Sequencing batch reactor for biotransformation of 2,4-dinitroanisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO)

Defense agencies are increasingly using insensitive munitions (IMs) in place of traditional explosives such as trinitrotoluene. In this study biotransformation of the IM formulation constituents 2,4-dinitroanisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO) were evaluated in oxic and anoxic sequencing batch reactors (SBRs). The oxic SBRs were fed minima media supplemented with 20.5 +/- 5.9 mg/L DNAN (average +/- standard deviation) and 9.5 +/- 6.6 mg/L NTO as the nitrogen source. The oxic SBRs were supplemented with 10% LB media during 4 cycles. The oxic SBR was operated over 6 months and 26 cycles. Between 52+/- 17 and 42+/-19 % of DNAN and NTO respectively were removed in the oxic SBR. However when LB media was also present in the reactor DNAN and NTO removal increased to 79 +/- 11 and 53 +/- 27 %, respectively. In total 52 +/- 26 percent of COD was degraded in the oxic SBR. The anoxic SBR was operated over 3 months and 12 cycles. The anoxic SBR was fed LB media supplemented with 18 +/- 6 mg/L DNAN and 11 +/- 4 mg/L NTO. Both DNAN and NTO were completely transformed in the anaerobic reactors within 4 hours to 2 days, respectively. In the anoxic SBR, an average of 35 +/- 15 % of COD was degraded during operation. Degradation products monitored in both reactors included nitrate, dinitrophenol and 5-amino-1,2,4-triazol-3-one. Metatranscriptomics was conducted on the anoxic SBR to identify genes upregulated during DNAN and NTO degradation compared to degradation of LB media.