Direct photolysis of polycyclic aromatic hydrocarbons in drinking water sources

► Low pressure UV photolysis can be used by drinking water utilities to degrade PAHs. ► Real water matrices with different compositions were tested. ► Photolysis kinetic parameters and by-product formation are described. ► The formation of photolysis by-products is highly dependent on the source waters. The widely used low pressure lamps were tested in terms of their efficiency to degrade polycyclic aromatic hydrocarbons listed as priority pollutants by the European Water Framework Directive and the U.S. Environmental Protection Agency, in water matrices with very different compositions (laboratory grade water, groundwater, and surface water). Using a UV fluence of 1500 mJ/cm 2, anthracene and benzo(a)pyrene were efficiently degraded, with much higher percent removals obtained when present in groundwater (83–93%) compared to surface water (36–48%). The removal percentages obtained for fluoranthene were lower and ranged from 13 to 54% in the different water matrices tested. Several parameters that influence the direct photolysis of polycyclic aromatic hydrocarbons were determined and their photolysis by-products were identified by mass spectrometry. The formation of photolysis by-products was found to be highly dependent on the source waters tested.