Anaerobic sequencing batch reactor for concurrent removal of multiple recalcitrant munition compounds

Abstract

Large-scale production, use, and disposal of munitions has resulted in widespread environmental contamination. A laboratory-scale anaerobic sequencing batch reactor (AnSBR) was initiated in this study to investigate the concurrent removal of multiple energetic compounds that comprise modern munition formulations. The AnSBR achieved high removal efficiencies of 2,4-dinitroanisole (DNAN, >99%) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX, 84 ± 16%), along with the partial removal of 1-nitroguanidine (NQ, 30 ± 27%). Specific DNAN, RDX, and NQ removal rates of 17.0 ± 0.1 µmol DNAN/g VSS/d, 22.0 ± 0.8 µmol RDX/g VSS/d, and 2.0 ± 0.3 µmol NQ/g VSS/d were recorded in the AnSBR under steady-state conditions, respectively. Long-term operation of the AnSBR selected Actinobacteria (2 – 58%) and uncultured Actinomycetaceae (1 – 58%) as the most abundant phylum and genus, respectively. Results from this study provide valuable insights into the development of anaerobic bioreactors for the remediation of sites impacted by modern munitions.