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Evaluation of loose deposits in distribution systems through: unidirectional flushing
Author(s) -
Carrière Annie,
Gauthier Vincent,
Desjardins Raymond,
Barbeau Benoit
Publication year - 2005
Publication title -
journal ‐ american water works association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.466
H-Index - 74
eISSN - 1551-8833
pISSN - 0003-150X
DOI - 10.1002/j.1551-8833.2005.tb07474.x
Subject(s) - flushing , organic matter , environmental science , fraction (chemistry) , environmental chemistry , mineralogy , composition (language) , hydrology (agriculture) , chemistry , environmental engineering , geology , chromatography , biology , geotechnical engineering , linguistics , philosophy , organic chemistry , endocrinology
The objective of this project was to evaluate the extent of loose deposit accumulation in distribution systems in three Canadian cities to determine optimal flushing frequency. Unidirectional flushing was used to remove the deposits. The results obtained were found to be highly system‐dependant. The normalized mass of flushed deposits varied from less than 0.1 g/m (0.03 g/ft) to approximately 40 g/m (12 g/ft). For the range of velocities attained during flushing (0.65–2.3 m/s [2.1–7.6 fps]), the quantity of collected deposits was not a function of velocity. Analysis of the composition of the deposits confirmed the specificity of each water system. In all systems, the major fraction was iron corrosion compounds (38–72%), but organic matter (14–24%) and silicoaluminum compounds (7–16%) were also found to account for an important part of the deposits. Microbiological analyses revealed concentrations of total bacteria of approximately 10 10 bacteria/g, but the presence of total coliforms was limited to 1.2% of the samples (n = 258).