Small-town Kalmar in Sweden builds full water recycling plant

In small-town Kalmar in Sweden the communal wastewater treatment plant (WWTP) is being replaced by a full water recycling plant. Resources will be recovered from incoming wastewater and useful products will be produced. One of the applications will be the possibility of making raw water for drinking water production.

It is important to use the right words. CEO Thomas Bergfeldt and Carolin Svensson, project manager and head of the sewage department, of the public water company Kalmar Vatten’s agree as we sit in their project office. “We are talking about a circular water treatment plant, not a sewage treatment plant. It is also about raising the status of our important business”, says Thomas Bergfeldt. The term technical water, which the water and sanitation industry has begun to use to some extent, is being abandoned. In Kalmar, they want to talk about recycled water, as it is more clearly and more positively charged.

Crisis due to bankruptcy of contractor

When Bergfeldt received a text message on the evening of January 7, saying the contractor had gone bankrupt, it was a cold shower. “At that time, we were in a positive trend after a turbulent period in terms of liquidity with the contractor. The text message was a message that Serneke’s then new owner Mutares had filed for bankruptcy. The construction contractor Serneke had been contracted as the general contractor in collaboration for the new Kalmarsundsverket since 2019. Now all activities were stopped pending notification. “It is important to understand the challenge for us public clients who have the Public Procurement Act to follow. The actor who receives the highest evaluation score according to the request will be awarded the project, and Serneke received the highest score when awarded in 2019. At that time, Serneke also met all requirements regarding financial standing and creditworthiness”, explains Thomas Bergfeldt.

Collaborative contract appeared to be of great importance

In retrospect, Thomas and Carolin see great value in the chosen form of procurement and collaboration, partnering. The choice of a collaborative contract instead of an execution contract was to some extent the key to managing the situation. Malmberg Water, today known as Eliquo Malmberg Water, was one of the strategic subcontractors in the construction. They were contracted as the process and machine contractor. “I called Erik Malmberg that same evening. It became a huge crisis, but everyone was involved and tried to find the best possible solution”, explains Thomas Bergfeldt.

Complex projects are built by individuals

After a round of legal discussions, it became clear that it is possible to transfer a contract to a strategic subcontractor in a direct procurement, provided that no major structural conditions are changed. It all depends on whether it is a socially critical project. “We quickly sent out a message to all important parties to sit tight for the time being, even those who were not classified as strategic subcontractors. We concentrated on those who would create value going forward. The vast majority saw that we were engaging as many parties as possible”, says Thomas Bergfeldt. “We were also able to capture some of Serneke’s key people and employ them temporarily while waiting for a further solution”, says Carolin Svensson. “It was probably one of our most important decisions, because complex projects like Kalmarsundsverket are not built by specific companies but by competent individuals! We absolutely did not want to risk losing important expertise that we had jointly built up over a long period of time”, Bergfeldt adds.

Limited delay

The effect was that important knowledge was retained within the project. That knowledge is now with the new construction contractor. Thanks to a number of rather courageous decisions, the delay in the schedule is moderate, it is only 3-4 months that disappeared. The sludge management plant should be operational in 2026 and the commissioning of the water phase will be in 2027.

Technical specifications of the advanced water treatment plant

In terms of process, the Kalmarsundsverket is an optimized activated sludge plant with pre-sedimentation, biostage, intermediate and post-sedimentation. Extensive automation will streamline the process with various variable zones where, for example, the air supply is demand controlled. The great feature, in addition to the advanced automation, is an advanced final polishing stage with both ultrafiltration and UV disinfection. Up to 80 percent of the water volume will be able to be reused. In final filtration, different lines are selected where a partial stream of the outgoing water will go through the entire system with bacterial killing.

Climate neutral operation

Hydraulically, the water flows by gravity from the intake building through all the treatment basins. There is backup power at the intake so that the plant can withstand longer power outages. Great importance has also been placed on managing air emissions. The plant has an environmental permit that requires an investigation into methane and nitrous oxide emissions. “When it comes to the climate issue, it is striking how little other factors within our operations affect when process emissions are included in our climate calculation models. Kalmarsundsverket is crucial for us in our goal of becoming climate neutral as an industry”, says Thomas Bergfeldt.

