Impact of Aged Contamination on Bioventing Performance

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Sites contaminated with petroleum hydrocarbons are a challenge worldwide. Site remediation is big business, with owners and governments looking for cost effective, yet environmentally responsible methods to clean up these sites. Bioventing is such a remediation method that it is classified as a biostimulation approach, where nitrogen is added to the soil to stimulate the petroleum degraders in the soil to reduce the petroleum hydrocarbon contamination level. However, studies are needed to determine how aged spills impact remediation efforts. Specifically, how does aging affect the degradation rate, the scale-up factor when extending the lab results to the field and the development of metabolites through the degradation process? Degradation studies using 200 g respirometers and 4 kg reactors will be used to investigate different types of aging procedures and durations using synthetic gasoline. Various bioventing conditions for both reactor sizes will allow determination of the degradation rate when no amendments are added to the soil, evaluation of degradation rate with amendments like nutrients and biochar, extraction efficiency as a function of aging and identification of possible metabolite formation. Comparing the first order degradation rates, along with extraction efficiencies and metabolite formation data will identify the critical factors. The resulting aging data will identify the impact on bioavailability, improving the implementation of bioventing at sites with decades old contamination. The degradation rates obtained from the laboratory experiments will allow development of a 3-D bioventing model. This model will give consultants a tool by which they can predict the effectiveness of bioventing for a given site and estimate the time needed to attain closure, a question site owners and government officials continue to ask. Having such a tool can assist with the cost effective remediation of petroleum contaminated sites in Canada and the world, providing many job opportunities.