Unique enzyme-biosurfactant caged mixes for biodegradation of high charge p-xylene contaminated sites

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Petroleum contamination is present to a depth of 12-15 m along the St-Lawrence River. Of various petroleum hydrocarbons present in this contamination, p-xylene is the most prevalent, its concentration can reach more than 10 000 mg/kg in soil, and it can also be observed as an immiscible phase (pure phase). In fact, decontamination of this soil is a challenge as one must bring down the water table to the proximity of the St-Lawrence River (due to high permeability). Due to its physico-chemical properties (i.e. density, volatility, etc.), common methods, such as the hydrogen peroxide or heating treatment, are not adequate to remove the p-xylene in contaminated soils. Hence, an alternative strategy, using effective and unique biosurfactant-enzyme mixes, is needed to efficiently address the p-xylene bio-decontamination. The proposed project is based on the hypothesis that the rhamnolipids as biosurfactants can help form micelles which can be further acted upon by enzymes to bring about the biodegradation. This hypothesis has been tested in our laboratory and we observed that the biosurfactant-enzyme conglomerate can help degrade recalcitrant compounds, such as p-xylene. However, research is still required to comprehend the details on kinetics, interaction of biosurfactants and enzymes and their behaviour in field studies. Hence, the specific objectives of the proposal comprise: 1) selection and production of copious amounts of enzymes at the laboratory scale; 2) Demonstration of rhamnolipids production at the pilot scale; 3) caged formulations of biosurfactants and enzymes; 4) laboratory testing of the biosurfactant-enzyme mixes in columns, kinetic studies and fine tuning of the formulations; and 5) Application of this formulation in an environmental chamber as well as field tests on p-xylene contaminated sites. The research outputs, including knowledge, tools and devices, will assist in the protection of populations, and fresh water and soil resources. An important number of HQP will be trained and join the workforce in the critically needing area of site remediation.