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.

摘要

当前，变色是全世界消费者抱怨的主要原因，主要是由于饮用水分配系统的内管壁中材料的积累和移动所引起的。由于其复杂性和缺乏数据，因此对从管道壁上分离物料的理解受到限制。这项研究的目的是使用大型实验室系统检查冲洗操作过程中PVC管壁材料分离的初始阶段。实验包括40到120天的材料堆积阶段，然后是壁剪切应力高于5 Pa的材料移动阶段。结果表明，材料的分离主要发生在速度增加的时期，速率为0.5到14 mNTU /秒。此外，