MONITORING DBP FORMATION WITH DIFFERENTIAL UV SPECTROSCOPY

The decrease in the ultraviolet (UV) absorbance of natural organic mat ter (NOM) induced by chlorination can be characterized by the differen tial UV spectrum of the water. Differential UV spectra of chlorinated NOM are remarkably similar for a wide range of water qualities and chl orination conditions, always exhibiting a band with a maximum near a w avelength of 272 nm. The magnitude of the decrease in A(272) (Delta A( 272)) is an excellent indicator of total organic halogen (TOX) formati on resulting from chlorination, independent of the ratio of chlorine t o dissolved organic carbon, bromide concentration, pH, reaction time, and NOM source. Use of Delta A(272) as a surrogate allows virtually in stantaneous and continuous monitoring of TOX and in some cases, specif ic disinfection by-products, at a much lower cost than is possible usi ng conventional analytical approaches.