TY - JOUR
T1 - Sequential anaerobic-aerobic biodegradation of emerging insensitive munitions compound 3-nitro-1,2,4-triazol-5-one (NTO)
AU - Madeira, Camila L.
AU - Speet, Samuel A.
AU - Nieto, Cristina A.
AU - Abrell, Leif
AU - Chorover, Jon
AU - Sierra-Alvarez, Reyes
AU - Field, Jim A.
N1 - Funding Information:
This study was supported by the Strategic Environmental Research and Development Program (SERDP project ER-2221 ). C. L. Madeira acknowledges the financial support from CAPES Foundation, Ministry of Education, Brazil , under grant 88888.075208/2013-00 , and the training core provided by University of Arizona NIEHS Superfund Research Program ( P42 ES04940 ). We acknowledge Raju Khatiwada for his help with the soil analysis, Guangbin Li for his help with the denitrification assay, and Stephan M. Cameron for the soil used in this study.
Publisher Copyright:
© 2016 Elsevier Ltd
PY - 2017/1/1
Y1 - 2017/1/1
N2 - Insensitive munitions, such as 3-nitro-1,2,4-triazol-5-one (NTO), are being considered by the U.S. Army as replacements for conventional explosives. Environmental emissions of NTO are expected to increase as its use becomes widespread; but only a few studies have considered the remediation of NTO-contaminated sites. In this study, sequential anaerobic-aerobic biodegradation of NTO was investigated in bioreactors using soil as inoculum. Batch bioassays confirmed microbial reduction of NTO under anaerobic conditions to 3-amino-1,2,4-triazol-5-one (ATO) using pyruvate as electron-donating cosubstrate. However, ATO biodegradation was only observed after the redox condition was switched to aerobic. This study also demonstrated that the high-rate removal of NTO in contaminated water can be attained in a continuous-flow aerated bioreactor. The reactor was first fed ATO as sole energy and nitrogen source prior to NTO addition. After few days, ATO was removed in a sustained fashion by 100%. When NTO was introduced together with electron-donor (pyruvate), NTO degradation increased progressively, reaching a removal efficiency of 93.5%. Mineralization of NTO was evidenced by the partial release of inorganic nitrogen species in the effluent, and lack of ATO accumulation. A plausible hypothesis for these findings is that NTO reduction occurred in anaerobic zones of the biofilm whereas ATO was mineralized in the bulk aerobic zones of the reactor.
AB - Insensitive munitions, such as 3-nitro-1,2,4-triazol-5-one (NTO), are being considered by the U.S. Army as replacements for conventional explosives. Environmental emissions of NTO are expected to increase as its use becomes widespread; but only a few studies have considered the remediation of NTO-contaminated sites. In this study, sequential anaerobic-aerobic biodegradation of NTO was investigated in bioreactors using soil as inoculum. Batch bioassays confirmed microbial reduction of NTO under anaerobic conditions to 3-amino-1,2,4-triazol-5-one (ATO) using pyruvate as electron-donating cosubstrate. However, ATO biodegradation was only observed after the redox condition was switched to aerobic. This study also demonstrated that the high-rate removal of NTO in contaminated water can be attained in a continuous-flow aerated bioreactor. The reactor was first fed ATO as sole energy and nitrogen source prior to NTO addition. After few days, ATO was removed in a sustained fashion by 100%. When NTO was introduced together with electron-donor (pyruvate), NTO degradation increased progressively, reaching a removal efficiency of 93.5%. Mineralization of NTO was evidenced by the partial release of inorganic nitrogen species in the effluent, and lack of ATO accumulation. A plausible hypothesis for these findings is that NTO reduction occurred in anaerobic zones of the biofilm whereas ATO was mineralized in the bulk aerobic zones of the reactor.
KW - 3-Amino-1,2,4-triazol-5-one
KW - 3-Nitro-1,2,4-triazol-5-one
KW - Biodegradation
KW - Insensitive munitions
KW - Soil
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U2 - 10.1016/j.chemosphere.2016.10.032
DO - 10.1016/j.chemosphere.2016.10.032
M3 - Article
C2 - 27750172
AN - SCOPUS:84992062737
SN - 0045-6535
VL - 167
SP - 478
EP - 484
JO - Chemosphere
JF - Chemosphere
ER -