• Journal of Environmental Health Sciences
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• v.29 no.3
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• pp.65-71
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• 2003

The injection concentration of corrosion inhibitor increases under the pH 7, temperature of 2$0^{\circ}C$, and alkalinity of 35 mg/l (as CaCO$_3$), the corrosion rate gradually decreased. When the corrosion inhibitor of 10 mg/l is injected, the corrosion rate for carbon steel pipe, galvanized steel pipe, and copper pipe reduces for 37, 66 and 61 % respectively that it is more efficient on galvanized steel pipe and copper pipe. As a result of examination of corrosion rate at pH 6, 7, and 8 when injecting 10 mg/l of corrosion inhibitor under the conditions of 2$0^{\circ}C$ in water temperature and 35 mg/l (as CaCO$_3$) in alkalinity, the efficiency of the corrosion inhibitor increases as the pH increases. For carbon steel pipe, it does not show much a difference with the change of the pH condition, but galvanized steel pipe and copper pipe clearly show the corrosion rate depending on the change of the pH condition. The efficiency of corrosion inhibitor is low as the concentration of residual chlorine is high, but it does not show a great influence at 0.4 mg/l or less. For each pipe type, in the case of carbon steel pipe, the range of increase of corrosion speed following the residual chloride is higher than the other pipe types. In the meantime, the effect following the residual chlorine in copper pipe is low.

• Journal of Environmental Health Sciences
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• v.20 no.1
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• pp.54-61
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• 1994

This study was carried out to investigate the degree of contamination in private-drinking water supply (PDWS) and simple-piped water supply (SPWS), and to compare of water quality between them for 3 years from 1990 to 1992. The results of the study were as follows: 1. Private-drinking water supply (PDWS) (1) Field-Site (ㄱ) The items which were very significantly over the criteria (p<0.01), were temp., pH, NO-N, standard plate count (S.P.C.) and Coliform. (ㄴ) No. of households which were over the criteria, were 11.2~51.7% in temp., pH, NH$_3$-N and NO$_2$-N, and 83.1~93.3% in NO-N, S.P.C. and Coliform. (2) Moutain-Site (ㄱ) The items which were over the criteria, were NO$_2$-N (p<0.05), S.P.C. (p<0.01) and Coliform (p<0.01). (ㄴ) No. of households which were over the criteria, were 33.6 ~ 75.6% in NO$_2$-N, S.P.C. and Coliform. (3) No. of households which were fit to the criteria of all items, were 9.0% in field-site and 14.1% in mountain-site. 2. Simple-piped water supply (SPWS) (1) The items which were very significantly over the critera (p<0.01), were standard plate count (S.P.C.) and Coliform. (2) The water qualities of adjacent and remote samples were better than those of source samples. (3) Residual chloride was not detected in any sample. In conclusion, rural community requires to be continually performed the policy of safety drinking water supply, and to be devised an epoch-making counterplan for the level-up of simple-piped water supply (SPWS), espically on the method of disinfection.

• Journal of Korean Society on Water Environment
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• v.23 no.2
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• pp.193-200
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• 2007

The AOPs research defined by creating a sufficient amount of OH radicals from the dissolution of organic materials through photoxidation and research for a complete elimination of residual organic materials by membrane are actively ongoing. This research focuses on the hybrid processing of AOPs and M/F membrane to dissolve and eliminate organic chemicals in drinking water which are suspected of carcinogens. For this purpose, underground water was used as a source of drinking water for the hybrid processing of AOPs oxidation and M/F membrane, and a pilot plant test device was installed indoor. Carcinogenic chemicals of VOCs and pesticide were artificially mixed with the drinking water, which was then diluted close to natural water in order to examine treatment efficiency and draw optimal operation conditions. The samples used for this experiment include four chemicals phenol, chloroform, in VOCs and parathion, carbaryl in pesticide. As a result of the experiments conducted with simple, and compound solutions, the conditions to sufficiently dissolve and eliminate carcinogenic chemicals from the hybrid processing of where carcinogens were artificially added are : (hydrogen peroxide) prescribed solution 100 mg/L under pH 5.5~6.0, and the temperature $12{\sim}16^{\circ}C$, at the normal temperature and pressure. $d-O_3$ volume of 5.0 ppm and above and 30-40 minutes of reaction time are most appropriate and using MF/UF for membrane was ideal.

