Phytoremediation of Salt and Petroleum Hydrocarbon Impacted Soil
Based on extensive chemical and biological research, we have successfully developed and implemented plant growth promoting rhizobacteria (PGPR) enhanced phytoremediation systems (PEPS). The scientifically advanced phytoremediation systems we deploy remove petroleum hydrocarbons (PHCs) and salt from soils. PEPS provide large amounts of root biomass in impacted soils, which promotes growth of rhizosphere microorganisms. The root and rhizosphere biomass allow rapid partitioning of contaminants out of the soil, and their subsequent uptake and/or metabolism by microbes and plants. This results in degradation of PHCs in soil and large amounts of biomass for sequestration of salt into plant foliage. We have deployed PEPS at over 35 full‐scale sites in Canada. PEPS, when deployed by our trained scientists, will result in PHC and salt remediation to Tier 1 standards. Not only is this a green solution for remediation of impacted sites, but the costs for PEPS are less than half the costs associated with landfill disposal. Between 2007 and 2012 we have deployed PEPS at more than 25 PHC impacted sites in Alberta, British Columbia, Ontario, Manitoba, the Northwest Territories and Quebec. At all sites we achieved ~ 35 % remediation per year of PHC from soil (mostly F2, F3 and F4). The first 7 sites treated have met Tier 1 standards while 18 other sites are being treated and are on target to reach remedial endpoints within an overall 2 to 3 year treatment period. Beginning in 2009, we initiated full scale deployments of PEPS at 13 salt impacted sites in Saskatchewan, Alberta, Manitoba and the Northwest Territories. PGPR greatly enhanced plant growth on the salt impacted soils, allowing excellent plant growth with soil ECe’s up to 25 dS/cm. Furthermore, the plants (both grasses and cereals) take up sufficient amounts of salt to result in 10 to 20 % remediation per year. Importantly, we have already achieved salt remediation to regulatory targets at 2 of the sites. We have an on‐going research program to improve PEPS. One aspect of this work is to properly maintain the PGPR currently utilized and to isolate new, more active PGPR. We are refining the CCME PHC analytical method to make phytoremediation and other green in situ remediation technologies more efficient. We are also using Tier 2 toxicity end points at a research level to assess when soil becomes non‐toxic during PEPS treatment – results indicate this will occur prior to meeting Tier 1 criteria. Our work with PEPS has shown that it is very effective for treatment of a wide variety of PHC and salt impacted sites (including sites with co‐contaminants).