Many technologies in developing Aarhus ReWater into a resource plant are already known and in use in Aarhus Vand’s existing wastewater treatment plants. Other technologies are yet to be developed.
Therefore, our strategy for Aarhus ReWater states 15 innovation challenges that have to be addressed early in the process, making sure that we will get a comprehensive input of technologies and solutions to choose from.
The approach is to openly invite companies, manufacturers, research institutions and alike to offer their products, services, knowledge, and know-how into the process by having them answer how they would solve one (or more) of the innovation challenges.
How do we utilize the site specific potential and the central location on Tangkrogen close to Aarhus centre, where the harbour meets Højbjerg, Havreballe Skov, the beach and Marselisborg Marina? How do we make sure Marselisborg ReWater becomes a local actor that contributes to the community with more than just water treatment?
The harbour area is fascinating, because its industrial character is different from other urban environments. The scale of the harbour is alienating, warehouses, cranes and the industrial layout captures our imagination and makes us feel small and thoughtful. The industrial environment makes us want to explore or reflect on our every-day routine and bustle of life. There is room for a harbour area in a diverse city, but since the law on port security came into force in 2009, the harbour area has been cut off from the public. It has also affected Aarhus, where the majority of Østhavnen and the area along Sydhavnsvej is enclosed and creates a barrier between the city and the water. The location of Marselisborg ReWater is situated between the enclosed harbour area and a public green area on Tangkrogen and a popular marina.
In Aarhus, the population is expected to grow by 4,000 persons per year until 2060, which on top of general centralization of treatment plants will impose greater demands for Marselisborg ReWater. At the same time, the expectations for a cleaner harbour and bay area creating liveability for plants, animals and people. It will therefore be essential to avoid polluting the receiving waters with the increased phosphorus and nitrogen discharges as a result of the population growth.
It must be considered to what extent, specific technology needs to be developed versus how flexible the system needs to be and how existing technology can be replaced over time.
Technology and requirements are constantly changing. What we are thinking today does not apply tomorrow. Micro plastics, pharmaceutical compounds, pathogens, hormones and pesticides might be the substances we need to treat in the future. Therefore, the task is not to build a finished plant, but to build a demo and test plant, that will be able to meet the existing demands while at the same time being adaptable and making us wiser. This requires a modular structure in which one part can be replaced (or tested) without affecting the rest of the plant.
At the same time, Marselisborg ReWater must set new standards for treatment and resource recovery plants, and therefore Aarhus Vand depends on an innovative water industry which is anchored internationally. Modularization allows system export of the value-generating elements and thus supports companies in continuously investing in technology development. It is therefore crucial that 10-20 % of the modular structure can serve as a ”test plant”, where development and test of new/optimized treatment processes can take place.
Today, the existing Marselisborg WWTP has a 150 % net energy-production. But in the new plant, where the catchments Aaby and Viby are added (which corresponds to 200,000 PE), it will be challenging to maintain the energy and CO2 neutrality. With the existing plant it will only be possible to achieve 40 % net energy production. The wastewater from the two catchment areas mainly comes from households with a lower nutrient content (carbon content) than today. Therefore, it is more difficult to produce energy from the wastewater.
The balance between wastewater treatment and energy production and consumption is crucial for the development of Marselisborg ReWater. Likewise, the ambition of energy efficiency in the processes must correspond to the overall economy of the plant.
Marselisborg ReWater will be located just 100 meters away from the restaurants on the marina and an event area used for many different cultural purposes. The plant will meet the legal requirements, but it is rare that a treatment plant is located in an urban context close to public activities. Therefore, the expectation is that there will be even stricter requirements in relation to odour than usually.
The challenge is to reconcile the need to avoid odour problems for users of the harbour while considering the working environment on the plant. In addition, the handling of the odour problems needs to be balanced with the energy consumption on the plant.
Carbon is a resource from wastewater, which can be used for phosphorus extraction, energy production and nitrogen extraction respectively. Phosphorus recovery is currently at 30 %, but the ambition is to raise it to 60-80 % using carbon, so phosphorus will be a refined resource that comes out of the plant. The goal is, that Marselisborg ReWater becomes 250 % net energy-producing, and therefore carbon must be used to produce biogas.
Nitrogen is also potentially a resource that can be extracted by means of carbon. It is currently unknown how much carbon will be needed for each process (And how much will remain in the sludge for the subsequent processes). It will therefore be essential to learn more about the energy balance that optimises the use of carbon.
Residual sludge is a resource, which can be a part of the circular economy, and the ambition is, that the residual sludge can be recycled, so that it will rank as high as possible in the waste hierarchy. So far, the very nutrious residual sludge has been used as a fertilizer on farmland (Biosolids), but there is a risk of contaminating the groundwater, raising demands on the quality of the sludge before it can be reused. Moreover, getting rid of the sludge has been a cost for Aarhus Vand and therefore it could be interesting to develop ways in which the sludge can be upgraded to make it more attractive for the recipient. In the residual sludge, there is still 30 % carbon left after dewatering, but the carbon is difficult to access, and will likely need to be further processed to be a resource.
In the extraction of resources from the residual sludge it will be necessary to balance the consideration of the residue with the consideration of the consumption of resources for the processing operation. It is important to avoid a situation.
There could be a potential associated with using different water qualities for industrial processes. Thereby, Aarhus Vand could deliver wastewater in lower quality than drinking water to the industry.
