• Journal of Korean Society of Water and Wastewater
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• v.32 no.2
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• pp.183-192
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• 2018

Applicability of corrosion inhibitor was evaluated using pilot scale water distribution pipe simulator. Calcium hydroxide was used as corrosion inhibitor and the corrosion indices of the water were investigated. Corrosion indices, Langelier saturation index (LI) increased by 0.8 and calcium carbonate precipitation potential (CCPP) increased by 9.8 mg/L. This indicated that corrosivity of water decreased by corrosion inhibitor and the effects lasted for 18 days. Optimum calcium hydroxide dose was found to be 3~5 mg/L for corrosion inhibition. We suggest that monitoring of CCPP as well as LI need to be conducted to control corrosivity of water.

• Journal of Korean Society on Water Environment
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• v.28 no.4
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• pp.615-623
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• 2012

In this study, we evaluate the corrosion indexes (CI) such as Langelier Index (LI), Larson ratio (LR), Ryznar saturation index (RSI), Aggressiveness index (AI) of water quality for raw water, treated water and water in distribution reservoir at major eight drinking water treatment plants (DWTPs) in Korea. By analyzing secondary contamination of tap water, the variation of secondary contaminants was investigated with regard to pipe materials, aging and corrosion index (CI). In addition, we suggested an appropriate CI applicable water quality and the management plan for CI monitoriing. All CI showed corrosive water quality, and they did not change significantly in the distribution network. However, Copper (Cu), iron (Fe) and zinc (Zn) concentrations as secondary contaminants increased through the distribution network. Among CI, LI was most sensitive to changes in raw water quality and drinking water treatment. Also, it has high correlations with other indexes such as RSI, AI. Therefore, LI is considered as an appropriate CI to the domestic water quality. Based on these result, we propose LI as a drinking water quality standard to control the pipe corrosion from DWTPs.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.5
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• pp.707-717
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• 2011

Replacement of old water distribution pipes for protecting water quality induced by pipe corrosion requires enormous budget. Even after the replacement, however, corrosion can occur again at any times and, therefore, inhibitive measure of the corrosion will be not only economical but needed to diminish the consumers' distrust on tap water quality. In 2008, National Environmental Research Institute did a survey on 8 major drinking water source and proposed to establish the Langelier Saturation Index(LI) as a corrosion index in Drinking Water Quality Criteria. Among the water industries of Korea, K-Water is the only one that set up the level of pH over 7.0 and LI above -1.5 on yearly average basis. However, no systematic regulation including LI to inhibit the corrosive tendency has been established yet. In this paper, LI values out of 31 drinking water treatment plants were analyzed and two-stage control of LI value as a measure of corrosive tendency of water is proposed. Primarily, water treatment facilities may operate the system at a target LI value below -1.5. Following the investigation on the effect caused by adjusting the LI value on water quality and corrosiveness, it will be desirable to improve LI value below -1.0 in the long run. In addition to the LI, supplemental use of Larson's modified ratio (LMR) which incorporates hydraulic detention time will be necessary. Several methods to prove the inhibitive effect of improving the LI value on water quality have been also suggested.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.545-551
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• 2011

Recently, demands for generating high quality tap waters are increasing with high concern of water pollution and corrosion of water pipelines. For the reasons, developing water quality stabilization technique in water purification system is sought rather than replacing to a new pipelines. In this study, high-purity liquid lime($Ca(OH)_2$) was introduced for a water quality stabilization technique in water purification process and simulated water distribution system of pilot-scale size was applied to evaluate anti-corrosion control effect. The effect of anti-corrosion control was calculated in terms of LSI(Langelier Saturation Index) In conclusion, the result of pilot plant showed improvement of corrosiveness by liquid lime($Ca(OH)_2$) with reduction of released iron(Fe). Application of anti-corrosion control technique to the mild steel coupon and the copper coupon were effective by indicating 35.4, 44.5% of improvements. Besides, sample pipes which were treated with liquid lime had formated more thicker layer of corrosion product inside of pipes. As a result, the process of injecting water stabilizer can greatly contribute to the high quality of tap water.

• Applied Chemistry for Engineering
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• v.16 no.3
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• pp.372-378
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• 2005

Calcium Carbonate Saturation Index (LI: Langelier Index), an indicator of $CaCO_3(s)$ saturation, indicates corrosiveness of drinking water and it has been used to monitor drinking water conditions in USA, E.U, and Japan. The objective of this research was to measure LI parameters including water temperature, pH, total alkalinity, calcium ion concentration, and electric conductivity, and to evaluate possibility of using LI in domestic system. Results showed that water temperature varied from 2.0 to $26^{\circ}C$ during 15 months, indicating an average annual temperature of $23.9^{\circ}C$. Total alkalinity was from 20 to 45 mg/L. The concentration difference between total alkalinity and $HCO_3{^-}$ value was hardly observed; the concentration of total alkalinity can be replaced by that of $HCO_3{^-}$. Tap water had a medium corrosiveness since LI values were from 2.0 to 0.5. To reduce the corrosiveness and to increase LI values of drinking water, the results of this study showed that chemicals such as $Ca(OH)_2$, $CaCO_3$, NaOH, or $NaHCO_3$ should be added to water treatment plants.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.701-708
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• 2008

