Green technology cleans the rain water in Ørestad South – University of Copenhagen

Green technology cleans the rain water in Ørestad South

Water Technology

Professor Marina Bergen Jensen

WaterCare Filtration A/S, HOFOR, CPH City & Port

A green technology that effectively cleans dirty road water, which relieves sewage systems and at the same time helps to safeguard Danish nature.

The story:
Cloudburst is a growing problem in Denmark, and the subsequent flooding puts pressure on sewage systems and contaminates the groundwater. Professor Marina Bergen Jensen from the Department of Geosciences and Natural Resource Management has found an innovative, green solution to that problem. The technology, called dual porosity filtration, cleans the water by mimicking nature's own processes. 

This video explains how the technology works:

In collaboration with the company WaterCare Filtration A/S, the technology has been tested in smaller plants before it was put into use at the end of 2018.

Large plant in Ørestad cleans 110 litres per second
Ørestad South in Copenhagen is now home to the first major purifications plant with dual porosity filtration. The system has been established for HOFOR (Greater Copenhagen Utility) and By & Havn. It can clean 110 litres dirty water from roads in Ørestad Syd per second.

Road water from urban areas is polluted with e.g. microplastics, heavy metals and nutritive salts. This may contaminate lakes, streams and groundwater, if led directly to them. The alternative is to spend energy to pumping road water to a purification facility along with other waste water. HOFOR chose to establish the dual dual porosity filtration plant as a solution to this dilemma.

- This solves a number of challenges associated with rain water. By purifying the water locally, we can also use it locally for recreational purposes instead of pumping it through the city to a purification facility. It is better for the local area and better for the environment. And the method is so compact that it can be established in urban area, explains Claus Mouritsen, project manager in HOFOR.

A green step towards climate protection
Cleaning the dirty road water has only become more relevant in recent years, where cloudbursts have challenged the Danish cities. The new wastewater treatment plant in Ørestad, it is a great tool in the efforts to climate-proof the city, says Anne Skovbro, who is the managing director CPH City & Port:

- It is a challenge for engineers and urban developers worldwide to climate-proof cities and adapt them to the increased precipitation. In the urban development of Ørestad, we have handled the rainwater falls on the "clean" surfaces locally from the outset that . Now the dirty road water also be cleaned locally in Ørestad South. That it is a big plus for climate-proofing.

CEO: There is great potential
It is WaterCare Filtration A/S, who holds the licensed on the dual porosity filtration. CEO Henrik Rønnest sees great potential in the technology, precisely because it can help both solve flood problems and ensure better water quality for the local countryside. Two problems that have only become more relevant:

- When there is every indication that the problems with heavy cloudbursts and flooding is only increasing, and we also see a growing desire to strengthen water quality and biodiversity in the Danish countryside, there is obvious potential in a proven technology that can convert the dirty water into a resource for the Danish countryside, he says.

Marina Bergen Jensen is still developing further use of technology. After a trip through the dual porosity filtration, water quality is so good that the road water could be used directly for toilet flushing, car washing or similar purposes.