Salt inhibition kinetics in nitrification of synthetic saline wastewater

Nitrification kinetics of synthetic saline wastewater was investigated by using an activated sludge unit. Initial experiments were performed with salt-free wastewater to obtain baseline information. Experiments with 3% salt concentration were performed at different sludge ages in order to investigate the system performance and salt inhibition effects on kinetic constants. Minimum sludge age required for complete nitrification increased from 12 days for salt-free wastewater to 25 days for 3% salt content. Salt inhibition was non-competitive type affecting both the maximum rate and the saturation constants. Inhibition constants were determined by using the experimental data as KT1 = 200 g/liter and KT2 = 7.4 g/liter. Further experiments were performed with salt concentrations between 0–5% to quantify variation of the rate and extent of COD removal with salt concentration. The rate and extent of nitrification decreased approximately 20% with 5% salt as compared to salt-free wastewater.