VortOx – Aeration and Oxidation with a Hyperbolic Vortex

The EU Climate and Energy Policy Framework targets a 40% reduction in Greenhouse Gases (GHGs) emission by companies (when compared to 1990’s values) in 2030 [1]. Preparing for that future, many companies are working to reach climate neutrality in 2030. For water and wastewater treatment plants aeration processes could represent up to 70% of the whole energy consumption of the plant. Thus, a process which must be carefully evaluated if climate neutrality is a target. VortOx is an alternative to reduce power consumption in aeration processes. It is structured to test the applicability of geometrically constrained vortices in a hyperbolic funnel (aka “Schauberger”- funnel) as an innovative aeration technique for this industry. Recent investigations have shown that such systems allow an average of 12x more oxygen transfer coefficients (KLa) than that of comparable methods like air jets or impellers [10]. However, the system has a relatively small hydraulic retention time (HRT), which compromises its standard oxygen transfer ratio (SOTR). Additionally, so far, the system has only been tested in pilot (lab) scale. Vortox will tackle both challenges. Firstly, it will test geometry and flow adaptations to increase HRT keeping the same KLa levels. And secondly, all will be done using a real scale hyperbolic funnel and real effluent from Leeuwarden’s wastewater treatment plant demo-site. If proven feasible, Vortox can be a large step towards climate neutral water and wastewater treatment systems.

Aeration is one of the largest operational and energy costs in water and sewage treatment plants. The known technologies vary between mechanical aeration and diffuse air systems, each with disadvantages such as high installation and maintenance costs, high energy demand, and clogging issues. This project reports a special type of free surface vortex, first proposed by Walter Schauberger in the 1960s, which has high volumetric oxygen mass transfer with low or no extra electrical energy cost, depending only on the shape and dimensions of a hyperbolic funnel. The advantages of this technology are its energy efficiency, simple design, and scalability. The flow in this hyperbolic funnel is characterized by strong turbulence and a larger air-water interface. Free surface vortices are present in the flow regulation, energy dissipation, and power generation sectors. Although they have been extensively investigated, there is a lack of detailed experimental data on these vortices, particularly regarding turbulence at the interface, aeration properties, and applicability to other processes. Research on these topics has been ongoing since 2018, and as a continuation, this work was carried out focusing on a possible use of the hyperbolic funnel for aeration systems and energy efficiency in water and sewage treatment. Three different adaptations were tested: funnels with removable parts, funnels in series, and funnels followed by a reservoir and recirculation. The experiments analyzed the dissolved oxygen concentration after the exit of each configuration. The results showed good aeration capacity, with better results close to 4 mg/L of dissolved oxygen with the funnel followed by a 4-liter volume reservoir. These results highlight the potential of this technology, but further research is needed to enable system scalability and optimize funnel sizing for broader applications.