Thesis title: Investigating the Role of Water Quality on the Galvanic Corrosion of Lead in Hard Water with a Focus on NOM
Lead is a toxic heavy metal that has been linked to neurological and neurodevelopmental disorders with a decrease in the intelligence quotient of children being the most studied health impact. The maximum acceptable concentration (MAC) is 5 µg/L in the Guidelines for Canadian Drinking Water Quality and the MAC in Ontario is 10 µg/L (Ontario Reg. 169/03). Although lead is seldom present in measurable quantities in natural waters, it can be released into drinking water from lead service lines, lead solder, and other lead containing plumbing fixtures. Water quality is known to have a large influence on lead release, but the impact of certain water quality factors such as hardness and natural organic matter (NOM) have not been well studied.
To look into the impact of these water quality factors on lead release, bench scale experiments were conducted using a “dump and fill” methodology for test pieces made of new lead and copper pipes with an external galvanic connection. The research was conducted in two phases. The first phase (Phase I) involved assessing the impact of pH, dissolved inorganic carbon (DIC), hardness, and NOM on the galvanic corrosion of lead using a variety of synthetic waters. It was determined that an increase in pH from 7 to 8.5 decreased the release of total lead; the addition of Suwannee River NOM increased the release of dissolved lead, and an increase in the DIC concentration increased the galvanic current between the lead and copper pipes. Phase II assessed if NOM in real drinking water would have a similar impact as Suwannee River NOM in synthetic water. In all, the real NOM did increase the release of dissolved lead but not to the same extent as Suwannee River NOM.
A pdf copy of the thesis is available on UWspace and questions can be sent to Patrick King.