As a countermeasure for reduction of corrosion in the delivery and distribution pipes used for tap water, materials for the pipelines in-houses and the effect of water quality on corrosivity of water pipelines were investigated in the distribution system of Han river. As the corrosion index at 6 water purification facilities of Han river, average Langelier Saturation Index (LI) of raw and finished water were -1.0 and -1.4 respectively and average Larson Index (LR) were 9.5 and 9.9, respectively. And also corrosion potential showed corrosivity in finished water (-431~-462 mV) as well as raw water (-426~-447 mV). This results indicate that tap water quality of han river have corrosivity. To understand the corrosivity effect in pipe material used for premise distribution system, water quality of stagnant tap water and tap water were analyzed and the differences between them were calculated. The difference concentration of iron, copper and zinc were $12.9{\mu}g/L$, $31.0{\mu}g/L$ and $45.0{\mu}g/L$ respectively in galvanized steel pipe for use more than 15 years and showed highest concentration. As a result, the control to corrosivity in the water pipelines, corrosivity control treatment in the water purification system can be applied. In advance it is necessary to monitor corrosivity of water quality using corrosive index because corrosivity may differ from the seasonal and regional characteristics and water chemicals dosage. For the future the guideline for corrosion index have to be established.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.1
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• pp.53-63
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• 1997

The corrosion problems in water distribution system are reduced by decreasing the agressivity of drinking water which is evaluated by marble test and saturation indices(LSI or CCPP etc.). Marble test is a reliable method to determine the actual saturation condition of treated water. This study was done to determined the aggressivity of tap water and the effectiveness of $Ca(OH)_2$ and NaOH dosage for corrosion control. The drinking water in Seoul were evaluated by marble test and Langelier Index(LSI) and Calcium Carbonate Precipitation Potential(CCPP). The results indicated that the drinking water in Seoul were undersaturated as Calcium Carbonate($CaCO_3$). The LSI and CCPP of the water treated with $Ca(OH)_2$ were higher than that of water treated with NaOH. Therefore, to increase the Alkalinity and Calcium Hardness for corrosion control in water distribution system, $Ca(OH)_2$ is more effective than NaOH.

• Journal of Environmental Science International
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• v.24 no.7
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• pp.907-915
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• 2015

The tap water is generally known to be corrosive in the pH range at 6.5 ~ 7.5. And the degree of corrosion varies depending on the types of raw water such as river surface water or lake water of the dam. Although several corrosion index represents the corrosivity of tap water, the typical corrosion indexes such as Langelier saturation index (LI) and calcium carbonate precipitation potential (CCPP) were calculated to monitoring the corrosive water quality about raw and tap water in water distribution system. To control the corrosive water quality, the correlation between corrosion index and water quality factors were examined. In this study, corrosion index (LI, CCPP) and the pH was found to be most highly correlated.

• Corrosion Science and Technology
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• v.8 no.6
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• pp.232-237
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• 2009

Copper tubes are widely used in the distribution systems of drinking water throughout the world because of their excellent corrosion resistance, high thermal conductivity, and ease of fabrication. However, corrosion problems from copper tubes as blue water phenomenon and leakage have been reported appreciably. The effect of pH on the corrosion behavior of copper tube for tap water was investigated by electrochemical voltammetric techniques in synthetic tap water. And the copper corrosion cases were discussed from the viewpoint of factors affecting the corrosion rate such as pH, alkalinity, LSI(Langelier Saturation Index), and concentration of bicarbonate and dissolved carbon dioxide.

• Environmental Engineering Research
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• v.17 no.1
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• pp.17-25
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• 2012

Concern about green water problem has surfaced as a serious issue in Korea. In order to solve this problem, it is necessary to research inhibition of green water and corrosion control of copper pipe in water service. This paper discovered that moderate corrosion inhibitors can solve the green water problem and copper corrosion in water service by adding the optimal concentration of corrosion inhibitors based on regulation. Firstly, in the case of phosphate based corrosion inhibitors, as dosage of the corrosion inhibitor increases from 1 mg/L to 5 mg/L, the relative effect of corrosion inhibitor declines rapidly. Secondly, except for 1 mg/L dosage of silicate based inhibitor, relative effects of the inhibitor displays a positive number depending on inhibitor concentration. The most significant result is that the amount of copper release shows a downward trend, whereas the phosphate based inhibitor accelerates copper ion release as the inhibitor dosage increases. Thirdly, as the dosage of mixed inhibitors increases to 10 mg/L, the copper release change shows a similar trend of phosphate based inhibitor. Lastly, according to the Langelier saturation index (LI), silicate based inhibitors have the most non corrosive value. Larson ratio (LR) indicates that phosphate based inhibitors are the least corrosive. Korea water index (KWI) represents that silicate based inhibitors are most effective in controlling copper pipe corrosion.