Simultaneous nitrification and denitrification in a moving bed hybrid bioreactor

Laboratory scale experiment was conducted in a moving bed hybrid bioreactor (MBHBR) under batch mode for removal of nitrogen from ammonium rich synthetic wastewater via nitrification. It was observed from experimental data that even in absence of organic carbon in the aerated completely mixed reactor, denitrification took place simultaneously with nitrification. It may be hypothesized that thick biofilms provided necessary conditions for denitrification in deeper regions, where byproducts of nitrification occurring at the outer layer of biofilm served as the substrates of denitrification. The study was conducted on varying ammonium nitrogen concentration between 500 mg/ L to 1000 mg/L. Maximum removal of ammonium nitrogen was observed to be 89%, corresponding to which nitrate and nitrite concentration produced as a result of nitrification was found to decrease by 69 and 82% thus confirming simultaneous nitrification and denitrification in MBHBR.