• Title/Summary/Keyword: Disinfection

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E. coli Inactivation using Complex Disinfection Process (복합 소독 공정을 이용한 E. coli 불활성화)

  • Kim, Dong-Seog;Park, Young-Seek
    • KSBB Journal
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    • v.25 no.1
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    • pp.33-40
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    • 2010
  • Conventional disinfectants and disinfection method are expensive, hazardous and often require long periods of exposure. Recently, there is growing interest in complex disinfection process as a disinfection technique in medical instruments such as endoscope, hand piece bur to improve the disinfection efficiency and conveniency. The aim of this study was to evaluate the performance of a new complex process for the purpose of disinfection of Escherichia coli in water. Three single process (electrolysis, UV and ultrasonic process) was combined dual and triple disinfection process. The order of disinfection performance for E. coli in dual process lie in: Electrolysis + UV > Electrolysis + Ultrasonic > UV + Ultrasonic process. Disinfection efficiency of E. coli and degradation of N, N-Dimethyl-4-nitrosoaniline (RNO, indicating material of OH radical formation) of dual process was higher than that of the triple process (Electrolysis + UV + Ultrasonic process). In electrolysis + UV process, disinfection tendency was well agreed with RNO degradation tendency.

Characteristics of Disinfection Performance in Water Treatment Plants with Introducing Treatment Technigue Requirement (정수 처리기술 기준 도입을 앞둔 전국 정수장의 소독능 관리 현황 및 특색)

  • Yeom, Cheolmin;Cho, Soonhaing;Jung, Haewoong;Yoon, Jeyong
    • Journal of Korean Society on Water Environment
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    • v.18 no.3
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    • pp.327-336
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    • 2002
  • Disinfection process in water treatment plants (WTPs) is one of the most important step in order to inactivate waterborne disease. However, what is the necessary disinfection in WTPs was not properly established in Korea. This study was conducted to evaluate disinfection performance in nationwide water treatment plants (n=474). Disinfection requirement based on the SWTR (Surface Water Treatment Rule) of the U.S. (1-log Giardia removal) was chosen in estimating the compliance. The scope of unit process for evaluating disinfection performance includes postdisinfection process in clearwells, pipeline, and storage tank. The worst water quality condition in individual WTPs was applied for the disinfection performance evaluation. The major results are as follows. First, it was appeared that 184 WTPs (39 %) provided insufficient disinfection performance. Disinfection performance was significantly improved during past 2 years. The ratio of the number of WTPs providing insufficient disinfection performance in 1999 and 2001 was 78 % and 41 %, respectively. One of major factors for this improvement was due to the improvement of $T_{10}/T$ value in clearwell, as a result of modification of clearwell facility. Second, if disinfection criteria is 3-log Giardia inactivation at worst water quality condition, then 19 % of all WTPs can not meet this disinfection criteria. And if disinfection criteria is strengthened to 4-log Giardia inactivation, then 58 % of all WTPs can not meet this disinfection criteria. Since disinfection criteria is decided by contamination level of Giardia in source water, it also needs the investigation of Giardia occurrence in source water.

Study on Water Treatment Improvement Measures based on Case Studies of Ozone Disinfection at Domestic Water Treatment Plants (국내 정수장의 오존 소독능 평가사례를 통한 정수처리기준 개선방안 연구)

  • Noh, Hee-Su;Lee, Kyung-Hyuk;Wang, Chang-Keun;Son, Dae-Ik;Kang, Joon-Wun
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.2
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    • pp.153-160
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    • 2011
  • Ozone process is currently applied in 24 water treatment plants in Korea to control micropollutants and taste & odor compounds. However, one of the chlorine resistant protozoa, cryptosporidium, is not being considered as ozone disinfection performance whereas U.S. is already regulate Cryptosporidium by ozone disinfection. two ozone plants(PH, UH WTP) operation conditions are investigated for disinfection performance comparing Korea disinfection regulation and U.S. regulation. The ozone plants are unable to get Cryptosporidium inactivation credits by Korea disinfection regulation. However, the inactivation credit for Cryptosporidum was increased when the U.S. disinfection regulation was applied. The Korea disinfection credit regulation need revision to practical aspects.

