Denitrifying kinetics involving the distributed ratio of reductases

A suspended-growth batch reactor was used to denitrify synthetic wastewater containing various proportions of nitrate and nitrite. A competitive phenomenon between nitrate- and nitrite-reductase was studied utilizing various proportions of nitrate and nitrite in an anaerobic environment with a temperature of 30°C and methanol as carbon source. By using a non-linear regression technique, biokinetic constants of the maximum specific reduction rates of nitrate and nitrite (k₁, k₂) and the Monod half-saturation coefficients of nitrate and nitrite (K_s1, K_s2) for the proposed two-step denitrifying kinetics were 1·29 day^?1, 0·89 day^?1 and 14·3 mg NO-N dm^?3, 10.9 mg NO-N dm^?3, respectively. The result obtained from a series of chemostat studies indicated the Monod-type kinetic model was more accurate when the distributed ratio of nitrate- and nitrite-reductase in the proposed two-step denitrifying kinetics was taken into account.