The Kakolanmäki wastewater treatment plant in Turku uses ferrous sulfate as a precipitation chemical and calcium carbonate to adjust alkalinity. In late summer 2022, a test run was conducted with magnesium hydroxide. Magnesium hydroxide maintained a stable pH and provided more alkalinity to the wastewater than calcium carbonate. It also positively affected phosphorus precipitation and nitrogen removal, says process engineer Jouko Tuomi from the plant.
Photo: Seija Laine