Removal of organic micropollutants from domestic wastewater: The effect of ozone-based advanced oxidation process on nanofiltration

The objective of this study was to develop an innovative and advanced integrated "membrane and oxidation" system for the treatment of domestic wastewater by coupling membrane bioreactor (MBR), nanofiltration (NF) and ozonation. Five contaminants were selected (acetaminophen, carbamazepin, sulfamethoxazole, tetracyclin and terbutryn). The MBR effluent samples have been fully characterized using conventional analysis (COD, TOC, UV254, ionic chromatography...) and advanced characterization analyses (3D fluorescence excitation-emission matrices (3DEEM)) before being spiked with 1 ppm of each of the selected pharmaceuticals. NF process experiments were carried out in batch and semi-batch mode using a flat sheet membrane system (NF-90). Selected OMPs were well rejected by NF (between 84 % and 98 %) and the main fouling mechanisms observed were pore blocking and gel layer formation. MBR effluent was then pre-treated in an ozonation pilot unit's with ozone gas inlet fixed at 5 g.Nm(-)(3).The complete degradation by ozonation of carbamazepine and sulfamethoxazole took 15-20 min and more than 30 min for terbutryn. Acetaminophen, tetracyclin and dissolved organic matter were almost totally ozonated in 5 min. The overall mineralization rate was low. The pre-ozonation enables the NF fouling resistance to be decreased by almost 40 %.