Nitrite Oxidation Kinetics for a Better Understanding of the Processes in the CAFOs Effluents Treatment

FLEITE S. N.; CASSANELLO MIRYAN; CHRISTIAN DE LOS SANTOS; ANA R. GRACÍA

RESEARCH JOURNAL OF CHEMISTRY AND ENVIRONMENT

DR JYOTI GARG

Año: 2021

0972-0626

Nitrite is an essential substance in the nitrification process; its oxidation in nature is carried out by the so-callednitrite oxidation bacteria (NOB). Understanding nitrite dynamics in natural waters or manure-contaminated waters(wastewaters) is fundamental to adjust treatment systems used in concentrated animal feeding operations (CAFOs);whose presence in the central region of the Argentine Republic has increased enormously in the last 10 years. Theaims of this work are to study the nitrite oxidation dynamics considering the effects of the DO concentrations andtemperature variations and define a model capable of describing this process. For these purposes, the nitriteoxidation kinetics is characterized, analyzing the effect of relevant factors (i.e., microbial growth, pH, temperatureand DO) under forced aeration (A) and anoxic conditions (NA) at 5, 10 and 20ºC. Results showed marked effectsof the temperature and OD in NOB growth rate and therefore, nitrite oxidation rate. At 20ºC, there weresignificantly higher rates of nitrite oxidation under NA condition than in A condition whereas at 5ºC this relationwas the opposite. This suggests that, at 20°C OD deficiency does not inhibit the growth of NOB, while at lowtemperatures (≤ 10°C), the OD is a conditioning factor for NOB growth. In addition, these results show thatcompetition with other microorganisms strongly depends on temperature and oxygen concentration.