Combining Aerobic Bioremediation with Chemical Oxidation for the In Situ Remediation of a MTBE Plume
Bibliographic record
Abstract
The use of in-situ techniques to address soil and groundwater impacts has increased significantly over the last decade with in-situ techniques being used at approximately one-third of all sites. In situ treatment using aerobic biodegradation or chemical oxidation has been shown to be effective on a large number of impacted sites. Typically aerobic biodegradation is accomplished by adding electron acceptors such as oxygen to the subsurface with the objective of stimulating naturally occurring micro-organisms that degrade the petroleum hydrocarbons. Chemical oxidation using a variety of oxidants such as percarbonate, persulphate, hydrogen peroxide, ozone and Fenton’s Reagent has also been shown to be effective if applied correctly. Groundwater and soil impacted by petroleum hydrocarbon additives such as MTBE have a shorter and less studied remedial history when addressed by aerobic bioremediation and chemical oxidation. The number of studies that combine both aerobic bioremediation and chemical oxidation are limited. At a site in southern Alberta, aerobic bioremediation and chemical oxidation was combined to address a petroleum hydrocarbon plume containing MTBE. Using the chemical oxidant, percarbonate, and combining it with the oxygen-releasing material, calcium peroxide, the groundwater plume was addressed over an 18-month period. The oxidant/calcium peroxide was delivered to the subsurface using direct push technology over a series of injections events. Monitoring of the plume indicated a continual reduction in mass and extent with each series of injections. Pre-treatment concentrations of MTBE were greater than 1,000 ug/L with post treatment concentrations being less than 5 ug/L. Long-term monitoring of the aquifer indicated that rebound was not an issue. Subsequent numerical modeling of the injection process indicated that one of the key design components is the persistence of the oxidant and oxygen-releasing material within the subsurface.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".