Removal of organic micropollutants by well-tailored granular zeolites and subsequent ozone-based regeneration

Abstract

Advanced technologies to remove organic micropollutants (OMPs) from municipal wastewater have gained much attention over the last decades. Adsorption by zeolites is one of these technologies. In this study, the regeneration performance of well-tailored granular zeolites loaded with OMPs was evaluated. The selected OMPs were categorized into three groups due to the adsorption performance: high, medium and low adsorbance. Gaseous ozone was directly applied to regenerate dried zeolite granules at an ozone concentration of 30 mg/L and a gas flow rate of 0.2 L/min (0.04 m/s). For the high and medium adsorbing OMPs, 45 min of ozonation was long enough to fully restore their adsorption capacity. For the low adsorbing OMPs, the regeneration efficiency reached 60% after 60 min of ozonation. Interestingly, their recovered adsorption capacities firstly decreased and subsequently increased along with the ozonation duration. The dramatically decrease was most probably due to the presence of the transformation products generated from the ozonation of some selected OMPs. In seven sequential adsorption-regeneration cycles, the adsorption capacity for 75% of the selected OMPs was fully recovered at an ozonation duration of 60 min in each regeneration. The assumed accumulation of the ozonation transformation products only influenced the adsorption of low adsorbing OMPs in 7 cycles.