Phytoremediation

 

Phytoremediation of petroleum and salt impacted soils

 

We have successfully developed and implemented advanced phytoremediation systems for removal of petroleum hydrocarbons (PHCs), PAHs, and salt from soils. The plant growth promoting rhizobacteria (PGPR) enhanced phytoremediation systems (PEPS) we deploy, provide large amounts of root biomass in impacted soils, which promotes growth of rhizosphere microorganisms.

The root and rhizosphere biomass facilitate rapid partitioning of contaminants out of the soil, and their subsequent uptake and metabolism by microbes and plants. PEPS result in degradation of PHCs in soil and large amounts of biomass for sequestration of salt into plant foliage. We have performed several full-scale deployments of PEPS. PEPS, when implemented by properly trained personnel, lead to aggressive plant growth on poor quality, contaminated soils. The result is PHC and salt remediation to Tier 1 standards. Not only are these ‘green’ solutions for remediation of impacted sites, but the costs for PEPS are less than half the costs associated with landfill disposal.

From 2007 to 2012, we utilized PEPS at 19 sites in Alberta, British Columbia, Manitoba, Ontario and Quebec for PHC remediation. At all sites, we achieved ~ 35 % remediation per year of PHC from soil (CCME fractions 2, 3 and 4). At 7 sites, we have met Tier 1 standards, and at the remaining 12 sites, we are well on our way to achieving remediation goals within a 2 to 3 year treatment period. We are now refining CCME PHC analytical methods to make phytoremediation and other ‘green’ in situ remediation techniques more efficient.

Our work shows that PEPS is broadly deployable at a wide variety of PHC impacted sites (including sites that have barite as a co-contaminant), with a time frame of only 2 to 3 years to complete remediation.

Beginning in 2009, we initiated full scale deployments of PEPS at 10 salt impacted sites in Saskatchewan, Alberta and the Northwest Territories. PGPR greatly enhanced plant growth on the salt impacted soils, allowing good plant growth on soils with ECe’s up to 25 dS/cm. Furthermore, the plants (both grasses and cereals) take up sufficient amounts of salt to make phytoremediation feasible. Notably, we have already achieved salt remediation to regulatory targets at two of the sites.

The advanced ‘green’ PEPS technologies described above are based on procedures that have been scientifically proven and are effective at full field-scale levels when deployed by highly trained scientists.