Abstract
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.
Original language | English (US) |
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Pages (from-to) | 478-484 |
Number of pages | 7 |
Journal | Chemosphere |
Volume | 167 |
DOIs | |
State | Published - Jan 1 2017 |
Keywords
- 3-Amino-1,2,4-triazol-5-one
- 3-Nitro-1,2,4-triazol-5-one
- Biodegradation
- Insensitive munitions
- Soil
ASJC Scopus subject areas
- Environmental Engineering
- Environmental Chemistry
- General Chemistry
- Pollution
- Public Health, Environmental and Occupational Health
- Health, Toxicology and Mutagenesis