By Dr. Mikael Khan and Paul Pickard
UK waterways face a persistent threat: nutrient pollution. As water companies gear up for AMP8, finding sustainable, cost-effective phosphorus removal solutions is crucial.
The health of UK watercourses has been deteriorating over the last few years. Environment Agency figures show that only 14% of rivers in England have good ecological status in 2023. Whilst recent headlines focus on uncontrolled discharges from storm overflows, nutrient pollution – particularly from excess phosphorus – remain a critical threat.
Eutrophication due to excess nutrients like nitrogen and phosphorus can lead to algal blooms in lakes, rivers, and oceans. Oxygen depletion then takes place, suffocating other aquatic life forms. The UN estimates that 30% to 40% of lakes and reservoirs worldwide have been affected.
Nutrient overload comes from several sources, including agricultural runoff from farms and wastewater discharges from urban areas. For farms, applying fertilisers responsibly is key. Regulators can create guidelines to help, but enforcing and monitoring across vast areas can be challenging. The issue of urban wastewater is complex, but there are solutions. Unlike agricultural runoff, urban wastewater falls squarely under the responsibility of UK water companies.
Clear targets for clean water
In the UK, strict environmental regulations govern phosphorus removal, including the Water Framework Directive (WFD) and the Urban Waste Water Treatment Directive (UWWTD). These laws set limits on phosphorus concentrations in wastewater discharges to protect water quality and prevent eutrophication.
Monitoring phosphorus in wastewater is critical to ensure compliance and identifying pollution sources. This data allows stakeholders to track phosphorus levels over time, assess treatment effectiveness, and make necessary changes to reduce environmental harm. Finally, monitoring confirms the success of these interventions, ensuring phosphorus levels stay within acceptable ranges.
Kicking off in April 2025, AMP8 is the eighth water management plan for England and Wales. This five-year plan by Ofwat, the Water Services Regulation Authority, prioritises tackling climate change, protecting the environment and delivering excellent service to both customers and society.
AMP7, implemented in 2020 until 2025, brought in strict phosphorus limits, some as low as 0.1mg/l. The amount of phosphorus allowed in wastewater can vary depending on the health of the receiving watercourse and some more sensitive locations may have very strict limits.
While biological phosphorus removal is promising, most wastewater treatment plants still use chemical precipitation with metal salts. This increases the need for coagulants like ferric, and pH-adjusting chemicals. Careful dosing studies are crucial to minimise waste and costs.
In AMP8, some water companies want to reduce phosphorus even in untreated storm flows. Constructed wetlands offer a sustainable, environment-friendly solution. They act as natural filters, absorbing nutrients and removing organic pollutants.
Phosphorus solutions start with smart data
Phosphorus pollution is a serious challenge, and pinpointing the source is the first step towards a cleaner water future. SUEZ’s river catchment sampling services offer a powerful solution to achieve this. Our site project management team, with over 30 years of experience conducting site sampling projects, ensures efficient and reliable data collection. Our sampling programme establishes baseline phosphorus levels and helps determine the impact of wastewater treatment compared to other sources like agricultural runoff.
Selecting the ideal wastewater treatment solution requires careful consideration of several key factors, including the volume of wastewater to be treated, the specific makeup of the wastewater, the quality of the treated effluent, the available space on the treatment site and the condition and performance of any existing wastewater assets. Having these data will allow water companies and their contractors to make informed decisions about appropriate treatment strategies and be fully compliant.
Informed decisions need accurate information. This is why SUEZ provides both wastewater sampling and chemical dosing optimisation studies to ensure efficient and effective phosphorus removal. In the last year alone, we have analysed over 100 sites, providing insights needed to design next-generation AMP8 solutions and successfully complete AMP7 upgrades.
Phosphorus challenges demand collaborative solutions. Let us all work together to safeguard our watercourses. With informed data and tailored solutions, we can build a cleaner future for our communities and the environment.
For more information about SUEZ’s services in the water sector, please email aquaenquiries.uk@suez.com or call 01924 242255.
