Case Study: In situ hydrocarbon removal from contaminated groundwater.

Challenge

The contaminated site is situated partly on private property and partly on public roadways, adjacent to Lake Simcoe, Ontario.

The local sandy aquifer had been historically impacted by petroleum hydrocarbon released over time through an underground fuel storage tank on a private property.

The historical impact of the aquifer by petroleum hydrocarbons (PHCs) continues to persist in high concentrations, as evident in the groundwater samples collected recently from the monitoring wells, which also indicate presence of free phase product, visible in the form of droplets.

This high concentration of the source zone, gradually and over a very long period of time, releases dissolved fractions of the PHCs into the groundwater stream, which finds its way persistently to the lake water and in the sediment located only a short distance away.

The environmental risks of PHC and BTEX migration towards the lake is to be passively managed through installation of a Permeable Reactive Barrier (PRB).

Results of the analysis on the groundwater sampled, October 2023 (Grafta Nanotech Inc.)

Existing Solution

There is no current solution. A Risk Assessment is being conducted for this impacted groundwater with the application of a possible Permeable Reactive Barrier (PRB) in future to manage the risks associated with the migration of the plume towards the lake. No measures have yet been implemented onsite.

GRAFTA™ Remediation Solutions

GRAFTA™ line of products has shown remarkable adsorptive capacity for a wide range of contaminants including but not limited to organic compounds and heavy metals, due to the graphene and graphene oxide nanosheets within the structure of GRAFTA™ which provide unprecedented surface area for adsorption.

In this particular case, relying on graphene high adsorptive capacity for organic compounds, GRAFTA™ was selected as the best fit to remove petroleum hydrocarbons and BTEX from the subject water.

Preliminary Performance Test Results

Bench Scale adsorption column tests indicated an unprecedented removal rate for various fractions of petroleum hydrocarbon as shown in the following table and charts.

Results of Petroleum Hydrocarbon adsorption by GRAFTA™- Column Test; Permeant: Impacted Groundwater

Conclusion

The very high adsorptive removal rates promise a sustainable long-term performance of a PRB as the main component of a Risk Management System to protect the local groundwater and more importantly the ecosystem of Lake Simcoe.