• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.170-170
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• 2023

Providing safe and readily available water is vital to maintain public health. One of the most prevalent methods to prevent the spread of waterborne diseases is applying chlorine injection to the treated water before distribution. During the water transmission and distribution, the chlorine will experience a reduction, which can imply potential risks for human health if it falls below the minimum threshold. The ability to determine the appropriate initial intensity of chlorine at the source would be significant to prevent such problems. This study proposes two methods that integrate hydraulic and water quality modeling to determine the suitable intensity of chlorine to be injected into the source water to maintain the minimum chlorine concentration (e.g., 0.2 mg/l) at each demand node. The water quality modeling employs the first-order decay to estimate the rate of chlorine reduction in the water. The first method utilizes a backtracking algorithm to trace the path of water from the demand node to the source during each time step, which helps to accurately determine the travel time through each pipe and node and facilitate the computation of time-dependent chlorine decay in the water delivery process. However, as a backtracking algorithm is computationally intensive, this study also explores an alternative approach using a water age. This approach estimates the elapsed time of water delivery from the source to the demand node and calculate the time-dependent reduction of chlorine in the water. Finally, this study compares the outcomes of two approaches and determines the suitable and effective method for calculating the chlorine intensity at the source to maintain the minimum chlorine level at demand nodes.

• Environmental Engineering Research
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• v.19 no.4
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• pp.375-380
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• 2014

Macro fouling due to blue mussels (Mytilus edulis) has affected negatively on the operation efficiency and eventual system failure of offshore structures and coastal power stations. A certain range of chlorine (0.05, 0.1, 0.3, 0.5, 0.7 and 1.0 mg/L) was applied on the mussel larvae to identify the survival rate with respect to various exposure times under laboratory condition. The ciliary movement of the larvae was used to check their survival. The 1.0 mg/L of chlorine shows to 97% of larvae mortality whereas 0.7 mg/L of chlorine shows only 16% of larvae mortality. Minimum exposure times for 100% larvae mortality ranged from 300 to 20 min for increasing concentrations of chlorine (0.05~1.0 mg/L). It was found that 1 mg/L of chlorine was 4 times more efficient than 0.7 mg/L of that, and 15 times more than 0.05 mg/L of chlorine dose. Data collected and analyzed here will help plant operators to optimize chlorine dosage and its scheduling.

• Korean Journal of Microbiology
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• v.16 no.2
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• pp.62-70
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• 1978

Chlorine was used for inactivation of bacteriophage f2 at pH 5.5, 7.5, and 10.0 at $10^{\circ}C$. The inactivation rate phage with chlorine varied depending on the pH value and reaction time. Hypochlorous acid appeared to be the major species of free chlorine for the inactivation. Suevival of the phage treated with chlorine and infectivity of the RNA extracted from the chlorinated phage were examined. The RNA extracted from untreatd phage was chlorinated and its infectivity was assayed. All three samples showed similar rates of inactivation at pH 5.5 and 7.5, but the naked RNA was more susceptible to chlorine at pH 10.0. The rate of inactivation was compared naked RNA was more susceptible to chlorine at pH 10.0. The rate of inactivation was compared with specific and non-specific attachment of the phasge f2. The specific attachment of the phage increased after the phage had been inactivated by extended chlorination. Chlorine may penetrate to the becteriophage f2 by altering the structural integrity of the protein coat, but the main target of free chlorine for inactivation of the phage appeared to be the phage RNA.

• Membrane and Water Treatment
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• v.10 no.6
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• pp.395-404
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• 2019

The influence of chlorine on marine bacterial communities was examined in this study. A non-chlorine-adapted marine bacterial community (NCAM) and a chlorine-adapted bacterial community (CAM, bacterial community treated with $0.2mg-Cl_2/L$ chlorine) were cultivated for 1 month. A distinct difference was observed between the NCAM and CAM, which shared only eight operational taxonomic units (OTUs), corresponding to 13.1% of the total number of identified OTUs. This result suggested that chlorine was responsible for the changes in the marine bacterial communities. Kordiimonas aquimaris was found to be a chlorine-resistant marine bacterium. The effect of intermittent chlorination on the two marine biofilm communities formed on the reverse osmosis (RO) membrane surface was investigated using various chlorine concentrations (0, 0.2, 0.4, 0.6 and 0.8 mg $Cl_2/L$). Although the average number of adherent marine bacteria on the RO membrane over a period of 7 weeks decreased with increasing chlorine concentration, disinfection efficiencies showed substantial fluctuations throughout the experiment. This is due to chlorine depletion that occurs during intermittent chlorination. These results suggest that intermittent chlorination is not an effective disinfection strategy to control biofilm formation.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.3
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• pp.287-297
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• 2014

