Simultaneous nitrification‐denitrification in a rotating biological contactor

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Abstract
Simultaneous nitrification\aerobic denitrification studies of a high strength synthetic nitrogenous fertilizer wastewater in a single stage were carried out using a rotating biological contactor (RBC). Mixed culture biofilm consisting of Nitrifiers and Thiosphaera pantotropha (a heterotrophic nitrifier and aerobic denitrifier) was acclimated to 1386 mg l‐1 of TKN & 400 mg l‐1 of nitrate nitrogen. The effect of different nitrogen loadings and hydraulic retention times (HRTs) on percentage removal of TKN and nitrate nitrogen simultaneously, was investigated. A maximum TKN removal of 95.6 percent could be achieved at a nitrogen loading of 9.36 gN m‐2 d‐1 and HRT of 2 days. The results showed that the process is zero order with respect to nitrogen removal. The HRT studied were in the range of 0.5–3 days. The corresponding percentage TKN removal ranged from 43.9–93.7. Nitrate removal of 97–98% could also be achieved simultaneously. Nitrite accumulated significantly throughout these studies. Nitrogen loading and hydraulic retention time were found to be important process control parameters. A theoretical estimation of Nitrifiers and T. pantotropha was also carried out based on nitrification and denitrification rates observed during these studies.