Simultaneous ozone and granular activated carbon for advanced treatment of micropollutants in municipal wastewater effluent

The main objective of this study was to compare the efficacy of ozone (O₃) and O₃ with granular activated carbon (GAC) (O₃/GAC) at pilot-scale for the enhanced removal of micropollutants (MPs) from wastewater effluent. The results revealed enhanced removal of tris (2-carboxylethyl) phosphine (TCEP), sucralose, and meprobamate during the O₃/GAC treatment experiments compared to the sum of their removal during isolated ozonation and GAC adsorption experiments. The long-term O₃/GAC experiment showed the promotive effect of GAC substantially decreased after 20 h of O₃ exposure. This decreased performance correlates with changes to GAC surface properties caused by O₃. After 6 h of operation, O₃ initially led to an increase in Brunauer-Emmett-Teller (BET) surface area on the GAC improving the elimination level of investigated MPs (except N-nitrosomorpholine (NMOR)). However, after 20 h of exposure, O₃ ultimately caused structural damages to the GAC surface, decreased the BET surface area in the final stages of the experiment, and a 4-fold increase in O_1s:C_1s ratio on the GAC surface was observed due to an increase in surface acidic functional groups caused by O₃ treatment.