Nitrogenated compounds' biofiltration under alternative bacterium fixation substrates

This study compares the behavior of nitrification (NH₄⁺, NO₂^- and NO₃^-), and performance, in terms of the surface TAN conversion rate (STR), volumetric TAN conversion rate (VTR) and removal percentage of TAN (PTR) among three fixation media of nitrifying bacteria (two alternatives (S₁, S₂) and one commercial (C_o)). The experiment was performed in two tests of 42 days each. Three isolated biofiltration systems were built for the experience, to which were added media colonized by bacteria as a "seed" to start the process of nitrification. Ammonium chloride (NH₄Cl) was attached as source of ammonium in reconditioned freshwater, also gradually adding inorganic carbon (HCO₃^-) to maintain moderate water hardness. The average results for both tests indicate that the substrates S₁ and S₂ show a statistically similar behavior to the substrate C_o (P > 0.05) during the first 33 days (until steady state). For the second test in terms of performance, STR values were 0.40, 0.39, 0.39 g TAN m^-2 d^-1 recorded for S₁, S₂ and Co, respectively; in terms of PRN, values were 92, 97 and 93% for S₁, S₂ and Co, respectively. Regarding VTR, values of 72.31, 114.94, and 39.02 gTAN m^-3 d^-1 were recorded for S₁, S₂ and C_o, respectively. Statistical analysis provided that for STR and PRN, no significant differences, were found. But for VTR, statistically significant differences between means were evaluated, registering for the S2 media the highest value of VTR.