement hydration reaction and the contaminant leachability.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.8
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• pp.996-1003
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• 2019

The undergrounding of diverse ground facilities has led to a decrease in issues, such as foul smell of water supply systems and wastewater, a fall of telephone poles, electromagnetic waves and breaking of wires caused by a railway work. On the other hand, there are new issues, including a fall accident, explosion affected by flammable gas, a choking accident by harmful gas and a lack of oxygen concentration, a fire coming from high-tension wire heating and flooding in the manhole. Besides, these issues damage the civil society and are an anxiety to public safety. Therefore, this paper is focused on a smart manhole device for stable communication environments inside and outside the manhole and wireless communication with various devices for managing facilities in the manhole, and aims to make a contribution to public safety by suggesting a direction of future underground facility management.

• Fire Science and Engineering
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• v.33 no.2
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• pp.107-113
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• 2019

Recently, due to global warming, the trend shows an increase in number of lightning strikes which increase risk regarding industry infrastructures. Especially in case where the lightning strikes infrastructures including refinery, petorchemical plant facilities or storage tanks, it can cause power failures, electrical machine malfunction and damage which can lead to fire explosion and multiple calamities. Therefore, detailed case studies must be conducted through a systematic research regarding lightning strike accidents in order to understand its mechanism and devise preventive measures. This paper aims to study cases of explosion regarding waste water storage tanks in refineries and petrochemical plants in order to analyze its root cause and provide preventive measures for avoiding lightning related incidents.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.877-884
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• 2011

In this paper, the removal characteristics of dissolved organic carbon (DOCs) by micro bubble ozonation process and $O_3/UV$ process were comparatively studied. In the point of DOC removing reaction coefficient, micro bubble ozonation system and $O_3/UV$ process had not significant difference, $0.0120sec^{-1}$ and $0.0141sec^{-1}$. Therefore micro bubble ozonation process is more suitable for tertiary treatment of sewage in the point of installation and maintenance cost-reducing. The optimum ozone injection rate was 2.0 g $O_3/g$ DOC and HRT was 3 min for the micro bubble ozonation process. The removal efficiency of DOC and SUVA in micro bubble ozonation system was 32.8% and 58.3% respective. Biological aerated filter (BAF) process was installed to remove soluble organic material increased by micro bubble ozonation system. And the effluent BOD of BAF was below 1.0 mg/L. In the view of cost-effectiveness, $O_3/BAF$ process was more profitable than $O_3/UV/BAF$ process for tertiary treatment of sewage. In order to nitrify ammonia in the BAF process completely, $NH_4{^+}-N$ concentration in the influent water of BAF should be designed considering low water temperature in the winter season.

• Journal of Environmental Science International
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• v.30 no.11
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• pp.945-956
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• 2021

In this study, the effects of single and binary heavy metals toxicity on the growth and phosphorus removal ability of Bacillus sp.. known as be a phosphorus-removing microorganism, were quantitatively evaluated. Cd, Cu, Zn, Pb, Ni were used as heavy metals. As a result of analysis of variance of the half of inhibition concentration and half of effective concentration for each single heavy metal treatment group, the inhibitory effect on the growth of Bacillus sp. was Ni < Pb < Zn < Cu < Cd. And the inhibitory effect on phosphorus removal by Bacillus sp. was Ni < Pb < Zn < Cu < Cd. When analyzing the correlation between growth inhibition and phosphorus removal efficiency of a single heavy metal treatment group, a negative correlation was found (R² = 0.815), and a positive correlation was found when the correlation between IC₅₀ and EC₅₀ was analyzed (R² = 0.959). In all binary heavy metal treatment groups, the interaction was an antagonistic effect when evaluated using the additive toxicity index method. This paper is considered to be basic data on the toxic effects of heavy metals when phosphorus is removed using phosphorus removal microorganisms in wastewater.