Controlling micropollutants in tertiary municipal wastewater by O_3/H_2O_2, granular biofiltration and UV_(254)/H_2O_2 for potable reuse applications

摘要

A comprehensive pilot study was carried out to experimentally assess the potential of newly developed treatment trains integrating two-stage AOPs and biofiltration to reach potable reuse water quality standards from municipal wastewater. The processes consisted of a two-stage AOPs with (carbon or limestone) biofiltration, the first AOP (O-3/H2O2) serving as pre-treatment to biofiltration and the second AOP (UV254/H2O2) serving as post-biofiltration finishing step to ensure advanced disinfection. A comprehensive monitoring campaign was put in place resulting from the combination of targeted, nontargeted and suspect screening measurements. It was found that 13 organic micropollutants were detected from a list of 219 suspects although at ng/L level only. For the treatment conditions piloted in this study (O-3=13 +/- 0.5 mg/L H2O2 = 11 +/- 0.4 mg/L for the O-3/H(2)O(2 )process, and UV = 410 +/- 63.5 mJ/cm(2), H2O2= 5 mg/l for the UV254/H(2)O(2 )process), it was possible to estimate the overall removal efficacy for each unit process, which was found to follow this order: RO (99%) > BAC (87%) > O-3-H2O2(78%) > BAL (67%) > UV/H2O2(43%) > AOP contact chamber (19%) > UF(0%), with the treatment train integrating two AOPs and granular biofiltration with activated carbon (O-3/H2O2+ BAC + UV254/H2O2) showing superior performance with a 99% abatement in total micropollutants. No ecotoxicologically-positive response was generally observed for any of the effluent samples from the tested trains, even when pre-concentration factors up to 100-1000 times were employed to increase the sensitivity of the bioassay methods. (C) 2019 Published by Elsevier Ltd.