Continuous culture studies of biofilm associated with copper corrosion

A survey was undertaken to compare the hot-water systms of four Scottish institutional buildings, two of which suffered severe corrosion of their copper pipe work. A number of parameters were investigated including temperature, dissolved oxygen concentration (DO) and assimilable organic carbon (AOC). Microbiological analysis was also carried out on the water supply and the inner surface of the pipes. The institutional buildings experiencing corrosion had a lower temperature and a higher AOC in their hot-water systems than those without this particular problem. These findings were similar to a 1987 survey, which suggested that the problem might be microbially induced corrosion. A two-stage continuous culture model was used to mimic the corrosive environment of one of the institutional buildings. Using a microbial inoculum from the surface of the copper pipe work and filter sterilised water supplying the building it was possible to show that biofilm could readily be established up to 55°C. However at temperatures above 55°C the biofilm was greatly reduced.