Bench scale evaluation of Fe(II) ions on haloacetic acids (HAAs) formation in synthetic water

Cast iron pipes were installed broadly in North American water utilities, particularly in older cities such as Halifax, NS, and other cities in the northeastern portions of Canada and the USA. Many of these cast iron pipes are corroded and are continuous sources of Fe(II) ions in drinking water distribution systems. In this paper, the results of an experimental investigation into the factors influencing haloacetic acids (HAAs) formation in the presence of Fe(II) ions are presented. The experiments were conducted using NaHCO₃ buffered synthetic water samples with different characteristics (i.e. pH, phosphate, stagnation time) simulating with water distribution systems. The results showed that Fe(II) ions significantly reduced HAAs formation in different reaction systems at a 95% confidence level. In control water systems, pH had no significant impact, however, in the presence of Fe(II) ions in water, pH had an obvious impact to increase HAAs formation (α = 0.05). In contrast, phosphate-based corrosion inhibitor significantly (α = 0.05) reduced HAAs formation in the presence of different dosages of Fe(II) ions in water samples for the reaction period of 24, 48, 84 and 130 h, respectively. Significant factors and their rank influencing HAAs formation and distribution were identified using a 2⁴ full factorial design approach.