The influence of two phosphate corrosion compounds on the growth and survival of coliform and other heterotrophic bacteria was investigated in laboratory, field, and model system studies. Growth of Citrobacter freundii, Enterobacter cloacae, and Klebsiella pneumoniae was not significantly influenced by the presence of Shan-No-Corr (0.1 to 2.0 mg/1) in laboratory studies. In the presence of Virchem 932 (0.01 to 1.0 mg/1, as zinc), growth of E. cloacae was unaffected; growth of C. freundii and K. pneumoniae was generally inhibited by Virchem at 0.3 mg/1 and above. The addition of Fe2O3 to the water enhanced the inhibitory action of Virchem 932, but not Shan-No-Corr, for all three coliforms. Field investigations were conducted in three water distribution systems. Changes in bacterial counts and the various physicochemical parameters were not conclusively correlated to the presence of the phosphate corrosion control compounds. In model distribution system studies, the addition of various concentrations of the phosphate compounds had no influence on the growth of the heterotrophic bacteria over the course of the experiments.

Microfiche.