Contribution to Exemplary In-house Wastewater Heat Recovery in Berlin, Germany

Thermal energy recovery from wastewater can be established from centralized wastewater treatment plants and sewage systems. Little attention has been given to In-house wastewater; although it can potentially pave way towards a sustainable heat source. The study was conducted inside student hostels in Berlin, in which water supply, wastewater, and room temperatures variations were observed during winter for one month. It was shown that water supply temperature has insignificant effect on the variations of in-house wastewater temperature as compared to room temperature and water use. The daily average temperature of the in-house wastewater was in a range of 11 °C to 20 °C, with an average of about 15 °C. It was illustrated that by selecting suitable combination of heat exchanger and heat pump, about 40 kWh/h (917 kWh/day) average in- house wastewater thermal heat can be recovered and about 230 €/day saved. This can contribute to reduction of energy needed for hot water provision by about 30% in the targeted hostels.