title: Pilot-scale study of powdered activated carbon recirculation for micropollutant removal.
abstract: Adsorption onto powdered activated carbon (PAC) is a promising technique for the removal of organic micropollutants (OMPs) from treated wastewater. To enhance the adsorption efficiency, PAC is recycled back into the adsorption stage. This technique was examined in pilot scale in comparison to a reference without recirculation. Coagulation with Fe(3+) was carried out simultaneously to adsorption. Extensive OMP measurements showed that recirculation significantly increased OMP eliminations. Thus, significant PAC savings were feasible. The PAC concentration in the contact reactor proved to be an important operating parameter that can be surrogated by the easily measurable total suspended solids (TSS) concentration. OMP eliminations increased with increasing TSS concentrations. At 20 mg PAC L(-1) and 2.8 g TSS L(-1) in the contact reactor, well-adsorbable carbamazepine was eliminated by 97%, moderately adsorbable diclofenac was eliminated by 92% and poorly-adsorbable acesulfame was eliminated by 54% in comparison to 49%, 35% and 18%, respectively, without recirculation. The recirculation system represents an efficient technique, as the PAC's adsorption capacity is practically completely used. Small PAC dosages yield high OMP eliminations. Poorly-adsorbable gabapentin was eliminated to an unexpectedly high degree. A laboratory-scale biomass inhibition study showed that aerobic biodegradation removed gabapentin in addition to adsorption.
authors.affiliation: Chair of Water Quality Control, Technische Universität Berlin, KF4, Str. des 17. Juni 135, Berlin D-10623, Germany E-mail: felix.meinel@tu-berlin.de.
authors.forename: F
authors.initials: F
authors.lastname: Meinel
authors.affiliation: Research & Development, Berliner Wasserbetriebe, Neue Jüdenstr. 1, Berlin D-10179, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Sperlich
authors.affiliation: Chair of Water Quality Control, Technische Universität Berlin, KF4, Str. des 17. Juni 135, Berlin D-10623, Germany E-mail: felix.meinel@tu-berlin.de.
authors.forename: M
authors.initials: M
authors.lastname: Jekel
mesh_terms: D000327:Adsorption; D001673:Biodegradation, Environmental; D002606:Charcoal / Q000737:chemistry*; D010865:Pilot Projects; D059027:Recycling; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D002606:Charcoal; D062065:Wastewater; D014874:Water Pollutants, Chemical