• Journal of Korean Society on Water Environment
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• v.24 no.4
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• pp.415-422
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• 2008

Drinking water treatment is enhanced by coagulant dosages and chlorine injection because of pH increase in raw water in droughty seasons such as spring and fall. But water quality deterioration is occurred by increase in residual aluminium and disinfection by-products. Coagulation process can be used to control natural organic matter (NOM) during water treatment. The effect of coagulation process appeared to depend on the pH of water rather than coagulant dosages. In this study, for water treatment in high pH season $H_2SO_4$ was applied for pH adjustment at full scale. Before and after pH adjustment by $H_2SO_4$ injection, water quality of drinking water was evaluate. In the result of investigation of total organic carbon (TOC) removal in high pH season, TOC was removed approximately 30~40%, which showed decrease in water treatment efficiency. Also, it is increased both particle numbers and residual Al concentration in the water. After $H_2SO_4$ injection for adjustment to pH<7.5 in settled water, treated water turbidity decreased in 0.047 NTU from 0.059 NTU, and particle numbers of filtered water decreased in 20/mL from 90/mL. On the other side, TOC removal efficiency increased in approximately 10% after adjustment of pH. In the result of decrease in pH in raw water through more coagulants and prechlorine without $H_2SO_4$ injection, trihalomethanes (THMs) concentration increased in $16{\mu}g/L$ from $8{\mu}g/L$.

• Corrosion Science and Technology
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• v.15 no.6
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• pp.303-310
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• 2016

The tap water used in Seoul was found to be corrosive. Its corrosivity was effectively reduced by that the additions of alkali agent such as NaOH, $Ca(OH)_2$ and corrosion inhibitor such as $H_3PO_4$. For the corrosion test, carbon steel pipe 50 m long was exposed to the drinking water produced by a pilot plant at $36.5^{\circ}C$, similar to the existing process where it takes about 20 minutes to reduce the initial chlorine content of 0.5 mg/L to 0.05 mg/L. $CO_2$ and $Ca(OH)_2$ was added not only to control the Langelier index (LI) above -1.0 and but also, to increase the duration time of residual chlorine by about 6 times. The persistence effect of residual chlorine was in the order of $H_3PO_4$ > $Ca(OH)_2$ > NaOH. Measurements of weight loss showed that corrosion inhibition was effective in order of $Ca(OH)_2$ > $H_3PO_4$ > NaOH > no addition, where the concentrations of $Ca(OH)_2$ and phosphate were 5 ~ 10 mg/L (as $Ca^{2+}$) and 1 mg/L (as $PO{_4}^{3-}$), respectively.

• Korean Journal of Ecology and Environment
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• v.49 no.3
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• pp.208-214
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• 2016

We analyzed research trend and public perception related with tap water to identify major factors affecting low consumption of tap water. 805 research articles were collected for text mining analysis and 1,000 on-line questionnaires were surveyed to find social variables influencing tap water intake. Based on the word network analysis, research topics were divided into 4 major categories, 1) drinking water quality, 2) water fluoridation, 3) residual chlorine, and 4) micro-organism management. Compared with these major research topics, scientific studies of drinking behavior, or social perception were rather limited. 22.4% of total respondents used tap water as drinking water source, and only 1% drank tap water without further treatments (i.e. boiling, filtering). Experience of quality control report (B=0.392, p=0.046) and level of policy trust (B=1.002, p<0.0001) were influential factors on tap water drinking behavior. Age (B=0.020, p=0.002) and gender (B= - 1.843, p<0.0001) also showed significant difference. To increase the frequency of drinking the tap water by social members, the more scientific information of tap water quality and the water policy management should be clearly shared with social members.

