Phosphorus is one of the central issues for wastewater treatment now and over the next two decades. Here Peter Balslev, our Senior Process Engineer outlines the current situation with regard to phosphorus treatment in the EU and the options for addressing this challenge.
Phosphorus is an important mineral; it is crucial for agriculture and essential for human health. However, excess quantities in the natural environment, especially in watercourses, can cause serious damage to the ecosystem. Therefore, phosphorus removal is a critical part of wastewater treatment, with progressively tightening regulatory limits driving improved water quality.
While overuse of fertilisers in farming has traditionally been associated with high levels of phosphorus in rivers, this is generally seasonal peaks. Although it varies by country and the level of urbanisation in any given area, it is estimated that in Europe treated wastewater accounts for around 50% of the phosphorus in rivers when it reaches the sea. Therefore, there is now a particular emphasis on reducing the contribution from this source.
Phosphorus is a key focus in the EU’s updated Urban Wastewater Treatment Directive (UWWTD), which came into force in January 2025. The new requirements include far stricter levels for phosphorus in effluent from wastewater treatment facilities. By 2045 sites with a population equivalent (p.e) of 10,000 to 150,000 must achieve 0.7 mg/l and 87.5% reduction while for sites with a p.e of more than 150,000 the target is 0.5 mg/l and 90% reduction.
For operators, this means that investment in more effective treatment and additional treatment steps is required in the coming years. This raising of standards also has an impact on some industrial businesses. For those whose wastewater has high levels of phosphorus, discharge permit conditions issued by water companies will also be tightened to support the overall goal. For both municipal and industrial applications, there are a number of options for wastewater treatment to achieve the required standards.
With this type of treatment, microorganisms are grown in the water that can assimilate phosphate for growth and also absorb and store phosphorus as polyphosphate in a process called enhanced biological phosphorus removal (EBPR). The phosphorus becomes part of the biomass, which is then separated from the treated water at the end of the process.
A treatment solution based around our Cella* Moving Bed Biofilm Reactor (MBBR) is ideal for municipal and industrial applications and can help to remove carbon, nitrogen and phosphorus. Cella is a highly sustainable solution that delivers excellent performance and allows the generation of biogas. Its small footprint relative to its capacity means it is suited to upgrade programmes.
This involves using metal salts, typically of iron or aluminium, to precipitate ortho-phosphate. Veolia's KlarAid* range offers several options for this. Phosphate precipitation often takes place in conjunction with coagulation and using Veolia's blended products and plant-based coagulants can offer benefits. Phosphate precipitates as a solid and is removed in either a settlement tank together with the biological sludge or in a tertiary solid capture process such as a disc or sand filter. Combining biological and chemical phosphorus removal is a very safe and chemical saving process that can easily meet <1 mg/l of total-P. When targeting even lower standards additional technologies are available. Our Actiflo* clarifier solution utilises microsand to ballast the chemical flocs, significantly increasing the settling velocity of the particles, and achieving low outlet standards < 0,1 mg/l of total-P. It delivers very short retention times and a more compact design. In fact, the footprint of an Actiflo system is as much as 40 times smaller than conventional clarifier systems.
Filtration technologies – especially disc filters, thanks to their compact footprint – can provide an excellent solution for sites looking to improve the effectiveness of their treatment process to meet more stringent standards. Disc filters use a fine media mesh mounted on a number of rotating discs to effectively remove nearly all suspended solids. In addition, our Hydrotech* Disc Filters provide a higher level of filtration for a smaller footprint than many standard drum or disc filters.
There are also solutions, such as our ZeeWeed* membrane bioreactor (MBR), that combine biological treatment with high-grade filtration to achieve very high levels of water quality. The ZeeWeed MBR features an ultrafiltration (UF) membrane, which will not only remove suspended solids and nutrients, but also bacteria and viruses, to achieve reuse-quality water.
Choosing the right solution based on the exact requirements of the site is essential to ensure an effective and cost-effective approach. As a leading water treatment specialist, our expert team will be able to provide guidance on the most appropriate technologies for each site based on decades of knowledge and experience at sites in every area of the world. We also have a wide range of solutions, meaning, unlike some, we can truly offer the right technology for every application.
Speak to one of our experts about how we can assist you with your site's phosphorus removal, HERE.
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