Degradation mechanisms of DDX induced by the addition of toluene and glycerol as cosubstrates in a zero-valent iron pretreated soil

• Published in: Journal of hazardous materials Vol. 321; pp. 681 - 689
• Main Authors: Velasco, Antonio, Aburto-Medina, Arturo, Shahsavari, Esmaeil, Revah, Sergio, Ortiz, Irmene
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05-01-2017
• Subjects: Bacteria; Biostimulation; Cosubstrates; DDT; Degradation; Glycerols; Iron; Rhodococcus ruber; Soil contamination; Soil improvement; Soil remediation; Toluene; Zero-valent iron; Biostimulation; Soil remediation; Cosubstrates; DDT; Zero-valent iron
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2016.09.047

[Display omitted]
•Biostimulation by cosubstrates addition enhanced the DDX degradation in soil.•Glycerol induced anoxic sulfidogenic process mediated by sulfate- reducing bacteria.•Toluene induced biotic degradation of DDX mediated by oxygenases as initial step.•Microbial community changes were observed after aerobic and anoxic treatments.
Abiotic and biotic processes can be used to remediate DDX (DDT, DDD, DDE, and DDNS) contaminated soils; these processes can be fostered using specific carbon-amendments to stimulate particular soil indigenous microbial communities to improve rates or extent of degradation. In this study, toluene and glycerol were evaluated as cosubstrates under aerobic and anoxic conditions to determine the degradation efficiencies of DDX and to elucidate possible degradation mechanisms. Slurry microcosms experiments were performed during 60 days using pretreated soil with zero-valent iron (ZVI). Toluene addition enhanced the percentage of degradation of DDX. DDNS was the main compound degraded (around 86%) under aerobic conditions, suggesting cometabolic degradation of DDX by toluene-degrading soil bacteria. Glycerol addition under anoxic conditions favored the abiotic degradation of DDX mediated by sulfate-reducing bacteria activity, where DDT was the main compound degraded (around 90%). The 16S rDNA metagenomic analyses revealed Rhodococcus ruber and Desulfosporosinus auripigmenti as the predominant bacterial species after 40 days of treatment with toluene and glycerol additions, respectively. This study provides evidence of biotic and abiotic DDX degradation by the addition of toluene and glycerol as cosubstrates in ZVI pretreated DDX-contaminated soil.