The occurrence of discoloured water at the tap is one of the most frequent reasons for customers to complain. Water discolouration arises from the re-suspension of loose deposits (LD) that accumulate in drinking water pipes, due to velocity increase. Because of its typical brownish/reddish colour, discoloured water is traditionally perceived as a consequence of cast-iron pipe corrosion, even in networks devoid of cast-iron pipes. Current approaches for LD sampling imply the use of high flow velocities within the range of those used for pipe self-cleaning (0.40 m/s) and/or pipe cleaning (1.50 m/s). Although useful for quantitative identification of critical zones and diagnosis of LD accumulation, the application of such high-velocities as routine methodologies for LD sampling may be difficult to perform on the field and provide samples with materials other than discolouration causing LD. In this study, sampling velocities from 0.02 to 0.52 m/s yielded relatively large samples (up to 2 g dry weight), thus allowing for extensive qualitative LD analysis and testing. Sample representativeness was analysed through the characterisation of LD key-constituents total iron (Fet) and volatile solids (VS). Turbidity decay trends showed the flocculent behaviour of discolouration causing LD.
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Research Article|
August 01 2013
Methodology for sampling drinking water discolouration loose deposits at low velocities Available to Purchase
Ana Poças;
Ana Poças
1LNEC, Laboratório Nacional de Engenharia Civil, Av. do Brasil, 101, 1700-066 Lisboa, Portugal
3TuDelft, Delft University of Technology, Faculty of Civil Engineering and Geosciences, Stevinweg, 1, 2628 CN Delft, The Netherlands
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Nazaré Rebola;
Nazaré Rebola
2EPAL, Empresa Portuguesa das Águas Livres, SA, Av. de Berlim, 15, 1849-033 Lisboa, Portugal
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Bruno Cordeiro;
Bruno Cordeiro
2EPAL, Empresa Portuguesa das Águas Livres, SA, Av. de Berlim, 15, 1849-033 Lisboa, Portugal
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Sérgio Rodrigues;
Sérgio Rodrigues
2EPAL, Empresa Portuguesa das Águas Livres, SA, Av. de Berlim, 15, 1849-033 Lisboa, Portugal
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Maria J. Benoliel;
Maria J. Benoliel
2EPAL, Empresa Portuguesa das Águas Livres, SA, Av. de Berlim, 15, 1849-033 Lisboa, Portugal
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Jan Vreeburg;
Jan Vreeburg
3TuDelft, Delft University of Technology, Faculty of Civil Engineering and Geosciences, Stevinweg, 1, 2628 CN Delft, The Netherlands
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José Menaia
1LNEC, Laboratório Nacional de Engenharia Civil, Av. do Brasil, 101, 1700-066 Lisboa, Portugal
E-mail: [email protected]
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Water Supply (2013) 13 (4): 1116–1122.
Article history
Received:
October 24 2012
Accepted:
January 18 2013
Citation
Ana Poças, Nazaré Rebola, Bruno Cordeiro, Sérgio Rodrigues, Maria J. Benoliel, Jan Vreeburg, José Menaia; Methodology for sampling drinking water discolouration loose deposits at low velocities. Water Supply 1 August 2013; 13 (4): 1116–1122. doi: https://doi.org/10.2166/ws.2013.096
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