Marselisborg sewage treatment plant
How a sewage treatment plant turns into an energy producer

The sewage treatment plant as an energy generator: This is what the future of water supply looks like! This is because it is one of the largest energy consumers within a municipality in the areas of water treatment and clarification. In Europe, water and wastewater treatment accounts for 30 to 50% of municipalities' electricity consumption. The municipality of Aarhuus in Denmark shows how things can be done much better. It has it through the use of optimized processes, more modern frequency converter With the highest level of energy efficiency and the use of the latest technologies such as district heating and biogas, the Marselisborg sewage treatment plant now generates net energy.

Energy generation in wastewater treatment in Marselisborg

Wastewater treatment plant as an energy producer: Discover how frequency frequency converters from Danfoss Drives drive all pumps, fans and other motors in the Marselisborg wastewater treatment plant and enable their transformation into energy producers.

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Wastewater treatment plant as an energy producer: What was the path from energy consumer to energy producer?

Energy generation from household wastewater

There are a few other plants in the world that operate in a similar way to Aarhus and pursue the same goal. "But it is important to understand that, unlike the others, our system generates energy exclusively with household wastewater - not with additional waste, for example from the food industry or from solar panels or wind turbines. This is Aarhus' s unique selling point," reports Claus Homann. In the water treatment plant in Marselisborg, since 2010 the focus has shifted from minimizing energy consumption to maximizing net energy surplus. Today the plant produces electricity and heat, and with this net production it supplies the local supply network of Aarhus, Denmark's second largest municipality. The CO2-Balance was reduced accordingly by 35%. 

Read the 'Tech Insight' to find out what technology you need to turn your wastewater treatment plant into an energy supplier.

Danfoss VLT® frequency frequency converters for all areas of water treatment

The water and wastewater treatment shows high load differences in the course of the day and at different times of the year. The use of frequency frequency converters has steadily increased to control fans, pumps and other powered equipment and adapt them to changing power requirements. At Marselisborg wastewater treatment plant, almost all moving parts have VLT® AQUA Drive frequency converter installed: They regulate fans, pumps and mixers. thanks to the frequency converter the system can react to load fluctuations with maximum flexibility.

Torque - the podcast driving you | episode 9

The water and wastewater treatment shows high load differences in the course of the day and at different times of the year. The use of frequency frequency converters has steadily increased to control fans, pumps and other powered equipment and adapt them to changing power requirements. In the Marselisborg waste water treatment plant, frequency frequency converters are installed on almost all moving parts: they control fans, pumps and mixers. thanks to the frequency converter the system can react to load fluctuations with maximum flexibility. 

In this episode of Torque - the podcast driving you, Claus Homann and Mads Warming explain how they converted the existing system into a global prosumer model. You can also read the interview right here.

Good prospects: on the way to becoming a municipal prosumer

Energy self-sufficient sewage treatment plant Marselisborg from a bird's perspective

The vision of the city of Aarhus is to expand energy production even further and to achieve a surplus production from its sewage treatment plants that is so high that it can also meet the energy needs for the city's drinking water supply. This turns the authority's largest single electricity consumer into an energy-neutral actor.

Read in the 'Tech Insight', what technology you need to transform your wastewater treatment plant into an energy supplier.

Tech-Insights: How does your sewage treatment plant become an energy producer?

  • Optimizing the nitrogen removal process: the VLT® AQUA Drive frequency converter adjusts the ventilation level exactly to the need. This control reduces energy consumption and increases the amount of carbon remaining in the system.

  • High-speed turbo blowers are used as the blower. This upgrade ensures a further reduction in energy consumption in the ventilation process.

  • Aerobic sludge aging control depending on the temperature and load on the system. Here is the frequency converter-Control of the return sludge pumps the key to energy saving and increased carbon retention in the system.

  • Improvement of the cogeneration process for energy generation with 90% energy efficiency.

  • These changes and improvements, including the effective co-production of electricity and heat based on methane gas from aerobic sludge digestion, have led to the impressive results:
    130% electricity generation (30% electricity surplus)
    Excess heat generation of approx. 2,5 GWh / year

Discover Danfoss Drives