Large Scale Bioventing Degradation Rates of Petroleum Hydrocarbons and Determination of Scale-up Factors

Abstract

Bioventing is a cutting edge, non-destructive treatment method that uses indigenous soil microorganisms in-situ to remediate petroleum hydrocarbons in the unsaturated soil zone. Transferring the application of this technology to a field environment still has some uncertainties due to scale-up challenges. In order to identify the scale-up factor, a 80 kg soil reactor system was developed, consisting of a custom made reactor, climate chamber, low flow venting system and an off gas capture device. Sandy and clayey soils were tested with known concentrations of spiked synthetic gasoline. Various environmental conditions were monitored which included: moisture levels, pH, microbial levels, nutrient and oxygen levels. Results show a second stage degradation rate similar to the degradation rate obtained from research conducted with a 4 kg reactor, giving an average scale-up factor of 2.3±0.4. The completed research shows that working with a 80 kg laboratory reactor is feasible, yet not always necessary for the development of scale-up factors. A complimentary study with aged soil contaminants was preformed and yielded degradation rates that were significantly reduced.