Modern wastewater treatment is about cleaning water, but also about increasing efficiency, reducing energy consumption and producing energy. VCS Denmark’s largest wastewater treatment plant, Ejby Mølle, is a technological frontrunner in this field. The plant treats wastewater from most of Odense municipality which produces more than 20 million cubic metres of wastewater annually.
The wastewater treatment plant — with a capacity of 385,000 person equivalents (PE) — has achieved a degree of electricity self-sufficiency of more than 110% through optimisation of the plant’s existing infrastructure. Further optimisation opportunities have been identified in cooperation with a number of consulting companies, which will enhance nutrient reuse and maximise biogas extraction for additional heat and electricity production.
Ejby Mølle wastewater treatment plant has five major elements: a mechanical treatment unit, an activated sludge unit, two sets of trickling filters for treating stormwater, a sand filter and a sludge dewatering unit. After treatment, an aeration unit assures a high oxygen level in the discharged water. At the plant, renewable energy is produced by turning sludge into biogas and biogas into heat and electricity. The plant now produces more electricity than it uses. The digesters and buildings are heated by waste heat from gas motors, and surplus heat production is sold to the regional district heating utility.
VCS Denmark holds more than 100 years of operational experience in wastewater and is known for finding innovative technical solutions. The solutions are translated into energy efficient practices at the utility’s treatment plants and into know-how which is shared with utilities around the world.