Determination of microbial available organic matter and microbial growth potentials in drinking water systems

There is a risk of deterioration of the quality of the raw (ground) water used for drinking water due to exploitation of resources with elevated content of organic matter or even with micropollutants. If these aspects are combined with the risk of increased hydraulic retention time in the distribution system (e.g. due to water saving campaigns) and the use of new materials of polymers used for the pipes, this might result in after-growth i.e. increasing number of bacteria in the drinking water in the distribution system after the water treatment at the water works. To quantify the part of the organic carbon available for microbial growth a range of methods are being evaluated: the biological available organic carbon method (BDOC), based on the change in content of dissolved organic carbon (DOC) during a standardized incubation in presence of sand from a sandfilter in a water works; the assimilable organic carbon method (AOC) based of the growth of pure cultures; and the rotating disc method, quantifying the growth rate of the autochthonous bacteria as microcolonies on a rotating disk as a result of the content of organic carbon.
Later in the project the microbial growth in the water as well as in the biofilm on the inner side of the tubes will be related to the quantification of organic carbon available for microbial growth.