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

Abstract

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 (NH 4 + + NH 3 )-N and with different molar ratios of HCO 3 - : (NH 4 + + NH 3 )-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 (NH 4 ++ NH 3 )-N m -3 d -1 . Under these conditions, the outflow pH was in the range of 5.9-6.5, outflow c (NO 2 - + HNO 2 )-N increased up to 400 mg L -1 and c (NO 3 - )-N dropped below 50 mg L -1 . Undissociated HNO 2 was confirmed as the main inhibitor of NOB.