Service life 14 years - efficient operation with low energy costs.

In 1996/1997, the Bottrop purification plant was equipped with more than 20,000 ENVICON EMS2 12 AeroBest membrane disc diffusers.

The wastewater of the purification plant comes to up to 60 % from industry and has a chloride content of about 2,000 mg/l. Due to the basin depth of 10 m, the compressed air from the compressors has a temperature of about 130 °C. At these high temperatures, standard aerator membranes cannot be used, which is why the customer opted for EMS2 12 AeroBest disc diffusers from ENVICON with a special EPDM membrane for use at high temperatures of up to 130 °C. Due to the depth of the basins, the membranes can be changed only during running operation, so that a long service life was also a basic requirement.

Despite the adverse conditions (wastewater composition, water depth) of the purification plant, the loss of operating pressure increased by only about 15 mbar – corresponding to an annual average increase of only 1 mbar – within an operating time of 14 years. This and the still very good bubble pattern result in highly efficient operation with low energy costs in the long-term.

In 2002, the Krefeld purification plant was retrofitted with 11,300 ENVICON EMS2 12 AeroBest membrane disc diffusers.

The aeration system used at the time for low-load biology (disc diffusers with an overall length of 1,500 mm) was to be optimised as the existing stainless-steel troughs already showed signs of metal fatigue. The system furthermore incurred high aeration costs in operation.

The requirements were:

• a significant efficiency boost
• a long service life
• a clamping system that had to be easy to operate by a diver
• adaptability of the system to the existing pipes

In the tendering process, ENVICON was able to convince the customer of the high quality of its products. Special transition adapters were developed for this order to allow a very quick replacement on site. This allowed the replacement of all of the 5,650 disc diffusers to be carried out in a mere 6 weeks.

Despite the very difficult wastewater conditions, a diffuser service life of 9 years was achieved. During this time, the customer regularly sent diffusers to ENVICON for in-depth inspection. In our status reports, which were free of charge for our customer, we were able to confirm the high quality throughout their service life. When the diffusers were finally replaced in 2011, our customer profited from the quick and easy tool-less replacement of the special membranes of the diffuser type used since the membranes are mounted with a clamping ring. The continued use of all parts of the diffuser except for the membranes avoided additional waste and kept the renewal costs very low. The adapters can also be used again.

In 2007/2008, the Pfützthal purification plant was expanded from 25,000 PE to 36,800 PE.

The aeration system to be implemented during the conversion of the biological purification stage was to be as efficient as possible. Originally planning to use disc diffusers of size 2000 x 1000 mm, our customer then opted for the especially efficient EMR 1000 AeroTop tube diffusers since ENVICON offered better guarantee values. After their installation, they were commissioned complete with a leak test and bubble pattern test.

In March 2008, the performance data was audited by an external lab. The verdict: Not only could the guarantee values be confirmed, they were even exceeded by up to nearly 40% at top level.

This project once again demonstrated the high performance of ENVICON products. The operator benefits from the fact that the required air flow rates can be achieved with significantly less energy.

In 2019, ENVICON has won the tender for a retrofit of the ceramic tube diffusers in the Dirnau (Landshut) purification plant.

As well as providing the diffusers, ENVICON also carried out the project coordination, removal, installation and commissioning as well as the disposal of the old diffusers. The existing plastic-bonded ceramic tubes were replaced.

Due to the design of our diffusers, some of the existing accessories could be re-used, resulting in reduced investment costs for our customer.

Despite a very ambitious deadline, all four aeration basins were retrofitted and taken into operation again within a mere 10 weeks of receiving the order – 2 weeks before the planned completion deadline.