Project Report

Our HYPERCLASSIC^®-Mixing and Aeration System Float, the world’s first floating mixing and aeration system, showed impressive results in the test application.

Pond treatment plants offer the capability of natural wastewater treatment with little setup and maintenance effort. The drawback is the space requirement. This is why in contrast to many other countries with lower populations – such as Sweden – we find fewer pond treatment plants in Germany.

To date, there have been limited options available to owners of pond treatment plants for mixing and aeration: Surface aerators and floating membrane aerators. The main problem with surface aerators is that, as the name suggests, they only function on the surface and do not have the capacity to circulate the entire volume of the pond. The enhancement of our HYPERCLASSIC^®-Mixing and Aeration System as a floating version solves this problem, and now also enables efficient wastewater treatment here.

Because the HYPERCLASSIC^®-Mixing and Aeration Systems have proven themselves for many years in conventional wastewater treatment plants, our engineers looked for a solution for their use in pond treatment plants and ultimately designed a floating platform. Pulled to the right place and fixed there with taut tie ropes, the hyperboloid-shaped agitator effectively mixes the wastewater pond.

The second function of the HYPERCLASSIC^®-Mixing and Aeration System, aeration with oxygenated process air occurs directly through the hollow shaft to which the mixer body is attached. The air is distributed in fine bubbles within a radius of up to twenty meters thanks to the uniform rotary motion of the mixing element. This also makes the clarification process considerably more energy-efficient than before. For the owners of pond treatment plants, but also for our company, the Floating HYPERCLASSIC^®-Mixing and Aeration System signals a milestone.

System installation, including the platform, is extremely straightforward. The main components are mounted in the immediate vicinity of the corresponding pond treatment plant. Except for regular visual inspections and an annual oil change, the system requires no major operation effort or maintenance.

Swedish customers are delighted

Successful field tests at a wood processing plant in Iggesund (central Sweden) yielded 19 times the amount of aerated water as compared to the previous basin equipment with surface aerators. At the same time, the energy input of the HYPERCLASSIC^®-Mixing and Aeration System Float proved to be only marginally higher.

Consequently, the Swedish operating company ordered four HYPERCLASSIC^®-Mixing and Aeration Systems Float for the aerated zone and four HYPERCLASSIC^®-Mixing Systems Float (without aeration) for the anoxic (oxygen-free) zone at the inlet for Iggesund. They also purchased two iTURBO^®-Blowers for the air supply.

The owners of a similar plant in Lessebo in southern Sweden were also not happy with their surface aerators. They had tested several until they heard about the HYPERCLASSIC^®-Mixing and Aeration System Float. So, on the way back from Iggesund, the test system dropped in at Lessebo and won over management there as well. They initially ordered a HYPERCLASSIC^®-Mixing and Aeration System Float and an iTURBO^®-Blower.

We are pleased that we were able to convince these two customers with our pioneering, energy-efficient product.

The fact that the HYPERMIX^®-Agitator has an excellent design was verified with the Red Dot Award 2021. More importantly, however, is just how well it works and how often it is used – as recently at a production facility of the renowned wine and juice producer García Carrión in Segorbe in eastern Spain.

The tradition of the innovative producer from Castellón province, where the Don Simón brand has become the best-selling Spanish wine in the world, is 130 years old. The producer’s line of products also includes juices, smoothies and soups, especially gazpacho. The Iberian Peninsula experiences increasing periods of water shortages from April to September, which particularly affects public utilities. All these years, García Carrión has also relied on a reliable supply of drinking water from the public network, until the volume of water it consumed exceeded the volume supplied. Nowadays, the producer needs three times more water in the summer months than the public supplier can deliver during that period.

To ensure the water supply for the production plant, García Carrión purchased two large tanks each with a holding capacity of 18,300 m³. In the meantime, five of the HYPERMIX^®-Agitators are in use in the tanks to prevent temperature stratification of the stored water and, consequently, post-germination and algae formation. In addition, continuous mixing ensures that a metered disinfectant is evenly distributed in the water.

