An investigation of the effects of residence time on anaerobic bacterial denitrification

To obtain data for comparison of anaerobic bacterial denitrification and other methods of nitrate removal, experiments were carried out on the effect of detention period on cell yields and rates in anaerobic bacterial denitrification, using a continuous flow stirred-tank reactor without recirculation. The composition of the influent was similar to that expected for irrigation drainage water in the San Joaquin valley, and methanol was used as the supplementary carbon source, It was found that bacterial physiology is important in bacterial denitrification, and this is affected by feed rate and feed composition. Optimal operating conditions exist for this process, and with the simulated irrigation drainage water used these required a 6-day detention period and complete mixing to prevent short-circuiting. There was no evidence in these experiments of build-up of nitrite.