Bioremediation: Bio-pile

A bio-pile is a bioremediation technology in which excavated soils are mixed with soil amendments, formed into compost piles, and enclosed for treatment. The basic bio-pile system includes a treatment bed, an aeration system, an irrigation/nutrient system and a leachate collection system.
Note. Systems known as Bio-Reactors are usually used to treat sewage water. They can also treat oily water, and testing is on going to treat polluted soils with this technique. Contaminated groundwater is circulated in an aeration basin where microbes degrade organic matter, forming a sludge that is disposed of or recycled.

Oily water
Lightly to medium polluted sediment (up to 5% of oil, more depending on installation)

Technically easy to implement if land is available on long term basis (few years).

Bio-pile is a more controlled and efficient treatment than composting, allowing treatment of more oiled sediment and waste.
The material may be returned on site once the treatment is completed.
 

Oil with a high asphaltene and resin content degrades slowly due to the molecular recalcitrance of the hydrocarbons while oil with a high aliphatic and aromatic content is a much more nutrient-dependent process and will degrade more rapidly within the adequate environment. It is recommended to carry out a GC/ MS analysis to define the composition of the oil and evaluate its biodegradability.
Treatability testing should be conducted to determine the biodegradability of contaminants and appropriate oxygenation and nutrient loading rates. Laboratory or field treatability studies are needed to identify the best amendments.

The site of implementation of the biopile depends on the land availability in the area and on the volume of waste to treat (cost of the transport).
Testing (in laboratory and on limited quantities) is necessary.
Continuous contaminant and environmental monitoring program is necessary (moisture, heat, nutrients, oxygen, and pH).

Biogas and leachate must be managed adequately.
The treatment area is generally covered or contained with an impermeable liner to minimize the risk of contaminants leaching into an uncontaminated soil.

Refer to waste and oily water / soil legislation.

Bioremediation is a long term process, although speed is increased in biopile, degradation of resistant oil compound may still take more than 2 years.
Bioremediation degrades aromatics, N-alkanes and iso-alkanes. Resins and Asphaltenes are usually resistant to bioremediation. Cyclic hydrocarbon (Saturated and Aromatics) are partially biodegraded.

Varies depending on the volumes to be treated.
Ranges from 60 to 200 euros per tons of waste to treat (if there is less than 100 tons) to 50 to 100 euros per ton (for 1,000 tons or more of waste) including the analysis.