Optoseven FSA-CT1000 analyzer in wastewater treatment flotation process control and purified wastewater quality monitoring Ekokymppi, Municipal Waste Authority of Kainuu, Kajaani, Finland

The Municipal Waste Authority of Kainuu operates throughout the Kainuu region and in the municipality of Vaala. The Majasaari waste center of the consortium is located in Kajaani and serves the needs of about 76,000 inhabitants.

Majasaari’s new wastewater treatment plant, completed in 2018, treats all water generated at the landfill that requires treatment. The design flow of the plant is approximately 52,500 m³ / year. The majority of the wastewater has seeped through the landfills and the water is collected for treatment by leachate pipelines around the landfills. In addition, wastewater is collected from an oily soil composting field, a biowaste field and a mixed waste storage area. Similarly, the wastewater generated in the office is led to the treatment plant.

Like the typical leachate from waste centers, the wastewater treated is challenging for the equipment, as it contains a lot of e.g. dissolved organic matter from the waste, nitrogen in the form of ammonium, iron, and phosphorus. The waters to be purified are also completely oxygen-free.

  1. The organic load of the water is measured from the incoming water using UV-COD. Based on this and the flow, the amount of flotation coagulant chemical is adjusted.
  2. Measurement after flotation ensures successful coagulation and can be used to fine-tune the control of the cleaning process.
  3. The measurement of purified water complements the laboratory measurements in accordance with environmental regulations, giving a continuous picture of the reduction of the process.


“The Optoseven analyzer was chosen due to its extractive sampling method,” says Eero Piirainen, Environmental Manager at Ekokymppi, Municipal Waste Authority of Kainuu.

Based on long-term practical experience, Piirainen states that operating conditions in an environment such as landfill water are not suitable for probe-type measuring devices. The need for washing of a probe-type device by maintenance personnel would be continuous, despite automatic wiping or blowing of the measuring cells.

In addition, one analyzer can now be used to measure at all points relevant to process control and monitoring, reducing the need for maintenance. UV-COD has proven to be a suitable measurement parameter for the control of flotation coagulation chemical.

Read more in our app brochure:

Case flotation process control