“Brazilian bugs” treat ammonia at utility


Severn Trent says it has achieved a reduction in costs for ammonia treatment by introducing a process called “annamox”, which uses bacteria imported from Brazil.

Use of the pea-sized bugs is part of a new approach to cleaning wastewater at its Minworth treatment works near Birmingham.

The Midlands based water and waste company is the first in the UK to import these bugs, reducing the amount of energy needed further down the treatment process.

The bacteria naturally strip away unwanted material such as ammonia by converting it to harmless gases – a process known as ‘annamox’, before it can be returned to rivers.

The biomass reacts anaerobically to convert ammonia into nitrogen, a process that depends upon the maintenance of key operating conditions such as temperature, pH and suspended solid concentrations. The key benefit is that the process uses significantly less air to complete the conversion, in comparison to the conventional approach,” added Hobbs.

Introducing the Brazilian bacteria to treat wastewater has already seen encouraging results, contributing to a 15% reduction in power usage.

Elliot Hobbs, project manager at Severn Trent, said: “Importing bugs from Brazil to treat our wastewater is a great way to cut costs and improve efficiency. This approach has reduced our operational costs and carbon footprint of our end-to-end sewage treatment process.

“The bugs, known as annomox biomass, will convert ammonia into nitrogen as long as key operating conditions such as temperature and pH are maintained, making it a more efficient process overall.”

More recently, the team has also imported the bacteria from the Netherlands.

As the process at Minworth matures and the biomass multiply, there will be the opportunity to export any excess bugs to other anammox plants around the world to support other water companies, as they look to introduce a similar process.

Elliot added: “Our focus now is to fine-tune the process, making the treatment of wastewater in this way even more efficient. These tweaks will help to drive down operational costs even further, which is great news for bill payers and the environment.”

The term “annamox” is an abbreviation for “anaerobic ammonium oxidation”. The name is also used as a trademark for a process that was developed in the Netherlands in the late 1990s.