The wastewater disposal cycle
How residual products from wastewater purification are transformed into energy and how the purified water helps to maintain the drinking water cycle.
Wastewater disposal is essential not only for maintaining the water cycle, but also for protecting drinking water supplies. Stateof-the-art technologies have made it possible for EVN’s subsidiary WTE to develop a practical use for the previously unpopular by-products from wastewater and waste disposal. With the help of four different technologies, WTE transforms these by-products into renewable energy carriers.
The operation of wastewater treatment plants requires substantial amounts of energy. When integrated as a module in the purification plant, a co-generation aggregate allows for nearly energy-autonomous operations. The biogas from the clarification process and sludge treatment is converted into electricity through incineration and used to operate the equipment or transformed into heat and used to dry the sewage sludge.
Thermal waste utilisation
The thermal utilisation of waste has proven to be an ecologically practical solution for energy generation. EVN Umwelt uses the heat released by the incineration process for heating operations and for the preparation of warm and hot water. The resulting steam is used to drive turbines.
The sludge incineration process used by EVN’s subsidiary WTE is based on the biological cleaning of wastewater. The sewage sludge is dried and then incinerated. The resulting heat can be used for energy-autonomous plant operations, to dry the sewage sludge, to generate hot water for steam-driven turbines or for long-distance heating.
EVN’s subsidiary WTE also uses energy exchangers to convert the heat released by wastewater treatment into energy. This energy is used to operate the equipment or fed into the public network. First pilot projects were already calculated.
Benchmark project: the Mia Milia/Haspolat energy-generating wastewater purification plant
One of the largest membrane bioreactors in Europe was opened in the Cypriote capital of Nicosia in April 2014. EVN’s subsidiary WTE was responsible for its construction and will now take over operations for a period of 10 years. This plant, which has a capacity to clean the wastewater for roughly 270,000 residents, generates biogas through sewage sludge treatment and digesting. The biogas is then used in co-generation plants to produce energy and heat.