The thousands of little plastic spheres that have been washing onto the beaches around Copenhagen since this summer come from the advanced waste treatment plant Mølleåværket.
It has been established that an employee from Mølleåværket – located in Lyngby-Taarbæk – accidentally opened a bulkhead between the old and new part of the plant in July resulting in the release of thousands of plastic bio-carriers from the post-denitrification tanks into Øresund Sound.
”There was a human error while we were refitting part of the old plant to the new plant,” Per Plannthin, the head of the waste treatment department at council Lyngby-Taarbæk Forsyning, told Ingeniøren newspaper.
”When we realised what had happened we immediately shut the plant down and began cleaning up, and we contacted the Council and the nature authorities Naturstyrelsen.”
Unknown amounts released
About two weeks after the accident, the plastic bio-carriers began washing up onto the beaches and employees have since periodically been out cleaning up the beaches and harbours along Øresund.
Lyngby-Taarbæk Forsyning said that there was about 200 cubic metres of bio-carriers in the post-denitrification tanks, but they are still unsure how much was released.
Mølleåværket – which is one of Denmark's most advanced plants when it comes to purifying nitrogen from waste water – releases its cleaned waste water about 500 metres from the coastline.