Controlling odour emissions

Taking greenhouse gas emissions into account already in the detailed design is innovative thinking. “We have brought in a modelling company to optimize the biostage and minimize nitrous oxide emissions”, says Carolin Svensson. “The odour issue has also been important from the start, with politics being the driving force. Our vision states that we will build Sweden’s best urban recycling plant. Partly it is linked to urban development, but for us it is also important from the perspective of raising the status of our business and the industry in general”, adds Bergfeldt.

Attractive design

Another part that has received extra care is the design of the facility. The hope is that the Kretsloppsverket will be in the public consciousness in the same way as Kalmar Castle and Kronan. Here again it is about status and attractiveness. Buildings and pools are dressed in a salmon pink color where occasional shiny areas are mixed into a matte surface. The effect on a sunny day should be striking. Even the choice of location posed a certain challenge as the land was previously a waste landfill, where land remediation was the first job.

Political support

Throughout the entire process, it has been important to have very close relationships with decision-makers in politics. With an investment decision of just over two billion kronor (1,8 billion euro), in a municipality with 72,000 inhabitants, it is a gigantic project. “A good dialogue with politicians is absolutely crucial for such a large project as this. They are the extended arm of democracy and we have a trust to nurture. My mission is to create the very best conditions for the project and for our employees”, believes CEO Thomas Bergfeldt.

Security issues

The changing world situation has also put safety issues higher on the agenda. Even though it is a facility that handles wastewater, it must also be able to produce raw water. Safety legislation is changing and those responsible have constantly tightened up safety issues. “Not least around working methods and information management, how consultants can and are allowed to work, emergency preparedness issues, sabotage and external threats. A lot is affected”, says Thomas.

Photography inside the facility not allowed

During the period, a new head of security has also been hired, reporting directly to the CEO. One concrete measure that we have reason to discuss is an internal photography ban. It is possible to show some pictures from the exterior, but it is prohibited to take pictures inside the facility. Among other things, this means that colleagues in the country are now not allowed to see the smart culvert that runs under all the pool blocks. Along the sides, batteries of small sludge pumps are set up. Everything is open and easy to handle. At various sections there are stairs up to the ground level that provide direct access to the right place in the facility.

Pilot plant for production of drinking water

A closed-loop water plant is more than just a name. The plant will be a complement to the basic supply of drinking water. Initially, it is important that there will be a water kiosk on site at the plant, but there are several stakeholders who demand the purified water. First, it will be used directly in the plant itself, a new headquarters for Kalmar Vatten will be built on site and there are also plans to use the water there. Municipal irrigation is another part. The county hospital has also shown interest. “The main track is to purify raw water to such a level that it can be used directly in a new drinking water plant. That project is well advanced in the planning and we are in the process of purchasing a pilot plant. At the same time, we are submitting an EU-life application”, tells Thomas Bergfeldt.

Energy production

Through Kalmarsundsverket we will be able to reuse the gas for heat and electricity, as well as solar cells at the facility. We will process the sludge into a fine soil improver that will be 100 percent returned to arable land. Together with Kalmar Energi, we will also investigate the possibility of recovering the heat from the wastewater and we will reuse the finely purified water for much more than just releasing it to the recipient, Thomas clarifies proudly. The new sludge management facility is already complete with two new digesters. Carolin is looking forward to the new volumes and the increased capacity that this means.

Old WWTP will be demolished

When we look out over the new facility, the current treatment plant from the 1960s is right next door. In comparison, it looks very small and worn out. However, this means another task for Carolin when the new Kalmarsundsverket is put into operation. Then the old facility will be demolished and the land will be restored. A challenging task when tough reinforced basins that are over 60 years old are to be removed.

This article was published first on the Swedish platform for water professionals cirkulation.se