Hot Bugs

The Atomic Energy Commission's "health-physics" experts, who worry about the problem of radioactive wastes, have given close attention to mildly radioactive plutonium. They are not much afraid of short-lived, fiercely radiating isotopes, which can be isolated for a while until their activity has died away. Other isotopes with longer radiant lives are comparatively harmless, too. If they, are eaten or drunk by accident, the body excretes them quickly.

Plutonium is different. When it gets into the human body, it accumulates in the bones and spleen and stays there, gradually killing the tissue cells around it. A mere trace is poisonous. Water containing more than one millimicrogram of plutonium per liter (one part in one trillion) is dangerous. Isolating it does no good: plutonium loses only one-half of its activity in 25,000 years.

Last week, AEC Engineers John F. Newell and C. W. Christenson told about a promising solution of the waste plutonium problem. They found that certain "zoogleal" bacteria (which form gelatinous masses in sewage-disposal systems) have a hearty appetite for plutonium. So they filled a tank-with stones inoculated with bacteria, and trickled through it artificial sewage made of water, sugar, ammonium phosphate and flour. When the bacteria were well established, they were fed some of the deadly waste water. The helpful bugs removed from 90% to 95% of the plutonium. A series of such tanks could reduce the water to complete harmlessness.

Apparently the plutonium does the bacteria no harm. If the bugs get too "hot," the sludge in which they live can be dried to a small volume and disposed of more easily than a pondful of dangerous water.

This file is automatically generated by a robot program, so reader's discretion is required.