Waste Water Directive

Extended connection requirements for smaller communities

What has often been handled in a decentralised way up to now will in future become part of centralised systems: smaller communities will also have to be connected to wastewater treatment. Lowering the connection limit to 1,000 population equivalent will significantly expand the infrastructure. New networks will be built, and existing ones will be extended and more heavily loaded.

This changes not only the structure of the systems, but also their complexity. Wastewater treatment plants are frequently merged – the number of treatment plants decreases while their size and catchment areas increase significantly. Greater distances, varying elevations and fluctuating inflows require precise hydraulic sizing and stable operation, even under changing conditions.

Wilo provides support with high‑performance systems for sewage pumping stations, sewage pumping stations solids separation (Wilo-EMUport CORE), as well as intelligent concepts for the control and management of sewer networks from Wilo FSM. In close cooperation with consulting engineers and planners, we ensure that new and existing systems operate reliably, can safely handle peak loads and are set up to remain resilient over the long term.

Reduced nitrogen and phosphorus limits for wastewater treatment plants

Nutrient inputs are among the primary sources of pollution in water bodies. Nitrogen and phosphorus drive eutrophication - leading to excessive algae growth, oxygen depletion, and significant impacts on ecosystems. The directive responds with stricter requirements for nutrient removal.

Stricter limit values will apply in future and must be achieved gradually by 2045. Existing facilities will come under greater pressure. Processes must be controlled more precisely and material flows managed more effectively. Operating conditions must also remain stable, even when inflow volumes vary greatly.

This is where we come in. With holistic solutions for the configuration and optimisation of biological processes, we create the basis for implementing the new requirements safely and cost‑effectively. Our focus is on a treatment plant that not only meets the required values, but operates reliably in the long term.

Speed-controlled recirculation, for example using Wilo-Flumen EXCEL-RZPE recirculation pumps, allows flexible control between nitrification and denitrification. Mixers and aeration systems ensure stable conditions in the tanks, while dosing systems from Wilo Likusta enable precise addition of precipitants and additives. In this way, effluent values can be reliably maintained – even under changing conditions.

Energy neutrality

Wastewater treatment plants are among the largest energy consumers in municipal infrastructure. At the same time, new requirements such as micropollutant removal are increasing energy demand. The goal is to turn this tension into a net‑zero energy balance by 2045.

Alongside on‑site energy generation, the main focus is therefore on reducing energy consumption. Energy audits and optimisation measures will become mandatory and require a detailed analysis of the entire facility.

Wilo views the plant as a complete system and systematically identifies the biggest levers for reducing energy use. Particularly in biological treatment, significant savings can be achieved through optimised recirculation, precise mixing and demand‑driven aeration. To this end, highly efficient recirculation pumps, powerful mixers and tailored aeration systems with compressors are used.

Complemented by efficient sewage pumps for internal transport, this creates a well‑coordinated interaction of all processes. Targeted modernisation in these areas can significantly improve existing treatment plants. This systematically reduces energy consumption and lays the foundation for a long‑term energy balance.

Micropollutant removal: Efficient integration of additional treatment stages

More than 175 pharmaceutical residues, hundreds of pesticides and numerous industrial chemicals – several hundred micropollutants can now be found in European water bodies. Many of them are not sufficiently removed during treatment in conventional wastewater treatment plants. The revised directive therefore promotes the introduction of an additional treatment stage for micropollutant removal in medium‑sized and large wastewater treatment plants.

This additional stage specifically reduces poorly degradable substances and significantly relieves pressure on water bodies. At the same time, it sets much higher demands for the treatment plants themselves: additional process steps, an increase in energy demand by up to 25 per cent and greater effort for operation and maintenance.

Depending on the boundary conditions, efficient combined processes using membrane bioreactors, activated carbon or ozonation are used. The key is safe integration into existing processes.

Wilo supports this with solutions for reliable feeding, mixing and further treatment within the micropollutant removal treatment stage. In particular, in PAC (powdered activated carbon) processes, precise dosing and precipitation, uniform mixing in contact tanks and controlled solids removal ensure stable conditions. Combined with powerful systems for transfer and return, the additional treatment stage is securely integrated into plant operation.

The result is an overall system that delivers the required wastewater treatment performance while ensuring stable operation.

Monitoring combined sewer overflows

As heavy rainfall events become more frequent, sewer networks are reaching their limits. Combined sewer systems have to absorb large volumes of water in a short time, yet the available storage volume in sewers and tanks is often not sufficient. The result: overflows from stormwater structures are occurring significantly more often and with higher volumes.

This increasingly leads to untreated wastewater entering water bodies. The UWWTD therefore calls for systematic monitoring of these overflows – including recording volumes flows and pollutant loads. At the same time, the pressure is increasing to reduce these discharges through targeted technical measures and permanently lower the burden on water.

Wilo helps to effectively reduce pollutant loads already during overflow events. Solutions for solids retention, such as lamella clarifiers in flow‑through tanks or Wilo FSM screening systems at overflow structures, tackle the problem directly at source. In addition, sewage pumps and mixers in stormwater tanks help to avoid sedimentation and ensure onward transfer of the collected volumes.

In this way, our solutions make a targeted contribution to better technical control of overflow situations.

Water reuse: Relieving pressure on an increasingly scarce resource

Longer dry periods and rising demand are putting existing water resources under increasing pressure. At the same time, large volumes of already treated wastewater are discharged unused. Water reuse opens up new options here and is becoming a key component of modern water strategies.

The directive provides clear guidance, with defined requirements for quality, monitoring and risk management. The main focus is on agricultural irrigation – with different quality classes depending on the intended use.

To make these applications safe, additional treatment steps are needed: fine filtration to remove remaining substances, advanced processes such as activated carbon or membrane technologies, and reliable hygienic treatment. This can be achieved, for example, through UV disinfection or the use of chlorine or chlorine dioxide in distribution networks

We support safe implementation along the entire process chain. High‑performance pumping systems handle transfer between treatment stages and to the point of use, while pressure-boosting systems ensure demand‑driven distribution. At the same time, our solutions help to maintain stable and hygienically safe conditions within the system.

This turns treated wastewater into a reliably usable resource – flexible in application and safe in operation.