Complexing of copper in drinking water samples to enhance recovery of Aeromonas and other bacteria

Abstract

The presence of copper in drinking water samples at concentrations as low as 10 .mu.g/l resulted in a rapid die-off of aeromonads. Coliform bacteria, heterotrophic plate count bacteria and faecal streptococci were also sensitive to copper but to a lesser degree than aeromonads. The effect was particularly noticeable in soft water (>3 meq/l Ca + Mg) and at pH-values below 8.0. The toxic effect of copper concentrations up to 500 .mu.g/l could be neutralized for a period of up to 24 h by the addition to samples of 50 mg/l of disodium-ethylene-diamino-tetraacetate (Na2EDTA) and keeping the samples on melting ice.