Wastewater heat recovery in sewer systems from wastewater treatment plant operational point of view

Wastewater in the sewer system is still an unused energy source in Austria. The first project of "wastewater heat recovery in front of a wastewater treatment plant (WWTP)" was not implemented until the year 2012. Building on this technology it is now intended to implement this method in the future since it is a promising new technology. In order to fulfill the EU 2020 targets. Reduction of greenhouse gas emissions and increased energy efficiency and more renewable energy must be achieved. However, if heat is removed which is generated in the sewer system process, negative effects can arise in the context of the actual cleaning performance of the wastewater treatment facility. In this respect the objective of this master thesis has been to create and develop a method, how it is possible to detect a general suitable WWTP in Austria in the context of wastewater heat recovery in the sewer system. The first part of the thesis focused on technical and legal fundamentals of different German-speaking countries with regard of wastewater heat recovery. The second part dealt with data validation and performance evaluation of a WWTP. The last part of the thesis will evaluate the detection and general suitability of a WWTP with respect to wastewater heat recovery in the sewer system. Since the experience of Austria is quite limited in this area it has been analyzed applicable wastewater recovery efforts in Switzerland during the past thirty years. Afterwards all parts have been combined to develop a theoretical method. This theoretical method has been applied on one national case study. According to the application of the method it has been determined that the developed method is applicable, consistent and valid results have been obtained. Further through the detection of a general suitable WWTP, it has been determined that the case study is not a suitable WWTP. Keywords: wastewater heat recovery, unused energy source