• 한국환경과학회지
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• 제28권3호
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• pp.291-301
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• 2019

This study was conducted to investigate the effect of salt concentration and turbidity on the inactivation of Artemia sp. by electrolysis, UV photolysis, electrolysis+UV process to treat ballast water in the presence of brackish water or muddy water caused by rainfall. The inactivation at different salt concentrations (30 g/L and 3 g/L) and turbidity levels (0, 156, 779 NTU) was compared. A decrease in salt concentration reduced RNO (OH radical generation index) degradation and TRO (Total Residual Oxidant) production, indicating that a longer electrolysis time is required to achieve a 100% inactivation rate in electrolysis process. In the UV process, the higher turbidity results in lower UV transmittance and lower inactivation efficiency of Artemia sp. Higher the turbidity resulted in lower ultraviolet transmittance in the UV process and lower inactivation efficiency of Artemia sp. A UV exposure time of over 30 seconds was required for 100% inactivation. Factors affecting inactivation efficiency of Artemia sp. in low salt concentration are in the order: electrolysis+UV > electrolysis > UV process. In the case of electrolysis+UV process, TRO is lower than the electrolysis process, but RNO is more decomposed, indicating that the OH radical has a greater effect on the inactivation effect. In low salt concentrations and high turbidity conditions, factors affecting Artemia sp. inactivation were in the order electrolysis > electrolysis+UV > UV process. When the salt concentration is low and the turbidity is high, the electrolysis process is affected by the salt concentration and the UV process is affected by turbidity. Therefore, the synergy due to the combination of the electrolysis process and the UV process was small, and the inactivation was lower than that of the single electrolysis process only affected by the salt concentration.

• 한국물환경학회지
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• 제22권4호
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• pp.672-677
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• 2006

Ozone/UV combined process is an effective technique to enhance generation of OH radical which is non-selective and powerful oxidant. The objective of this study is to evaluate the inactivation rates of B. subtilis spores by three candidate processes (ozone alone, UV alone, ozone/UV combined processes) at 4 and $20^{\circ}$ and to investigate the effects of OH radical on inactivation of B. subtilis spores. On the UV alone process, required UV dosages for lag phase and 3-log inactivation of B. subtilis spores were determined as $8.9mJ/cm^2$ and $47mJ/cm^2$. However, the inactivation of B. subtilis spores didn't occured beyond 4.5-log inactivation despite increasing UV dose. The inactivation of B. subtilis spores by ozone alone and ozone/UV combined process was investigated with ozone CT (Concentration of disinfectant ${\times}$ Contact time) concept. As a result, inactivation of B. subtilis spores by ozone/UV combined process was faster than by ozone alone, and especially $CT_{lag}$ value B. subtilis spores in the presence and absence of t-BuOH, OH radical scavenger, was investigated to evaluate effects of OH radical formed during ozone/UV combined process. We found that OH radical plays important roles on inactivation of B. subtilis spores.

• 대한환경공학회지
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• 제29권1호
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• pp.31-39
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• 2007

본 연구에서는 오존 및 UV 소독을 통해 Cryptosporidium 불활성화 특성을 파악하고 소독의 방향성을 제시하고자 하였다. ozone을 이용한 Cryptosporidium 불활성화 효과는 소독지표의 하나인 CT값$(mg{\cdot}min/L)$으로 평가할 수 있으며, 1 log(90%) 불활성화 CT값은 5.77 $mg{\cdot}min/L$이고 2 log(99%) 불화성화 CT값은 21.30 $mg{\cdot}min/L$인 것으로 나타났다. UV 소독을 통한 Cryptosporidium oocysts 불활성화 효과의 경우 pH(5, 7, 9)와 저탁도(5 NTU 이하) 그리고 UV 강도(0.2, 0.6 $mWs/cm^2$)에 따른 효과는 뚜렷하게 나타나지 않았다. 그러나 20 NTU 이상의 고탁도인 경우에는 불활성 효과가 뚜렷하게 감소하였다. 따라서 정수처리공정에서 UV 소독을 실시할 경우 탁도를 충분히 낮춰야만 만족할 만한 소독 능을 얻을 수 있으며 높은 UV 강도에서 충분한 시간 동안 UV가 조사된다면 더 높은 Cryptosporidium oocysts의 불활성화 효과를 얻을 수 있을 것으로 사료된다.

