title: Nitrogen removal in a single-chamber microbial fuel cell with nitrifying biofilm enriched at the air cathode.
abstract: Nitrogen removal is needed in microbial fuel cells (MFCs) for the treatment of most waste streams. Current designs couple biological denitrification with side-stream or combined nitrification sustained by upstream or direct aeration, which negates some of the energy-saving benefits of MFC technology. To achieve simultaneous nitrification and denitrification, without extra energy input for aeration, the air cathode of a single-chamber MFC was pre-enriched with a nitrifying biofilm. Diethylamine-functionalized polymer (DEA) was used as the Pt catalyst binder on the cathode to improve the differential nitrifying biofilm establishment. With pre-enriched nitrifying biofilm, MFCs with the DEA binder had an ammonia removal efficiency of up to 96.8% and a maximum power density of 900 ± 25 mW/m(2), compared to 90.7% and 945 ± 42 mW/m(2) with a Nafion binder. A control with Nafion that lacked nitrifier pre-enrichment removed less ammonia and had lower power production (54.5% initially, 750 mW/m(2)). The nitrifying biofilm MFCs had lower Coulombic efficiencies (up to 27%) than the control reactor (up to 36%). The maximum total nitrogen removal efficiency reached 93.9% for MFCs with the DEA binder. The DEA binder accelerated nitrifier biofilm enrichment on the cathode, and enhanced system stability. These results demonstrated that with proper cathode pre-enrichment it is possible to simultaneously remove organics and ammonia in a single-chamber MFC without supplemental aeration.
authors.affiliation: Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Hengjing
authors.initials: H
authors.lastname: Yan
authors.forename: Tomonori
authors.initials: T
authors.lastname: Saito
authors.forename: John M
authors.initials: JM
authors.lastname: Regan
mesh_terms: D000641:Ammonia / Q000378:metabolism; D001674:Bioelectric Energy Sources / Q000382:microbiology*; D018441:Biofilms; D058440:Denitrification; D055664:Electrochemical Techniques / Q000379:methods; D004566:Electrodes / Q000382:microbiology; D058465:Nitrification; D009584:Nitrogen / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D000641:Ammonia; D009584:Nitrogen