Household Water Recycling System to Be Tested in Germany
John Simpson | June 04, 2016Researchers from the Fraunhofer Institute for Systems and Innovation Research have developed a system designed to recycle household water and encourage the efficient production of biogas and biomass.
At the core of the i.WET system is the separation of less and more heavily contaminated wastewater in the household. As buildings are renovated, separate pipes would be installed for "gray" water from showers, wash basins and sinks on the one hand, and "black" waste water from toilets, washing machines and dishwashers on the other.
Approximately 110 liters of water per day are consumed in households in Germany. “Up to 50% of this water is required for showers and baths. This water is good for reuse—such as for flushing the toilet," says Fraunhofer scientist Dr. Thomas Hillenbrand.
i.WET is to be implemented as a pilot project in a housing association in Lünen, Germany. Image credit: ©Fraunhofer ISI.Gray water not recycled in the household would flow into an "energy alley"—a green strip with vegetation that thrives on moisture. “The result is biomass; the cities are greener and the threat of flooding is reduced," Hillenbrand says.
Under the i.WET system, only highly concentrated wastewater would reach the treatment plant. It could be routed directly into the biogas plant in order to recover methane, thus reducing the energy demand for wastewater treatment.
“The energy gain is significant," says Hillenbrand. "We can also recover nitrogen and phosphorus."
According to Hillenbrand, such a system can be operated more efficiently than standard sewers. Fraunhofer scientists want to initially keep the current sewers operable through regular surge irrigation with recycled water from households and, over the long term, replace them with vacuum dewatering.
Over the next three years, i.WET is to be implemented as a pilot project in a housing association in Lünen, Germany, as buildings undergo scheduled renovations to their water pipes.