Enhancing remediation of RDX-contaminated soil by introducing microbial formulation technology coupled with biostimulation. Issue 5 (October 2021)

• Record Type: Journal Article
• Authors: Khan, Mohd Aamir; Sharma, Abhishek; Yadav, Sonal; Celin, S. Mary; Sharma, Satyawati; Noureldeen, Ahmed; Darwish, Hadeer
• Is Part Of: Journal of environmental chemical engineering. Volume 9:Issue 5(2021)
• Publication Date: 2021-10
• Subjects: RDX -- Bioaugmentation -- Water-dispersible granules -- Wheat straw -- Biostimulation; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2021.106019
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: The degradation of Hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine (RDX) through bioaugmentation and biostimulation was investigated. Aqueous phase experiment established the potential of Kinneretia asachharophila strain 12853 in invigorating the RDX-degradation. The microbe denitrified 75.7% RDX from the minimal salt medium by utilizing it as a nitrogen source based on nitrite production. High-Performance Liquid Chromatography (HPLC) and Liquid Chromatography-Mass Spectrometry (LCMS) analyses confirmed the presence of methylenedinitramine (MEDINA) and 4-nitro-2, 4-diazabutanal (NDAB) as intermediate metabolites. The microbe formulated into powder and beads showed 29% and 14% loss in viability, respectively, after a storage period of 3 months at 25 °C. The third type of formulation, i.e., water-dispersible granules (WDG), retained 98.52% viability at similar experimental conditions. The microcosm studies revealed a 40% RDX degradation in soil using WDG, while unformulated fresh cultures showed 29% degradation. The process became 1.9–2.4 times more efficient when WDG coupled with stimulants, wheat straw, or sucrose (0.5% w/w). We recorded first-order degradation kinetics with an RDX soil half-life of 16.54–24.15 days. The current study demonstrates the enhanced RDX remediation from the contaminated soil using a robust microbial formulation compatible with wheat straw as an organic stimulant. Graphical Abstract: ga1 Highlights: Kinneretia asachharophila aerobically utilized RDX as a nitrogen source in the aqueous phase. Methylenedinitramine and 4-nitro-2, 4-diazabutanal were detected as RDX intermediate metabolites. K. asachharophila formulated into beads, powder, and water-dispersible granules (WDG). 1.9 times enhanced RDX degradation achieved through combined use of WDGs and wheat-straw in soil.