Advanced In Situ Chemical Oxidation with ZVI Activation
Technology Overview
Zero Valent Iron (ZVI) Catalyzed Oxidation is an innovative in-situ chemical oxidation (ISCO) technology that uses zero-valent iron metal (2-4 microns in size) to activate both persulfate and peroxide species in-situ. This unique approach combines free radical chemistry, direct oxidation chemistry, and facultative biological oxidation to extend oxidant and free radical residuals while creating an environment suitable for biologically-based attenuation.
This technology is particularly effective for treating benzene, toluene, ethylbenzene, and xylenes (BTEX) contamination in soil and groundwater. The process utilizes a patented injection method (US Patent #7,044,152) that delivers materials in a controlled manner to achieve optimal in-situ activation.
Oxidation Reactions
The technology leverages multiple oxidation pathways:
H₂O₂ + Fe⁰ → Fe⁺³ + OH⁻ + OH•
Fe⁺³ + H₂O₂ → Fe⁺² + H⁺ + HO₂•
S₂O₈²⁻ + Fe⁰ → Fe⁺³ + SO₄⁻ + SO₄⁻•
Plus direct oxidation from persulfate and peroxide
Secondary Attenuation Process
The technology provides a unique two-phase approach combining oxidation with enhanced bioremediation:
1) Sulfate Residual Enhancement
After dissolved oxygen depletion, sulfate from persulfate decomposition serves as an electron acceptor for anaerobic biodegradation. Stoichiometrically, each 1.0 mg/L of sulfate consumed results in approximately 0.21 mg/L of BTEX destruction.
2) Ferric Iron Utilization
Ferric iron serves as an electron acceptor during anaerobic biodegradation. The degradation of 1 mg/L of BTEX results in approximately 21.8 mg/L of ferrous iron production, which can be monitored as an indicator of anaerobic activity.
3) Enhanced Long-Term Treatment
The first phase (oxidation) addresses the majority of dissolved and sorbed compounds, while the second phase (biological attenuation) provides polishing and maintains treatment goals over time.
Technology Advantages
Advanced Activation
Evolution of free radicals offers higher oxidation capabilities and broader spectrum of target compounds
Extended Residual Activity
Combines immediate oxidation with long-term biological enhancement
Dual Mechanism
Treats contaminants through both chemical oxidation and biological processes
Controlled Application
Patented injection process ensures controlled in-situ activation
Rebound Prevention
Biological component helps prevent concentration rebound commonly seen with oxidation-only approaches
Target Contaminants
This technology is highly effective for treating:
- •Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX)
- •Petroleum hydrocarbons
- •MTBE and other fuel additives
- •Naphthalene and related compounds
Featured Case Study
See how Zero Valent Iron Catalyzed Oxidation achieved an 81.5% reduction in total BTEX concentrations at a petroleum-impacted site in St. Augustine, Florida.
Interested in applying Zero Valent Iron Catalyzed Oxidation to your site?