A current membrane replacement project at the wastewater treatment plant in Neustadt near Coburg highlights how AEROSTRIP strip diffusers significantly contribute to resource conservation. After more than 25 years of continuous operation, AQUACONSULT Anlagenbau’s remarkably durable diffusers have now been restored to full performance through a smooth and efficient maintenance cycle.

Traiskirchen, July 1, 2025 – The AEROSTRIP strip diffusers at the central wastewater treatment plant in Neustadt near Coburg had been in uninterrupted operation for over a quarter of a century. This year, the membranes are being replaced to restore their original performance. This is made possible by a sustainable refurbishment concept developed by AQUACONSULT Anlagenbau, based in Traiskirchen, Lower Austria. The project sets an example for efficient plant operation and underlines the technical quality of the diffusers that have been in use since 1999.

Austrian Diffuser Technology in Germany’s “Doll Town”

The treatment plant of Neustadt near Coburg – known as the center of German doll manufacturing – processes approximately 1.8 million cubic meters of wastewater annually from the city and 22 surrounding districts. With a treatment capacity of approximately 30,000 population equivalents (PE), and advanced sludge treatment including digestion and a CHP plant, it exemplifies the combination of ecological responsibility and efficient plant operation. The heart of the biological treatment stage comprises two U-shaped aeration tanks with upstream denitrification and phosphate precipitation. Efficient aeration has been ensured since 1999 by 120 AEROSTRIP T-15 strip diffusers, a pioneering technology at the time, which have proven their reliability over the past 26 years.

Refurbishment After 26 Years in Operation

“In the first ten years of operation, the diffusers ran maintenance-free in continuous service,” says plant manager Oliver Hofmann. Later, following a maintenance recommendation, an automated relief valve was installed that provides a ten-minute weekly pressure release. “This has served us well, as seen in the 26 years of trouble-free operation,” Hofmann adds.

In spring 2025, the plant decided to replace all membranes on their 120 AEROSTRIPs. In this concept, the diffuser bodies remain fully reusable. Only the high-performance membranes are replaced, restoring the diffusers to their original installation performance. AQUACONSULT developed this sustainable, cost-effective, and technically advanced refurbishment process to further extend the diffusers’ service life.

Plug-and-Play Diffuser Exchange

For the membrane exchange, the diffusers are first removed by plant personnel, old membranes are taken out, and components are cleaned. The units are then securely packaged and shipped to AQUACONSULT Anlagenbau in Traiskirchen. Each diffuser is fully disassembled; plastic parts are replaced, while high-grade stainless steel components are cleaned, inspected, and often reused. The diffusers are equipped with new high-performance membranes and tested for tightness and function. Afterwards, the refurbished units are returned to the plant on schedule. On-site teams can then handle reassembly – just as in Neustadt near Coburg, where the replacement process was implemented swiftly and easily.

“The entire membrane exchange process went smoothly, and reinstallation was a breeze,” reports Hofmann. “It was basically plug-and-play – couldn’t have been easier.” After restarting the system, the bubble pattern was once again uniform and fine. “Performance was already good before, but now it’s even more consistent,” Hofmann adds. The initial pressure behavior also left a positive impression. The second tank is scheduled for conversion in July, using the same procedure.

Cost- and Material-Efficient Solution for WWTPs

Thanks to the successfully completed membrane replacement, the diffusers are now restored to a state equivalent to new and ready for many more years of reliable service. “By selectively replacing the membranes and key components, we can offer our customers a diffuser product that matches new devices in performance and lifespan, while saving significant resources and costs,” explains Rüdiger Vrabac, Head of AQUACONSULT Anlagenbau GmbH Germany. “For plant operators, this is an ideal solution both technically and ecologically.” The refurbished diffusers provide the same oxygen transfer rate as new units. Warranty coverage also restarts with the refurbishment. Additionally, operators benefit from low capital expenditure and significant energy efficiency: the fine bubble structure of AEROSTRIP diffusers ensures high oxygen transfer with minimal energy demand – a major advantage for continuous operation.

AEROSTRIPs from Traiskirchen, Austria, are now used in over 2,500 municipal and industrial wastewater treatment plants worldwide. AQUACONSULT Anlagenbau proudly counts flagship plants in Germany among its references, such as the “Alte Emscher” WWTP in Duisburg – one of the country’s largest – or the Zweibrücken WWTP in Rhineland-Palatinate, which stands as a benchmark for efficient plant operation. The decision of plant operators to use strip diffusers from AQUACONSULT always results in impressive energy and CO₂ savings.