title: Upgrade of deep bed filtration with activated carbon dosage for compact micropollutant removal from wastewater in technical scale.
abstract: The removal of micropollutants from drinking and wastewater by powdered activated carbon (PAC) adsorption has received considerable attention in research over the past decade with various separation options having been investigated. With Switzerland as the first country in the world having adopted a new legislation, which forces about 100 wastewater treatment plants to be upgraded for the removal of organic micropollutants from municipal wastewater, the topic has reached practical relevance. In this study, the process combination of powdered activated carbon (PAC) adsorption and deep bed filtration (DBF) for advanced municipal wastewater treatment was investigated over an extended period exceeding one year of operation in technical scale. The study aimed to determine optimum process conditions to achieve sufficient micropollutant removal in agreement with the new Swiss Water Ordinance under most economic process design. It was shown that the addition of PAC and Fe(3+) as combined coagulation and flocculation agent improved effluent water quality with respect to dissolved organic pollutants as well as total suspended solids (TSS), turbidity and PO4-P concentration in comparison to a DBF operated without the addition of PAC and Fe(3+). Sufficient micropollutant (MP) removal of around 80% was achieved at PAC dosages of 10 mg/L revealing that PAC retained in the filter bed maintained considerable adsorption capacity. In the investigated process combination the contact reactor serves for adsorption as well as for flocculation and allowed for small hydraulic retention times of minimum 10 min while maintaining sufficient MP removal. The flocculation of two different PAC types was shown to be fully concluded after 10-15 min, which determined the flocculation reactor size while both PAC types proved suitable for the application in combination with DBF and showed no significant differences in MP removal. Finally, the capping of PAC dosage during rain water periods, which resulted in lower dosage concentrations, was efficient in limiting PAC consumption during these events without suffering from negative effects on process performance or effluent quality.
authors.affiliation: University of Applied Sciences and Arts Northwestern Switzerland, Gründenstr. 40, CH-4132 Muttenz, Switzerland.
authors.forename: Jonas
authors.initials: J
authors.lastname: Löwenberg
authors.affiliation: University of Applied Sciences and Arts Northwestern Switzerland, Gründenstr. 40, CH-4132 Muttenz, Switzerland.
authors.forename: Armin
authors.initials: A
authors.lastname: Zenker
authors.affiliation: University of Applied Sciences and Arts Northwestern Switzerland, Gründenstr. 40, CH-4132 Muttenz, Switzerland.
authors.forename: Thérèse
authors.initials: T
authors.lastname: Krahnstöver
authors.affiliation: Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Überlandstrasse 133, P. O. Box 611, CH-8600 Dübendorf, Switzerland.
authors.forename: Marc
authors.initials: M
authors.lastname: Boehler
authors.affiliation: WABAG Water Technology, Bürglistrasse 31, CH-8401 Winterthur, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Baggenstos
authors.affiliation: Amt für Industrielle Betriebe, Bau- und Umweltschutzdirektion, Freulerstrasse 1, 4127 Birsfelden, Switzerland.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Koch
authors.affiliation: University of Applied Sciences and Arts Northwestern Switzerland, Gründenstr. 40, CH-4132 Muttenz, Switzerland. Electronic address: thomas.wintgens@fhnw.ch.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wintgens
mesh_terms: D000327:Adsorption; D002606:Charcoal / Q000737:chemistry*; D005374:Filtration; D005427:Flocculation; D012722:Sewage / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*; D060753:Water Quality
chemical_list: D002606:Charcoal; D012722:Sewage; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Advanced wastewater treatment; Deep bed filtration; Micropollutants; Powdered activated carbon