• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.2
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• pp.344-349
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• 2001

The removal of chlorine from aqueous solutions on dried Chlorella vulgaris(DCV) and green tea powder(GTP) were investigated as a function of contact time, pH and initial chlorine concentration. Removal by DCV and GTP reached equilibrium after 3hrs and 0.5hr, respectively. Optimum removal pH values of DCV and GTP were determined as above 10. Both Langmuir and Freundlich adsorption models were suitable for describing the short-term removal of chlorine by DCV and GTP. According to Langmuir adsorption isotherms the maximum removal capacity of DCV (2.75mg $Cl_2/mg$) was nearly two times greater than those of GTP (1.53mg $Cl_2/mg$) and activated carbon (1.47mg $Cl_2/mg$). These results suggested that Chlorella vulgaris biomass might potentially be used as an alternative to traditional water treatment materials for removal of residual chlorine in drinking water or process waste-water.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.2
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• pp.22-27
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• 2017

During the water treatment process for household water supply, a reservoir is the last place the water is stored before being supplied to users, and the duration of the water's stay is an important factor that affects its safety. This may cause the concentration of the residual chlorine disinfectant to increase and thus lower the water's quality. The concentration and discharge efficiency of residual chlorine must be verified and managed, because these are key factors that affect the reservoir's performance. Because the actual verification test for analyzing the efficiency of a reservoir and the disinfectant's dilution capacity is difficult, simulations are generally conducted using the computational fluid analysis method. However, the simulation results require validation with experiments. The error and drainage efficiency were analyzed in this study by comparing and analyzing the actual tracer test and simulation so that the actual test for a hexagonal drainage can be replaced by the computational fluid analysis method. Based on the results of the efficiency analysis, the hexagonal reservoir was found to be appropriate, and the simulation's reliability was verified with a tracer test.

• Food Science and Preservation
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• v.24 no.2
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• pp.312-319
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• 2017

In the present study, disinfection efficacy of slightly acidic electrolyzed water [SlAEW, 30 ppm of effective chlorine at $20{\pm}1^{\circ}C$, oxidation-reduction potential (ORP) $562{\pm}23mV$, pH 6.4] on 4 kinds of vegetables (lettuce leaf, endive leaf, perilla leaf and kale leaf) was evaluated to obtain a microbial reduction characteristics which are necessary to design a process control for non-thermal sterilization of fresh vegetables. Active chlorine, residual chlorine, microbial counts and residual microbial counts, which are the key factors in the non-thermal sterilization process were measured by dipping them in SlAEW three times for 30 minutes in order to analyze the relationship between factors. Total microbial count was decreased mostly during the first 10 minutes of washing, and the limit value that can be reduced by immersion treatment was 3 log CFU/g for the total microbial count surviving in 4 kinds of vegetables. The total number of microorganism that can be reduced by washing in SIAEW for 10 min was found to be about 2 log CFU/g on average. In addition, the active chlorine decreased in the initial 10 minutes in 2.2 ppm, 2.0 ppm, 1.7 ppm and 2.5 ppm in lettuce, perilla leaf, endive leaf and kale leaf, respectively, and about 50-80% of the chlorine was reduced in the initial 10 min appear.

• Journal of Korean Society of Water and Wastewater
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• v.14 no.2
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• pp.164-173
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• 2000

Fluoridation of drinking water to a level of about 0.8mg/l (below 1.5mg/l) for reducing the incidence of tooth decay is recommended. However, concerns about potential problems of unknown effects and overdosing hinders the fluoridation. This study describes the work performed to obtain information on the behavior of fluoride under various conditions in the process of water fluoridation. Effects of water treatment chemicals, water treatment unit, and water distribution on water fluoridation were investigated at both lab and an actual water treatment plant. Residual fluoride concentration was not affected by lime and chlorine dosage up to 20mg/l. Flocculation with PAC slightly decreased the residual fluoride concentration as PAC dosage increased. Average fluoride concentration of 0.87mg/l at an intake basin was decreased to 0.83mg/l by sedimentation, 0.81mg/l by dual media(sand+anthracite) filtration, and 0.79mg/l by granular activated carbon filtration in the water treatment plant.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.505-510
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• 2000

In this study the effects of pre-chlorination on the coagulation of water which contain Microcystis aeruginosa. were investigated on the laboratory scale. We prepared the sample of $10^5cell/mL$ Microcystis aeruginosa and then applied 0.2, 1.0, 10 mg-Cl/L chlorine on the sample After reaction period(1 minute and 1 hour), each sample was coagulated. As a result, after 0.4 mg-Al/L coagulant dose, turbidities of all samples were below 2 mg-Kaolin/L. Turbidity was not affected by chlorine dose. As the dose of chlorine was increased, the residual aluminum was decreased, but result of $UV_{254}$ was adverse.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.6
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• pp.757-764
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• 2002

Chlorination dosage in water treatment plant of field is determined by chlorination demand experiment through two or three hours after raw water was sampled in inflow. It is impossible to continuously control for real time because the sampled water is adapted chlorination dosage after water treatment process had been proceeded. Therefore in this study, we will design informal chlorination demand system, this designed system will be experimented as to water quality and accuracy of control in various conditions. Throughout these experimental results, we will revise the system and the revised system is enable to optimal control of chlorination dosage. Finally, we have developed chlorination demand system, which can automatically determination of chlorination dosage to be determined according to variety of raw water quality inflow in water treatment plant.

