Sustainable Remediation

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  • New options in sustainable remediation

    A number of new alternative techniques utilize an in situ, low-invasive approach using plants (with or without chemical additives) to reduce contaminant transfer to the environment by direct extraction of pollutants (clean up) or to stabilise soil (using biological or chemical processes). Collectively, these techniques are sometimes referred to as “gentle” remediation options (Onwubuya et al., 2009).

    Recent studies have given attention to the biochar technique as a soil amendment to enrich lands for agricultural purposes (Barrow, 2012, Hammondn, 2011, Lehmann et al., 2006, Sohi et al., 2010, Verheijen et al., 2010) and also as “gentle” remediation option for reduction of contaminants (Beesley et al., 2011, Namgay, 2010, Tang et al., 2013).
    Biochar can be produced by several thermo-chemical processes, however, fast pyrolysis has been shown to be one of the most highly effective, producing good quality biochar at low cost from a wide range of feedstocks, meeting current air emission standards and being easy to operate. (Garcia-Perez et al., 2013, Lehmann and Joseph, 2009).

    Biochar is defined as a carbon-rich solid material, fine-grained and porous.  It is produced by thermal decomposition of biomass under oxygen-limited conditions and at relatively low temperatures (>700 ⁰C) (Lehmann and Joseph, 2009).  The physical characteristics of biochar can changes depending of the temperature and the residence time in the fast pyrolysis process. One of the most important of these characteristic is the surface area that can vary between 1 m2/g to  750 m2/g.

  • Benefits

    Some befenits are:

    • Allows rapid re-vegetation on heavy metal impacted deposits.
    • Significantly reduces operational mine restoration timeframe as part of mine closure plans.
    • Promotes strong plant root growth on contaminated soils.
    • Prevents fugitive dust reléase.
    • Prevents long term leaching of heavy metals as part of an engineered solution.
    • Fast adsorption of leachable metals and metalloids to meet EQS.

  • Advantages againts others techniques

    Some advantages are:

    • A process that deals with both heavy metals and hydrocarbons
    • A process that is fast acting
    • A process that requires minimum space
    • A process that is easy to implement
    • A process that can be implemented ‘on site’
    • A low energy solution
    • A solution that does not require expensive treatment infra-structure