Applying sustainable remediation to petroleum-contaminated soils

Eng Mohamed Zhioua of Enviro-Experts KSA reviews petroleum-related contaminants, available remediation techniques, and provides a deep dive into the framework of in-situ bioremediation, highlighting its application through a successful case study in downtown Montreal, Canada

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THE petroleum industry plays a pivotal role in modern infrastructure and mobility, but it is also a leading contributor to environmental pollution, particularly soil and groundwater contamination.

Activities such as fuel storage, distribution, and dispensing at gas stations often result in the release of toxic compounds into the environment.

Petroleum-related soil contaminants common contaminants from petroleum activities include benzene, toluene, ethylbenzene, xylene (BTEX), total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbons (PAHS), fuel additives (for example, MTBE), solvents (for example, TCE, PCE), and heavy metals (for example, lead, zinc, chromium).

These contaminants behave differently in the subsurface depending on their physicochemical properties:

Light non-aqueous phase liquids (LNAPLS): These are less dense than water and float on the water table (for example, gasoline, diesel).

Dense non-aqueous phase liquids (DNAPLS): Heavier than water, they sink through the aquifer and accumulate in low-permeability zones (for example, chlorinated solvents).

Depending on the nature and extent of contamination, various remediation approaches are employed.

In-situ bioremediation, a sustainable approach, is a naturally driven yet scientifically optimised process that utilises the metabolic activity of microorganisms to degrade petroleum hydrocarbons directly within the soil or groundwater.

"This process minimises the need for excavation or off-site transport, thereby offering an ecologically responsible and cost-efficient alternative to traditional remediation methods," says Eng Mohamed Zhioua, General Manager of Canadian environmental consultancy Enviro-Experts KSA.

Microorganisms, either indigenous or introduced, break down pollutants such as BTEX compounds, TPH fractions, and PAHs by using them as a carbon and energy source.