Browsing by Author "Huang, Kochin"

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Characteristics of low and high SUVA precursors: Relationships among molecular weight, fluorescence, and chemical composition with DBP formation
(2020-07-20)
Hua, Lap-Cuong
;
Chao, Shu-Ju
;
Huang, Kochin
;
Huang, Chihpin
;
環境工程研究所
Disinfection by-products (DBPs) formed upon water treatment is an emerging issue worldwide. While monitoring of DBP precursors can easily be achieved for high specific UV absorbance (SUVA) organic (>6 L/mg.m), low and extremely low SUVA precursors (<2 L/mg.m) are difficult to monitor or even to predict their DBP formation behaviour. This study investigated the relationships among NOM characteristics, such as molecular weight (MW), fluorescence, and chemical composition, with DBP formation resulting from the chlorination of relatively high and low SUVA precursors. High SUVA precursors were formed by C-rich substances (82-85% of total mass) corresponding with high C/N and C/O (>100 and >5, respectively). Such precursors exhibited the fluorescence of long-wavelength humic-like signal and occurred at a high MW range (>30 kDa). By contrast, low SUVA precursors were either N-rich and/or O-rich substances, associated with much lower carbon content (40-70%). Low SUVA, N-rich precursors particularly also occurred at a high MW region (>100 kDa) and produced a strong protein-like fluorescence signal. When SUVA values of O-rich precursors were extremely low (<1 L/mg.m) they were accompanyied by short-wavelength humic-like fluorescence. During DBP tests, high SUVA produced only high yields of carbonaceous DBPs (e.g trichloromethane, haloacetic acids, haloketones), whereas low SUVA Nrich precursors yielded high levels of both C and NDBPs (e.g. haloacetonenitrile, chloropicrin). By contrast, extremely low SUVA precursors produced significantly lowlevels of both C and NDBPs (total <30 mu g/mgC). Furthermore, 19 of 20 regression models of DBP formation using log-transformed MW gave R-2 = 0.50-0.97. The strong regressions and correlations of NOM characteristics with DBPs in this study provide a better understanding of the influence of precursors characteristics on DBP monitoring, especially for low SUVA NOM. (C) 2020 Elsevier B.V. All rights reserved.
Establishment of a large-diameter pipeline failure risk matrix in water distribution systems in Taiwan
(2019-08-01)
Huang, Kochin
;
Chuo, Paul
;
Lin, Kim-loong
;
Yu, Mengsyu
;
Huang, Chihpin
The bursting of large-diameter water pipelines in distribution systems will lead to industrial, economic, and public safety impacts. Therefore, multi-criteria analysis (MCA) was applied in this study, which utilizes a series of quantifiable parameters to establish the mathematical method of a risk model. The risk matrix of a pipeline was defined as the multiple of the probability of pipeline failure and potential consequences of pipeline failure. By combining the GIS (geographic information system), each evaluation unit was assigned to different risk levels. The large-diameter (above 800 mm) pipeline length statistic for various risk evaluation units of Taiwan Water Corporation reveals the length of high risk is 171 km (7.7%), secondary high risk 574.6 km (25.8%), middle risk 714.3 km (32%), low risk 701.5 km (31.5%), and the unranked length is 67.8 km (3.0%). Finally, the detection frequencies were classified as high risk with a term check of every five years, sub-high risk with planned check every five to ten years, medium risk with checking/monitoring if needed, and low risk with quick repair and no need to take measurements and monitoring. Therefore, we can significantly lower the probability of bursting for large-diameter pipelines in the water distribution system.