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.
Teemu Peltonen, water management technician at Kokemäki Water Utility, reports (May 3, 2023) that magnesium hydroxide works excellently at the wastewater plant. Thanks to its phosphorus precipitation properties, the dosage of ferrous sulfate used as a phosphorus precipitation chemical at the plant decreased by up to 40%. Magnesium hydroxide was in use at the plant for about a year.
Photo: Seija Laine