Energy neutral wastewater management at Danish city

  A water and wastewater treatment facility in the Danish city of Aarhus is claimed to be the first in the world to achieve energy neutrality. The Marselisborg plant, operated […]

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By Priyanka Shrestha
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A water and wastewater treatment facility in the Danish city of Aarhus is claimed to be the first in the world to achieve energy neutrality.

The Marselisborg plant, operated by Aarhus Water, provides water and wastewater services to 200,000 people.

It has managed to reduce its energy usage through efficient optimisation techniques in all areas of the process – from pumping and distributing water to pumping and treating wastewater.

Water management is said to consume up to 8% of global electricity and represent up to 40% of local authorities’ power usage.

The facility in Marselisborg is energy self-sufficient, acts as a power station, a biorefinery and is claimed to the world’s first energy neutral water service company to decouple water from energy.

It produces 40% more electricity than it needs and 2.5GW of a year of heat, supplying the district heating system in the city. Together that  represents around 192% in energy, equivalent to the total energy needs for the drinking water supply and the wastewater treatment in the catchment area.

Mads Warming, Global Director of water and wastewater at Danfoss, which has provided the technologies explains: “In the wastewater treatment side, besides major energy reduction, they have been able to increase the energy production quite a lot by doing clever process regulation and have achieved a situation where they are able to produce 230% energy at the wastewater facility.

“So for the first time, you have for 200,000 people, an area in the city where they don’t use any energy neither for the drinking water side or the wastewater side and that’s purely based on the wastewater itself from the households. So there’s no external carbon coming in from the food industry or from other wastewater facilities. There’s no wind or solar power used. It’s purely based on what these 200,000 people consume of drinking water and produce wastewater.”

 

Danfoss has installed energy-saving technologies such as advanced control systems and turbo compressors as well as optimised the fine bubble aeration system, which have helped reduce around 1 GWh of power usage a year.

Lars Schrøder, CEO at Aarhus Water spoke to ELN about the benefits.

He said: “Most of them, of course, are economic. Energy is costly so if we produce our own energy, we save money. Besides that, our owner, the Municipality of Aarhus, has a goal to be CO2 neutral in 2030 and we’re moving very fast [towards] that goal and that’s very beneficial too. And then of course, to have better management of the wastewater treatment.”

He adds wastewater should be used as a resource and the company could possibly be paying consumers for providing wastewater in the future.

Jacob Bundsgaard, Mayor of the Aarhus Municipality, which owns the facility, believes the project is a “no-brainer”.

He said other local authorities should help businesses promote and implement their technologies with an ambition of reducing climate effects and eventually cutting costs for consumers.