title: Improving phosphate buffer-free cathode performance of microbial fuel cell based on biological nitrification.
abstract: To reduce the amount of phosphate buffer currently used in Microbial Fuel Cell's (MFC's), we investigated the role of biological nitrification at the cathode in the absence of phosphate buffer. The addition of a nitrifying mixed consortia (NMC) to the cathode compartment and increasing ammonium concentration in the catholyte resulted in an increase of cell voltage from 0.3 V to 0.567 V (external resistance of 100 Omega) and a decrease of catholyte pH from 8.8 to 7.05. A large fraction of ammonium was oxidized to nitrite, as indicated by an increase of nitrate-nitrogen (NO(3)(-)-N). An MFC inoculated with an NMC and supplied with 94.2 mgN/l ammonium to the catholyte could generate a maximum power of 2.1+/-0.14 mW (10.94+/-0.73 W/m(3)). This compared favorably to an MFC supplied with either buffered or non-buffered solution. The buffer-free NMC inoculated cathodic chamber showed the smallest polarization resistance, suggesting that nitrification resulted in improved cathode performance. The improved performances of the phosphate buffer-free cathode and cell are positively related to biological nitrification, in which we suggest additional protons produced from ammonium oxidation facilitated electrochemical reduction of oxygen at cathode.
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment (SKLUWRE), Harbin Institute of Technology, Harbin 150090, PR China. sjyou@hit.edu.cn
authors.forename: Shi-Jie
authors.initials: SJ
authors.lastname: You
authors.forename: Nan-Qi
authors.initials: NQ
authors.lastname: Ren
authors.forename: Qing-Liang
authors.initials: QL
authors.lastname: Zhao
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Kiely
authors.forename: Jing-Yuan
authors.initials: JY
authors.lastname: Wang
authors.forename: Feng-Lin
authors.initials: FL
authors.lastname: Yang
authors.forename: Lei
authors.initials: L
authors.lastname: Fu
authors.forename: Luo
authors.initials: L
authors.lastname: Peng
mesh_terms: D018407:Bacterial Physiological Phenomena / Q000187:drug effects*; D001674:Bioelectric Energy Sources / Q000382:microbiology*; D002021:Buffers; D004563:Electrochemistry / Q000295:instrumentation*; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D000644:Quaternary Ammonium Compounds / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D002021:Buffers; D000644:Quaternary Ammonium Compounds