BIOKINETICS OF NITRIFICATION IN THE ACTIVATED-SLUDGE PROCESS WITH BIOAUGMENTATION

A laboratory study was conducted to determine the effect of bioaugmentation on nitrification performance in activated sludge process for treating municipal wastewaters. Two continuous flow bench-scale activated sludge systems consisting of 3 reactors each were operated for 30 months. The bacterial culture product used in bioaugmentation contained supplementary heterotrophic and nitrifying microorganisms. Parameters investigated included wastewater strength, hydraulic detention time, and sludge age in an activated sludge reactor system, which were low, medium and high strength; 6, 12, and 24 hours detention time; and 5, 10, and 20 days sludge age. A first reaction order mathematical model was developed for the nitrification process. Statistical fitting of the experimental data to the mathematical model allowed for determination of nitrification rate constant, decay coefficients, minimum aeration time required for initiation of the nitrification process, and the ability of the system to perform nitrification for the applied operation conditions. The results indicated that bioaugmentation improved nitrification at higher influent strength and at longer sludge age, did initiate nitrification earlier in the reactors, and did not affect the nitrification rate nor the decay coefficients.