Eiroa, MartaKennes, ChristianVeiga, María Carmen2014-10-202014-10-202005-11Eiroa M, Kennes C, Veiga MC. Simultaneous nitrification and formaldehyde biodegradation in an activated sludge unit. Bioresour Technol. 2005;96(17):1914-8.DOI: 10.1016/j.biortech.2005.01.041http://hdl.handle.net/2183/13691The simultaneous removal of formaldehyde and ammonium in a lab-scale activated sludge unit was investigated. The unit was operated at a hydraulic retention time of 2.4 days with an ammonium concentration in the influent of 350 mg 〖NH〗_4^+-N/L, maintaining the ammonium loading rate at 0.15 g 〖NH〗_4^+-N/L d during the operation time. However, the applied organic loading rate was increased stepwise by increasing the formaldehyde concentration from 26 up to 3168 mg/L, corresponding to 0.01–1.40 g COD/L d. High formaldehyde removal efficiencies, around 99.5% (±0.38), were maintained at all the formaldehyde concentrations. Ammonium removal was also very high during the operation period, around 99.9% (±0.01). The ammonium concentration in the effluent was lower than 0.1 mg 〖NH〗_4^+-N/L at all applied organic loading rates, indicating that there was no inhibition of nitrification by formaldehyde.engFormaldehydeAmmoniumAerobic biodegradationNitrificationActivated sludge reactorjournal articleopen access