Activated carbon coupled with advanced biological wastewater treatment: A review of the enhancement in micropollutant removal

This study consists of a review on the removal efficiencies of a wide spectrum of micropollutants (MPs) in biolog-ical treatment (mainly membrane bioreactor) coupled with activated carbon (AC) (AC added in the bioreactor or followed by an AC unit, acting as a post treatment). It focuses on how the presence of AC may promote the re-moval of MPs and the effects of dissolved organic matter (DOM) in wastewater. Removal data collected of MPs are analysed versus AC dose if powdered AC is added in the bioreactor, and as a function of the empty bed contact time in the case of a granular activated carbon (GAC) column acting as a post treatment. Moreover, the enhance-ment in macropollutant (organic matter, nitrogen and phosphorus compounds) removal is analysed as well as the AC mitigation effect towards membrane fouling and, finally, how sludge properties may change in the pres-ence of AC. To sum up, it was found that AC improves the removal of most MPs, favouring their sorption on the AC surface, promoted by the presence of different functional groups and then enhancing their degradation processes. DOM is a strong competitor in sorption on the AC surface, but it may promote the transformation of GAC in a bi-ologically activated carbon thus enhancing all the degradation processes. Finally, AC in the bioreactor increases sludge floc strength and improves its settling characteristics and sorption potential. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).

Automated summary

This study reviews the removal efficiencies of micropollutants in biological treatment coupled with activated carbon, finding that activated carbon can enhance the removal of micropollutants and improve degradation processes for organic matter. Additionally, it was observed that activated carbon can positively impact sludge properties.