Alternative processes of nitrogen removal from wastewater — startup of nitritation reactor

Efficient nitritation was tested in SBR with the aim to accumulate nitrites and to minimize nitrates production in reject wastewater with 500 mg L^-1 (NH₄⁺+ NH₃)-N and with different molar ratios of HCO₃^-: (NH₄⁺+ NH₃)-N (1.1-2.1). More than 80 % efficiency of nitritation and permanent inhibition of NOB were achieved at the ratios of 1.71.9 and at the loading of 0.16-0.6 kg (NH₄⁺⁺ NH₃)-N m^-3 d^-1. Under these conditions, the outflow pH was in the range of 5.9-6.5, outflow c (NO₂^- + HNO₂)-N increased up to 400 mg L^-1 and c (NO₃^-)-N dropped below 50 mg L^-1. Undissociated HNO₂ was confirmed as the main inhibitor of NOB.