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).