Today the industry on the harbour use seawater in some processes that do not require drinking water. Perhaps, the industry can receive wastewater and thereby avoid having to treat more wastewater than necessary to drinking water quality – and at the same time letting the seawater stay in nature.
It will require more clarification of the water demand in the harbour industry and possible operational challenges in the use of sea water, which wastewater might be able to cope with. Conversely, water symbiosis between industrial companies reduces the amount of wastewater led to the treatment plant.
A treatment plant is inherently a dirty affair. And even though we have come far in improving the working environment, there is still a number of working processes, where the employees have to perform work that requires safety measures, e.g. cleaning mechanical filters and sand and grease traps in pre-treatment or in connection with removing the algae in the cleaning basins.
Therefore, Aarhus Vand wants Marselisborg ReWater to be a fully automated treatment plant. The goal is to eliminate all manual processes throughout the entire treatment process. In addition to making the work more attractive for current employees, these actions shall in time help turning the treatment plant into a high-tech workplace that attracts specialized and competent workers.
If this goal is to be reached, it is important that the plant is designed for this purpose. So workflows are either avoided completely or are prepared for sensors and robots to be incorporated.
The treatment plant changes character from just treating wastewater to extracting and utilizing valuable resources. This opens the possibility for new business areas and symbioses. For example, the sale of electricity, heat and biogas, extraction of resources such as heavy metals, phosphorus and plastic, or cultivation of crops that both cleans and can be used for fuel or industrial production.
Furthermore, one could imagine that the water was to be treated more differentiated, so it would be optimized for different use situations.
The focus of this challenge is the commercial and marketing aspects by entering symbiosis. This should be seen as a supplement to the technical aspects pinpointed in innovation challenge # 6 - 8.
Marselisborg ReWater is estimated to cost DKK 1.6 billion (in 2016 prices) (approx. EUR 215 million). The estimated amount is based on the unit prices, that characterize the market today.
As part of ensuring customers the lowest prices as well as promoting an overall efficiency in the industry, Aarhus Vand expects that it is possible to implement savings compared to current practices without compromising the quality – both as a result of the project size and the time available to identify efficiency possibilities in collaboration with the industry.
Aarhus Vand has through repeated cooperation’s made significant improvements in other areas, and expects it to be possible to achieve similar effects by designing the construction project, so repetition and learning is possible.
Today, wastewater treatment plants, sewerage and other ”water infrastructure” is owned entirely by Aarhus Vand. It does not have to be this way in the future, and there may be a limit to what Aarhus Water can finance.
In a market with low rates of return on traditional assets the investors are looking for new investment opportunities. For instance, pension funds’ time horizon and risk profiles match investments in infrastructure that have a low but long-lasting and safe return. In addition to lower investments and liquidity pressures, external capital and related ownership help to professionalize the utilities’ operational role.
And last but not least, external capital can help accelerate commercial-borne development for the benefit of Aarhus Vand as well as growth and exports.
It is crucial for Aarhus Vand to be a part of and contribute to cluster cooperation. Cooperation with other utilities, businesses and knowledge institutions ensures long term efficiency and creates the conditions for growth and exports. Aarhus Vand has a long tradition of partnerships and clustering, which among others is reflected in 3Vand, a strategic collaboration between the leading utilities in Denmark: HOFOR, Vandcenter Syd and BIOFOS.
Aarhus is a key actor in the Danish water cluster; In Denmark, as the initiator and participant in several research and development projects and as a pioneering example of usage of the latest technology. Internationally, as the focal point for export oriented campaigns such as the Water Technology Alliance in Chicago and San Francisco.
Marselisborg ReWater must be a reference project, a test site, and a hub for business and research cooperation, which accelerates this development. Marselisborg ReWater may also be an opportunity to promote cooperation with other key business clusters in Business Region Aarhus – the food cluster and the cluster for ICT and smart communities.
Future resource scarcity requires an increased environmental awareness on citizen and business level, and thought leadership and ‘water wisdom’ may help spread the responsibility awareness. In the future, water needs to be a resource that creates greener and more liveable urban spaces, and wastewater must be differentiated so the many types of water can be used in the industry, in the city and in the garden.
Moreover, the utilities are often subcontractors of both water supply and wastewater management for companies that represent and communicate their own environmental values. The future requires great environmental awareness both from costumers and the municipality of Aarhus that has ambitions to become a CO2 neutral city in 2030.
Marselisborg ReWater has the potential to become a symbol of the future sustainable transition, and to achieve total CO2 neutrality in energy consumption in the treatment process from methane and nitrous oxide evaporation, electricity, heat and transport.
Tangkrogen is located near Marselisborg marina, the event space on Tangkrogen and beach, and within one kilometer are Tivoli Friheden, Marselisborghallen, Ceres Park Arena, Aarhus cycling track, Jysk race course, Marselisborg Castle and Memorial Park and Havreballe forrest, as with its proximity to downtown is a popular destination for the Aarhus citizens.
The name Friheden originates from the late 1800s, when the forest was opened up to the public. Tangkrogen is located at the foot of the forest, and at the beginning of an attractive coastline, which most people associate with leisure and pleasure. The limited space to realize the vision for both the marina, the event space and treatment plant suggests that an interaction between the many functions related to Tangkrogen’s location is explored.
The ambition is to obtain multi-functionality in design and land use, and build on the activities which are already linked to the area. Interaction with existing players could be achieved through shared land and resource use such as lighting, energy and water.