TranslateZero Valent Iron Activated Oxidation
St. Augustine, Florida - BTEX Treatment Using ZVI-Catalyzed Persulfate and Peroxide
Location
St. Augustine (Northern Florida)
Project Date
April 2008
Technology
ZVI Catalyzed ISCO
IET performed a series of in-situ oxidation injections and remediation pits at a petroleum-contaminated site in northern Florida. The site was impacted by benzene, toluene, ethylbenzene, and xylenes (BTEX) in both soil and groundwater.
Field observations during excavation revealed dark, unconsolidated sand from the surface to approximately 10-12 feet below grade. Below this layer, a light cream silty clay layer was encountered, which contained the majority of entrained petroleum odors and contamination.
Benzene
Toluene
Ethylbenzene
Xylenes (BTEX)
Additional compounds detected: MTBE and Naphthalene
IET applied a unique application of zero-valent iron metal (2-4 microns in size) to activate both persulfate and peroxide species in-situ, effecting oxidation and biological remedial processes in a single injection event. The materials were delivered via:
- Patented injection process and apparatus (US Patent #7,044,152)
- Remediation pits (5'x5' excavations reaching approximately 12 feet below grade)
- Treatment focused around monitoring wells MW-2, MW-3, and DW-2
Two-Phase Approach: Phase 1 (oxidation) addresses the majority of dissolved and sorbed compounds. Phase 2 (biological attenuation) polishes and maintains treatment goals through enhanced bioremediation.
81.5% Reduction
Total BTEX concentrations at directly affected wells (4 months post-treatment)
MW-1 (Downgradient)
- • Benzene: 94.8% reduction
- • Ethylbenzene: 99.3% reduction
- • Total Xylenes: 80% reduction
- • Total BTEX: 95.6% reduction
MW-2 (Treatment Area)
- • Benzene: 75.7% reduction
- • Total Xylenes: 82.4% reduction
- • Naphthalene: 64.9% reduction
- • Total BTEX: 79.8% reduction
MW-3 (Treatment Area)
- • Benzene: 98% reduction
- • Ethylbenzene: 99.7% reduction
- • Total BTEX: 98.8% reduction
- • Most compounds below detection
DW-2 (Treatment Area)
- • Benzene: 26.8% reduction
- • Ethylbenzene: 82.5% reduction
- • MTBE: 46.3% reduction
- • Transitioning to biological processes
Note: The disappearance of toluene across all wells indicates excellent biological activity, with additional reductions expected to continue. After initial rebound in May 2008, total BTEX decreased by 86.9% by August 2008.
- Active oxidation processes continued in MW-1 and MW-2, with ongoing contaminant reduction
- Oxidation trailed off in MW-3 as transition to biological processes began
- DW-2 fully transitioned to biological attenuation phase, demonstrating the technology's dual-mechanism approach
- Concentration trends followed typical IET oxidation injection programs, with initial increases followed by dramatic reductions
- Indirectly affected wells (MW-4, MW-6, MW-7) also showed significant improvements, with most compounds below detection limits
