Effect of Stannous Chloride on Bacterial Growth in Distribution Systems

摘要

Lead corrosion inhibitor is necessary for water services utilizing lead-containing servicelines. Stannous chloride is a new corrosion inhibitor that can be used in distribution system todepress the lead pipe corrosion. The application of low level of stannous chloride (0.125 mg/L asSn) in water as corrosion inhibitor not only avoid the addition of phosphate, which is a essentialnutrition to bacteria, but its toxicity can also inhibit drinking water bacterial activities or eveninactivate some bacteria while being safe to human being. Heterotrophs such as Escherichia coli.and Pseudomonas aeruginosa are susceptible to Sn toxicity, and autotrophs such asNitrosomonas europea, was less susceptible to Sn toxicity. In a laboratory test, the oxygenuptake rate of a P.aeruginosa batch in 1.0 mg/L SnCl2 decreased by 30% to 50%, and the oxygenuptake rate of a E.coli batch decreased almost a magnitude in 2.0 mg/L SnCl2. However, theoxygen uptake rate of N. europea had no significantly change in 2.0 mg/L SnCl2. Sn-contactexperiment was conducted also to test the viability of bacteria. In 1.0 mg/L SnCl2, 20 minutesinactivation rate ranged from approximately 60% to 95% at low bacterial concentration (<106CFU per mL) suspensions for these two heterotrophs. And the 20 minutes N.europea inactivationrate appeared to be insignificant.