Enhanced Ozonation of Trace Organic Contaminants in Municipal Wastewater Plant Effluent by Adding a Preceding Filtration Step: Comparison and Prediction of Removal Efficiency

Ozonation is an efficient method for removing trace organic contaminants (TrOCs) and improving the quality of municipal wastewater plant effluents. Nevertheless, the wide application of ozonation is still challenging because of various wastewater matrices, ozone dose design, and ozone-refractory compounds. An enhanced ozonation supported by adding an additional filtration step was studied to overcome these limitations. A municipal wastewater plant effluent spiked with 6 structurally different TrOCs was employed to investigate the efficiency of TrOCs elimination and water quality improvement when combining ozonation with filtration. A kinetic approach, based on ozone and hydroxyl radicals (•OH) exposure, was used to predict TrOCs abatement and to evaluate ozone dose demand. A significantly more efficient removal of dissolved organic carbon (DOC) was observed when combining ozonation with filtration. Furthermore, the •OH scavenging rate of the effluent matrix was decreased from 6.4 × 10–4 s–1 for conventional ozonation to 1.2 × 10–4 s–1 when combining anion resin filtration (ARF) with ozonation. An improved removal (38% removal at 0.1 g O3/g DOC) of atrazine (which is a typical ozone-refractory compound) was achieved by combining granular activated carbon filtration (GAF) with ozonation compared to stand-alone ozonation (8% removal at 0.5 g O3/g DOC). The measured and predicted elimination demonstrated that the kinetic approach was reliable to predict target contaminants abatement in effluent by use of combined filtration–ozonation systems.