In the summer of 2024, PPU Umwelttechnik GmbH was entrusted with an urgent project in Spain through its Spanish trading partner Protecnia. A cardboard factory operates its own wastewater treatment plant in the basement of its facility. The wastewater treatment plant was originally designed as an SBR (Sequencing Batch Reactor) system but was implemented as a continuous-flow multi-chamber oxidation plant with a total volume of approximately 8 m³. The plant had been modified by the operator to ensure at least basic aeration and oxygen input. During daily operation, approximately 140 people work in three shifts.
The wastewater originates mainly from sanitary facilities – toilets and hand basins – with also a minor contribution from industrial process wastewater. The original plant had long since reached its load limit, which resulted in repeated exceedances of legal discharge limits.
Initial analyses already revealed critical exceedances, particularly in nitrogen compounds:
These values led to repeated complaints from the municipal water authority, which ordered the operator to promptly improve the system. In addition, blockages in the coarse filter area occurred weekly, resulting in the regular use of external vacuum trucks – with corresponding follow-up costs.
Although the existing plant was able to reduce the COD (chemical oxygen demand) to acceptable levels through its aeration, the nitrifying microflora was suppressed by the high carbon content in the influent, which severely hindered biological nitrogen conversion. In short: The system in its configuration was not capable of ensuring nitrification and denitrification.
After a detailed evaluation of the laboratory analyses, volume data, and hydraulic load, PPU Umwelttechnik GmbH developed a compact downstream solution: a two-stage biological treatment system with fixed-bed biological reactors (FBBR) and a subsequent secondary clarifier to separate the activated sludge.
Installed components:
The entire retrofit solution was installed directly behind the existing effluent and, thanks to its compact modular design, could be integrated into the existing system without any intervention or construction work.
Just a few weeks after commissioning, the effluent analyses showed a significant improvement in all relevant parameters. Particularly noteworthy:
In addition, improved sludge separation in the lamella clarifier significantly reduced maintenance requirements in the primary clarifier. The use of vacuum trucks was significantly reduced.
The customer was very satisfied with both the technical performance and the short implementation time. The project is a successful example of an intelligent, modular retrofit in which an existing system was raised to a new level of performance through targeted additions – cost-effective, space-saving, and sustainable.
Yes, in many cases. Our modular fixed bed biological technology (FBBR) is particularly suitable for existing wastewater treatment plants with limited space, insufficient nitrification or high nitrogen levels. After conducting an individual analysis of your wastewater volume, composition and existing technology, we develop a suitable retrofit solution – without the need for major conversion work.
Our FBBR systems are particularly effective for municipal and industrial wastewater with a high organic load, such as from canteens, sanitary facilities, paper or food processing. Mixed wastewater (sanitary + industrial) can also be treated efficiently.
No. One major advantage of our approach is that it can be retrofitted. The new cleaning stages are installed downstream and can usually be integrated into the existing structure without intervention – often without shutting down the old plant.
All you need is a suitable area for installing the modules near the outlet of your existing system, as well as power and air connections. Our systems are designed for confined spaces and can often be installed inside buildings.
Thanks to targeted ventilation control, energy-efficient pumps and improved sludge treatment, our systems are cost-effective in continuous operation. They also reduce the need for frequent maintenance and the use of external disposal services such as vacuum trucks.
