Nitrite effect on ammonium and nitrite oxidizing processes in a nitrifying sludge

Abstract

Nitrite accumulation can be undesirable in nitrifying reactors used for the biological elimination of nitrogen from wastewaters because the ammonium oxidation process was seen to be inhibited. There is a need to better understand the effects of nitrite on both ammonium and nitrite oxidizing processes. In this paper, the effect of nitrite on the nitrifying activity of a sludge produced in steady-state nitrification was evaluated in batch cultures. At 25 mg N/l of added nitrite, nitrification was successfully carried out. Addition of higher nitrite concentrations to nitrifying cultures (100 and 200 mg N/l) provoked inhibitory effects on the nitrification respiratory process. Nitrite at 100 and 200 mg N/l induced a significant decrease in the values for nitrate yield (-20% and -34%, respectively) and specific rate of nitrate formation (-26% and -67%, respectively), while the ammonium consumption efficiency kept high and the specific rate of ammonium oxidation did not significantly change. This showed that the nitrite oxidizing process was more sensitive to the presence of nitrite than the ammonium oxidizing process. These results showed that as a consequence of nitrite accumulation in nitrification systems, the activity of the nitrite oxidizing bacteria could be more inhibited than that of the ammonium oxidizing bacteria, provoking a higher accumulation of nitrite in the medium.

Anaerobic Processes

“…Toxicity from phosphorusprecipitation spectator ions, heavy metals, and cyanide against anammox was reported. Silva et al (2011a) studied the effect of nitrite on batch sludge cultures. High nitrite concentrations inhibited nitrite-oxidizing processes more than ammonium-oxidizing processes.…”

Simultaneous Elimination of Carbon and Nitrogen Compounds of Petrochemical Effluents by Nitrification and Denitrification

“…Nitrous acid is known to inhibit nitrification, thus, low pH values must be avoided in nitrifying processes (Anthonisen et al, 1976;Vadivelu et al, 2006aVadivelu et al, , 2006b. Recently, Silva et al (2011) reported that the nitrite-oxidizing process was more sensitive to the presence of nitrite than the ammonium-oxidizing process, suggesting that nitrite accumulation in nitrification systems should be controlled to avoid a higher accumulation of nitrite and a decrease in nitrate yield. In consequence, pH value is generally controlled in nitrifying systems and maintained between 7.5 and 8.0 to avoid operational problems.…”

“…In the last decades, several nitrifying consortia have been reported to oxidize simultaneously ammonium and various recalcitrant aromatic compounds, such as phenolic compounds (phenol, 2-chlorophenol, p-cresol, p-hydroxybenzaldehyde) (Amor et al, 2005;Martínez-Hernández et al, 2011;Silva et al, 2009Silva et al, , 2011Vázquez et al, 2006;Yamaghisi et al, 2001) and BTX compounds (Zepeda et al, 2003(Zepeda et al, , 2006(Zepeda et al, , 2007. In some cases, nitrate and carbon dioxide were the major products from the process.…”

“…In some cases, nitrate and carbon dioxide were the major products from the process. As a consequence, nitrifying processes have been recently proposed as novel alternative technologies for the simultaneous removal of ammonium and aromatic pollutants from industrial wastewaters of chemical complexity such as effluents generated by the petrochemical industry (BeristainCardoso et al, 2011, Silva et al, 2011. Nitrification as the initial step in the removal of ammonia from wastewaters might be also used to oxidize simultaneously ammonia and aromatic compounds, allowing their mineralization or the production of intermediates that can be totally oxidized by denitrification (Beristain-Cardoso et al, 2009).…”

Nitratation Promotion Process for Reducing Nitrogen Losses by N2O/NO Emissions in the Composting of Livestock Manure

“…Generally, NO 2 -is scarcely observed in the natural environment because nitrite oxidizers, such as Nitrobacter and Nitrospira, oxidize NO 2 -to NO 3 -immediately. However, it is also a fact that NO 2 -accumulation is observed under several environmental conditions (Burns et al 1996;Corriveau et al 2010;Silva et al 2011). In swine manure composting, notable N 2 O emission begins after the thermophilic phase, because nitrifying bacteria cannot be active under thermophilic conditions, such as high temperature, high free ammonia and high organic matter content.…”