Living organisms obtain energy by oxidation reactions. For humans and animals, this means consuming food, capturing the energy from the food source, and reducing it to carbon dioxide, water and solids. Biological oxidation is a natural reaction where micro-organisms capture the energy in an organic substance (food source) and use it for the oxidation process. This allows biological oxidation to take place without a large increase in temperature or energy usage. The results of bio-oxidation are CO2, water and inert bio-solids.

As contaminants (food source) come in contacts with micro-organisms, they are biologically oxidized to CO2 and water. Heavy metals and solids are consolidated and rendered harmless.

For example, benzene is oxidized to CO2 and water in the following way: