title: Ammonia removal in the carbon contactor of a hybrid membrane process.
abstract: The hybrid membrane process (HMP) coupling powdered activated carbon (PAC) and low-pressure membrane filtration is emerging as a promising new option to remove dissolved contaminants from drinking water. Yet, defining optimal HMP operating conditions has not been confirmed. In this study, ammonia removal occurring in the PAC contactor of an HMP was simulated at lab-scale. Kinetics were monitored using three PAC concentrations (1-5-10 g L(-1)), three PAC ages (0-10-60 days), two temperatures (7-22 °C), in ambient influent condition (100 μg N-NH4 L(-1)) as well as with a simulated peak pollution scenario (1000 μg N-NH4L(-1)). The following conclusions were drawn: i) Using a colonized PAC in the HMP is essential to reach complete ammonia removal, ii) an older PAC offers a higher resilience to temperature decrease as well as lower operating costs; ii) PAC concentration inside the HMP reactor is not a key operating parameter as under the conditions tested, PAC colonization was not limited by the available surface; iii) ammonia flux limited biomass growth and iv) hydraulic retention time was a critical parameter. In the case of a peak pollution, the process was most probably phosphate-limited but a mixed adsorption/nitrification still allowed reaching a 50% ammonia removal. Finally, a kinetic model based on these experiments is proposed to predict ammonia removal occurring in the PAC reactor of the HMP. The model determines the relative importance of the adsorption and biological oxidation of ammonia on colonized PAC, and demonstrates the combined role of nitrification and residual adsorption capacity of colonized PAC.
authors.affiliation: NSERC Industrial Chair on Drinking Water, Department of Civil, Mining and Geological Engineering, École Polytechnique de Montreal, CP 6079, Succursale Centre-Ville, Montréal, QC, Canada H3C 3A7; Ecologie des Systèmes Aquatiques, Université Libre de Bruxelles, Campus de la Plaine, CP 221, Boulevard du Triomphe, 1050 Bruxelles, Belgium. Electronic address: celine.stoquart@polymtl.ca.
authors.forename: Céline
authors.initials: C
authors.lastname: Stoquart
authors.affiliation: Ecologie des Systèmes Aquatiques, Université Libre de Bruxelles, Campus de la Plaine, CP 221, Boulevard du Triomphe, 1050 Bruxelles, Belgium. Electronic address: pservais@ulb.ac.be.
authors.forename: Pierre
authors.initials: P
authors.lastname: Servais
authors.affiliation: NSERC Industrial Chair on Drinking Water, Department of Civil, Mining and Geological Engineering, École Polytechnique de Montreal, CP 6079, Succursale Centre-Ville, Montréal, QC, Canada H3C 3A7.
authors.forename: Benoit
authors.initials: B
authors.lastname: Barbeau
mesh_terms: D000327:Adsorption; D000641:Ammonia / Q000302:isolation & purification*; D002244:Carbon / Q000737:chemistry; D060766:Drinking Water / Q000592:standards*; D005374:Filtration / Q000379:methods*; D007700:Kinetics; D008567:Membranes, Artificial; D008962:Models, Theoretical; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*
chemical_list: D060766:Drinking Water; D008567:Membranes, Artificial; D014874:Water Pollutants, Chemical; D002244:Carbon; D000641:Ammonia
keywords: Ammonia adsorption; Colonized PAC; Drinking water; Hybrid membrane process; Nitrification; Pseudo-second order kinetics