• Analytical Science and Technology
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• v.28 no.1
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• pp.58-64
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• 2015

This study aimed to investigate the concentration distributions and formation characteristics of trihalomethanes (THMs) in drinking water supplies to rural communities. Water samples were collected twice from 40 rural households located on the outskirts of Chuncheon city of Gangwon Province in the summers of 2010 and 2011, and urban drinking water samples were collected from 20 faucets during the same period in 2011 for comparison purpose. Water temperature, pH, and residual chlorine (total and free) concentrations were measured in the field, and samples were analyzed for dissolved organic carbon (DOC) and THM concentrations in the laboratory. The average DOC concentrations in rural water samples were not greatly different between groundwater (n = 20) and surface water (n = 20) which were used as sources for drinking water (1.81 vs. 1.91 mg/L). However, the average concentrations of total THMs (TTHMs) in groundwater ($9.77{\mu}g/L$) were much higher than those in surface water ($2.85{\mu}g/L$) and similar to those in urban drinking water samples ($10.8{\mu}g/L$). Unlike urban water supply, rural water (particularly groundwater) contained more brominated THM species such as dibromochloromethane (DBCM), suggesting its relatively high content of bromide ion (Br-). This study showed that rural water supplies have different THM formation characteristics from urban water supplies, probably due to their differences in source water quality properties.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.2
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• pp.147-154
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• 2014

In this study, chlorine modeling technique based on fuzzy system is proposed to reduce the carcinogenic substance and decide the optimal chlorine injection rate, which is affected by chlorine evaporation rate in sedimentation basin according to detention time, weather and water quality. The additional chlorine meter is installed in the inlet part of sedimentation to reduce the feedback time and implement cascade control, which leads to maintaining the residual chlorine concentration decided by fuzzy rule. It helps to take a preemptive action about long time delay, the characteristics of the disinfection process, and reduce the variation of residual chlorine rate by 7.3 times and the chlorine consumption by 40,000 dollars. It made a significant contribution to supply hygienically safe drinking water.

• Korean Chemical Engineering Research
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• v.51 no.6
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• pp.645-654
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• 2013

In this study, the management polices of micropollutants (MPs) were reviewed and the future management strategy was discussed considering climate change and etc. In Korea, the investigation of drinking water has been actively carried out for the priority contaminants as well as MPs. Recently river and lake waters have been also examined for MPs. However, the coverage and depth of the investigation is limited. Moreover, climate change is likely to increase air & water temperature and it will affect the hydrological cycle. Such changes may increase the residual concentrations of MPs in water system. As water reuse increases, the residual MPs of the recycled water may create public concerns. Thus, in a viewpoint of the precautionary principle, more stringent management of MPs is recommended for the drinking water and the body-contact water use. For the surface water, more studies are necessary to understand the ecological risk by MPs.

• Journal of Environmental Science International
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• v.17 no.8
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• pp.899-905
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• 2008

Quality test for activated carbon(AC) filter used for drinking water purifier is now an obligatory test and the standard material for valid purifying amount in water purifier performance test has been changed from residual chlorine to chloroform according to the notice of Ministry of Environment in 2006. Therefore, this study aimed to compare the ingredients of AC filters by confirming chloroform removal rate of AC filter and conducting 4 adsorption tests (Iodine, methylene blue decolorization, phenol value, ADS value) for AC filters provided by manufacturers. With water pressure of $1kgf/cm^2$, 1,500 liters of prepared inflow went through to check chloroform removal rate. As a result, product with removal rate of below 60% from all products. On the other hand, 4 adsorption tests were conducted for filters in the market and filters from manufacturers. None of the products satisfied all 4 tests. In particular, they showed great shortage to the standard in phenol value and ADS value test. However, manufacturers' filter showed much better performance than filters in the market. Also, the result of valid purifying amount test for each of five products of appropriate product and inappropriate product based on filter quality test showed average 4,440 liters for appropriate product and average 2,620 liters for inappropriate product. According to the result, it is shown that the filter with good adsorption also had good chloroform removal efficiency and adsorption efficiency. Therefore, it is expected that customers can screen good quality product through obligatory conduct of filter quality test. However, it is considered that complementation in system is required for future inspection.