Nitrification in a vertically moving biofilm system

A laboratory continuous feed biofilm reactor, comprising a bulk fluid reactor, a biofilm plastic module, a feed tank, and pneumatic devices and controls, was operated for a total period of 257 days, including seeding time, to treat domestic-strength synthetic wastewater under increasing ammonium nitrogen (NH4+-N) loading rates, ranging from 0.17 + - 0.01 (0.71 + - 0.06 g m(-2) d(-1)) to 0.70 + - 0.02 kg m(-3) d(-1) (2.9 + - 0.1 g m(-2) d(-1)). The biofilm plastic module was moved vertically in and out of the wastewater in continuous cycles. The maximum NH4+-N removal rate was reached during the maximum loading phase, when a NH4+-N loading rate of 0.70 + - 0.02 kg m(-3) d(-1) (2.9 + - 0.1 g m(-2) d(-1)) was applied to the system. During this loading period, the average NH4+-N removal rate was 0.30 + - 0.10 kg m(-3) d(-1) (1.30 + - 0.40 g m(-2) d(-1)). (c) 2005 Elsevier Ltd. All rights reserved.