Northern Stockholm, or the island of Lidingö to be more specific, hosts Käppala water treatment plant which is one of the world’s cleanest facilities of its kind. On Monday morning Lidingö Mayor Paul Lindquist and Käppala Manager Director Per Manhem offered me a tour of this facility. This facility serves approximately 600,000 people in eleven municipalities in the Stockholm area.
The purpose of the visit was to learn more about Käppala’s active role in providing not just clean water, but the city buses with biogas, local farmers with fertilizer and adjacent households with district heating. The plant was inaugurated in the 1950s but as a result of the rapid growth of Stockholm the plant underwent an expansion in the late 1990s.
At Käppala, sludge is considered valuable stuff and serious business. It is one of few waste water plants in the world that actually generates annual revenue of several million dollars a year alone for the biogas. This is hardly surprising since it has the capacity to provide 100 buses with biogas and 30,000-40,000 houses with district heating. Käppala also generates approximately 20,000 tons of sludge annually which it gives away for free to farmers who use it as fertilizer.
Before sending the fertilizer to farmers, the plant removes 98 percent of the phosphorus in the sludge to make sure it does not end up in surrounding lakes and rivers causing eutrophication. People often talk about the danger of reaching peak oil — the point at which the production of oil begins an irreversible decline — but very few ever speak of peak phosphorus!
Phosphorus is crucial to a plant’s root, flower, fruit or vegetable and seed
development – and we are slowly running out of it. The work at Käppala is therefore important in order to avoid wasting this precious mineral. The plant does not only remove phosphorus but also traces of pharmaceuticals, some of which affects the reproduction of fish.
Käppala clearly serves the people of Stockholm in a number of ways which is probably why it has become such an integrated part of society. I was excited to see how much the United States can learn about how not to waste our waste.