A case of circular economy in Słupsk, Poland: Wastewater to resources


Słupsk is using innovative methods to recycle sludge from water treatment. With financial support from a European grant in 2004, the Polish city has built a brand new wastewater treatment plant that manages the water of three municipalities, but also produces sludge, which can later be used as fertilizer after being treated and composted. This example of circular economy highlights an innovative model for reusing waste. The treatment plant treats and reuses wastewater and it also provides self-sufficient energy thanks to the biogas produced in the fermentation process.

Follow the interactive visit of the treatment plant here.

From dirty wastewater to clean water and sludge

For the water to be turned into nutrient-rich sludge, it goes through several steps of purification:

  • The first phase of purification includes a mechanical treatment, followed by a sedimentation of sludge.
  • This is followed by a biological treatment. The treated clean water is discharged into the river Słupia at a rate of 18 000 m3/day. The treatment that the water undergoes results in its quality being good enough to improve the water quality in the river.
  •  The sludge left from the wastewater treatment is then composted and is used as fertilizer. 

Reaching sustainable development goals one at a time

The wastewater treatment plant is doing more than cleaning water.  Three municipalities (City of Słupsk, Słupsk municipality and Kobylnica municipality) cooperate to improve the state of their river, and their impact on the Baltic Sea.

Education on sustainable development and promoting public awareness on water issues is an important part of the work at the new treatment plant. The ‘Ecological Education Center’ situated on the treatment plant is open to the public and is visited by thousands of people every year, especially by schools. It enables promotion of new technological solutions in water, a wastewater economy and informs and engages citizens about water issues - both challenges and innovative solutions.

PROJECT TEAM: Dariusz Szwed