ADVANCING PHOTOELECTROCHEMICAL OXYGEN DEMAND ANALYSIS FOR WASTEWATER TREATMENT PROCESS APPLICATIONS

Abstract

Photoelectrochemical oxygen demand (peCOD) can provide wastewater treatment facilities (WWTFs) with rapid insight into oxidizable organic matter using greener and user-friendly reagents compared to dichromate chemical oxygen demand (COD). PeCOD uses UV light to activate a TiO2 photocatalytic cell to oxidize and detect COD. PeCOD technology in wastewater applications could be beneficial; however, standard methods only apply to freshwater sources for drinking water treatment plants and treated drinking water. This research investigates the relationship between peCOD and potential wastewater interferences (e.g., solids, inorganics) in comparison to dichromate COD in environmental and controlled conditions. Inorganic ions in ultra-pure water simulated wastewater and identified chloride, bromide, ammonium (500 mg/L) and nitrite (>25 mg/L) as peCOD interferences. A preprocessing method was investigated to increase the peCOD signal using real wastewater matrices. Environmental samples with lower dichromate COD (<150 mg O2/L) and solids (TSS <50 mg/L) had higher peCOD-to-COD ratios.