Heat Recovery Systems in Wastewater Management

Heat recovery from wastewater exploits the latent thermal energy carried by domestic, commercial and industrial effluents to displace conventional heating and cooling demands. Wastewater temperatures typically range between 10 °C and 35 °C, making them a viable low-grade heat source for heat pumps and heat exchangers. At building scale, drain water heat recovery devices reclaim energy from showers, sinks and kitchen outlets, while at neighbourhood and treatment plant scales large heat pump installations capture heat directly from sewer networks or primary effluent streams. The recovered heat can supply domestic hot water, space heating or district heating grids, contributing to decarbonisation and reducing reliance on fossil fuels. Key challenges include variable flow rates and temperatures, fouling risks, hydraulic impacts on sewer hydraulics and wastewater treatment processes, and the need for robust economic and regulatory frameworks. Recent advances in heat-exchanger design, materials resistant to biofouling, real-time monitoring and integrated modelling have improved performance and system resilience. Cross-sector collaboration among engineers, urban planners and policymakers is critical to leverage wastewater heat recovery as a widely deployable renewable energy solution.

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Heat Recovery Systems in Wastewater Management publication trend

The graph below shows the total number of articles in heat recovery systems in wastewater management across all publications each year (not limited to Nature Index journals).

Technical terms

Greywater: Wastewater from domestic activities such as showers, sinks and laundry, distinct from toilet waste, often used for low-grade heat recovery.

Heat exchanger: A device that transfers thermal energy between two fluids without mixing them, commonly constructed as coil, plate or shell-and-tube units.

Heat pump: A mechanical system that upgrades low-temperature heat to a higher usable temperature via a refrigeration cycle, enabling efficient heat recovery.

Thermal stratification: The formation of temperature layers within a fluid body, which can influence the effectiveness of heat-exchanger placement and design.

References

1. Techno-economic analysis of a novel retrofit solution for the domestic hot water system: A comparative study. Energy Conversion and Management (2023).
2. Experimental and numerical investigation of drain water heat recovery in a grease interceptor. Journal of Cleaner Production (2023).
3. Heat Recovery from Wastewater—A Review of Available Resource. Water (2021).
4. In-building heat recovery mitigates adverse temperature effects on biological wastewater treatment: A network-scale analysis of thermal-hydraulics in sewers. Water Research (2021).