As water stress intensifies, treated wastewater inputs compose an increased share of natural streams. Treated wastewater contains organic contaminates in addition to effluent organic matter, which differs significantly in composition to natural organic matter. These compositional differences are the basis for an array of differences their behavior during photochemical processes. While past studies have highlighted these differences for the production of reactive intermediates, it is still unclear exactly how effluent organic matter impacts the levels of photobleaching occurring in natural systems. This study examines the photobleaching of effluent organic matter collected from Boulder, CO and compares it with the natural organic matter present in Boulder Creek prior to the inflow from the treatment plant. The degradation of these two water sources was compared against Suwannee River Natural Organic Matter, which is well-characterized organic matter isolate. Photobleaching was also monitored in the presence or absence of hydroxyl radical, singlet oxygen, and triplet excited organic matter, which are the well-established reactive intermediates. The compositional changes that occurred were monitored using optical parameters from both fluorescence and absorbance data in addition to the quantum yields and formation potentials for reactive intermediates. As has been previously demonstrated, hydroxyl radical played a limited role in the photobleaching process. However, other reactive intermediates had a significant impact on photobleaching rates, including singlet oxygen and triplet-excited organic matter. This study also saw evidence of the antioxidant capacity of Boulder Creek and effluent organic matter.<br/>

Photochemical processing of wastewater impacted streams

249th National Meeting (2015)

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