• Journal of Microbiology
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• 제40권2호
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• pp.119-124
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• 2002

Experiments for the characterization of inactivation were performed in a series of batch processes with the total coliform used as a general indicator organism based on the chlorine residuals as a disinfectant. The water samples were taken from the outlet of a settling basin in a conventional surface water treat- ment system that is provided with the raw water drawn from the mid-stream of the Han River, The inactivation of total coliform was experimentally analysed for the dose of disinfectants contact time, filtration and mixing intensity. The curves obtained from a series of batch processes were shaped with a general tailing-off and biphasic mode of inactivation, i.e. a sharp loss of bacterial viability within 15 min followed by an extended phase. In order to observe the effect of carry-over suspended solids on chlorine consumption and disinfection efficiency, the water samples were filtered, prior to inoculation with coliforms, with membranes of both 2.5$\mu$m and 11.0 $\mu$m pore size, and with a sand tilter of 1.0 mm in effective size and of 1.4 in uniformity coefficient. As far as the disinfection efficiency is concerned, there were no significant differences. The parameters estimated by the models of Chick-Wat-son, Hom and Selleck from our experimental data obtained within 120 min are: log(N/N$\_$0/)=-0.16CT with n=1, leg(N/N$\_$0/)=-0.71C$\^$0.87/ with n 1 for the Chick-Watson model, log (N/N$\_$0/)=-1.87C$\^$0.47/ T$\^$0.36/ for the Hom model, log (MHo)=-2.13log (1+CT/0.11) for the Selleck model. It is notable that among the models reviewed with regard to the experimental data obtained, the Selleck model appeared to most closely resemble the total coliform survival curve.

• 한국물환경학회지
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• 제20권3호
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• pp.275-280
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• 2004

This study was performed to investigate the disinfection efficiency and the formation characteristics of disinfection by-products(DBPs) by chlorination in the sewage effluent. The effluent was sampled from the sewage treatment plants operated in the activated sludge process and the advanced sewage process. The type of DBPs investigated were Trihalomethanes(THMs), Dichloroacetonitrile(DCAN), Chloral hydrate(CH), Dichloroacetic acid(DCAA), Trichloroacetic acid(TCAA). Major findings are as follows. First, the optimum injection concentration for chlorination in sewage effluent were found to be in the range $0.5{\sim}1.0mg\;cl_2/L$. Also, It was found that the chlorine dosage in the effluent of activated sludge process was higher than in the effluent of advanced sewage process. Second, the maximum formation concentration of THMs were $12.7{\mu}g/L$. The THMs formation reaction was finished in a short time of several seconds and chloroform was mainly formed. Also, it was found that the concentration of ammonium nitrogen is higher, the concentration of THMs is lower. Third, it was found that DCAA and TCAA were mainly formed as DBPs by disinfection.

• 대한환경공학회지
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• 제30권8호
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• pp.755-759
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• 2008

모노클로라민과 디메틸아민 농도와 관련 있는 염소, 질소, 탄소 비율에 따라서 소독부산물인 NDMA 생성을 여러 조건에서 조사하였다. 디메틸아민/모노클로라민 비율이 1에 근접 할 경우에 NDMA 생성이 높게 나타났으며 아주 작거나 너무 클 경우 생성은 급속하게 감소하였다. 염소/질소 비율이 증가함에 따라 NDMA 생성도 증가하는 것으로 조사되어 염소 성분이 생성에 중요한 지표가 됨을 알 수 있었다. 접촉시간에 따른 NDMA 생성 영향을 조사한 결과, 본 연구에서는 72시간에서 급속하게 증가하는 것을 볼 수 있다. 기존연구에서와 같이 본 연구에서도 pH는 NDMA 생성에 중요한 영향을 주는 요소로 조사되었다.

• 상하수도학회지
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• 제23권3호
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• pp.339-344
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• 2009

The authors investigated the bacterial community attached to granular activated carbon(GAC) particles and the susceptibility of the community to chlorine disinfection. The study was carried out at the G Water Treatment Plant in Seoul, which was in full-scale operation. Bacteria attached to the surface of GAC increased gradually with treatment from $0.4{\times}106{\sim}8.5{\times}106 CFU/g$. TOC removal was under 1.0 mg/L due to increased bacterial community on the surface of GAC. It was found that TOC removal was closely related with physical and biological parameters such as pore volume and the number of attached bacteria. When the washed and the attached cells were disinfected with 1.0mg/L of chlorine for 1 hour, the washed cells with chlorination could be controlled, but the number of the attached cells increased gradually. The results suggest a possibility that the treatment and disinfection barriers can be penetrated and pathogenic bacteria may break into the drinking water supplying system.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.47-47
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• 2010

Discharge under the water is very hard and demand considerable high voltage. But specially improved electrode can generate plasma discharge to salty water with relatively low voltage. A round shape ceramic electrode having many pinholes combined with metallic one can generate plasma. 400 volt, 10 kHz and 3 micro second pulse width were applied to repeatedly running synthetic seawater with 10 L/m velocity, containing cultivated E. coli and Bacillus. As a result, 18, 94, 99.97, 100, 100 % disinfection rates to E. coli and 17.1, 17.1, 82.9, 99.4, 99.9 % disinfection rates to Bacillus subtilis were achieved to 1, 2, 3, 4, 5 times repetitive treatment respectively. In the plasma condition, the ions and electrons are separated and new kinds of components are re-synthesized by the intensive movement of the components. Especially chlorine ions are separated and recombined to residual free chlorine like HOCl, $OCl^-$. The residual free chlorine concentrations of discharged water were 0.25, 0.88, 1.39, 1.59, 1.66 mg $Cl_2$/L after 5 times treatment respectively. Another unconfirmed radical and oxidants for example, OH, $H_2O_2$, and $O_3$ can have an effect on microorganism of course.

