Modelling water quality in tropical water distribution systems

Devietti, Jenna Leigh (2011) Modelling water quality in tropical water distribution systems. PhD thesis, James Cook University.

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Abstract

At present, water treatment and distribution is of high priority to ensure that communities have access to safe and affordable drinking water. To achieve the desired outcomes for the drinking water distribution system, every aspect of the system must be designed to the water quality and drainage characteristics, and the nature and conditions of the infrastructure. Due to these design requirements, it can be considerably difficult to implement goals relating to the provision of safe drinking water.

This study aimed to quantify key water quality parameters, such as chlorine concentration, flow velocity, pH, and biofilm growth, and evaluate the influence of these parameters on corrosion and iron release in a tropical drinking water distribution system.

The approach of this study was split into three (3) components:

• Conduct a pilot study on a distribution system in the tropics and assemble, calibrate and validate a network model, based on this water distribution system;

• Design, construct and install an economic Biofilm Corrosion Reactor (BCR), to allow monitoring and evaluation of water quality parameters found within the distribution system;

• Perform accelerated corrosion tests to investigate the effect of water quality parameters on corrosion rate.

The outcomes of the study components provided knowledge and understanding on the performance of the drinking water distribution system. This understanding, combined with the observed relationships found during this research, allowed the development of corrosion management strategies relevant to the Ingham Water Supply Scheme.

In general, the following relationships were observed during this research and were consistent with compared literature sources:

• Corrosion rate increased significant with chlorine concentration above 1 mg/L;

• During the initial phase of corrosion higher velocity results in higher corrosion rate;

• During the final phase of corrosion lower velocity results in higher corrosion rate;

• Corrosion rate increased with a decrease in pH;

• Higher velocity results in increased iron release and therefore increased corrosion rate; and

• Corrosion rate increased with increase in microorganisms/biofilm.

Overall, the combination of the simulated network model for the Ingham Water Supply Scheme and the observed results and relationships during this research, resulted in the development of the Corrosion Hotspot Tool for Hinchinbrook Shire Council. The aim of the tool is to improve the management of the distribution system operationally and financially and also indicated some key aspects to monitor, in regards to corrosion such as chlorine residual levels.

Furthermore, the research techniques and outcomes can be replicated with other water supply authorities, to assist in developing management strategies to improve drinking water quality and the operation of water treatment and distribution systems.

Item ID: 23654
Item Type: Thesis (PhD)
Keywords: corrosion management; corrosion; disinfection; distribution system; drinking water; EPANET; Ingham Water Supply Scheme; potable water; residual chlorine; safe drinking water; tropical water distribution systems; water purification; water quality; water supply; water treatment
Date Deposited: 16 Oct 2012 00:06
FoR Codes: 09 ENGINEERING > 0907 Environmental Engineering > 090701 Environmental Engineering Design @ 33%
09 ENGINEERING > 0907 Environmental Engineering > 090702 Environmental Engineering Modelling @ 33%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050299 Environmental Science and Management not elsewhere classified @ 34%
SEO Codes: 90 COMMERCIAL SERVICES AND TOURISM > 9004 Water and Waste Services > 900404 Water Services and Utilities @ 100%
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