The relative influence of influent ammonium concentration, pH, temperature, filter height and liquid and gas superficial velocities over the biofilm growth and activity in submerged nitrification biofilters has been experimentally studied. The goal is to quantify the relative contributions of the different control parameters over the biofilm growth and the specific activity of ammonia and nitrite oxidizer microorganisms.

The use of statistical tools like the experimental design methods, allows to characterize quantitatively the control parameters of the system and the levels providing the most favorable response of the system, in such a way that the noise factor influence is minimized. The experimental period is reduced eight times comparing to the traditional study of parameters influence.