Polluted sites and soils
Context & Risks
In the context of a cost/benefit analysis, an active industrial site seeks to evaluate the performance of bioremediation as a method for treating hydrocarbon-contaminated soil. Bioremediation has a cost from 20 to 80 €/t, while excavation for these soils represents a cost between 120 and 200€/t.
If time constraints are compatible with the method (up to more than 1 year of treatment), and if space can be dedicated to the realization of decontamination windrows, the main risk is not reaching the acceptable concentration objectives defined by the risk assessment procedure.
Solutions & Results
Hydreka carried out a laboratory pilot to evaluate the effectiveness of bioremediation treatment. The combination of chemistry and molecular biology results identifies the optimal conditions for bacterial stimulation, demonstrate of the treatment’s impact on biology, and evaluate the residual concentrations that can be achieved an optimized context. The pilot was maintained for 2 months, the time necessary to allow for the biostimulation of present bacteria and hydrocarbon biodegradation.
The results showed 85-90% degradation of the pollution at the end of the pilot in the two optimized conditions. Treatments improved the specific activity of hydrocarbon degradation by 50% and 75%, respectively. Finally, degradation kinetics were multiplied by 10 and 15 depending on the observed condition.
Biostimulation through the addition of structuring agents and nutrients allowed for better decrease, more efficient stimulation of bacterial communities, and accelarated degradation kinetics in the laboratory.
In this pilot, the target concentration was achieved, and the obtained kinetics favored bioremediation treatment of these soils.
Customer Opinion & Perspectives
The pilote determined favorable degradation kinetics for on-site treatment. The target concentration was achieved in the laboratory, securing bioremediation as a treatment process with achievable concentration objectives to downgrade and keep the soils on-site.
During the final phase of the site management plan, this allowed for the selection of bioremediation for on-site treatment of this pollution. Through experience, the customer determined a transposition value of x4 for the delay and applied biostimulation recommendations, allowing them to achieve their goals.
Hydreka thus supported the client in securing their on-site treatment and reconciling their regulatory obligations and budget control, at a cost 6 times less than excavation and landfilling (excluding transportation).
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