Study of the Secondary Contamination in the Water Distribution Pipeline S.J.YU, S.J.PARK, H.K.KIM, K.H.AHN, Y.H.LEE, C.S.KIM Drinking Water Division Environmental Diagnostics Research Department National Institute of Environmental Research Waterworks Research Institute of Seoul Metropolitan City Water Quality Research Center of Incheon Metropolitan City Water Quality Research of Busan Metropolitan City Water Quality Research Institute of Daegu Metropolitan City Water Service Technology Laboratory of Daejoen Metropolitan City Water Quality Research Institute of Gwanju Metropolitan City Water Quality Institute of Ulsan Metropolitan City Korea Water Resources Corporation
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In this study, water quality and corrosivity were evaluated for raw water, treated water and water in distribution reservoir at major 8 drinking water treatment plants(dwtps) in Korea. By analyzing secondary contamination of tap water, the evolution of secondary contaminants was investigated with regard to pipe materials, aging and corrosion index(ci). Finally, an appropriate CI was developed and the management plan for monitoring CI was proposed. The results of this study are as follows. According to 'Statistics of Waterworks(2007)' published by Ministry of Environment, the water pipe network was composed of water conduit pipe (48.6%), water supply pipe(42.8%), transmission pipe(6.5%) and aqueduct pipe(2.1%). PVC was mostly used as a pipe material(24.9%). Other materials were ductile cast iron(22.6%), stainless steel(13.9%), cast iron(11.5%), wrapped steel(10.4%), copper(0.3%) and others(14.9%). In case of aqueduct pipe, the pipe material was mainly composed of wrapped steel(64.6%) and cast iron(13.4%). Transmission pipe was made of wrapped steel(47.0%), ductile cast iron(30.1%), In case of conduit pipe, ductile cast iron(40.9%) and PVC(20.2%) were mostly used. PVC(42.4%) - xiii -
and stainless steel(32.4%) were widely used in water supply pipe. Copper, iron and zinc concentrations increased in the distribution network. The average copper concentrations in the finished water, the water in distribution reservoir and the water at tap water cock were 0.0011 mg/l, 0.0048 mg/l, and 0.0176 mg/l, respectively. Although the values were only 0.1%, 0.5% and 1.8% of drinking water standard(1 mg/l), respectively. The average iron concentrations in finished water, water in distribution reservoir and POU were 0.0041 mg/l, 0.0100 mg/l, 0.0255 mg/l, respectively, and they were 1.4%, 3.3% and 8.5% of drinking water standard(0.3 mg/l). The average zinc concentrations in finished water, water in distribution reservoir and POU were 0.0067 mg/l, 0.0085 mg/l and 0.0346 mg/l, respectively. The zinc concentrations were 0.2%, 0.3% and 1.2% of drinking water standard(3 mg/l). LI was investigated in raw water, finished water, water in distribution reservoir, and POU. All values showed corrosive water quality, and they did not change significantly in the distribution network. The average LI values in raw water, treated water, water in distribution reservoir and POU were -0.9, -1.6, -1.6 and -1.5, respectively, which were lower than the standard corrosivity, 'zero(0)'. - xiv -
