It is time to rethink our urban wastewater treatment plants. The current generation of wastewater treatment systems focus on the destruction of carbon compounds and of nutrients, instead of on energy and nutrient recovery. Can we turn this around and go to energy positive wastewater treatment plants that harvest valuable materials? This is an ambitious topic which involves combining many innovative, as well as existing technologies, of both biological and physical-chemical nature. In this manner, a positive impact can be made on the footprint of wastewater treatment, to achieve a circular wastewater treatment plant.