GENERAL REMOVAL

1) Robert Niven of Uni of NSW (in Australia) had been particularly helpful in providing ideas to rid Mercury from drinking sources which appears to be quite common to cases that l have seen. Metal remediation is quite difficult, in general, but two technologies come to mind: 1. Permeable treatment barriers, and 2. Electrokinetics. Permeable barriers consist of some kind of fairly porous trench, filled with iron filings or some such reactive material which "mops up" the Hg as it passes through. The site is also important with consideration given for the soil structure. If there is too much clay or fine structure, the process may be slowed down. Secondly, electrokinetics is the use of an electrical gradient to mobilise metals towards a negative electrode. This technology is still rather experimental at present - and full of technical complications.

MERCURY AND SILVER REMOVAL

2) But the most interesting new idea that might help the environment (because it is cheap) comes from Macquarie University (Australia). Nicole Pickup perfected an inexpensive way by using polypyrrole, a conducting polymer whose unique properties can effectively remove toxic metal solutions from waste water samples. The polypyrrole draws the metal solution into and onto its surface with a thin film of metal becoming visible in its solid state. Both Mercury and Silver were tested with success. l met up with Dr Danny Wong (Nicole's supervisor) when l was in Sydney recently and Dr Wong said that it is also useful as a form of "detector" to very low parts per billion. Dr Wong also mentioned that the process is extremely easy even for someone like myself who have no chemistry training. It is hope that localised manufacturing of this material will begin soon and be available to those who are most endangered by such irresponsible threats and for those who are extracting for silver. There is no guarantee that the above will completely remove all the metal and hence making it completely "safe". Depending on the source, one may even need several treatment otherwise, the only alternative is not to drink from that source at all.

ARSENIC REMOVAL

3)Australian scientists of the Co-operative Research Centre for Waste Management and Pollution Control use sunlight and air to remove the contaminant. Project leader Dr Ging Khoe from the Australian Nuclear Science and Technology Organisation (ANSTO) said. " We use sunlight (or ultraviolet light) to increase the rate of natural change from the highly poisonous version of arsenic known as arsenic (III) into less harmful arsenic (V) by 10,000 times. " A recent demonstration funded by the USEPA took place at an abandoned mining town in Montana, results will be out by Jan 1997.