Securing a hydrocarbon clean-up site by bioremediation

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).

Assessment of the organic load and the quality of wine effluents upstream of a wastewater treatment plant

Sewage network sectorisation

Context

A biological wastewater treatment plant in the Beaujolais region treats, during the grape harvest period, a large part of the discharges from the wineries in its sector. These effluents can affect the proper functioning and performance of the WWTP, due to their high organic load and/or their toxic nature for the plant’s biomass. 

In order to identify the most polluting sections of the sewage network, the Villefranche-Beaujolais-Saône urban community (CAVBS) mandated HYDREKA to carry out continuous monitoring of the quality of the effluents entering the WWTP and a sectorization of the main sections of the network. The objectives for the CAVBS were to identify the origin of the problematic effluents in order to improve its knowledge of the transited flows and to carry out actions with the concerned wineries.

Solutions & Results 

To meet these objectives, HYDREKA deployed 5 NODE multiparametric solutions over a period of 3 months at the WWTP inlet and in the sewer system. This instrumentation enabled real-time and continuous evaluation of several key parameters such as the organic load (NODE biosensor : DBO5eq), flow rate, pH, conductivity and toxicity of the effluents.

The network was thus sectorized into four strategic zones. Long-term events (increases in organic load over several days) and more occasional events (peaks in load and/or conductivity, toxicities) were detected and attributed to one of the four zones of the network. In total, 95%of the events affecting the WWTP were qualified (nature and intensity of the pollution) and could be attributed to one of the upstream instrumented branches.

The relative contributions of each of the branches in terms of organic load, flow rates and number of remarkable events could thus be defined. 

Feedback & Perspectives

This study enabled our customer to have a better understanding of its wastewater network, the amount and the origin of the organic load, the types of events that can impact the performance of the plant and the seasonal phenomena  linked to the grape harvest. This study has enabled the urban community to meet its objectives, which can now lead discussions and consider actions with the actors concerned.