Newly discovered bacteria can remove nitrogen from wastewater

Researchers have come across a type of bacteria that could fundamentally reshape efforts to cut the huge amount of electricity consumed during wastewater clean-up.

The serendipitous discovery was made by scientists working on the Healthy Drinking Water project, funded by the Engineering and Physical Sciences Research Council (EPSRC). The project is being led by the University of Glasgow, working in collaboration with the University of Michigan.

The newly discovered microorganisms, known as comammox (complete ammonia oxidising) bacteria, can completely turn ammonia into nitrates. Traditionally, this vital step in removing nitrogen from wastewater has involved using two different microorganisms in a two-step approach: ammonia is oxidised into nitrites that are then oxidised into nitrates, which are turned into nitrogen gas and flared off harmlessly.

Research team leader Dr Ameet Pinto said the discovery of the bacteria in a US drinking water system “took us completely by surprise”.

Wastewater treatment is a huge consumer of electricity, accounting for 2–3% of all power usage in western countries, and no less than 30% of its energy bill results from the need to remove nitrogen. Furthermore, most of the sector’s efforts to reduce its energy use have focused on the two-microorganism approach. The discovery of a microorganism capable of full nitrification will therefore have a significant impact on efforts to manage nitrogen pollution, said Dr Pinto.

“The potential is there for the wastewater treatment sector to exploit this breakthrough, which other teams in Europe have made in parallel with us,” he said.

“That would be an important step towards informing the development of robust approaches in terms of cutting costs and reducing carbon emissions associated with generating the huge amounts of electricity that the sector uses.”

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