Influence of dissolved organic matter on the removal of 12 organic micropollutants from wastewater effluent by powdered activated carbon adsorption

Ronan Guillossou (1) , Julien Le Roux (1) , Romain Mailler (2) , Caroline Soares Pereira-Derome (1) , Gilles Varrault (1) , Adèle Bressy (1) , Emmanuelle Vulliet (3) , Catherine Morlay (4) , Fabrice Nauleau (5) , Vincent Rocher (2) , Johnny Gasperi (1, 6)

1 LEESU - Laboratoire Eau Environnement et Systèmes Urbains
2 SIAAP - Direction du Développement et de la Prospective
3 ISA-TRACES - Technologie et Recherche en Analyse Chimique pour l'Environnement et la Santé
4 MATEIS - Matériaux, ingénierie et science [Villeurbanne]
5 SAUR - Direction de la Recherche et Développement
6 GERS-LEE - Eau et Environnement

The presence of dissolved organic matter (DOM) in wastewater effluents is recognized as the main factor limiting the adsorption of organic micropollutants (OMPs) onto activated carbon. The degree of the negative effect that DOM, depending on its quality, exerts on OMPs adsorption is still unclear. The influence of the interactions between DOM and OMPs on their removal is also not fully understood. Adsorption isotherms and conventional batch tests were performed in ultra-pure water and in wastewater effluent to study the influence of DOM on the adsorption of 12 OMPs onto powdered activated carbon. Best fit of adsorption pseudo-isotherms was obtained with the Freundlich equation and showed, as expected, that OMPs adsorption was higher in ultra-pure water than in wastewater effluent due to the presence of DOM leading to pore blockage and competition for adsorption sites. LC-OCD analysis revealed that biopolymers and hydrophobic molecules were the most adsorbed fractions while humic acids were not removed after a contact time of either 30 min or 72 h. The presence of DOM had a negative impact on the removal of all OMPs after 30 min of adsorption, but similar removals to ultra-pure water were obtained for 6 OMPs after 72 h of adsorption. This demonstrated that competition between DOM and OMPs for adsorption sites was not a major mechanism as compared to pore blockage, which only slowed down the adsorption and did not prevent it. The charge of OMPs had a clear impact: the adsorption of negatively charged compounds was reduced in the presence of wastewater effluent due to repulsive electrostatic interactions with the adsorbed DOM and the PAC surface. On the other hand, the removal of positively charged compounds was improved. A 24 h pre-equilibrium between OMPs and DOM improved their removal onto PAC, which suggest that OMPs and DOM interacted in solution which decreased the negative effects caused by the presence of DOM, e.g. through co-adsorption of an OMP-DOM complex.

Mots clés: Activated carbon adsorption; Dissolved organic matter; Organic micropollutants; Wastewater advanced treatment

Domaines: Autre; Ingénierie de l'environnement

Ronan Guillossou, Julien Le Roux, Romain Mailler, Caroline Soares Pereira-Derome, Gilles Varrault, et al.. Influence of dissolved organic matter on the removal of 12 organic micropollutants from wastewater effluent by powdered activated carbon adsorption. Water Research, 2020, 172, pp.115487. ⟨10.1016/j.watres.2020.115487⟩. ⟨hal-02433266⟩