Behaviour of Particle Attachment and Mobilization under Flushing Conditions in PVC Pipes using a Full-Scale Laboratory System
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Authors
Anderson, Benjamin
Date
2025-01-03
Type
thesis
Language
eng
Keyword
Drinking Water Distribution System , Unidirection Flushing , Iron Oxide , PVC Pipes
Alternative Title
Abstract
Within a drinking water distribution system, materials such as metals and biofilms are known to accumulate on the inner surface of pipes. This accumulation poses the risk of drinking water contamination. Due to the corrosion of iron components within a distribution network, iron oxide has proven to be one of the most prevalent metals that accumulates in drinking water pipes. As a result, water utilities invest in technologies to identify and flush material deposits from sections of their pipe networks. Nevertheless, the development of preventative strategies is still limited by the lack of knowledge about the material accumulation process and the behaviour of resuspended particles during flushing. In this thesis, a set of four experiments was conducted using a full-scale PVC pipe loop laboratory to better understand the attachment and mobilization of iron oxide particles on PVC pipe walls. Specifically, the investigation wanted to test the effectiveness of reversing the flushing direction from the operational flow to achieve increased material mobilization. To better quantify the results, a method was used to transform live turbidity readings into mass values. The experimental results showed that: (1) accumulation in the invert position of the pipes dominated with deposition affected by fluid velocity and particle size. Much of the total injected mass was attached to the pipe wall soon after it entered the system; (2) reversing the direction of the flushing flow can have a small increase in mobilization effectiveness. Using the reverse direction can also target material that was otherwise protected from flushing in the forward direction; (3) particles can be mobilized and then reattach under flushing conditions at faster rates than previously understood. This suggests that the total mobilized material is almost always higher than the amount of material removed from the system, and (4) pipe features such as wye-section or 90° elbows produce small flow recirculation zones that can become areas of high material accumulation. The research findings contribute to a better understanding of particulate deposition in drinking water pipes as well as their mobilization and reattachment behaviour under flushing conditions. It further identifies possible areas of concern within a distribution system and strategies to address them to improve overall water quality.
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This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NoDerivatives 4.0 International
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NoDerivatives 4.0 International