Start up of an Oxygen-Limited Nitrification Denitrification (OLAND) lab scale rotating biological contactor (RBC)

In this study, the start-up of a lab-scale OLAND RBC was examined. After 221 days of operation, a maximum nitrogen removal rate of 2092 mg N/L.d or 6261 mg N/m.d and a removal efficiency of about 91% were observed. During six operational periods, different supplements were added to the influent and several operational variables were manipulated. The influence of adding hydroxylamine, Dranco compost extract and humic acids (HA) were investigated. The reactor achieved the highest removal rate at a dissolved oxygen (DO) concentration equal to 0.26 ± 0.10 mg O2/L and pH 8.0±0.1 while adding humic acids at 25 mg/L. High nitrite concentrations up to 200 mg N-NO2/L did not cause irreversible inhibition. Successful inhibition of nitrite oxidizing bacteria (NOB) was achieved by hydroxylamine addition at a concentration of 50 – 65 mg N-NH2OH/L in the influent.