Intermittent anaerobic-aerobic biopiling for remediating energetic compound-contaminated soils

Demolishing obsolete ammunition and live fire training, along with other military activities, contaminated military sites with energetic compounds (ECs), are raising human concerns. Biopiling is a green and sustainable technology for soil remediation due to its low cost and minimal secondary pollution. This study investigated the effects of various bio-stimulants in enhancing intermittent anaerobic-aerobic biopiling for ECs degradation in soil. The results showed that intermittent anaerobic-aerobic biopiling with municipal sludge, livestock and poultry manure, and agricultural and forestry wastes degraded 93.7 % 2,4,6-trinitrotoluene (TNT), 79.5 % hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and 92.0 % octahydro-1,3,5,7-tetranitro - 1,3,5,7tetrazocine (HMX) in 15 days. Correlation analysis of the energetic compounds showed that the TNT concentration and its reduction products changed conversely under anaerobic conditions, indicating a faster TNT reduction. Analysis based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) database revealed an increase in the abundance of genes (nemA & porA) associated with nitrotoluene reduction. This study demonstrated that bio-stimulants composed of a mixture of municipal sludge, manure, and soil conditioner (SLA) could improve the physicochemical properties of the biopiling system and the microbial community structure, promoting the growth of Firmicutes that respond for the degradation of energetic compounds, including the influence of functional genes for TNT degradation.