Ph control of water in newly laid pipes

• Main Author: Lim, Kim Shin.
• Other Authors: Chui, Peng Cheong
• Format: Final Year Project
• Language: English
• Published: 2008
• Subjects: DRNTU::Engineering::Environmental engineering::Water supply
• Online Access: http://hdl.handle.net/10356/14149
• Institution: Nanyang Technological University

Drinking water from treatment works is transmitted and distributed by a network of pipelines made of steel or ductile iron to consumers. These pipes are lined internally with cement or concrete to protect the metal from corrosion. However, water that remains stagnant in newly laid pipe sections for a relatively long time exhibits a significantly high pH value. Although there appears to be little health issues associated with high-pH water, quality of such water may lead to customer dissatisfaction such as those from the semi-conductor industry. As water utilities today are becoming more concerned with the quality of finished water being delivered to customers instead of just quantity, this problem has became an important issue. The purpose of this study was to evaluate possible solutions to the problem of elevated pH in newly laid water pipes. Three methods were investigated through immersion tests carried out on both concrete cubes and actual 300 mm diameter pipe-sections. The findings provide evidence that method of wet curing and pre-chlorination treatment are simple, safe and cost-effective means of achieving the objectives. Although phosphatisation treatment also seems to be effective, further investigations are needed to examine its consistency and side-effects. It is recommended that the effect of wet curing be tested on actual pipes. Future research should be carried out to investigate the effectiveness of using pre-chlorination treatment on different pipe sizes and trials on actual system of pipelines are strongly recommended.