It is important to predict chlorine decay with different water purification processes and distribution pipeline materials, especially because chlorine decay is in direct relationship with the stability of water quality. The degree of chlorine decay may affect the water quality at the end of the pipeline: it may produce disinfection by-products or cause unpleasant odor and taste. Sand filtrate and dual media filtrate were used as influents in this study, and cast iron (CI), polyvinyl chloride (PVC), and stainless steel (SS) were used as pipeline materials. The results were analyzed via chlorine decay models by comparing the experimental and model parameters. The models were then used to estimate rechlorination time and chlorine decay time. The results indicated that water quality (e.g. organic matter and alkalinity) and pipeline materials were important factors influencing bulk decay and sand filtrate exhibited greater chlorine decay than dual media filtrate. The two-component second-order model was more applicable than the first decay model, and it enabled the estimation of chlorine decay time. These results are expected to provide the basis for modeling chlorine decay of different water purification processes and pipeline materials.

• Korean Journal of Food Science and Technology
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• v.24 no.2
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• pp.132-136
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• 1992

The effects of chlorine treatment on the lipid composition of wheat flour were studied by treating flour with different amounts (1, 2 and 4 ounces per 100 pounds of flour) of liquidized chlorine gas. The contents of free lipid increased slightly while those of the bound lipid decreased at all levels of chlorine used. The contents of neutral lipid in the free lipid decreased while those in the bound lipid increased as the level of chlorine increased. The contents of triglycerides in the free and bound lipids decreased as the level of chlorine increased. As the level of chlorine increased, digalactosyl diglycerides in the bound lipid decreased, whereas those in the free lipid increased within the range of 1 to 2 oz of chlorine. The phosphatidylcholine content in the free and bound lipids decreased while the lysophosphatidylcholine increased in both free and bound lipids as the level of chlorine increased. The content of saturated fatty acids increased while that of unsaturated ones decreased as the level of chlorine increased.

• Resources Recycling
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• v.29 no.6
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• pp.48-56
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• 2020

In this study, raw mix was mixed with CaCl2 for analyzing characteristics of clinker added chlorine and chlorine was added by 2,000ppm at high concentration condition. The raw mix added chlorine was burned at 1250℃~1350℃ and maintained during 10minutes at each maximum temperature. Clinker target modulus was LSF 92, SM 2.5 and IM 1.6 in this study. The burnability of clinker added chlorine was identified by free-CaO content. Free-CaO content decreased as chlorine content increased and free-CaO content of 1350℃-2000ppm clinker decreased by 1.5%. Optical microscope and XRD Analyses were used for identify mineral properties of clinker added chlorine. The mineral of clinker could not be observed at 1250℃ and the size of alite grew larger as chlorine content increased at 1350℃. It showed a good crystallizability as chlorine content increased. As chlorine content of clinker increased, clinker showed a good burnability and mineral property.

• Analytical Science and Technology
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• v.12 no.5
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• pp.403-407
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• 1999

A method for detecting chlorine dioxide in drinking water was developed by the modified iodometric titration. This method requires prior removal of interfering chemicals such as chlorine and/or other oxidants: the interferents are removed by $N_2$ purging. Chlorite and chlorate were successfully quantified by the ion chromatography-conductivity detection. Stabilized chlorine dioxide that is commercially available contained only traces of chlorine dioxide (0.01-0.09%). In reality, its main component is chlorite.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.04a
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• pp.78-83
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• 1999

In this paper the extinction coefficients of molecule chlorine ($Cl_2$), chlorine dioxide (ClO$_2$), hypochlorous acid (HClO), chlorous acid ($HClO_2$$_2$) were determined using a PDA UV-VIS spectrophotometer. Based on these, the concentrations of $Cl_2$, $ClO_2$, and HClO in general chlorine dioxide bleaching liquor can be measured. The concentrations of $Cl_2$, $ClO_2$ and $HClO_2$ produced during the generation of methanol based chlorine dioxide generator can also be determined use the same method. The method was thought to be able to give more information in chlorine dioxide bleaching chemistry if combine its use with titration and ion chromatography.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.5
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• pp.625-631
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• 2005

Disinfection characteristics of mixed oxidants produced by mean of electro-chemical method were evaluated. Inactivation rate of B. subtilis spore on the mixed oxidants were similar with that of chlorine. Based on the experimental results, activation energy of mixed oxidants and chlorine with B. subtilis spore at pH 8.3 were calculated as 30.8, $34.7kJ{\cdot}mol^{-1}$ respectively. UV absorption spectrum of both chlorine and mixed oxidants present similar. Molar extinction coefficients of chlorine and mixed oxidants at 292nm, which is maximum absorption wavelength of $OCl^-$ were 357, $377M^{-1}cm^{-1}$, respectively. Disinfectant decay rate and formation rate of THM in the S WTP filtrate also shows insignificant difference for both mixed oxidants and chlorine. In consequent, it was confirmed that high portion of chlorine presents in the mixed oxidants.