In Denmark, a wastewater treatment plant explores wastewater’s true power

Marselisborg Wastewater Treatment Plant in Aarhus, Denmark. Photo credi: Aarhus Vand via Thomas Reuters Foundation

Since the Marselisborg Wastewater Treatment Plant in Aarhus, Denmark, generated more energy than it needed in 2016 and became what is called a “green power station”, engineers from China to Serbia descended on it to learn how it managed to convert wastewater to valuable energy in the race to uncover new technologies that are able to lower electricity consumption while also cutting costs and saving the environment.

Majority of the water treatment plants found in the world do transform sewage and wastewater into something that can be safely discharged back into the water cycle, but water treatment plants are not famously known for being energy guzzlers for nothing

Thus, international interest was aroused amidst heightening interest in converting wastewater into a useable resource when the Marselisborg Wastewater Treatment Plant in Denmark’s second-largest city generated almost 70 per cent more energy then it needed in 2016 after a €3 million (US$3.2 million) improvement. Additionally, it put Aarhus on the map for being the very first metropolis in the world to offer fresh water treated with energy created from household sewage and wastewater to all its residents.

“We are only using the potential of wastewater,” Per Overgaard Pedersen said in an interview with the Thomson Reuters Foundation. Pedersen is a chief engineer at Aarhus Vand, the water company that operates Marselisborg. “We’re not using heat pumps, wind mills…like many other places.”

Marselisborg said that it became energy self-sufficient when it began drawing carbon from wastewater and sludge before pumping into digesters filled with bacteria in order to make biogas – mostly methane – that would be burned to generate heat and electricity.

While this procedure is certainly not new, the success rate definitely is, and Marselisborg credited their achievement to investments in new technologies and customised equipment used to stop leaks and lower maintenance costs.

Pedersen added that investments to adopt new technologies between 2003 and 2016 helped the Marselisborg utility in bringing down its power consumption by 33 per cent. “It’s quite important for a utility like us,” he explained.

As attitudes toward wastewater keep changing around the world, international organisations are increasingly using Marselisborg as a benchmark.

During the World Energy Outlook 2016, hosted by the International Energy Agency in Paris, France, Marselisborg Treatment Plant was used as an example of how wastewater treatment had the potential to be energy neutral in the foreseeable future.

More recently, the United Nations (UN) released the 2017 World Water Development Report, stipulating that wastewater should not be seen as a costly issue, but rather a valuable resource that can help meet the growing demand for water and other raw materials*.

Energy efficiency is vital for water utilities such as Aarhus Vand, as it can help the company lower costs while helping the environment.

Although now that the international spotlight has been turned on it and engineers from all over the world have visited Marselisborg to study it, Pedersen said that reapplying plant’s model in their countries may not work for everyone, even if it has been adapted to the environment there.

“It’s going to be difficult because for a smaller plant it will probably be too expensive to do the investment in the digesters,” Pedersen explained. “In our context here in Denmark, I think 100,000 persons would be a good guess [for the investment to be feasible] but it simply depends on what facilities you have in the plant and the local context.”


Sources: Thomson Reuters Foundation, Eco-Business