Innovative Advanced Oxidation Processes for the Treatment of Pharmaceuticals and EDCs

            Due to recent changes in water quality regulations and increased awareness of contaminants of emerging concern, some water and wastewater utilities are augmenting their treatment trains with advanced oxidation processes (AOPs). The most common AOPs are peroxide-assisted UV or ozone, but there are also novel alternatives such as photocatalysis and nonthermal plasma (NTP). Photocatalysis involves the irradiation of titanium dioxide (TiO₂) nanoparticles with UV light in order to catalyze the formation of hydroxyl radicals. NTP generates ozone, UV light, and hydroxyl radicals by discharging high-voltage electrical pulses across flat and fiber-like electrodes. Both treatment technologies are capable of oxidizing contaminants without the addition of costly hydrogen peroxide. In this study, a pilot-scale photocatalysis reactor was evaluated based on its ability to degrade 32 pharmaceuticals, endocrine disrupting compounds (EDCs), and estrogenic activity in drinking water. Similarly, a pilot-scale NTP reactor was evaluated based on its ability to degrade seven indicator compounds in tertiary-treated wastewater and drinking water. The photocatalysis experiments were performed in a single-pass configuration, and the NTP tests were conducted in batch and single-pass modes to examine the kinetics and remediation capabilities of the technology, respectively. For photocatalysis, 29 of the target compounds, in addition to total estrogenic activity, were 70–100% removed, and only three compounds were less than 50% removed following the highest level of treatment (4 kWh/m³). For NTP, values for electrical energy per order (EEO) of magnitude destruction ranged from <0.3 kWh/m³-log for easily degraded compounds (e.g., carbamazepine) in surface water to 14 kWh/m³-log for more recalcitrant compounds (e.g., meprobamate) in wastewater. Changes in bulk organic matter were also monitored and correlated to contaminant destruction. These results indicate that photocatalysis and NTP may be viable alternatives to more common AOPs due to their chemical-free processes and comparable energy requirements for contaminant destruction.