title: Comprehensive analysis of step-feeding strategy to enhance biological nitrogen removal in alum sludge-based tidal flow constructed wetlands.
abstract: Step-feeding strategies have been extensively studied and comprehensively analyzed in this study for a four-stage alum sludge-based tidal flow constructed wetlands (AlS-TFCWs) system. Enhanced total nitrogen removal of 83% is achieved under high nitrogen loading rate of 19.1 g N/m(2)d. The key issues towards the success of a significant nitrogen removal in step-feeding TFCWs are the bed resting time (which provides better aeration for nitrification) and up flow stage/delayed input of side stream(s) (which ensure favorable environment for better denitrification). Simultaneous nitrification and denitrification (SND) was found effective in the 1st stage of the system and SND via nitrite is the main nitrogen conversion mechanism. The optimal influent distribution fraction for step-feeding purpose can be estimated from a theoretical basis, which is a function of the influent BCOD/TKN ratio. Therefore the influent distribution fraction should be adjusted according to the variety of influent characteristics, rather than a fixed value.
authors.affiliation: Centre for Water Resources Research, School of Civil, Structural and Environmental Engineering, University College Dublin, Newstead Building, Belfield, Dublin 4, Ireland.
authors.forename: Y S
authors.initials: YS
authors.lastname: Hu
authors.forename: Y Q
authors.initials: YQ
authors.lastname: Zhao
authors.forename: X H
authors.initials: XH
authors.lastname: Zhao
authors.forename: J L G
authors.initials: JL
authors.lastname: Kumar
mesh_terms: D000534:Alum Compounds / Q000737:chemistry*; D009584:Nitrogen / Q000302:isolation & purification*; D012722:Sewage; D014872:Water Movements; D053833:Wetlands
chemical_list: D000534:Alum Compounds; D012722:Sewage; C041524:aluminum sulfate; D009584:Nitrogen