Feasibility Study of UV-Disinfection for Water Reuse of Effluent from Wastewater Treatment Plant (용수재이용을 위한 하수처리 유출수의 UV 소독 효율 연구)

  • 윤춘경;정광욱;함종화;전지홍
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.45 no.2
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    • pp.126-137
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    • 2003
  • The feasibility study of UV-disinfection system was performed for disinfection of effluent from wastewater treatment plant. Three low-pressure UV lamps of 17, 25, and 41 W were examined with various flow rates. Low-pressure UV lamps of 17W were examined with various turbidity, DOM (dissolved organic matter), and SS (suspended solid). The pilot plant was a flow-through type UV-disinfection system, and the range of exposure time varied from 5 to 40 seconds, turbidity from 0 to 40 NTU, DOM from 0 to 30 mg/L, and SS from 10 to 40 mg/L. The 41W lamp demonstrated complete disinfection showing no survival ratio in all the experimental conditions, and generally 17W and 25W lamps also showed high removal ratio over 97%. For the same UV dose (UV intensity times exposure time), high intensity-short exposure conditions showed better disinfection efficiency than low intensity-long exposure conditions. While the effects of turbidity and DOM were not apparent, the effects of SS was significant on the disinfection efficiency which indicates that SS control before UV-disinfection appears to be necessary to increase removal efficiency. Considering characteristics of effluent from existing wastewater treatment plants, cost-effectiveness, stable performance, and minimum maintenance, the flow-through type UV-disinfection system with high intensity and low-pressure lamps was thought to be a competitive disinfection system for wastewater reclamation.

Photoreactivation Study of Wastewater Treatment Effluent Disinfected by UV-disinfection for Water Reuse (용수재이용을 위한 하수처리 유출수의 UV 소독 후 광회복 조사)

  • 윤춘경;정광욱;함종화;전지홍
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.45 no.3
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    • pp.84-93
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    • 2003
  • Photoreactivation of microorganism following UV-disinfection is one of the research topics of interest in assessing the UV-disinfection performance. Apparent photoreactivation was examined under fluorescent lamp and solar radiation as well as in darkness. Total coliform, fecal coliform, and Escherichia coli were used as indicator microorganisms, and their concentration was monitored with time after UV-disinfection. Under the darkness, their initial concentration of 10∼30 MPN/100 mL increased to the level of 100 MPN/100 mL after 24 hours, which implied that part of damaged microorganisms by UV-disinfection might be repairable with time. Under the fluorescent lamp, photoreactivation was more apparent that their concentration increased up to 1,000 MPN/100 mL which might significantly impair the water uses specially in reuse of reclaimed wastewater. However, their concentration further decreased down to below 2 MPN/100 mL under the solar radiation primarily due to additional disinfection by solar radiation rather than photoreactivation. Samples not disinfected by UV-disinfection also demonstrated substantial decrease of their concentration under solar radiation from about 5,000 MPN/100 mL to less than 30 MPN/100 mL in 24 hours. But direct reuse of effluent without disinfection is not recommended because natural decay by solar radiation may take time and be affected by climatic conditions. The result suggests that photoreactivation of pathogenic microorganisms may not be concerned in agricultural reuse of reclaimed wastewater because solar radiation may provide further disinfection after UV-disinfection.

Disinfection of Wastewater by UV Irradiation: Influence of Hydrodynamics on the Performance of the Disinfection

  • Brahmi, Mounaouer;Hassen, Abdennaceur
    • Environmental Engineering Research
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    • v.16 no.4
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    • pp.243-252
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    • 2011
  • Several mathematical relationships have been developed to describe bacterial responses to UV irradiation. Pseudomonas aeruginosa was taken as a bacterial model. The results obtained showed that the kinetics of disinfection is far to be as uniform. In fact, application of the model of Chick-Watson in its original form or modification, taking into account the speed change during the disinfection process, has not significantly improved results. The application of both models of Collins-Selleck and Hom constitute a major opportunity to simulate goodly the kinetics of UV disinfection. The results obtained showed that despite the major advantage held by applying the Hom model in this process of disinfection and for all strains studied, the model of Collins-Selleck gave the best results for the description of the UV inactivation process. The design of reactors, operating in continuous disinfection system, requires taking into account the hydrodynamic behaviour of water in the reactor. Knowing that a reduction of 4-log is necessary in the case of wastewater reuse for irrigation, a model integrating the expression of disinfection kinetics and the hydrodynamics through the UV irradiation room was proposed. The results highlight the interest to develop reactors in series working as four perfectly mixed reactors.

A Study on Escherichia Coli Disinfection by the Electrochemical Method for Small Sewerage System (소규모 오수처리를 위한 전기화학적 방법에 의한 대장균 소독에 관한 연구)

  • Park, Young-Seek;Jeong, No-Sung;Kim, Dong-Seog
    • Journal of Environmental Science International
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    • v.16 no.4
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    • pp.441-447
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    • 2007
  • This study was carried out to investigate the effect of electrochemical (EC) disinfection of artificial wastewater contaminated by Escherichia coli culture. Circulated batch type electrochemical disinfection system using three plates electrodes was used. Also, the several factors (pH, ORP, DO, temperature, current, conductivity) were measured in order to investigate the fundamental design factor in the EC disinfection system. It was demonstrated that the EC process was highly effective for wastewater disinfection. At the constant voltage, the disinfection efficiency was increased according to time. The disinfection efficiency and current increased as the increase of voltage. The variation of conductivity was a little related to the variation of CFU (colony forming units). The differences in disinfection efficiency according to the ice pack and the variation of electrodes were not occurred. The EC disinfection efficiency and current increased according to the increase of circulating flow rate.

