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Pilot test

A unique research facility in Sweden is taking new ideas in
wastewater treatment and seeing if they can actually work in practice.

Wastewater treatment plants aren’t typically known for their sweeping city views, but Sjöstadsverket occupies a prime location. Set on a hillside overlooking Stockholm, Sweden, the facility has spectacular setting; however, that’s not the only thing that makes it unique. For starters, it’s purely dedicated to research – even water that it successfully cleans gets sent to another facility nearby for treatment. 

Sjöstadsverket was built as part of the city’s bid for the Olympic Games in 2004 as a pilot-testing station for innovative treatment technologies. Comprising three different plants, the center has built-in access to two different kinds of wastewater for testing: standard municipal sewage (that includes stormwater) and a more modern effluent stream from Hammarby Sjöstad, a new neighborhood nearby that was developed according to strict environmental standards.

Lars Bengtsson, the man who heads up Sjöstadsverket, is eager to highlight the facility’s potential. “There are a lot of embryos in those white papers waiting to be tested,” he says, referring to academic papers that he gets primarily from the Swedish Royal Institute of Technology (KTH). “There are a lot of good ideas – but if they don’t get tested, they don’t go anywhere.”

Sjöstadsverket tests those ideas at pilot scale – for most, a prohibitively expensive development step – with its treatment plants. The facility’s first line is designed as a conventional Swedish plant – a combination of biological treatment and sand filtration – to serve as a reference for the other two lines. The second line tests aerobic treatment with a membrane bioreactor and reverse osmosis, while the third line is equipped for anaerobic treatment (upflow anaerobic sludge blanket) and biological nitrogen reduction.

These technologies may be used separately or in combination. Recently, a temporary fourth line was added to monitor temperature change in a system similar to the facility’s first line. After testing is complete, this equipment will be shipped to Oskarshamn, Sweden.

Some of the ideas currently being explored at Sjöstadsverket are removal of pharmaceuticals from wastewater through various processes and more efficient biogas production by utilizing organic substances found in incoming water. KTH PhD student Jingjing Yang is working on a project focused on anammox technology for nitrogen reduction. She explains, “We are using recently discovered bacteria which create shortcut pathways in the traditional nitrogen cycle.”

Bengtsson points out his facility’s unique ability to go from an idea to a running experiment within a single day. “Of course, not all of our tests reach their goals,” he acknowledges, “but we have learned something from every test. Today we can combine those lessons into an extremely efficient process.”

Another remarkable feature of Sjöstadsverket is its goal of spreading new information. “No other treatment research facility at this scale is open to the public,” says Bengtsson. “A similar undertaking would more likely exist behind closed corporate doors.”

While supported by companies such as Xylem, the facility makes it a point to publish its results. The chairman of Sjöstadsverket’s research board, Ulf Arbeus, is Xylem’s Director of Product Development. “In a way, we [at Xylem] view this as an extension of our lab facilities, and we want to be part of the research community. We encourage openness and partnerships for the sake of the common good.”

Sjöstadsverket also hosts a steady stream of visitors from all over the world. In fact, more and more are coming to see the technologies in action – 1,000 visitors came in 2010, a three-fold increase over the year before. Bengtsson says, “Customers want to see the technology for themselves, to make sure the sizes and the engineering will work in their own systems.” Of course, with so much research to sort through and with so many visitors coming by, Bengtsson and his team have developed a pretty good read on what the trends are in wastewater treatment research.

“First the questions were about how pure the water can get,” he says, “and then there was a big interest in biogas recovery. Lately we’ve been seeing a lot on water reuse and energy efficiency.” When asked what Sjöstadsverket means to him personally, he replies, “If you’re like me and interested in researching these processes, there is no better place in the world to be. There are so many different techniques in one spot – and you can combine them! It’s a fantastic place.”

by Linas Alsenas