Waste water treatment plant as energy Hub and Resource Supplier

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by Oxana Schmidt

The online seminar series will be continued due to the vivid interest on September 9, 2020 at 10:00 a.m . More information on registration and topics is to follow soon.

Waste Water Treatment Plants as energy hub and resource suppliers

The online seminar series will be continued due to the vivid interest on September 9, 2020 at 10:00 a.m . More information on registration and topics can be found here.

Sewage treatment plants (STP) are often still the largest energy consumers in a municipality at present. But experts agree that sewage treatment plants will also play a role in energy supply in the future. Accordingly, there was great interest in the online seminar series “Wastewater treatment plants as an energy hub and resource supplier”, held as part of the NEFI – New Energy for Industry (NEFI_Lab) showcase region. Between 50 and 70 participants informed themselves and discussed STP as an integral part of energy and nutrient recovery with experts on three dates. The seminars were organised by the Cleantech Cluster of the Upper Austrian location agency Business Upper Austria, AEE INTEC and the Chair for Energy Network Technology of the University of Leoben.

DI Wolfgang Gruber-Glatzl from the non-university research institute AEE INTEC presented on June 8, 2020 the Decision Support Tool (DEST) developed by his researchers. The tool allows various conventional and novel technologies to be combined and calculated on wastewater treatment plants. These technology variations are evaluated energetically, economically and ecologically in the tool. The result supports the decision-making process regarding the use of innovative technology scenarios as well as the possible uses of different forms of energy at the wastewater treatment plant site in interaction with the energy networks gas, electricity and district heating. The speaker addressed the energy potential in the overall STP system and also provided exciting insights into the material use of wastewater and sewage sludge to close critical material cycles. The reuse of essential raw materials, which are concentrated in the STP sink, is a much-discussed possibility for increasing the efficiency of resources.

Search and find energy resources

One fifth of the energy demand of municipalities is due to waste water treatment plants (STPs). On the other hand, there are often unused energy resources in wastewater treatment plants. Where these can be found and how they can be used was explained by Dr. Ingo Leusbrock of AEE INTEC at the second seminar on 25 June. Technical solutions for this are partly available or under development. But all sophisticated concepts are not yet sufficient for the expert. While STP has so far focused on self-supply or energy self-sufficiency, in future it must become an energy and resource hub. Leusbrock is convinced that this requires cooperation between all players. With more than 3,000 district heating systems in Austria, the expert sees great synergy potentials, for example, through the integration of STP into district heating, but the potential must be actively sought and its use must be promoted.  Kerstin-Pfleger Schopf, the Chair for Energy Network Technology of the University of Leoben presented the „Optievlex“ tool. This can be used to determine time-triggered flexibility potentials to provide electrical balancing or control energy. Rainer Wiedemann (Rabmer Group) presented examples of how heat from sewage treatment plants is now successfully used.

Waste water treatment plant as biorefinery

On 8 July, the participants learned how chemicals and nutrients can be recovered from wastewater and sewage sludge. In his introduction, DI Wolfgang Gruber-Glatzl referred to legal changes which will greatly limit the spreading of sewage sludge on agricultural land in the future and pose great challenges for sewage plant operators. He therefore sees a clear trend towards mono-combustion of sewage sludge, in accordance with the precautionary principle. It was therefore important to identify possibilities that would make risk-free recycling of valuable materials possible. After all, STPs are not only a sink for recyclable materials but also for pollutants. How a combined nutrient recovery of nitrogen, phosphorus and potassium works with a zeolite-based process was presented by DIin Dr. in Bettina Muster-Slawitsch from AEE INTEC and Ass.Prof. DI Dr. Markus Ellersdorfer from the University of Leoben. These elements are the most important macronutrients of the plant world and are indispensable for growth and development. In the meantime, cellulose can also be recovered from wastewater, as Jacob Schwarz from PVS GmbH reported. He explained the technical and economic feasibility of this innovative technology.