Copper, iron, manganese, nickel, lead, iron concentrations were investigated in the water supply pipes whose usage time were classified as 'less than 10 years', '10 to 20 years' and 'more than 20 years'. Copper, iron and zinc were mainly detected and the concentrations were different according to the usage time of pipe. In tap water, the average copper concentration was 0.0277 mg/l for '<10 years', 0.0148 mg/l for '10 20 years' and 0.0130 mg/l for '>20 years'. In the stagnant tap water, it was 0.0412 mg/l, 0.0342 mg/l, and 0.0111 mg/l, respectively. In tap water, iron concentration was 0.0172 mg/l for '<10 years', 0.0242 mg/l for '10 20 years' and 0.0371 mg/l for '>20 years'. It was 0.0266 mg/l, 0.0423 mg/l and 0.0425 mg/l, respectively, in the stagnant tap water. In tap water, zinc concentration was 0.0335 mg/l for '<10 years', 0.0385 mg/l for '10 20 years' and 0.0329 mg/l for '>20 years'. It was 0.1251 mg/l, 0.1139 mg/l and 0.0608 mg/l, respectively, in the stagnant water. The relationship between CI and the concentration of the secondary contaminant in distribution system was investigated. As LI corrosivity of tap water increased, the copper and zinc concentration also increased. However, iron concentration was not affected by LI. - xv -
The average corrosion index was changed by the drinking water treatment. LI changed from -0.9 to -1.6(74% reduction) and LR did from 1.0 to -1.6(60% reduction). RSI changed from 9.5 to 10.3(8% increase) and AI decreased from 10.4 to 9.8 by 7%. LI and LR were dependent on the characteristics of raw water, seasonal variations and drinking water treatment. LI showed high correlation with RSI and AI(r 2 > 0.99) as well as CCPP(Calcium carbonate precipitation potential)(r 2 > 0.9). LI is sensitive to the change of raw water quality and drinking water treatment and it has high correlations with other indexes. Therefore, LI is considered as an appropriate CI to the domestic water quality. To control the pipe corrosion from DWTPs, LI was investigated as a drinking water quality surveillance item. The examination period of the corrosion index and the test method of Langelier index were proposed according to ph, calcium ion, alkalinity, conductivity and water temperature. The corrosion control strategy in the lead-copper rule of US EPA, where ph, alkalinity control and anti-corrosion agent were simultaneously used for the control of pipe corrosion, was investigated. - xvi -
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21 년이상 17.0% 5 년이내 22.1% 16~20 년 19.2% 6~10 년 20.2% 11~15 년 21.4% - 11 -
도수관 2.1% 송수관 6.5% 급수관 42.8% 배수관 48.6% - 12 -
기타 14.9% 도복장강관 ( 강관 ) 10.4% 주철관 11.5% 스테인리스강관 13.9% 동관 0.3% 아연도강관 1.5% 흄관 0.1% 덕타일주철관 22.6% 합성수지관 24.9% - 13 -
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250,000 200,000 150,000 100,000 50,000 0 도수관 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 도복장강관 ( 강관 ) 주철관 덕타일주철관 합성수지관 흄관 아연도강관 동관 스테인리스강관 기타 500,000 송수관 400,000 총연장 (m) 300,000 200,000 100,000 0 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 도복장강관 ( 강관 ) 주철관 덕타일주철관 합성수지관 흄관 아연도강관 동관 스테인리스강관 기타 2,500,000 배수관 2,000,000 총연장 (m) 1,500,000 1,000,000 500,000 0 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 도복장강관 ( 강관 ) 주철관 덕타일주철관 합성수지관 흄관 아연도강관 동관 스테인리스강관 기타 총연장 (m) 2,500,000 2,000,000 1,500,000 1,000,000 500,000 0 급수관 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 도복장강관 ( 강관 ) 주철관 덕타일주철관 합성수지관 흄관 아연도강관 동관 스테인리스강관 기타 - 15 -
