Biofilm formation and PAH migration in HDPE drinking water pipes

A previous study on the migration of polyaromatic hydrocarbons (PAHs) from uPVC pipes into drinking water through aging distribution systems found that the main cause was the biodegradation of the pipe material due to biofilm formation, which led to water quality deterioration. In this research, extensive laboratory-scale experiments focused on biofilm formation and the migration of PAHs from HDPE pipes. An eight-inch HDPE pipe was tested under low-flow and stagnant conditions using tap water to simulate dead-end scenarios and facilitate the detection of low concentrations. Water analysis showed increased levels of PAHs passing through the HDPE pipe, especially naphthalene, which exceeded permissible limits. Pipe samples were examined using energy-dispersive X-ray spectroscopy, scanning electron microscopy, and heterotrophic plate counts. Results revealed biofilm formation on the inner surface with high populations of Bacillus, elevated carbon content, and deterioration of the pipe wall, confirming the migration of PAHs from HDPE pipes due to biodegradation.