Photochemical Formation of Hydroxyl Radical from Effluent Organic Matter: Role of Composition

The photochemical formation of hydroxyl radical (HO center dot) from effluent organic matter (EfOM) depends upon the chemical properties of this heterogeneous mixture. In this study, two EfOM samples collected from wastewater treatment plants (WWTP A and B) were fractionated by both hydrophobicity (bulk and non-humic) and apparent molecular weight (A/v1W). The apparent quantum yield for HO center dot formation ((Phi(center dot)(HO)) and the maximum fluorescence quantum yield (Phi(F)) were subsequently measured for each subfraction. The formation rates of HO center dot (considering only the 10 hydrogen-peroxide-independent pathways) for the bulk waters were 4.8 X 10(-10) and 9.6 X M s(-1) for WVVTP A and B, respectively. For the AMW fractions, the values of Phi(center dot)(HO) increased as the AIVIVV of the material decreased. For the W1NTP A sample, the Phi(center dot)(HO) increased from 2.54 x 10(-4) (bulk water) to 6.29 X 10(-4) for the