Effect of Water Quality of Artificial Sewage on E. coli Disinfection Using Electrolysis Process (전기분해 공정을 이용한 E. coli 소독에 미치는 인공하수 수질의 영향)

  • Park, Young-Seek;Kim, Dong-Seog
    • Journal of Environmental Science International
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    • v.20 no.9
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    • pp.1115-1124
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    • 2011
  • There is an increasing incidence in health problems related to environmental issues that originate from inadequate treatment of sewage. This has compelled scientists to engage in innovative technologies to achieve a effective disinfection process. Electrolysis has emerged as one of the more feasible alternatives to conventional disinfection process. The objectives of the present paper were to investigate the effect of chemical characteristics on oxidant formation and Escherichia coli (E. coli) disinfection in synthetic sewage effluents. The influence of parameters such as COD, SS, T-N and T-P were investigated using laboratory scale batch reactor. The results showed that the higher COD, T-N and T-P concentration, the lower N, N-Dimethyl-4-nitrosoaniline (RNO, indicator of the generation of OH radical) degradation and E. coli disinfection was observed. The order of effect of RNO degradation and E. coli disinfection was T-P > COD > T-N > SS. When 4 parameter of water quality were worked simultaneously, oxidants formation and disinfection was decreased with increase of the concentration of sewage. To increase of the disinfection performance, the increase of disinfection time or electric power was need.

Nurse's Knowledge, Attitude and Practice of Skin Disinfection (간호사의 피부소독에 대한 지식, 태도 및 수행과의 관계)

  • Yang, Nam-Young;Choi, Jeong-Sil
    • Korean Journal of Adult Nursing
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    • v.23 no.3
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    • pp.278-287
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    • 2011
  • Purpose: This study was to provide baseline data about knowledge, attitude and practice of skin disinfection and to identify the influencing factors among nurses related to skin disinfection. Methods: The subjects were 174 nurses who worked at one Hospital in A city. Data were collected by self-reported questionnaires during August, 2010. The collected data were analyzed with use of SPSS/WIN 18.0. Results: The knowledge of skin disinfection varied significantly according to unit, position and job satisfaction. Nurses' attitude towards skin disinfection differed significantly according to age, unit, career, position and job satisfaction. Nurses' practice of skin disinfection varied according to unit and position. Significant correlations were found between knowledge, attitude and practice. The attitude and knowledge were influencing factors of practice (55.6%). Conclusion: An educational program focusing on changing nurses' knowledge and attitude can be effective for the practice of skin disinfection.

Kinetic examination on synergistic effect of co-use of ultrasonic wave and ultraviolet radiation on bacterial disinfection in a household humidifier (초음파와 자외선(UV) 동시 적용이 가정용 가습기 내 살균에 미치는 시너지 효과에 대한 반응속도론적 연구)

  • Kim, Seunga;Kim, Jihyun;Lee, Minjoo;Kim, Jayun;Jung, Woosik;Park, Joonhong
    • Journal of Korean Society of Water and Wastewater
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    • v.35 no.3
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    • pp.227-235
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    • 2021
  • This study examined the effect of ultraviolet (UV) application on bacterial disinfection in a commercialized humidifier using ultrasonic wave (UW). To accurately examine disinfection kinetics in tap-water condition, tap-water was sterilized using a filter, and then inoculated with pure cultures of E. coli and P. putida with known viable counts. The disinfection kinetic characteristics were experimentally compared when UV alone, UW alone, and UW+UV together were applied in disinfecting the added bacteria in the commercialized humidifier. When UV alone was applied, bacterial disinfection kinetics followed a first-order decay reaction, and showed an approximately 10-time weaker disinfection compared to the typical UV disinfection in water treatment or wastewater treatment. When UW alone was applied, bacterial disinfection kinetics followed a second-order decay reaction with a low disinfection rate constant of 0.0002 min-1(CFU/mL)-1. When UV and UW were applied together, however and interestingly, the disinfection rate constant (0.0211 min-1(CFU/mL)-1) was approximately 100 times increased than that for the UW alone case. These results revealed that the co-use of UV and UW can provide synergistic effect on bacterial disinfection in a tap-water condition in household humidifiers.