Effects of different nutrients on bacterial growth in a pilot distribution system.

The growth of bacterial communities in drinking water distribution systems can lead to the development of problems incompatible with water quality requirements. This study was carried out in order to determine which factors promote bacterial growth in distribution networks. A pilot distribution system was used to perform these experiments. After addition of three different inorganic elements to the network (N, P and S) the results obtained show that they did not contribute to the growth or bacteria either in the circulating water or on the surface of the pipes of the distribution system. However, when organic carbon was added an increase in the number of circulating bacteria was observed though the number of bacteria in the biofilms of the network was constant. These results indicate that in the drinking water of the Barcelona distribution system the factor that controls the growth of bacteria is organic carbon. Moreover, bacteria from the biofilm growing on the surface of the pipes may cause the problems of bacterial growth.