• Title/Summary/Keyword: Chlorine disinfection

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Reflection on Kinetic Models to the Chlorine Disinfection for Drinking Water Production

  • Lee, Yoon-Jin;Nam, Sang-ho
    • Journal of Microbiology
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    • v.40 no.2
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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.

Formation Characteristics of Disinfection By-Products using Chlorine Disinfection in Sewage Effluent (하수 염소 소독시 소독부산물 발생 특성)

  • Beck, Young-Seog;Song, Min-Hyung;Jung, Kyung-Hun;Kwon, Dong-Sik;Lee, Gi-Gong
    • Journal of Korean Society on Water Environment
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    • v.20 no.3
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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.

Effect of Monochloramine and Dimethylamine Concentrations on the NDMA Formation (모노클로라민과 디메틸아민 농도가 NDMA 생성에 미치는 영향)

  • Kim, Jong-O
    • Journal of Korean Society of Environmental Engineers
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    • v.30 no.8
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    • pp.755-759
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    • 2008
  • As a disinfection byproduct, N-nitrosodimethylamine(NDMA) formation was studied according to chlorine, nitrogen, and carbon composition related to monochloramine and dimethylamine(DMA) concentrations. The highest NDMA formation was observed when the dimethylamine/monochloramine ratio was close to 1, and the formation was rapidly decreased when the ratio was less or greater than 1. The formation of NDMA increased with increasing chlorine/nitrogen ratio indicating the chlorine is a limiting factor. A rapid disinfection byproduct was formed at 72 hour contact time in this study. As the previous researches, pH was a significant factor for the NDMA formation.

Bacterial attachment on granular activated carbon and effect of chlorine disinfection (입상활성탄 부착세균과 염소소독 연구)

  • Baek, Youngae;Joe, Woohyun;Hong, Byungeui;Choi, Youngjune;Ahn, Seoungkoo
    • Journal of Korean Society of Water and Wastewater
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    • v.23 no.3
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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.

Disinfection of Escherichia coli and Bacillus subtilis using underwater plasma

  • Yu, Seung-Min;No, Tae-Hyeop;Seok, Dong-Chan;Yu, Seung-Ryeol;Hong, Yong-Cheol;Lee, Bong-Ju
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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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.

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Most suitable design method of post-chlorination process in portable water process by using CFD (전산유체를 활용한 정수공정에서 후염소 투입공정 최적설계 방안)

  • Cho, Youngman
    • Journal of Korean Society of Water and Wastewater
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    • v.27 no.3
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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.

Serichlor, A New Disinfectant in Indian Sericulture

  • Balavenkatasubbaiah M.;Nataraju B.;Sharma S.D.;Selvakumar T.;Chandrasekharan K.;Rao P. Sudhakara
    • International Journal of Industrial Entomology and Biomaterials
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    • v.12 no.1
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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.

Studies on Chlorine Demand and Its Decay Kinetics in Chlorinated Sewage Effluents (하수의 염소 소독시 총잔류염소 감소 특성에 관한 연구)

  • Beck, Youngseog;Sohn, Jinsik
    • Journal of Korean Society on Water Environment
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    • v.21 no.2
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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.

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.

Effects of Disinfectant Concentration, pH, Temperature, Ammonia, and Suspended Solids on the Chlorine Disinfection of Combined Sewer Overflow (소독제 농도, pH, 온도, 암모니아 농도, 부유물질이 강우 월류수 염소 소독에 미치는 영향)

  • Kim, Sang-Hyoun
    • Journal of Korean Society of Environmental Engineers
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    • v.36 no.10
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    • pp.685-690
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    • 2014
  • The treatment of combined sewer overflow (CSO) is one of potential concerns in domestic wastewater treatment in Korea due to the pre-announce of CSO regulations. This work investigated the effects of disinfectant (NaOCl) concentration (0.11 to 4.0 mg $Cl_2/L$), pH (6.5 to 8.0), temperature (15 to $25^{\circ}C$), ammonia (10 to 41 mg N/L), and suspended solids (91 to 271 mg SS/L) on the chlorine disinfection of CSO. The effect of NaOCl concentration on the pseudo-$1^{st}$ order reaction rate for total coliform inactivation was described well with a saturation-type model with the half-velocity constant of 1.212 mg/L. The total coliform inactivation reaction rate decreased with SS and pH, and increased with temperature. Ammonia in the examined range did not affect the disinfection kinetics. A chlorine contact tank with the injection chlorine level of 1 mg $Cl_2/L$ and the hydraulic retention time of 1.25 min is estimated to reduce total coliform from $1{\times}10^5MPN/mL$ to 1,000 MPN/mL at 271 mg SS/L, $15^{\circ}C$, and pH 8.0. Chlorine would be a proper option for the disinfection of CSO.