Wastewater Treatment Aided by Hungry Microbes

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wastewater treatment
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Microbiologists have long suspected that the methane and iron “eating” Archaea bacteria must exist, but previously had no concrete evidence. Now, researchers have discovered an archaea bacterium that converts methane into carbon dioxide with the help of iron. These microbes contributed to shaping Earth’s atmosphere in our planet’s early stages and now, they could prove extremely useful in wastewater treatment.

Some geological and biological processes produce methane while others consume it. The balance between the release and use of methane determines the global amount of this greenhouse gas in our atmosphere.

Whether inside a rock buried deep in the seabed or in a mineral-rich hot spring, microbes oxidize hydrocarbon to create enough energy to survive. Some require the presence of certain metals in order to “digest” methane.  For instance, this newly-discovered microorganism converts methane into carbon dioxide using iron.

An international research team from Radboud University and the Max Planck Institute for Marine Microbiology in Bremen, Germany have for the first time discovered a microbe that ingests both methane and iron oxide.

Since these microbes incorporate metallic atoms into the enzymes that they use to break down methane, researchers are exploring how to leverage these single-celled organisms to aid in wastewater treatment.

“Archaea can convert nitrates into ammonium, which is the Anammox bacteria’s favorite food.”

Rust-Eating Microbe Finally Found

The single-celled organism belonging to the microbe Archaea of the order of Methanosarcinales and uses iron and the anaerobic oxidation of methane to produce carbon dioxide in low-oxygen conditions.

In the course of this transformation, reduced iron is released, which is then available to other organisms. Thus, these microbes activate an energy cascade which affects both iron and methane circulations.

Archaea in Wastewater Treatment?

Aside from the ability to consume rust and release iron, these Archaea can convert nitrates into ammonium, which is the Anammox bacteria’s favorite food. This microbe then breaks down ammonium into nitrogen gas under anaerobic conditions.

“This is relevant for wastewater treatment,” said Boran Kartal, the microbiologist who led the team.

Kartal suggests the construction of a bioreactor containing two microorganisms that react anaerobically. Ammonium, methane and oxidized nitrogen from wastewater introduced into the reactor could be converted into nitrogen gas and carbon dioxide. Small quantities of nitrogen already help make up the air that we breathe, and carbon dioxide is significantly less climate-active than methane.

Furthermore, since rice fields generate an estimated one-fifth of man-made methane, the same process could also be used to cull methane emissions from global rice production.

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