Transforming Waste into Usable Soil: An Inside Look at New Soil’s Bioremediation Process at its Soil Recycling Facility

Home > Perspectives > Transforming Waste into Usable Soil: An Inside Look at New Soil’s Bioremediation Process at its Soil Recycling Facility

Bioremediation is a process that promotes the natural microbes in soil to digest hydrocarbon-based contaminants, such as polycyclic aromatic hydrocarbons (PAHs) and petroleum hydrocarbons (TPHs). These contaminants are commonly found in waste by-products from gas manufacture and at service stations, respectively. Bioremediation can be done in-situ or ex-situ, where a dedicated bio-pad or treatment pad is required.

The bioremediation process at the Soil Recycling Facility of EESI’s long–standing remediation partner New Soil involves stockpiling the impacted material on the bio-pad in the treatment area and mixing it with additives such as surfactant (EESI18), green mulch, manure, and a nitrogen source. The stockpiles are cultivated via turning with an excavator on a regular basis to allow air into the stockpiles, and soil testing is undertaken regularly to measure the progress of the treated material and analysed for contaminants of concern.

The process is repeated until validation samples show that the soil has been successfully decontaminated to an acceptable level for reuse off-site or on-site. Independent consultants collect validation samples, which are analysed at NATA approved laboratories. The stockpiles must remain aerobic through turning with an excavator to allow the conversion of hydrocarbon compounds to carbon dioxide, water, and microbial cell mass.

The treated and validated soil can be reused in three potential ways: it can be returned to the site where the contaminated soil has been sourced from to back-fill excavations, it can be remediated to NSW guidelines for re-use at landfill as day cover, or it can be re-used on site.

All soil material brought to the Soil Recycling Facility to be treated and recycled meets the requirements of the NSW EPA Environment Protection Licence (EPL number 13413) for the SRF. The process may vary slightly depending on specific contaminants and matrix materials in each batch of hydrocarbon-contaminated material received, but the technology is based on soil science principles and involves continually assessing the properties of input material and the material undergoing treatment to ensure the maximum bioremediation rate is achieved.

How it works: Bioremediation at New Soil's Soil Recycling Facility:

  1. Impacted material is stockpiled on bio-pad and mixed with additives (surfactant, green mulch, manure, nitrogen source) using Mobile Unit for Soil Treatment (MUST).
  2. Stockpiles are turned regularly with an excavator to allow air into the stockpiles.
  3. Soil testing is done regularly to measure progress and analyse contaminants of concern.
  4. Process is repeated until validation samples show successful decontamination to an acceptable level for reuse off-site or on-site.
  5. Validated samples are collected by independent consultants and analysed at NATA approved laboratories.
  6. Stockpiles must remain aerobic to allow conversion of hydrocarbon compounds to CO2, water, and microbial cell mass.

The treated and validated soil can be reused in three potential ways:

  1. Can be returned to source site for back-filling excavations.
  2. Can be remediated to NSW guidelines for reuse at landfill as day cover.
  3. Can be reused on-site.

Visit the New Soil website to learn more about soil remediation services offered in partnership with EESI

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