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Sewage heat recovery via pump system

A sewage heat recovery via pump system is designed to withdraw heat from warm wastewater (12-15°C) through heat exchangers, in a closed loop to avoid mixing; preheating cold tap water, and reducing heating demands and fossil fuel consumption.

These systems can be implemented for individual buildings to pre-heat tap water for domestic hot water and space heating demands, or on a larger scale in sewer plants and channels having the potential to supply low-heat to a district heating network (DHN). The system can be implemented with heat pumps to raise its temperature for consumption.

The benefits are its simple and robust design with a long-life span, and that is an accessible low-heat source of energy, with great potential (5% of the heat demand of cities).

Other benefits are that it allows coupling with RES sources like solar thermal or other waste heat sources like industrial heat or exhaust air recovery and that it’s compatible with a low-heat DHN due to the fact that the points of source heat are the same as the points of consumption so the transmission losses are reduced.

The main drawbacks are economic for both cases, but especially for the sewer scale plant because of the expensive civil works required for a district heating network and greater installations; along with soiling by the wastewater and the big maintenance effort. Furthermore, at the building scale there might be limitations on space availability, it needs about 2 m of height; and the pumping consumption could be avoided using a passive configuration locating the tank in the lowest point of the sewage system.

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Circular economyClimate resilienceWasteWaterBuildingEnergyTechnology
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