Micropollutant Removal Potential by Aged Powdered Activated Carbon

The main objective of this study is to present a first demonstration of the potential of aged powdered activated carbon (PAC) to remove micropollutants during batch tests. Three PACs of varying ages (0, 10, and 60 days) were added (1??g/L1??g/L) in settled and preozonated settled water, in which a mixture of 10 micropollutants had been spiked at environmentally relevant concentrations. Under these operating conditions, direct competition with natural organic matter was not evidenced when decreasing absorbability of the organic matter through ozonation. All the micropollutants were rapidly adsorbed on the three PACs, and removals superior to 95% were reached within 5 min of contact time for all the micropollutants investigated. PAC aging decreased the adsorption kinetics of atrazine, deethylatrazine, and caffeine. PAC age is thus expected to reduce significantly the process performance at contact times less than 15 min. This study demonstrates that aged PAC suspensions allowing the removal of ammonia and dissolved organic carbon also have the potential to efficiently remove a wide variety of micropollutants by adsorption and comply with current World Health Organization guideline values for microcystin-LR (1???g/L1???g/L) and atrazine (2???g/L2???g/L).