Brownfield RemediationClean-up

Part III

Urban agriculture

• Has potential to improve the quality of life in urban areas by increasing food security, providing opportunities for community development, and improving the aesthetics of the urban landscape.

• Obstacles: • land availability• restricted budgets • soil contamination.

Soil Contamination

• A major barrier to urban agriculture initiatives, because contaminants are present in most urban soils at levels higher than are accepted for agricultural use.

• These contaminants can be taken up by plants grown in these soils, and can be harmful to human health if the produce is consumed.

• The barrier of land availability could be partially overcome if brownfields could be used as sites for urban agriculture.

Remediation

• Remediation involves the removal of contaminants.

Physical remediation techniques

• Excavation

• Geotextiles

• Soil washing

• Soil vapour

Excavation

• refers to physically removing contaminated soil, normally for disposal at a landfill.

• Excavation is generally accomplished with heavy machinery.

• New soil is needed after the excavation.

Geotextiles

• are a synthetic blanket-like material.

• They can be used after the excavation process to provide a protective barrier, impermeable to contaminants which may otherwise migrate into the new soil after excavation.

Soil washing

• A technique which involves the physical removal of the contaminated soil, followed by treatment at a plant on or off-site.

• After the contamination is removed through the treatment process, the soil is put back into the ground.

Soil vapour

• extraction involves the installation of wells and pipes in the soil, through which soil contaminants are extracted in vapour form.

Biological Remediation

• Microbial remediation

• Phytoremediation

• Fungal remediation

• Compost remediation

Microbial remediation

• Refers to the use of microbes in degrading contaminants into a less toxic form.

• This technique can be very effective in the treatment of hydrocarbons, PAH's, pesticides, and PCB's.

Phytoremediation

• The process of using plants to degrade organic contaminants or to extract toxic metals from the soil and transport them into the above-ground shoots.

• In the case of extraction, the contaminated plants must later be disposed of soil.

Fungal remediation

• The use of certain species of fungus to degrade contaminants, particularly hydrocarbons.

Compost remediation

• The addition of compost to the soil.

• It is not a true remediation technique, as the contaminants generally remain intact in the soil.

• The addition of compost can, however, be used to create a raised bed, in which the plant roots may not reach the contaminated