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100% 80% 60% 40% 20% 0% 서울 인천 부산 대구 광주 대전 울산 경기 강원 충북 충남 전북 전남 경북 경남 제주 수공 도복장강관 ( 강관 ) 주철관덕타일주철관합성수지관흄관 아연도강관동관스테인리스강관기타 - 17 -
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μ μ μ μ - 19 -
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30 20 10 0 April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. Turb. April June Aug. Oct. ph 10 8 6 4 2 0 한강팔당호낙동강 1 낙동강 2 회야댐대청호금강주암호 25 KMnO4 TOC 20 15 10 5 0 April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. 한강팔당호낙동강 1 낙동강 2 회야댐대청호금강주암호 100 80 60 40 20 0 April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June alkalinity conductivity Aug. Oct. 400 300 200 100 0 한강팔당호낙동강 1 낙동강 2 회야댐대청호금강주암호 80 60 40 20 chloride sulfate 0 April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. 한강팔당호낙동강 1 낙동강 2 회야댐대청호금강주암호 - 22 -
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1 0 April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April -1 한강팔당낙동강1 낙동강2 회야댐대청호금강주암호 -2 June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. -3 20 15 10 5 0 April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. 한강팔당낙동강 1 낙동강 2 회야댐대청호금강주암호 20 15 10 5 0 April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. 한강팔당낙동강 1 낙동강 2 회야댐대청호금강주암호 3 2 1 0 April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. April June Aug. Oct. 한강팔당낙동강 1 낙동강 2 회야댐대청호금강주암호 - 30 -
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3 2 1 LI LR 0 원수 -1-2 정수배수지수 수도꼭지수 원수 정수 배수지수 수도꼭지수 원수 정수 배수지수 수도꼭지수 원수 정수 배수지수 수도꼭지수 -3 April June Aug. Oct. 15 10 RSI AI 5 0 원수 정수 배수지수 수도꼭지수 원수 정수 배수지수 수도꼭지수 원수 정수 배수지수 수도꼭지수 원수 정수 배수지수 수도꼭지수 April June Aug. Oct. - 37 -
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Cu 600 400 200 0 0 10 20 30 40 경과연수 ( 년 ) Fe 400 Fe conc.(ug/l) 300 200 100 0 0 10 20 30 40 경과연수 ( 년 ) 500 Zn Zn conc.(ug/l) 400 300 200 100 0 0 10 20 30 40 경과연수 ( 년 ) - 39 -
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수돗물 정체수 Zn Zn Pb Pb Ni Ni Mn Mn Fe Cu 20 년이상 10-20 년 10 년미만 Fe Cu 20 년이상 10-20 년 10 년미만 0.00 0.05 0.10 0.15 conc.(mg/l) 0.00 0.05 0.10 0.15 conc.(mg/l) - 45 -
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Cu 0.5 conc.(mg/l) 0.4 0.3 0.2 0.1 0.0-4 -3-2 -1 0 1 2 3 4 5 LI LR F e 0.4 conc.(mg/l) 0.3 0.2 0.1 0.0-4 -3-2 -1 0 1 2 3 4 5 LI LR Z n 0.5 conc.(mg/l) 0.4 0.3 0.2 0.1 0.0-4 -3-2 -1 0 1 2 3 4 5 LI LR - 51 -
Cu 0.5 conc.(mg/l) 0.4 0.3 0.2 0.1 0.0-4 -3-2 -1 0 1 2 3 4 5 LI LR F e 0.3 conc.(mg/l) 0.2 0.1 0.0-4 -3-2 -1 0 1 2 3 4 5 LI LR Z n 0.5 conc.(mg/l) 0.4 0.3 0.2 0.1 0.0-4 -3-2 -1 0 1 2 3 4 5 LI LR - 52 -
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LR RSI AI 15 12 y = 1.0224x + 11.394 R 2 = 0.99 y = -1.5696x + 7.7929 R 2 = 0.9752 9 6 3-4 -3-2 -1 0 LI 0-58 -
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탄산칼슘포화지수 ( 랑게리아지수, LI) 1.0 개요 1.1 목적 1.2 제한 - 62 -
1.3 적용범위 1.3.1 2.0 탄산칼슘포화지수 ( 랑게리아지수 ) 결정 2.1 수소이온농도 2.2 알칼리도 2.3 칼슘 - 63 -
2.4 전기전도도 2.5 탄산칼슘포화지수 ( 랑게리아지수, Langelier saturation index, LI) 2.5.1 개요 2.5.2 계산 - 64 -
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μ μ μ μ μ μ μ μ μ - 72 -
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NSF : National Sanitation Foundation JWWA : Japan Water Works Association DWI : Drinking Water Inspectorate - 74 -
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알칼리도 (CaCO 3 으로 ) - 87 -
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알칼리도 (CaCO 3 으로 ) - 90 -
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