Bülk sewage treatment plant is expanding a pilot plant for CO2 capture

In the future, less climate-damaging carbon dioxide (CO2) should be released into the atmosphere from the Bülk sewage treatment plant in Strande (Rendsburg-Eckernförde district). A test system that removes CO2 from the exhaust gas of the combined heat and power plant is being expanded into a larger pilot system. The biogas from the sewage sludge burns in the combined heat and power plant and supplies electricity and heat.

The test facility makes use of a natural reaction of the gas dissolved in water with limestone, as the city of Kiel, operator of the sewage treatment plant, announced. In nature, CO2 and rainwater become weak carbon dioxide. If this water seeps through limestone, hydrogen carbonate is formed. This is the natural process of limestone weathering.

Together with the Hamburg company Planeteers, the process has been technically accelerated so that up to 625 tons of CO2 can be separated from the exhaust gas in the pilot plant every year. The hydrogen carbonate is intended to flow into the Baltic Sea with the water from the sewage treatment plant and remain there for the long term.

Scientists at the GEOMAR Helmholtz Center for Ocean Research Kiel want to investigate what effects the process has on the Baltic Sea. The water enriched with hydrogen carbonate has a higher alkalinity than the water previously introduced. According to the information, this value at the outlet of the sewage treatment plant is already more than twice as high as in the Baltic Sea water. The new process is intended to increase the alkalinity of the water introduced by a maximum of nine percent. Alkalinity refers to the ability of a soil, rock or, in this case, water to bind acids.