ELSA – Efficient aeration at the Swedish wastewater treatment plants

Previous studies show that the potential to make municipal wastewater treatment plants (WWTPs) more energy efficient is great. The largest energy use at WWTPs is found in the aeration of the biological processes in the wastewater treatment.

In the ELSA project, the foremost Swedish experts in aeration and operation and process engineers and technicians as well as project managers met to work together on guidelines for design, operation, maintenance and procurement of aeration equipment at Swedish WWTPs. The result was the Swedish Water Development report “Effective aeration – Design, operation, maintenance and procurement of aeration equipment for WWTPs” which was published at the end of 2019.


When renovation and upgrading is required, normally only parts of the aeration system are replaced and/or supplemented, which can cause problems as the change may not achieve the efficiency that the system could achieve if the entire system had been replaced. As these needs arise every 10-20 years, there is sometimes a lack of documentation, but also knowledge of the aeration system’s various functions, underlying design and relevant requirements to ensure that an energy-efficient aeration system is obtained. The follow-up and evaluation of the operation and maintenance of the aeration facilities are also often inadequately carried out.

The project’s parties represented all important stakeholders regarding aeration facilities at municipal WWTPs such as utilities, suppliers, consultants, contractors, research institutes and universities.


Bengtsson, S., Fujii, D., Andersson, S., Arnell, M., Fredriksson, O. & Gustavsson, D.J.I. (2019) Energy efficient aeration in the Swedish wastewater sector Nordic Wastewater Conference (NORDIWA) 2019, Helsinki, Finland, September 23-25, 2019.,