CEPSA Colombia developed an improved technique for bioremediation; implemented since 2012 in the onshore Caracara field. This optimizes the processes of biostimulation and bioaugmentation by introducing exogenous bacteria, with efficiency (reduction of grease and oil) close to 90%.

The technique exceeds the performance of other published methods, as it has been used successfully for the biotreatment of soils and fluids impregnated with hydrocarbons at concentrations of fats and oil of up to 20 ± 2 wt%, equivalent to 200,000 ± 20,000 ppm (mg carbon/kg soil). Previous studies have suggested that oily sludges only with concentrations of fats and oils below approximately half that level can be bioremediated to achieve a compliance criterion standard close to 1 wt% as established in Chapter III of Louisiana Protocol 29-B and commonly adopted as an oil industry norm.

It is an ‘ex situ’ process since although applied at the field location the sludge is first collected and stored prior to batch biotreatment. The technique is most applicable to oily sludges that do not have an excessive asphaltene and resins content: asphaltenes are not biodegradable by microorganisms, given their structural complexity and resistance to the enzymatic attack produced by bacteria.

Our successful field pilot has been expanded to an industrial scale and has over a six-year period effectively treated the environmental liability of sludge ponds of approximately 12,000 m3 inherited when CEPSA assumed its interest in the Caracara field. Operations continue, treating ongoing generation of oily waste at an estimated cost saving of 54% relative to the treatment and transport costs of contracting an external bioremediation service provider.

We have developed simple criteria to screen the suitability of oily sludges for our process, which is simple, easy to implement and cost-effective, as it relies on bacteria generated from waste products readily available in the field at no cost. It should be applicable to other fields with similar environmental conditions.

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