• Journal of Yeungnam Medical Science
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• v.5 no.1
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• pp.69-75
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• 1988

The drinking water in the apartment is stored in reservior tank and thereafter supplied each household. In case the drinking water is stored too long or insanitary, tap water might change in quality. This study was carried out to evaluate the physico-chemical and microbiological conditions of 36 samples of tap water of apartments compared to 18 samples of tap water of independence houses in Taegu City from May to October, 1987. Main findings are summarized as follows : PH values were within normal range in all samples. Samples less than 0.2ppm in residual chlorine accounted for 16.7% in the appartment and 5.6% in the independence house. Nitrite nitrogen was detected 2.8% of apartment samples only. Among the total of 54 samples, 11.1% of the apartment and independence samples were over the normal value in standard plate count. Samples more than 1.8 of most probable number(MPN) accounted for 27.8% in the apartment and 33.3% in the independence house. In result of test for residual chlorine, nitrite nitrogen, standard plate count, and MPN, the proportion of the samples revealed inappropriated in respect of drinking water standards. In case of all sorts of tests was 2.7% in apartment and nothing in independence houses, in case of 3 sorts of tests was 2.7% in apartment and 5.6% in independence houses, in case of 2 sorts of tests was 8.3% in apartment and 5.6% in independence houses, and in case of only 1 test was 25.0% in apartment and 22.2% in independence houses. Correlation between residual chlorine and standard plate count, and between standard plate count and MPN were observed. It was found that the more years since construction of apartment were, the worse tap water was in quality.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.9
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• pp.511-516
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• 2015

On this study, we investigated the removal characteristics of residual chlorine and DBPs in tap-water during boiling. Also we investigated the releasing characteristics of essential minerals in infusion tea. While recent studies focused on removal mechanisms of harmful heavy metals in infusion tea, this study tried to suggest the way to drink tap-water healthier and safer by examining releasing mechanisms of essential minerals in infusion tea. As a result, residual chlorine(initial conc. was 0.7 mg/L) was all removed in 20 minutes after heating and DBPs (the sum of THMs, HAAs and CH) were removed up to 65%. 6 kinds of essential minerals (Ca, K, Na, Mg, S, P) were released from 5 kinds of infusion tea (barley tea, corn tea, brown rice tea, cassia seed tea, solomon's seal tea) on the market. In cassia seed tea, the amount of essential minerals released from tea showed the highest values, 9.6 mg/g, and brown rice tea was the lowest, 1.6 mg/g. Particularly, the released amounts of potassium, playing a key role in human body in maintaining normal blood pressure, cell metabolism and enzyme action, showed relatively high. Through this study, we got to know that essential minerals can be obtained up to 40% of recommended nutritional intake for Korean by boiling tap-water with infusion tea.

• Journal of Korean Society on Water Environment
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• v.20 no.4
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• pp.313-320
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• 2004

In this study, variable characteristics of drinking water and the influences on underground water reservoirs, rooftop water tanks, and service water pipes in the building were assessed. The influence of underground water reservoir material and water capacity on water quality also were assessed. The results are the following as; First of all, the drinking water passing through underground water reservoirs or service water pipes in the building, averagely metal component concentration more increased from percent of 41.3 to percent of 74.2 totally than other items of water quality. On the other hand, both residual chlorine and total solid highly decreased 65.6 percent and 35.3 percent, respectively. Therefore, it was thought that water quality could be getting worse for microorganism re-growth by residual chlorine reduction, and total solid also could be a cause for extraneous matters accumulated in water reservoir. Secondly, the variations on water quality of each stage for water supply system in the building were higher in water service pipes connected from rooftop water tanks to the tap than in underground water reservoirs. In addition to, among of twelve items on water quality, ten items on water quality except dissolved oxygen and residual chlorine increased. Therefore, it was thought that the influence of water service pipes connected from rooftop water tanks to the tap on water quality were higher than other stages of water supply system in the building. Thirdly, in case of materials of underground water reservoir, it was likely that the variation on water quality by stainless steel and concrete materials got some similar. In case of water capacity, the variations on water quality of underground water reservoirs over $1,000m^3$ higher than those under $1,000m^3$. That reasons was likely that the retention time(49.72 hours averagely) of underground water reservoirs over $1,000m^3$ was two times longer than it of those under $1,000m^3$(23.37 hours). Therefore, it was thought that the influence on water quality by materials were some similar, but in case of water capacity, the influence of underground water reservoirs were higher.

• Journal of Aquaculture
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• v.16 no.3
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• pp.151-158
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• 2003

This study was conducted to estimate the effects of residual chlorine dioxide ($CIO_2$) in chlorinated seawater on survival and physiological responses (hematocrit: Ht, hemoglobin: Hb, serum electrolyte and glucose levels, and osmolality) of olive flounder, Paralichthys olivaceus. All the flounders were exposed for 10 min to different concentrations of residual $CIO_2$ just after chlorination for 1 min in each experimental aquarium (EA). ClO$_2$-free seawater was continuously supplied to each EA after 10 min exposure to $CIO_2$. By means of probit analysis, the median lethal times (LT$_{50}$, min) of flounder exposed to 0.43 and 0.51 ppm $CIO_2$, were at 103 and 32 min, respectively. In the range from 0.34 to 0.51 ppm $CIO_2$, the values of Ht, Hb, electrolytes and osmolality of fish exposed to $CIO_2$ were significantly elevated as elapsed time and residual concentrations of $CIO_2$ increased after chlorination. The levels of Ht, Hb, electrolytes and osmolality in flounder exposed to 0.27 ppm $CIO_2$ were not significantly different compared to control fish, which were maintained in $CIO_2$-free seawater; however, the levels of serum glucose were significantly increased with elapse times.