• 상하수도학회지
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• 제27권3호
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• pp.331-337
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• 2013

Post-chlorination for disinfection in portable water process is final process. The design factors of post-chlorination are inflow pipe line from tank of filtrated water to cleanwell, injection point of chlorine, appropriate shape of baffle in cleanwell for disinfection efficient improvement. Until now, we did not have the design standard for post-chlorination. we evaluated most suitable design method of post-chlorination process in portable water process by using computational fluid dynamics in this research. We found the result that the pipe to connect the cleanwell should be one. If pipe line split into two or more, uniform distribution of the flow is difficult. Second, optimal injection point of chlorine is the middle of pipe line to connect the cleanwell. Therefore, it is not economical to install chlorine contact basin in cleanwell. Third, the shape of baffle should be designed in order to water flows in one direction. And we found that it is better to design the low number of flow turning.

• International Journal of Industrial Entomology and Biomaterials
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• 제12권1호
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• pp.7-14
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• 2006

Silkworm diseases are better prevented than cured. Disinfection and hygiene are the two important aspects in silkworm rearing to prevent the diseases. Suitable disinfectant is the primary need to disinfect the rearing house, its surroundings and appliances to eliminate the persistent pathogens from the rearing environment. In this direction, Serichlor, a new disinfectant in Indian Sericulture marketed as Serichlor-60 (contains 60,000 ppm of chlorine dioxide) and Serichlor-20 (contains 20,000 ppm of chlorine dioxide) has been evaluated for its germicidal effect against the pathogens of silkworm, viz., spores of Nosema bombycis, Bacillus thuringiensis, polyhedra of BmNPV and conidia of Beauveria bassiana both in vitro and in vivo. Results indicated that high concentration (2,500 ppm of chlorine dioxide) is required to kill all the pathogens at 100% level. The efficacy of the Serichlor was greatly enhanced by the addition of 0.5% slaked lime solution. 500 ppm of chlorine dioxide in 0.5% slaked lime solution was found effective against all the pathogens tested. This concentration of disinfectant was also found effective for disinfection of rearing house, rearing appliances and silkworm egg surface. The disinfectant is stable, non hazardous, least corrosive and most suitable for Indian Sericulture.

• 한국물환경학회지
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• 제21권2호
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• pp.176-183
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• 2005

Chlorination of wastewater is recently practiced in Korea. While many researchers have studied the kinetics of aqueous chlorine(HOCl) with nitrogeneous compounds and other organic/inorganic contaminants in drinking water, the researches of wastewater chlorination are relatively few. The purpose of this study was to investigate the chlorine decay kinetics and parameters on wastewater chlorination. Chlorine decay rate increased with increasing initial chlorine concentration. The parameters affecting chlorine decay rate were different in each wastewater treatment plant. One of the most important parameters affecting chlorine decay was initial chlorine concentration, and other parameters such as $NH_3-N$, total coliform, $UV_{254}$ and Fe were also affected. The decay ratio of chlorine was decreased with increasing initial chlorine concentration, and the disinfection efficiency showed good correlation with the decay ratio.

• 상하수도학회지
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• 제25권2호
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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.

• 대한환경공학회지
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• 제36권10호
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• pp.685-690
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• 2014

하수처리시설 초과유량에 대한 처리 규제 입법 예고로 인해 강우 월류수 처리에 대한 관심이 증가하고 있다. 본 연구에서는 강우 월류수 염소(차아염소산나트륨) 소독 시 소독제 농도(0.11-4.0 mg $Cl_2/L$), pH (6.5-8.0), 온도($15-25^{\circ}C$), 암모니아 농도(10-41 mg N/L), 부유물질(91-271 mg SS/L)이 대장균군수 감소 속도에 미치는 영향을 고찰하였다. 차아염소산나트륨 농도 효과는 반속도 상수가 1.212mg $Cl_2/L$인 saturation-type model로 잘 모사되었다. 소독 반응 속도는 SS와 pH 증가에 따라 감소되는 반면, 온도에 따라서는 증가하였고, 암모니아 농도에는 영향을 받지 않았다. 월류수 유입 조건을 $1{\times}10^5MPN/mL$, 271 mg SS/L, $15^{\circ}C$, pH 8.0로 가정할 때, 염소 주입 농도 1 mg/L, 수리학적 체류시간 1.25 분인 염소 소독조를 통해 입법예고 된 수질 기준의 1/3 수준인 대장균군수 1,000개/mL를 달성할 수 있을 것으로 계산되어, 염소 소독이 강우 월류수 소독에 유효하게 사용될 수 있을 것으로 판단된다.