title: Impacts of coagulation on the adsorption of organic micropollutants onto powdered activated carbon in treated domestic wastewater.
abstract: The application of powdered activated carbon (PAC) as an advanced wastewater treatment step for the removal of organic micropollutants (OMP) necessitates complete separation of the PAC particles, e.g. by coagulation. In this study, potential positive or negative indirect or direct effects of coagulation on the adsorption of OMPs onto PAC in treated wastewater were investigated. Although the concentration of dissolved organic matter (DOM) was significantly reduced by coagulation, the selective removal of mainly larger DOM components such as biopolymers and humic substances did not improve subsequent OMP adsorption onto PAC, demonstrating that coagulation has minor effects on DOM constituents that are relevant for direct competition or pore blocking. The combination of coagulation and adsorption yielded the sum of the individual removals, as adsorption predominantly affected smaller compounds. While the formation of flocs led to visible incorporation of PAC particles, no significant mass transfer limitations impeded the OMP adsorption. As a result, the dosing sequence of coagulant and PAC is not critical for efficient adsorption of OMPs onto PAC. The relationships between adsorptive OMP removal and corresponding reduction of UV absorption at 254 nm (UVA254) as a promising surrogate correlation for the real-time monitoring and PAC adjustment were affected by coagulation, leading to individual correlations depending on the water composition. Correcting for UVA254 reduction by coagulation produces adsorptive UVA254 removal, which correlates highly with OMP removal for different WWTP effluents and varying coagulant doses and can be applied in combined adsorption/coagulation processes to predict OMP removal and control PAC dosing.
authors.affiliation: Technische Universität Berlin, Chair of Water Quality Control, Str. des 17. Juni 135, 10623 Berlin, Germany. Electronic address: johannes.altmann@tu-berlin.de.
authors.forename: Johannes
authors.initials: J
authors.lastname: Altmann
authors.affiliation: Technische Universität Berlin, Chair of Water Quality Control, Str. des 17. Juni 135, 10623 Berlin, Germany.
authors.forename: Frederik
authors.initials: F
authors.lastname: Zietzschmann
authors.affiliation: Technische Universität Berlin, Chair of Water Quality Control, Str. des 17. Juni 135, 10623 Berlin, Germany.
authors.forename: Eva-Linde
authors.initials: EL
authors.lastname: Geiling
authors.affiliation: Technische Universität Berlin, Chair of Water Quality Control, Str. des 17. Juni 135, 10623 Berlin, Germany.
authors.forename: Aki Sebastian
authors.initials: AS
authors.lastname: Ruhl
authors.affiliation: Berliner Wasserbetriebe, Cicerostr. 24, 10709 Berlin, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Sperlich
authors.affiliation: Technische Universität Berlin, Chair of Water Quality Control, Str. des 17. Juni 135, 10623 Berlin, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Jekel
mesh_terms: D000327:Adsorption; D002606:Charcoal / Q000737:chemistry*; D005427:Flocculation; D006812:Humic Substances / Q000032:analysis; D014466:Ultraviolet Rays; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D002606:Charcoal; D006812:Humic Substances; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Coagulation; DOC competition; Organic micropollutants; Powdered activated carbon; UVA(254); Wastewater treatment