Biodecontamination of aquifers polluted by hydrocarbons by means of oxigen gas
The system based on dissolving the oxygen gas in the aquifer enables to decontaminate polluted aquifers The system has been developed jointly by Petroltecnica and SIAD, leading company in the production of technical gasses,
ADVANTAGES – Compared to present technologies
1) Simple application
It can be applied through already existing piezometers, just adding adequate spaces where to place the bottle and the pneumatic control panel. Excavated connections between application points and control system are not required.
2) Complete site availability
Plants are underground, therefore the site shall require neither surface civil work nor space occupation for placing the water treatment machines. Hindrances to site normal activities are minimized.
3) Saving
Compared to the other systems normally used to decontaminate a polluted aquifer (Air Sparging, Pump & Treat, Dual Phase High Vacuum Extraction), no wastes are created (activated carbons, contaminated water).
SCHEMATIZATION
System to spread pure oxygen in aquifer
- Pure oxygen (bottle)
- Pressure reducer
- Flowmeter
- Feeding line
- Diffuser
PILOT TESTING ON SITE
The described technology requires a pilot testing on site to define those parameters necessary to carry out site remediation through bio decontamination.
Pilot test execution requires implementation of a test field.
LAB TESTS
A series of chemical analysis and lab tests are required to check the aquifer reactions to the variations induced during the pilot testing, from the microbiological point of view.
RESULTS
Tests carried out till today by direct application of the bio-oxygenation can be summarized as follows:
- Respirometric lab tests validated the removal of the contamination through biological oxidation;
- The pure oxygen insufflations enables to completely remove TPH and BTEX and to decrease the contamination in a range of 5 meters from the injection point;
- Contaminations of civil organic origin can be a limiting factor;
- Microbiological analysis carried out on aquifer water samples pointed out the presence of a generic and specific bacterial load, spread in the entire site;
- Check tests with tracing inert gas (Neon) confirm the aquifer diffusion times;
- The site specific range of influence is estimated at about 5 meters;
- No “waste” production.
