It has been demonstrated that thermal energy can be recovered from the wastewater due to its high temperatures. Since the wastewater temperature is higher than the air temperature, it becomes a valuable source of energy. The heat gained can be used in different activities (e.g. heating and cooling houses, pre-heating domestic or regenerating heat recovery systems). In recent years, technologies for exploiting this potential have been continuously improved in Switzerland and Germany. These technologies consist in installing heat exchangers in the sewer system connected to a heat pump in order...