Reducing costly water imports
With its long white sandy beaches, Öland is perhaps better known as a summer holiday destination for Swedish families.
Yet the inauguration of a 'self-adapting' water reuse plant could soon put Sweden's second-largest island on the European water technology map.
The municipality of Mörbylånga was previously facing challenges on drinking water supply, worsened by tourist-induced peaks and high water demands from local industry.
Water was transported to the island, not only creating a dependency on external supply, but it also brought with it increased environmental pollution and disturbances.
Designing 'multi-functionality' water treatment
Following a tender process from the municipality of Mörbylånga, Luxembourg clean-tech company Apataq secured the project to design and build a system to ensure continuous freshwater supply.
Referenced by the company as the “first of its kind in Europe”, a plant was developed to treat brackish water, as well as pre-treated industrial water within a single installation.
What’s unique about the development is the inclusion of dedicated software that enables the treatment plant to “self-adapt”, depending on the different water qualities.
Designed to handle a flow capacity between 500-4000 m3/day, depending on seasonal demand, the system uses a combination of technologies to achieve what Apateq calls “multi-functionality”.
Once treated, effluent will then be further disinfected and re-mineralised up to drinking water levels, according to the Swedish and international regulations.
The treatment process
The Luxembourg company Apateq has historically focused on the oilfield market, designing turn-key oil-water separation systems and compact wastewater treatment plants for “demanding applications”.
For the Öland application, pre-treated industrial wastewater flowing into the plant comes from the local poultry slaughterhouse. For the primary black water treatment, a specially configured ultrafiltration system is used, which can filter residual concentrations of oils and fats (up to 20 mg / l) from the raw water without blocking it.
The high bacterial content of the raw water can also be reliably eliminated using the selected treatment stage.
Due to the geographical proximity to the Baltic Sea, the remaining raw water streams are very saline well water with larger concentrations of divalent iron and 2-valent manganese (up to a maximum of 4 mg / l).
The well water is pre-treated in a first step by oxidation with potassium permanganate. Effluent from the two pre-treated water streams is mixed in a basin and sent to the joint final cleaning station, which is configured in four identical streets, consisting of ultrafiltration and reverse osmosis.
Each street has a maximum cleaning capacity of 1,000 cubic meters per day; this can be reduced to a minimum of 500 cubic meters per day as needed (high volatility of water due to seasonal tourist peaks on the island).
A royal inauguration
The Öland treatment plant was inaugurated in early July by the Royal Highnesses Victoria, Crown Princess of Sweden, and Prince Félix of Luxembourg.
"Geographically located on an island, our municipality is facing a limited availability of fresh groundwater,” said Peter Asteberg, project manager for the municipality of Mörbylång. “With the prevailing conditions, population growth or any extension of water-consuming industry represents a challenge in terms of water supply.”
Ulrich Bäuerle, chief technology officer of Apateq, said that the Öland installation is likely to be the start of similar water-reuse operations across Europe.
"So far, direct water reuse systems have been only installed in Namibia and the US to our knowledge,” he said. “Considering the increasing demand for freshwater resources worldwide, smart water reuse systems will inevitably play a major role in the global future, tackling the challenges of population growth and climate change."