An Assay for Estimating UV Disinfection Dose by Direct Quantification of DNA Damage in Indigenous Microorganisms in Drinking Water

A new method was developed for estimating the ultraviolet (UV) dose that is delivered by operating UV disinfection reactors in drinking water treatment plants, through the quantification of pyrimidine (i.e. thymine-thymine) dimer formation in the DNA of indigenous microorganisms (i.e. no organisms spiked into the water). An enzyme-linked immuno-sorbent assay (ELISA) was applied to the indigenous DNA that was extracted from water samples that were collected from drinking water treatment plants and from lab tap water and exposed to collimated beam UV doses, resulting in a near-linear relationship between the assay response and UV dose. The new method has the potential to provide a relatively quick, sampling-based means of monitoring the UV dose being delivered by operating UV reactors in drinking water treatment plants, without the need to spike a biodosimeter or actinometer into the water.