TY - JOUR
T1 - Nitrate and nitrite inhibition of methanogenesis during denitrification in granular biofilms and digested domestic sludges
AU - Banihani, Qais
AU - Sierra-Alvarez, Reyes
AU - Field, James A.
N1 - Funding Information:
Acknowledgments This research was supported in part by grants of the University of Arizona Water Sustainability Program (TRIF-WSP) and from the International Arid Lands Consortium (IALC award # 06R-02).
PY - 2009/10
Y1 - 2009/10
N2 - Anaerobic bioreactors that can support simultaneous microbial processes of denitrification and methanogenesis are of interest to nutrient nitrogen removal. However, an important concern is the potential toxicity of nitrate (NO3-) and nitrite (NO2-) to methanogenesis. The methanogenic toxicity of the NOx- compounds to anaerobic granular biofilms and municipal anaerobic digested sludge with two types of substrates, acetate and hydrogen, was studied. The inhibition was the severest when the NOx- compounds were still present in the media (exposure period). During this period, 95% or greater inhibition of methanogenesis was evident at the lowest concentrations of added NO2- tested (7.6-10.2 mg NO2--N l-1) or 8.3-121 mg NO3--N l-1 of added NO3-, depending on substrate and inoculum source. The inhibition imparted by NO3- was not due directly to NO3- itself, but instead due to reduced intermediates (e.g., NO2-) formed during the denitrification process. The toxicity of NOx- was found to be reversible after the exposure period. The recovery of activity was nearly complete at low added NOx- concentrations; whereas the recovery was only partial at high added NOx- concentrations. The recovery is attributed to the metabolism of the NOx- compounds. The assay substrate had a large impact on the rate of NO2- metabolism. Hydrogen reduced NO2- slowly such that NO2- accumulated more and as a result, the toxicity was greater compared to acetate as a substrate. The final methane yield was inversely proportional to the amount of NOx- compounds added indicating that they were the preferred electron acceptors compared to methanogenesis.
AB - Anaerobic bioreactors that can support simultaneous microbial processes of denitrification and methanogenesis are of interest to nutrient nitrogen removal. However, an important concern is the potential toxicity of nitrate (NO3-) and nitrite (NO2-) to methanogenesis. The methanogenic toxicity of the NOx- compounds to anaerobic granular biofilms and municipal anaerobic digested sludge with two types of substrates, acetate and hydrogen, was studied. The inhibition was the severest when the NOx- compounds were still present in the media (exposure period). During this period, 95% or greater inhibition of methanogenesis was evident at the lowest concentrations of added NO2- tested (7.6-10.2 mg NO2--N l-1) or 8.3-121 mg NO3--N l-1 of added NO3-, depending on substrate and inoculum source. The inhibition imparted by NO3- was not due directly to NO3- itself, but instead due to reduced intermediates (e.g., NO2-) formed during the denitrification process. The toxicity of NOx- was found to be reversible after the exposure period. The recovery of activity was nearly complete at low added NOx- concentrations; whereas the recovery was only partial at high added NOx- concentrations. The recovery is attributed to the metabolism of the NOx- compounds. The assay substrate had a large impact on the rate of NO2- metabolism. Hydrogen reduced NO2- slowly such that NO2- accumulated more and as a result, the toxicity was greater compared to acetate as a substrate. The final methane yield was inversely proportional to the amount of NOx- compounds added indicating that they were the preferred electron acceptors compared to methanogenesis.
KW - Biological nutrient removal
KW - Denitrification
KW - Dissimilatory nitrate reduction to ammonium (DNRA)
KW - Methanogenic inhibition
KW - Upflow anaerobic sludge blanket (UASB)
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U2 - 10.1007/s10532-009-9268-9
DO - 10.1007/s10532-009-9268-9
M3 - Article
C2 - 19449209
AN - SCOPUS:70350268387
SN - 0923-9820
VL - 20
SP - 801
EP - 812
JO - Biodegradation
JF - Biodegradation
IS - 6
ER -