Biodegradation of the emerging contaminant 3-nitro-1,2,4-triazol-5-one and its product 3-amino-1,2,4-triazol-5-one in perlite/soil columns

Erika E Rios-Valenciana; Osmar Menezes; Corey Blubaum; Jonathan Romero; Mark J Krzmarzick; Reyes Sierra-Alvarez; Jim A Field

doi:10.1016/j.chemosphere.2023.139121

Biodegradation of the emerging contaminant 3-nitro-1,2,4-triazol-5-one and its product 3-amino-1,2,4-triazol-5-one in perlite/soil columns

Chemosphere. 2023 Sep:335:139121. doi: 10.1016/j.chemosphere.2023.139121. Epub 2023 Jun 2.

Authors

Erika E Rios-Valenciana¹, Osmar Menezes¹, Corey Blubaum¹, Jonathan Romero¹, Mark J Krzmarzick², Reyes Sierra-Alvarez¹, Jim A Field³

Affiliations

¹ Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, P.O. Box 210011, AZ, 85721, USA.
² School of Civil and Environmental Engineering, Oklahoma State University, Stillwater, OK, 74078, USA.
³ Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, P.O. Box 210011, AZ, 85721, USA. Electronic address: jimfield@arizona.edu.

PMID: 37271465
DOI: 10.1016/j.chemosphere.2023.139121

Abstract

3-Nitro-1,2,4-triazol-5-one (NTO) is an ingredient of new safer-to-handle military insensitive munitions formulations. NTO can be microbially reduced to 3-amino-1,2,4-triazol-5-one (ATO) under anaerobic conditions if an electron donor is available. Conversely, ATO can undergo aerobic biodegradation. Previously, our research group developed an anaerobic enrichment culture that reduces NTO to ATO. A second culture could aerobically mineralize ATO. This study aimed to combine anaerobic/aerobic conditions within a down-flow perlite/soil column for simultaneous NTO reduction and ATO oxidation. Acetate biostimulation was investigated to promote oxygen depletion and create anaerobic micro-niches for NTO reduction, whereas perlite increased soil porosity and oxygen convection, allowing ATO oxidation. Two columns packed with a perlite/soil mixture (70:30, wet wt.%) or 100% perlite were operated aerobically and inoculated with the NTO- and ATO-degrading cultures. Initially, the influent consisted of ∼280 μM ATO, and after 30 days, the feeding was switched to ∼260 μM NTO and ∼250 μM acetate. By progressively increasing acetate from 250 to 4000 μM, the NTO removal gradually improved in both columns. The perlite/soil column reached a 100% NTO removal after 4000 μM acetate was supplemented. Additionally, there was no ATO accumulation, and inorganic nitrogen was produced, indicating ATO mineralization. Although NH₄⁺ was produced following ATO oxidation, most nitrogen was recovered as NO₃^- likely via nitrification reactions. Microbial community analysis revealed that phylotypes hosted in the enrichment cultures specialized in NTO reduction (e.g., Geobacter) and ATO oxidation (e.g., Hydrogenophaga, Ramlibacter, Terrimonas, and Pseudomonas) were established in the columns. Besides, the predominant genera (Azohydromonas, Zoogloea, and Azospirillum) are linked to nitrogen cycling by performing nitrogen fixation, NO₃^- reduction, and nitroaromatics degradation. This study applied a bulking agent (perlite) and acetate biostimulation to achieve simultaneous NTO reduction and ATO oxidation in a single column. Such a strategy can assist with real-world applications of NTO and ATO biodegradation mechanisms.

Keywords: ATO; Aromatic amine; Bioremediation; Insensitive munitions compound; NTO; Nitroaromatic compound.

MeSH terms

Biodegradation, Environmental
Nitro Compounds* / metabolism
Nitrogen / metabolism
Soil*

Substances

3-nitro-1,2,4-triazol-5-one
Perlite
Soil
Nitro Compounds
Nitrogen