The effect of nitrite correction on the evaluation of the rate of nitrate utilization under anoxic conditions

The nitrogen utilization requirement (NUR) test is a useful respirometric p rocedure for the assessment of major kinetic constants in activated sludge systems designed for nitrogen removal. The electron transfer mechanism of n itrogenous compounds often involves significant nitrite accumulation which impairs the accuracy of the NUR test. Experimental results revealed no mean ingful correlation between nitrite accumulation and the initial nitrate con centration or the food/microorganism (F/M) ratio. Significant impact of nit rite accumulation was observed both on the assessment of the readily biodeg radable COD component, the correction factor for anoxic growth and the deni trification rates applicable to domestic sewage and a number of industrial wastewaters. (C) 1999 Society of Chemical Industry.