Bioremediation specifically targets organic contaminants and it cannot be used to treat inorganic contaminants. Microbes breakdown organic contaminants naturally during respiration, bioremediation seeks to enhance this natural process by either increasing the population or selecting specific organisms for a targeted organic contaminant.
TRM commonly use the following In-situ and Ex-situ methods:
In-situ:
- Bio-stimulation: injection of nutrients / fertilisers & organic materials to provide nutrition to enhance the microbial population within the ground to stimulate breakdown of organic pollution
- Bio-sparging / Bio-venting: injection of air / oxygen via injection wells into the ground / groundwater at a low flow rate to enhance the microbial respiration and breakdown of organic contaminants
- Bio-augmentation: selection of micro-organisms to target specific contaminants, the microbes are isolated & cultured in a bio-reactor and then injected into targets spots in the soil / groundwater
Ex-Situ:
Excavated contaminated soil is mixed with an organic substrate e.g. wood chips / straw, nutrients, fertilisers & water if required then periodically rotivated to aerate the soil. This method stimulates microbial growth & respiration thereby enhancing breakdown of organic contaminants and can be undertaken in different techniques:
- Land farming: placement of mixed soil in one flat bunded areas then periodically rotivated
- Biopiles: placement of mixed soil into a cell / pile; warm air / nutrients is then periodically injected into the cell. The cell / piles may be covered to maintain a constant temperature
- Windrowing: placement of mixed soil into long lines which are periodically rotivate
Soil Augmentation
