Strategies and opportunities for energy optimization in recycling water | Strategien und Potenziale zur Energieoptimierung bei der Wasserwiederverwendung
2016
Drewes, Jörg E. | Horstmeyer, Nils
The energy and materials derived from treating sewage are becoming increasingly important worldwide and are thus progressively considered resources rather than a disposal problem. This is also apparent in the growing interest in recycling water from municipal wastewater for both non-potable and potable purposes, supplementing the drinking water supply in the latter case. However, the energy consumption of about 0.9–1.8 kWh/m³, required to recycle drinking water, is not insignificant. Due to the lack of national as well as international standardized regulatory specifications for recycled water quality, very different technical solutions for potable water reuse have been deployed worldwide. Therefore, energy-saving measures often can only be applied to internal operational optimizations and the achievable savings are rather limited. Strategies for integrated energy recovery, the increased use of anaerobic biological processes and combined heat and power (CHP) for water recycling are hence very promising. These provide opportunities for internal power provision and therefore options to reduce the specific energy requirements for potable water reuse to well below 1 kWh/m³, despite the necessary treatment processes. However, the greatest potential for energy-efficient water recycling is at the regional planning level. Recycling water is only attractive where local freshwater resources are insufficient or there is a dependency on imported water, and it is the significantly more cost-effective option than the treatment of brackish or sea water.
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