Öland, Sweden – Operating treated water system using industrial process water

A popular holiday town on the island of Öland was facing water shortages due to high demand from tourism and local industry. The island relied heavily on groundwater, supplemented by truck deliveries of fresh water from external sources, which caused environmental and noise pollution.

One of the largest local industries is a food processing plant which sent wastewater to the old wastewater treatment plant. Engineers realised that this water was a valuable resource that could be cleaned and reused as drinking water, reducing dependence on rainfall.

They met the challenge by creating the first direct potable water reuse system in Europe. A treatment system was commissioned that treats brackish well water and pre-treated abattoir process water within one single installation. This multi-functionality comes from a combination of technologies that enable the plant to monitor incoming water quality and ‘self-adapt’. This is innovative, as typically the two streams would be treated at two separate plants.

A specially configured ultra-filtration system is used for the industrial process water, and the raw water stream of saline well water is pre-treated by oxidation. The two water streams are mixed in a basin then undergo ultra-filtration and reverse osmosis. The entire system can treat up to 4 million litres (1 million gallons) per day, depending on seasonal demand. The water is finally disinfected and remineralised to meet drinking water standards.

After transparent stakeholder engagement, including leaflet drops and information sessions, there was community and political support for the project. The plant’s opening was attended by Their Royal Highnesses Viktoria, Crown Princess of Sweden, and Prince Félix of Luxembourg.

Background article in AquaTech