Traditionally, wastewater is seen as a burden that needs treating and disposing of. However, as demand for water grows and the quantity of wastewater produced increases, many places around the world are beginning to see wastewater as a resource Click & Tweet! to be exploited.
In this new paradigm, the phase ‘reuse, recycle and recover’ means wastewater becomes a source of resources Click & Tweet! such as a cost-efficient source of energy and nutrients. The positive impacts include wastewater having a role in increasing food and energy security as well as mitigating climate change.
One city taking the lead is Aarhus, Denmark who is aiming to build the world’s most efficient wastewater resource plant.
Aarhus’ wastewater odyssey
Over a decade ago, Aarhus decided to optimize its wastewater structure by reducing the operation costs of its wastewater treatment plants (WWTP). It did so by consolidating its wastewater treatment operation into two large-scale, efficient plants that aimed to reduce operating costs by 40%. However, with the city’s population increasing by 4,000 people per annum the WWTPs will have to increase their capacity and performance in the years to come.
One of the two WWTPs, Egaa WWTP, has already undergone an extensive energy renovation and now produces more electricity than it uses. Meanwhile, the other WWTP, Marselisborg, is too small to meet this increased demand and its current location, bordering on the harbor, does not allow expansion: the city is aiming for a cleaner harbor and bay area creating a healthy habitat for plants, animals and people, therefore, there is a need to avoid phosphorus and nitrogen discharges as the population grows. As such, the current Marselisborg WWTP will be demolished and a new one built for EUR 215 million, with the completion date set for 2026.
A future-proof wastewater resource plant
The new plant at Marselisborg, Marselisborg ReWater, will not be a traditional WWTP but instead a ‘resource plant’ that will produce energy and extract nutrients from the wastewater with the ‘Re’ standing for ‘resources’, ‘recycle’, ‘reuse’ and ‘rethink’. This allows a change in mindset on how to manage wastewater in the future. What Marselisborg ReWater will look like exactly in 2026 is unknown as its development will involve an open call to attract companies, knowledge institutions and citizens to develop future technologies and processes in collaboration with Aarhus Vand. As such, the plant will serve as a ‘test-bed’ for new or optimized innovations.
Shining a light into the future
To guide this innovative process, Aarhus Vand has developed an innovation strategy that states 15 innovation challenges that must be solved in the development of the world’s most resource efficient WWTP. The challenges are:
- How do we best exploit the central location in Aarhus and the site-specific potential of the plant?
- How do we create a cleaner harbor and bay area while at the same time treating the water from a growing city?
- How do we support constant changes and flexibility in relation to new demands such as having to treat new substances in the future?
- How do we achieve energy and CO² neutrality in the water cycle throughout the Marselisborg catchment?
- How do we avoid odor problems when the plant is located in an urban setting?
- How do we optimize the use of resources in wastewater?
- How do we handle residual sludge so that it contributes to the circular economy?
- How can different water qualities be included in industrial symbiosis?
- How do we develop a fully automated wastewater treatment plant where no humans are in contact with untreated and dangerous material?
- How do we increase the earnings of Aarhus Van through symbiosis and new business areas?
- How can we design and build in the most efficient way?
- How can Aarhus Vand attract external capital and co-owners?
- How can Marselisborg ReWater strengthen the Danish water cluster internationally and what are the opportunities available with the regional food and ICT clusters in Business Region Aarhus?
- How can Marselisborg ReWater, as a plant and a visitor center, become a place for ‘water wisdom’ with understanding and experience of the water cycle?
- How can we ensure Marselisborg ReWater will be a good neighbor in the local area by opening its doors and sharing?
To start the journey, there will be a series of one-on-one meetings where all interested parties can discuss the potential for collaboration and determine whether there are mutually beneficial opportunities available.
Rather than locking in current technologies, Denmark’s new WWTP is future-proofing itself by exploring all possibilities.
*Robert C. Brears is the author of Urban Water Security (Wiley), and of the forthcoming titles Blue and Green Cities (Palgrave Macmillan) and The Green Economy and the Water-Energy-Food Nexus (Palgrave Macmillan). He is Founder of Mitidaption, which consults on climate change risks to business, governance and society.