Energy Neutral and Beyond: The City of Aarhus’ Journey Towards Wastewater Treatment Optimization

Traditional treatment of wastewater is an energy intensive process. Energy consumption has primarily been assessed in terms of electricity demand and chemical consumption; these utility expenditures account for a large proportion of operational expenditures at wastewater treatment plants. Recognizing the expenditures associated with operating wastewater treatment plants and the potential for optimization, the City of Aarhus, Denmark, set a goal to be energy neutral in their operations by 2030; in turn the goal of energy neutrality is also in place at the City’s wastewater treatment plants. As a driver for this the utility, Aarhus Water, who operates the water supply and the wastewater collection and treatment systems sought to exceed the energy neutrality goal by becoming energy neutral by 2020. As a secondary driver for energy auditing Aarhus Water looked to process optimization as a way to reduce bottom line costs associated with wastewater treatment.