Photochemically Induced Formation of Reactive Oxygen Species (ROS) from Effluent Organic Matter

The formation of reactive axygen species (ROS) from effluent organic matter (EfOM) was investigated under stimulated solar irradiation. In this study, EfOM was isolated into three different fractions based on hydrophobicity. The productivity of ROS in EfOM was measured and compared with that of natural organic matter (NOM) isolates, including Suwanee River humic acid/fulvic acid (SRHA/FA) and Pony Lake fulvic acid (PLFA). The hydrophilic (HPI) component had a greater quantum yield of O-1(2) than those of the hydrophobic (HPO) and transphilic (TPI) fractions because the HPI contained peptides and proteins. Regarding O-2(center dot-), the phenolic moieties acted as electron donating species after photochemical excited amd therefore electron transfer to oxygen. A positive correlation was . found between the phenolic concentrations and the steady state O-2(center dot-) concentrations H2O2 accumulated during the irradiation process from superoxide as precursor. Potentially, due to the presence of proteins or other organic species in the HPI fraction, the decay rates of H2O2 in the dark for both the effluent wastewater and the HPI fraction were significantly faster than the rates observed standard NOM isolates, the HPO and TPI fractions. Autochthonous NOM showed a higher center dot OH productivity than terrestrial NOM. The [center dot OH](ss) was lowest in the fraction tine to the Tack of humic fraction and existence of soluble microbial products (SMPs), which easily reacted with center dot OH. Overall, the HPO and TPI fractions were the major sources of superoxide, H2O2 and center dot OH under simulated solar irradiation. The HPI fraction dominated the production of O-1(2) and acted as a Sink for H2O2 and center dot OH.