• 한국물환경학회지
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• 제28권1호
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• pp.57-62
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• 2012

In this study, the inactivation efficiency of Mycobacterium marinum was evaluated in buffered water (pH 7) using a low pressure ultraviolet (LP-UV) lamp, ultrasonic (US), and UV/US sequential processes. In the UV alone process, 3 log inactivation of the M. marinum was achieved with a UV dose of $120mJ/cm^2$. However, a tailing phase was later observed because M. marinum has a high tendency for cell aggregation. Even though the M. marinum was not inactivated in the US alone process, the hydrophobicity decreased and turbidity increased due to the crumbling of the cell aggregation. Among the candidate processes which were UV alone, US-UV sequential process and UV-US-UV sequential process, the US-UV sequential process showed the highest synergistic effects for M. marinum inactivation. Consequently, US is a very useful process as a UV irradiation pre-treatment to inactivate M. marinum in water.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2002년도 학술발표회 발표논문집
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• pp.421-424
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• 2002

Deterministic and probabilistic approaches to the design of ultraviolet (UV) disinfection system for water reclamation are reviewed and discussed. The high inactivation of TC, FC and E. coli by UV disinfection was demonstrated and the inactivations of TC, FC and E. coli were 97%, 98% and 99%, respectively. Within the range of 0.3-4.5mWs/cm, the effect of UV does on the inactivation ratio was not observed. However, in the highest wattage of UV lamp, 39W, the inactivation ratio of TC, FC and E. coli was 100%, regardless of the UV does so the UV density was more effective on inactivation ratio of TC, FC and E. coli rather than UV does. Under the 0.4 mWs/cm and 16W of UV lamp, the effect of dissolved organic matter and turbidity on the inactivations of TC, FC and E. coli could not be observed in this study within the range of 0-60mg/L and 0-40 NTU respectively.

• 한국환경과학회지
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• 제23권3호
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• pp.369-378
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• 2014

Effect of improvement of the dielectric barrier discharge (DBD) plasma system on the inactivation performance of bacteria were investigated. The improvement of plasma reactor was performed by combination with the basic plasma reactor and UV process or combination with the basic plasma reactor and circulation system which was equipped with gas-liquid mixer. Experimental results showed that tailing effect was appeared after the exponential decrease in basic plasma reactor. There was no enhancement effect on the Ralstonia Solanacearum inactivation with combination of basic plasma process and UV process. The application of gas-liquid mixing device on the basic plasma reactor reduced inactivation time and led to complete sterilization. The effect existence of gas-liquid mixing device, voltage, air flow rate (1 ~ 5 L/min), water circulation rate (2.8 ~ 9.4 L/min) in gas-liquid mixing plasma, plasma voltage and UV power of gas-liquid mixing plasma+UV process were evaluated. The optimum air flow rate, water circulation rate, voltage of gas-liquid mixing system were 3 L/min, 3.5 L/min and 60 V, respectively. There was no enhancement effect on the Ralstonia Solanacearum inactivation with combination of gas-liquid mixing plasma and UV process.

