ABSTRACT
Discoloration is currently the major cause of consumer complaints worldwide, being mainly caused by the accumulation and mobilization of materials in the inner pipe walls of drinking water distribution systems. The understanding about material detachment from pipe walls is limited due to its complexity and lack of data. The purpose of this study was to examine the initial stages of material detachment from PVC pipe walls during flushing operations using a full-scale laboratory system. Experiments consisted of a material accumulation phase with periods from 40 to 120 days, followed by a material mobilization phase with wall shear stresses above 5 Pa. Results indicated that material detachment mainly occurs during the periods of velocity increase, at rates ranging from 0.5 to 14 mNTU/s. In addition, a second stage of material detachment was observed during steady flow conditions, and a fast detachment event highlighted impacts of curved sections on the mobilization phenomena.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Notes
1. PODDS = Prediction Of Discoloration in Distribution Systems