title: Understanding the fate of organic micropollutants in sand and granular activated carbon biofiltration systems.
abstract: In this study, sand and granular activated carbon (GAC) biofilters were comparatively assessed as post-treatment technologies of secondary effluents, including the fate of 18 organic micropollutants (OMPs). To determine the contribution of adsorption and biotransformation in OMP removal, four reactors were operated (two biofilters (with biological activity) and two filters (without biological activity)). In addition, the influence of empty bed contact time (EBCT), ranging from 0.012 to 3.2d, and type of secondary effluent (anaerobic and aerobic) were evaluated. Organic matter, ammonium and nitrate were removed in both biofilters, being their adsorption higher on GAC than on sand. According to the behaviour exhibited, OMPs were classified in three different categories: I) biotransformation and high adsorption on GAC and sand (galaxolide, tonalide, celestolide and triclosan), II) biotransformation, high adsorption on GAC but low or null adsorption on sand (ibuprofen, naproxen, fluoxetine, erythromycin, roxythromycim, sulfamethoxazole, trimethoprim, bisphenol A, estrone, 17β-estradiol and 17α-ethinylestradiol), and, III) only adsorption on GAC (carbamazepine, diazepam and diclofenac). No influence of EBCT (in the range tested) and type of secondary effluent was observed in GAC reactors, whereas saturation and kinetic limitation of biotransformation were observed in sand reactors. Taking into account that most of the organic micropollutants studied (around 60%) fell into category II, biotransformation is crucial for the elimination of OMPs in sand biofilters.
authors.affiliation: Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain. Electronic address: lidia.paredes@usc.es.
authors.forename: L
authors.initials: L
authors.lastname: Paredes
authors.affiliation: Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain. Electronic address: eduardo.fernandez.fontaina@usc.es.
authors.forename: E
authors.initials: E
authors.lastname: Fernandez-Fontaina
authors.affiliation: Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain. Electronic address: juan.lema@usc.es.
authors.forename: J M
authors.initials: JM
authors.lastname: Lema
authors.affiliation: Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain. Electronic address: francisco.omil@usc.es.
authors.forename: F
authors.initials: F
authors.lastname: Omil
authors.affiliation: Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain. Electronic address: marta.carballa@usc.es.
authors.forename: M
authors.initials: M
authors.lastname: Carballa
mesh_terms: D000327:Adsorption; D001711:Biotransformation; D002606:Charcoal; D005374:Filtration / Q000295:instrumentation* / Q000379:methods; D012822:Silicon Dioxide; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification
chemical_list: D014874:Water Pollutants, Chemical; D002606:Charcoal; D012822:Silicon Dioxide
keywords: Adsorption; Biotransformation; Empty bed contact time; Granular activated carbon; Organic micropollutant; Sand filtration