Extensive simulations and test procedures before and after installation

After the last vintage was completed, the order from Spain arrived at our offices. Before the HYPERMIX^®-Agitators could be delivered ready for use, CFD (Computational Fluid Dynamics) simulations were first conducted to confirm the required quantity and positioning of the agitators given the complexity and size of the tanks. Because the tanks have the same volume but are shaped differently, three agitators proved to be optimal for one tank and only two for the other.

In a next step, they were assembled from the individual components (agitator, drive, lifting cables, connection cable including protective hose, frame and small parts) at INVENT in Erlangen and then tested. The frequency converters used to control the agitators were also configured. Prepared so well, the following spring, the customers in Spain were able to install the five HYPERMIX^®-Agitators in their tanks themselves. In mid-June, two of our employees set off for Segorbe to test the agitators in operation. Since then, the units have been working perfectly to everyone’s satisfaction.

The joint wastewater association Staufener Bucht, Germany, has placed its trust in the hyperboloid mixing technology of INVENT Umwelt- und Verfahrenstechnik AG. After 21 years in operation, the association has made the decision to replace the 15 HYPERCLASSIC^®-Mixers of the second generation with even more energy efficient mixers of the seventh generation.

A resolution was made in Bad Krozingen in 1967 to clean and treat the wastewater of 24 communities as a joint operation at a central location. This marked the launch of the powerful central wastewater treatment plant (wwtp) named Staufener Bucht. It has been in operation as a community wwtp since 1978. When the population number grew and the load limit was reached, the association expanded the wwtp in 1993. These days, it treats wastewater of a population that has since grown to 114,000, thus it is categorized under size class 5. By aerating and mixing in eight cascades in series, the plant achieves optimal environmental conditions for the activated sludge and the respective process.

Until the mid 1990s, the wastewater treatment focused primarily on carbon decomposition. Due to the Wastewater Ordinance amended at the time, the plant was designed and equipped in accordance with DWA-A 131 for nutrient elimination, in particular nitrogen and phosphorus. As a result of the more stringent requirements, the existing equipment of the wastewater treatment plant was no longer sufficient. For this reason, 15 second generation HYPERCLASSIC^®-Mixers of the same design were installed in the anoxic and optionally aerobic basins in 1996.

Because the hyperboloid mixer is positioned close to the ground, radially high sediment velocities are generated to efficiently suspend the activated sludge flocks. At the same time, the high pumping capacity of the mixer ensures a thorough mixing of large volumes. In this way, the content of the basin is quickly homogenized. Until 2017, the mixers were operated with minimum maintenance requirements, trouble-free and reliably.

Constant improvements in research and development in the laboratory and on large-scale test benches as well as simulations by the specialists of THINK Fluid Dynamix^®, the department for numeric techniques such as CFD and artificial intelligence, have over the years contributed to the improvement of the HYPERCLASSIC^®-Mixer benchmark product. Minor changes to the mixer body, the connection to the shaft and the drive technology had a major effect on the mixer’s efficiency. As such, the seventh generation proved to deliver huge energy savings as compared to the installed second generation.

In 2017, after 21 years in operation, all 15 of the Staufener Bucht wastewater treatment plant’s mixers were replaced with 15 of the latest generation HYPERCLASSIC^®-Mixers. This allows the association Staufener Bucht to save close to 54% electric output. The rated output was reduced from 1.5 kW to 0.75 KW, the output speed from 20.8 rpm to 15.8 rpm. Now, three years later, the energy savings can be confirmed.

“By replacing the existing mixers from 1996 with seventh generation mixers in 2017, by making a comparatively small adjustment to the inventory, we were able to reduce the total energy requirement of the wastewater treatment plant long-term and noticeably,” explains graduate engineer Michael Hacker, CEO of the joint wastewater association Staufener Bucht.

A large number of wastewater treatment plants that INVENT has equipped with the revolutionary hyperboloid technology since the mid-1990s when the company was established follow the example of the Staufener Bucht wastewater treatment plant and to this day still rely on the products supplied by the experts in water and wastewater treatment from Erlangen when upgrading their plants.