title: Determining the optimal transmembrane gas pressure for nitrification in membrane-aerated biofilm reactors based on oxygen profile analysis.
abstract: The goal of this study was to investigate the effect of transmembrane gas pressure (P g) on the specific ammonium removal rate in a membrane-aerated biofilm reactor (MABR). Our experimental results show that the specific ammonium removal rate increased from 4.98 to 9.26 gN m(-2) day(-1) when P g increased from 2 to 20 kPa in an MABR with a biofilm thickness of approximately 600 μm. However, this improvement was not linear; there was a threshold of P g separating the stronger and weaker effects of P g. The ammonium removal rate was improved less significantly when P g was over the threshold, indicating that there is an optimal threshold of P g for maximizing ammonium removal in an MABR. The change in oxygen penetration depth (d p) is less sensitive to P g in the ammonia-oxidizing active layer than in the inactive layer in membrane-aerated biofilm. The location of the P g threshold is at the same point as the thickness of the active layer on the curve of d p versus P g; thus, the active layer thickness and the optimal P g can be determined on the basis of the changes in the slope of d p to P g.
authors.affiliation: Institute of Biofilm Technology, Key Laboratory of Yangtze Aquatic Environment (MOE), State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China. wangrongchang@tongji.edu.cn.
authors.forename: Rongchang
authors.initials: R
authors.lastname: Wang
authors.affiliation: Institute of Biofilm Technology, Key Laboratory of Yangtze Aquatic Environment (MOE), State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Xiao
authors.affiliation: Institute of Biofilm Technology, Key Laboratory of Yangtze Aquatic Environment (MOE), State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
authors.forename: Yanan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Center for Biofilm Engineering, Montana State University, Bozeman, MT, 59717, USA.
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Lewandowski
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism*; D018441:Biofilms; D019149:Bioreactors; D008567:Membranes, Artificial; D058465:Nitrification / Q000502:physiology; D010100:Oxygen / Q000378:metabolism*; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
chemical_list: D064751:Ammonium Compounds; D008567:Membranes, Artificial; D010100:Oxygen; D062065:Wastewater
keywords: Active layer; Membrane-aerated biofilm reactor; Nitrification; Oxygen penetration depth; Transmembrane gas pressure