Written by Provectus Environmental Products

Beginning in June 2023, Provectus and AECOM launched a field pilot deployment of the Provect-EBR® technology. The goal of this two-phase pilot program was to demonstrate that the Provect-EBR system could effectively eliminate elevated benzene contamination in challenging, low-permeability, dense clay soils. The Provect-EBR system is a unique, patented, and leading-edge technology that continuously generates highly reactive oxidative molecules throughout the designed treatment zone.

The Provect-EBR® system accomplishes treatment without the need for injection of any solid or liquid chemical component. The technology utilizes fuel cell concepts to liberate elemental oxygen from site groundwater, which is then reduced on the cathodic surface of reactors to create hydrogen peroxide. The system simultaneously provides a continuous source of ferrous iron (Fe2+) to propagate the redox reactions and facilitate the creation of various reactive oxygen species such as hydroperoxyl (HO2∙), superoxide (O2∙), and hydroxyl radicals (OH∙). Leveraging system-specified thermodynamic properties and reaction chemistries, these reactive oxygen species are continuously regenerated by propagating reaction fronts throughout the designed radius of influence at each system deployment location.

The Provect-EBR pilot operation was separated into two phases at the project site that included unfractured and hydraulically fractured tight, dense clay soils. Benzene contamination at the site in the unfractured area averaged between 480,000 ug/L to 640,000 ug/L in groundwater. Contaminant concentrations in the fractured area averaged between 260,000 ug/L to 460,000 ug/L in groundwater. The project design was to operate the system for three months in each of the test areas.

Groundwater samples were taken weekly to monitor groundwater geochemistry as well as evaluate contaminant concentrations at both on-site and third-party testing facilities. At the conclusion of the pilot, soil samples were taken at various points in each test area to determine impacts on sorbed phase contaminant levels. The goal of the pilot test was to prove the system’s effectiveness in reducing both aqueous and sorbed benzene mass concentrations.

Phase 1 operations in the unfractured area showed radial influence from operating points of up to 15 feet in the 90 days of system operations. Aqueous phase contamination in the Phase 1 area showed greater than 90% reduction in the system wells and greater than 75% in the site monitoring and piezometer test wells. Sorbed phase concentrations showed between 20% to 40% reductions at sampling 60 days following completion of Phase 1 operations.

Phase 2 operations were performed in an area previously hydraulically fractured for the potential implementation of a site soil vapor extraction (SVE) system. Previous tests showed limited effectiveness of the SVE system, and further use was abandoned. The Provect-EBR system operated in this area for 90 days as well with similar sampling and testing protocols in place.

The system demonstrated significant in situ benzene destruction with a greater than 90% reduction in groundwater concentrations. Radial impact distance during operation was documented as 15 to 20 feet from each of the reactor positions based on subsurface geochemistry changes.

The piezometer test wells, which were spaced at four to five-foot intervals from a particular reactor well, showed reductions of 95% to 99% in groundwater concentrations. Soil testing in the Phase 2 area demonstrated soil concentration reductions up to 40% near the monitoring wells and between 45% to 85% near the system wells, which proved the system was effective but would require extended operation time beyond the 90-day pilot test.