Currently, the EPA does not regulate concentrations of pharmaceuticals and personal care products (PPCPs) in wastewater effluent; however, some PPCPs are known to cause adverse effects to the environment so presence of PPCPs in effluent is of worthwhile concern. Wetland natural treatment systems offer a sustainable alternative to traditional wastewater treatment systems. Constructed wetlands, such as those incorporated in the Arcata Wastewater Treatment Facility (AWWTF) in northern California, provide interaction between dissolved organic carbon (DOC) in the wastewater and sunlight, promoting photochemical reactions and producing reactive oxygen species (ROS). ROS, particularly hydroxyl radical (.OH), have been shown to react with PPCPs, leading to transformation/removal. Characterization of DOC is an ideal first step in assessing conditions for formation of .OH within wetlands. The AWWTF treatment train includes oxidation (OX) ponds, followed by treatment wetlands (TW), and enhancement wetlands (EW). The hypothesis: .OH production at AWWTF changes throughout the treatment process with respect to plant matter and sunlight exposure. Biological, phyto, physical, and other mechanisms transform the DOC within the wastewater, altering its potential to photo react and produce .OH which then transforms/removes PPCPs. Wastewater samples were collected at locations along the treatment train of AWWTF. Samples were analyzed for water quality: DOC, BOD5, and pH. Fluorescence excitation emission spectra (EEMs) were collected and used to construct parallel factor analysis (PARAFAC) models to identify the contribution of different organic groups comprising the fluorescence signal of the wastewater. Experiments are being conducted on wastewater samples using a solar simulator to quantify .OH production potential and assess how it changes along the treatment train. Initial DOC characterization at AWWTF suggests that DOC increases along the treatment train, even though BOD5 decreases. Additionally, EEMs show a larger fulvic peak in TW effluent compared to OX pond effluent. This correlates the increased plant matter concentrations in the TW with increased .OH production potential. On the other hand, the EEMs also show the emergence of a humic peak in the TW, which has been known to quench .OH production. The humic peak was smaller than the fulvic acid peak suggesting an increase in .OH production potential as the wastewater leaves OX ponds and flows through the TW.

Identification and quantification of OH formation potential in constructed wetlands treating wastewater for the removal of pharmaceuticals

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