In a municipality in southern Germany, the municipal wastewater treatment plant with rotating immersion disks for 3,500 PE could no longer comply in part with the limit values for direct discharge. The biological growth on the disk baffles became so dense over time that the cleaning efficiency decreased. Even the attempt by an engineering firm to clean the growth carriers with chemicals proved futile after a brief reloading, as the same growth reappeared within weeks.
The municipal wastewater treatment plant receives around 280 cubic meters of wastewater per day. Since the existing disc immersion heater could no longer meet the discharge values, the engineering office asked for a ClearFox® containerized wastewater treatment system with fixed-bed technology to pre-treat the wastewater and thus relieve the disc immersion heater.
There are two options when upgrading a municipal wastewater treatment plant: A containerized wastewater treatment plant is suitable for pretreatment on the one hand, and for secondary treatment on the other. Both processes have advantages and disadvantages. The advantage as pre-treatment is that the contamination can be broken down very easily. However, this also creates a strong biofilm on the fixed-bed material. This must be removed and separated at regular intervals. The advantage as an after-treatment process is the lower dirt load that flows into the wastewater treatment plant. However, the lower the dirt load, the more difficult it is to achieve an even better standard of purification.
PPU Umwelttechnik GmbH has already equipped numerous municipal wastewater treatment plants with container solutions. Depending on the individual project, there are different possibilities to treat the specific wastewater in a guaranteed and efficient way.
To achieve the required discharge values, PPU Umwelttechnik GmbH planned two 20-foot fixed-bed containers connected in parallel. The wastewater passes through three cascades in which the growth area of the fixed bed material increases from stage to stage. These provide increasingly thorough wastewater treatment. Following the biological treatment, two lamella clarifiers separate the sludge and the partially flushed biological lawn from the clear water.
This project was realized by the Bayreuth company together with an engineering office, which was responsible for the design and planning. PPU Umwelttechnik GmbH was responsible for the manufacture, delivery, installation and commissioning on site as well as the instruction of the sewage treatment plant attendant.