Scientists at the University of Brighton have discovered a new way
of treating chromium VI contaminated soil which could save industry and
developers millions of pounds.

It involves placing contaminated
soil in a specially kitted out industrial skip, placing two arrays of
iron electrodes at opposite ends of the skip and applying a low
intensity electric current.

The toxic chromium VI contaminant in
the soil moves in response to the electric field and is transformed to
low toxicity chromium (III), and together with iron derived from the
sacrificial electrodes, the chromium is effectively locked within an
“iron curtain” which can be subsequently removed.

The low-energy
method is called Ferric Iron Remediation and Stabilisation (FIRS) and
has been developed by Dr Laurence Hopkinson and Professor Andy Cundy of
the University of Brighton’s School of Environment and Technology. They
have developed the system for commercial use on chromium VI and other
metallic contaminants with Churngold Remediation Ltd, although the
system can be applied to a much wider range of problem pollutants. The
technology is protected via a patent jointly owned by the universities
of Brighton and Sussex. Licensees are currently being sought in the UK
and abroad to ensure that FIRS contributes to major land clean-up
projects involving a variety of heavy metal, chlorinated solvent, and
radioactively contaminated land.

Current methods of
decontaminating soil tend to be expensive and labour-intensive. Many,
for instance, require the removal of soil to landfill sites, which has
been subject to heavy taxing and restriction under UK and EU
regulations.

Pilot studies on more than 500 cubed metres of soil
show that FIRS was able to reduce the level of hexavalent chromium, one
of the most common and toxic heavy metal contaminants found in heavy
clay soil in industrial and mining areas, by up to 85 per cent over 42
days. Electrokinesis was also used to reduce contamination in soil
water through an electrokinetic holding tank in the skip, in the
process yielding purified water which comfortably surpasses the
European Union’s 0.05mg/L maximum contaminant level of Cr(VI) in
drinking water.

Because FIRS uses about a tenth of the energy
required by standard electrokinetic systems, it is highly cost
effective. One of the most significant findings of the pilot studies
involved the ability to decontaminate water on site which means the
system can be completely self-contained and generate nominal amounts of
waste. Accordingly, FIRS appears to represent a comparatively simple,
low energy, low cost, and low maintenance approach to abate
environmental risk.”

Initial research into FIRS was funded by the
Engineering and Physical Sciences Research Council with further funding
for scale up of the technology provided via the government’s Knowledge
Transfer Partnership scheme and Churngold Remediation Ltd.
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