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Flower power and heavy metals

Flowers and plants can help clean chemicals out of water and soil, reports Bill Holdsworth.

According to the Swedish Institute of Occupational Health, a potentially harmful new chemical enters industrial use every twenty minutes.

At the last major count in 1986, some 80,000 chemicals were identified and to date only a small proportion have been analysed.

This means that every time we dig a hole, start to tunnel or work on an old industrial tip, a toxic bomb awaits in both soil and water. So there is a constant struggle to find ways of reducing toxic contamination, and to make sure it is profitable too.

In the old mining town of Leadville, Colorado, a floral answer has been found that would gladden the heart of Prince Charles.

Mining engineer Frank Burcik, with 40 years experience, has discovered that particular biological properties within certain plants are in fact able to remove a multiplicity of heavy metals and other contaminants from polluted ground water.

He has taken this discovery forward by inventing a technology that can actually mill profitable amounts of metal from his crop, and at the same time use the crop residue for environmentally friendly building materials.

Burcik has been carrying out his research since January 2000, by designing a phyto-remediation system, as the technology is called. His system is a 140m length of underground tunnel, lying in the old Climax mine where molybdenum was once extracted.

'It's my scientific greenhouse, ' says Burcik of the tunnel, where complete control of air and water temperatures, water pH, growth medium, humidity and light intensity and duration can be achieved.

'It gives us the most viable conditions to maximise growth, remediation and profit.'

A combination of quinoa, Indian mustard and yarrow and duckweed is grown in a controlled compartment of three 15m long hydrophonic channels.

There are four compartments, three of which contain one of the plants, while the fourth is a mix of the three test plants.

Each channel is divided into thirds, dependent on the growth medium of sand, nutrient film technique (NFT) or glass beads.

Flow rates through the channels are varied while all channels are supplied with constant levels of fertiliser and light, leaving Burcik able to treat 38 L/s of contaminated water per minute.

Burciks' revolutionary work, kick-started by funding from the US Government's Environmental Protection Agency, is also being given scientific backup from Colorado's State University. Here it has been discovered that duckweed (lemna minor) is an important plant for the safe extraction of heavy metals. This plant can absorb up to 4,000ppm of zinc, as measured by dry weight, and 6,714ppm of copper and cadmium. As a result duckweed greatly reduces the amount of material to be properly and benignly disposed. The secret has been to harvest the saturated plants and reseed new ones.

Burcik, who has had his own company Water Treatment & Decontamination International since 1993, claims his proprietary phyto-remediation system can remove 80-95 % of toxic trace elements and other contaminants from highly toxic mine water in a range of conditions and that the technology is usable for many other applications.

If his claims prove to be true, then Burcik's recyclable and self financing technology is a winner for site remediation.

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