Radiation-Eating Bacteria Can Help Clean Up Nuclear Wastes by Bioremediation of Toxic Elements

Nuclear energy is considered one of the safest and cleanest sources of energy humans can utilize. There are 450 commercial nuclear reactors in 30 countries, providing about 30% of the zero-emission electricity in the world. Despite these advantages, nuclear power plants are subject to environmental concerns due to producing radioactive waste materials.

In the US alone, an estimated 2,205 tons of nuclear waste are produced yearly. Almost 4.5 million cubic meters of nuclear waste have been accumulated in the UK. Most of it is stored in ponds and silos located at surface level in Sellafield, Cumbria. Government authorities plan to dispose of the most highly active waste underground in repositories covered by cement to prevent the radioactive chemicals from escaping.

An Encounter with the Unusual Bacteria

A group of researchers led by geomicrobiologist Jonathan Lloyd from the University of Manchester investigated a lime kiln site in UK's Peak District to find out if microbes can grow in a type of environment similar to those in a nuclear disposal site. It was believed that cement in these sites would make the conditions too alkaline for bacterial growth, and Lloyd's team would like to confirm this theory.

The scientists discovered that bacteria could grow at pH values of around 11. They also found that the radiation levels at nuclear waste dump sites did not kill the bacteria. Instead, the microbes are stimulated by these conditions.

The way the bacteria process the waste products means the toxic materials are less likely to seep into the surroundings. Some nuclear wastes are composed of cellulose which, under alkaline conditions, can decompose to form isosaccharinic acid (ISA). ISA forms a soluble compound with uranium that helps it escape the repository. However, the bacteria tend to use ISA as a source of carbon. As these microorganisms degrade the ISA, the radionuclides are kept solid. Hence, they are prevented from going out of the container.

Aside from destroying ISA, the bacteria also help prevent radioactive gases from escaping. While chemical reactions occur inside the repositories, hydrogen gas builds up pressure and explodes in the container. The microbes use up the hydrogen gas and keep it at lower levels.

Threats from Nuclear Wastes

Nuclear or radioactive waste is the byproduct of nuclear reactors, fuel processing plants, research facilities, and hospitals. According to the U.S. Environmental Protection Agency (EPA), radioactive wastes are grouped into five general categories: high-level waste, transuranic waste, uranium or thorium mill tailings, low-level waste, and technologically enhanced naturally-occurring radioactive material (TENORM).

Processed nuclear fuel is dangerously radioactive and releases toxic elements such as plutonium. Humans that are exposed to nuclear waste can develop the growth of cancerous cells. Meanwhile, such wastes can also trigger genetic damage or mutation in plants and animals, preventing an organism from reproducing. Moreover, waste of the leftover fuel from nuclear reactors can remain active even after thousands of years.

Check out more news and information on Radiation in Science Times.