Between micropollutants, energy efficiency and operational reliability: wastewater treatment for modern treatment plants
Wastewater treatment plants are undergoing a fundamental transformation. New pollutants in wastewater, rising requirements for water quality and an expanding regulatory framework are significantly changing how plants are designed and operated. The revised Urban Waste Water Treatment Directive (UWWTD) further tightens existing regulations. Among other things, it requires additional treatment stages to remove micropollutants. Persistent substances such as pharmaceutical residues, hormones, PFAS and microplastics are therefore moving into sharper focus in wastewater treatment.
In addition, the energy use of wastewater treatment plants is coming under greater regulatory focus. This is hardly surprising: wastewater treatment plants can account for a significant share of municipal energy consumption. Processes such as aeration and recirculation in particular have a major influence on energy demand during plant operation.
The revised UWWTD therefore introduces phased requirements for energy neutrality. For wastewater treatment plants with a load of 10,000 population equivalents (p.e.) or more, a balance between annual energy consumption and eligible energy from renewable sources, as defined by the Directive, is to be achieved at national level by 2045. Phased interim targets apply until then. Regular energy audits are also intended to identify potential for reducing energy consumption and for using and generating renewable energy.
Economic pressure is also increasing. Many wastewater treatment plants are already decades old and need to be modernised or expanded, often while remaining in operation. At the same time, investments must be planned in such a way that wastewater charges remain predictable for customers in the long term. Reliable processes and plant operation can help support compliance with discharge limits and contribute to the long-term protection of water bodies.
The challenge lies in balancing all these requirements—higher treatment performance, stable processes, cost-effective operation, and compliance with new regulatory standards. Modern wastewater treatment therefore requires one thing above all else: the precisely coordinated interaction of all process stages within the wastewater treatment plant.
Requirements for modern wastewater treatment
- Removal of nitrogen and phosphorus
- Reduction of micropollutants
- Compliance with European wastewater directives
- Stable operation under fluctuating inflow volumes
- Energy-efficient plant management
Typical wastewater treatment process
- Mechanical treatment
- Biological treatment
- Chemical treatment
- Micropollutant removal
Our solutions for modern wastewater treatment
Wastewater treatment is a multi‑stage process in which different treatment methods must be precisely coordinated. We support you with comprehensive system expertise – from dimensioning and integration of the individual treatment steps through to the long‑term optimisation of existing plants.
This creates solutions that can support compliance with new requirements while integrating effectively into existing infrastructure.
Mechanical treatment
Reliably removing disruptive solids and stabilising inflow
Mechanical treatment forms the first stage of the wastewater treatment process. Here, coarse and fine solids such as hygiene products, plastics, wood and other foreign objects are removed from the wastewater before it enters the subsequent treatment stages. This is also crucial for protecting technical components. The consistent removal of disruptive solids at this early stage can help support stable and efficient operation of the downstream biological and advanced treatment stages
We offer utility companies solutions for reliable solids retention and the transfer of raw sewage within the plant. Wilo FSM filter screens support the removal of coarse and fine material, including under fluctuating inflow conditions. Sewage pumps can support the reliable conveyance of large water volumes, including during periods of high hydraulic load after heavy rainfall.
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In addition, we support an even feed to subsequent treatment stages. With a carefully matched combination of screens, pumping technology and pump systems, the inflow is reliably pre‑treated and the transfer of wastewater within the treatment plant is controlled. This creates robust pre-treatment processes that form the basis for high‑performance biological treatment and further advanced treatment stages.
Biological treatment
Supporting targeted control of biological processes and efficient energy use
In the biological treatment stage, dissolved organic matter as well as nitrogen and phosphorus compounds are broken down with the help of micro‑organisms. For these processes to operate reliably, oxygen input, mixing and sludge recirculation need to be precisely coordinated. Only when these factors work together optimally can biological processes and effluent values be maintained.
Aeration plays a central role. It supplies the oxygen needed for biological degradation. At the same time, however, it is one of the most energy-intensive processes in a wastewater treatment plant. Activated sludge tanks must also be evenly mixed to prevent deposits and to provide micro‑organisms with an optimal supply of oxygen and nutrients. Recirculation of activated sludge between treatment zones is equally critical to ensure that nitrification and denitrification proceed as effectively as possible.
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We support wastewater treatment plants with solutions for precisely controlled biological process management. Aeration systems can be operated according to demand, while mixers support even mixing within the tank. In addition, pump systems enable reliable recirculation of activated sludge and process water flows within the plant.
We also support consultants and operators right from the design phase. Using modern CFD simulation methods, flow conditions and oxygen transfer can be analysed in detail and tailored to the specific conditions of each plant. This creates an optimally coordinated interaction between aeration, mixing and recirculation.
Micropollutant removal
Advanced treatment stages for stricter water quality requirements
The revised Urban Waste Water Treatment Directive (UWWTD) places greater emphasis on the removal of micropollutants in wastewater treatment plants. For certain plants, additional treatment stages may be required in future to remove trace substances from wastewater and address stricter water quality requirements.
Many anthropogenic substances can only be removed to a limited extent using conventional processes. These include pharmaceutical residues, hormones, pesticides and microplastics. Micropollutant removal therefore relies on a range of technologies and process combinations, such as adsorption using activated carbon, oxidative processes or membrane‑based filtration. It is crucial that these additional treatment stages are reliably integrated into existing plants and continuously supplied with wastewater from upstream process steps. At the same time, new processes must be operated safely and efficiently embedded into the existing infrastructure.
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We support wastewater treatment plants with pump and system technology for the various processes within this treatment stage. Coordinated pump systems handle transport between the individual treatment steps and provide the required feed. Mixers support mixing within the tank and the even distribution of activated carbon or other reaction media. This allows the additional treatment stage to be integrated into existing plant operation from both a hydraulic and process engineering perspective.
This can facilitate the integration of new treatment processes into existing wastewater treatment plants and support their ongoing operation.
Services and solutions for the entire lifecycle of your plant
Wilo supports you reliably in every project phase – from planning and design through to commissioning and maintenance. The goal is safe, efficient and predictable system operation.
Our offering at a glance:
- Support with planning and design (e.g., product selection, simulations, documentation)
- Commissioning and acceptance testing
- Maintenance, repair, and spare parts service
- Energy analyses
- Digital services for condition monitoring and predictive maintenance
- Trainings for operation and maintenance
With standardised and individually tailored packages and digital tools, we help improve visibility into operating conditions and support reliable, long-term infrastructure operation.
Optimise wastewater treatment processes holistically
Whether you are modernising existing infrastructure, adding new treatment stages or planning entirely new treatment systems – precisely coordinated process technology is key to reliable operation.
Talk to us about your project. Together, we will develop wastewater treatment solutions that are designed to respond to evolving operational and regulatory requirements.
Contact our expertsSolutions across the water cycle
Our solutions cover the entire water cycle – from extraction and storage, through responsible use, to treatment and return to the natural environment. In this way, we support efforts to protect water quality and maintain water availability over the long term.