• Environmental Engineering Research
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• 제21권4호
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• pp.350-354
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• 2016

There is an urgent need to identify more reliable indicator systems for human pathogenic viruses in water reuse practice. In this study, we determined the response of different bacteriophages representing various bacteriophage groups to different ultraviolet (UV) technologies in real wastewater in order to identify more reliable bacteriophage indicator systems for UV disinfection in wastewater. Bacteriophage ${\varphi}X174$ PRD1, and MS2 in two different real wastewaters were irradiated with several doses of both low pressure (LP) and medium pressure (MP) UV irradiation through bench-scale UV collimated apparatus. The inactivation rate of ${\varphi}X174$ by both LP and MP UV was rapid and reached ${\sim}4{\log}_{10}$ within a UV dose of $20mJ/cm^2$. However, the inactivation rates of bacteriophage PRD1 and MS2 were much slower than the one for ${\varphi}X174$ and only ${\sim}1{\log}_{10}$ inactivation was achieved by the same UV dose of $20mJ/cm^2$. Overall, the results of this study suggest that bacteriophage MS2 could be a reliable indicator for human pathogenic viruses for both LP and MP UV disinfection in wastewater treatment processes and water reuse practice.

• 상하수도학회지
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• 제30권2호
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• pp.139-145
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• 2016

Disinfection of microorganisms using UV light is widely used in the field of water supply and wastewater treatment plant, In spite of high germicidal effect and relatively clean by-product, UV disinfection has fundamental defeat that is accumulation of fouling materials at the interface of water and lamp sleeve. Non-contact type of UV photoreactor which can avoid this fouling generation was developed and the experimental performance evaluation of the system was carried out in this study. Log inactivation rate of E. coli was selected as a disinfection index. The concentration of E. coli of second clarifier effluent was $8.2{\times}10^1-8.2{\times}10^3$ colony per mL and was well inactivated by the non-contact type of UV photoreactor. Under the UV intensity condition of $2.1-2.5mW/cm^2$, E. coli removal rate was observed in the range of 54 - 95% when the HRT was increased from 10 to 52 seconds. Experimental results showed that log inactivation of E. coli was proportional to UV dosage and $200mJ/cm^2$ of UV dose is expected for the 2.0 log inactivation of E. coli from the second clarifier effluent. Between the two parameters of UV intensity and contact time which are consist of UV dose, UV intensity was 4 times more effective than contact time.

• 상하수도학회지
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• 제33권5호
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• pp.379-388
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• 2019

Chlorination and UV illumination are being widely applied to inactivate a number of pathogenic microbials in the environment. Here, we evaluated the inactivation efficiency of individual and combined treatments of chlorination and UV under various aqueous conditions. UV dosage was required higher in waste water than in phosphate buffer to achieve the similar disinfecting efficiency. Free chlorine generated by electrolysis of waste water was abundant enough to inactivate microbials. Based on these, hybrid system composed of sequential treatment of electrolysis-mediated chlorination and UV treatment was developed under waste water conditions. Compared to individual treatments, hybrid system inactivated bacteria (i.e., E. coli and S. typhimurium) and viruses (i.e., MS-2 bacteriophage, rotavirus, and norovirus) more efficiently. The hybrid system also mitigated the photo re-pair of UV-driven DNA damages of target bacteria. The combined results suggested the hybrid system would achieve high inactivation efficiency and safety on various pathogenic microbials in wastewater.

• 한국미생물·생명공학회지
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• 제11권3호
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• pp.155-161
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• 1983

Bacteriophage f2에 대한 자외광선의 살균효과와 외투막 단백질의 구조에 미치는 영향을 Ray-onet photoreactor PPR-208을 사용하여 300nm의 광선으로 연구하였다. 처음 20분간의 조사에서는 약 4 log의 phage가 감소되고 그후 완만한 살균효과를 보이다가 90분 이상의 조사에서는 생존 바이러스가 발견되지 않았다. Tryptophan residue의 fluorescenve quenching, 자외선으로 조신한 phage에 부착시킨 ANS (8-anilino-1-napht-halene sulfonate)의 fluorescence emission의 감소, tryptophan에서 ANS로의 energy transfer 의 감소 등 spectroscopic technique에 의한 결과와 자외선 조사에 의하여 단백질 외투만이 파손되는 전자현미경 관찰의 결과에 의하여 자외광선은 phage f2의 외투막 단백질의 구조에 변화를 일으킨다는 것이 밝혀졌다.