Phosphorus & nitrogen in wastewater – what are the environmental issues?
Nicola De Moraes
Why it is important to remove nitrogen and phosphorus from wastewater?
When wastewater (from households, industry, commerce) is treated and then discharged into rivers, estuaries or coastal waters, it inevitably carries nutrients such as nitrogen (in various chemical forms) and phosphorus (often as phosphate). If these nutrients are not adequately removed, a number of environmental issues arise — especially in the UK where many freshwater and coastal systems are already under pressure.
Plantwork Systems is working with various UK water companies to remove excess phosphorus and nitrogen from wastewater before returning it to our waterways…
The risks of nutrient rich wastewater discharge…
Eutrophication
Excess nitrogen and/or phosphorus in receiving waters can stimulate the growth of algae and aquatic plants far beyond natural levels. This is the process commonly called ‘eutrophication’. In the UK’s rivers, lakes and estuaries, high nutrient loads are a recognised cause of such problems.
When algal blooms occur:
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They can block sunlight reaching deeper plants, reducing submerged vegetation.
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When the algae and plants die, their decomposition uses up oxygen in the water, leading to hypoxia or even anoxia (low or zero oxygen). This harms fish and other aquatic life.
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- The altered community structure means biodiversity can decline (some species dominate, others vanish) and water quality deteriorates.
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In estuaries and coastal zones, nutrient loads can trigger harmful algal blooms which may have further knock-on effects (toxins, beach closures, impacts on tourism/fisheries).
So, if nitrogen and phosphorus is not removed from wastewater, you risk pushing aquatic ecosystems into degraded states.
Regulatory compliance and sensitive catchments in the UK
In England (and the wider UK), environmental regulators are increasingly designating “sensitive catchment areas” for nutrients. For example the Environment Agency has published that many wastewater treatment works must meet nutrient-pollution standards for phosphorus and nitrogen in certain catchments by specific deadlines, usually 2030 at the latest.
This means that failing to remove nutrients can lead to non-compliance with permits, increased cost and potentially regulatory action or required upgrades of treatment plants.
Protecting water supply, recreation and nature
Clean rivers and estuaries are not just good for wildlife: they’re important for human use (recreation, angling, tourism), for drinking-water quality and for natural capital (ecosystem services). The degradation of water bodies via nutrient pollution undermines those basic values.
Government ‘Water Special Measures Act 2025’.
The new bill aims to tighten the regulation of water companies and address the pollution of UK waterways, responding to growing concerns about sewage discharges into rivers, lakes, and seas, a critical issue in recent years.
Criminal liability: The Water (Special Measures) Act 2025 allows for criminal prosecution of company executives for obstructing investigations into pollution, with potential prison sentences of up to two years.
Executive bonuses: Regulators now have the power to ban executive performance bonuses for companies that fail to meet standards related to consumer issues, the environment, criminal liability, or financial resilience.
Increased compensation: As of July 2, 2025, water companies are required to increase customer compensation payments up to tenfold.
Environment Agency funding: The Environment Agency has received an increased budget, funded by charges from water companies, to hire more enforcement officers, improve equipment, and increase inspections of water company assets.
Special administration: The government has new powers to put failing water companies into a special administration regime, which involves an insolvency process
Water companies and regulation
While companies remain privatized and are not being nationalized, the government is taking significant steps to increase oversight and accountability.
There has been a proposal to abolish Ofwat, the water regulator, and replace it with a new structure, but the new powers granted by the Water (Special Measures) Act 2025 are already in effect.
On the other hand, the benefits of these nutrients are critical to the environment!
Phosphorus and Nitrogen are key components to survival and the environment, so the balancing act is crucial to save these important nutrients as well as removing them from wastewater…
Food production: Agriculture depends on nitrogen and phosphorus inputs (fertilisers) to grow crops. Global food security is linked to the availability of these nutrients.
Ecosystem productivity: Plants, algae and thus the entire food web depend on N and P. Without them, ecosystems would be nutrient-starved; with too much, they collapse into low-diversity, degraded states.
Resource constraints & sustainability: Especially phosphorus being finite means that how we use and reuse it matters. Waste streams (including wastewater) present both a risk (loss of P to the environment causing pollution) and an opportunity (recovering P for reuse).
Global cycle disruption: Human activities have altered the natural cycles of N and P substantially, causing global environmental issues (water pollution, greenhouse-gas interactions, biodiversity loss). For example, rising reactive nitrogen (Nr) in the environment is a recognised planetary-boundary issue.
The UK is making meaningful progress in protecting nitrogen and phosphorus supplies via strategies for efficient use, recovery, reducing losses and regulating pollution. For phosphorus, the national transformation strategy marks a significant step. For nitrogen, the forthcoming push towards a nitrogen national strategy will be critical. However, full implementation, coordination, innovation-scale-up and strong regulatory enforcement remain key to fully realising the benefits.
Plantwork Systems – our work with Nitrogen and Phosphorus Removal
We work closely with various water companies to remove nutrients from wastewater processes and help the water companies meet their ever tightening consent levels.
Our flagship product, NUTREM® is a unique, compact and efficient advanced Biological Nutrient Removal (BNR) system offering industry-leading levels of Total Phosphorus (TP) removal, with the added ability to remove Total Nitrogen (TN) in the same tanks, so avoiding significant cost. NUTREM® is also effective in all seasons, with lower capital expenditure and lower operating costs.
- Total Phosphorus (TP) removal – below 0.25 mg/l
- Total Nitrogen (TN) removal – below 5 mg/
NUTREM® secured joint first place out of 29 competing technologies in the UKWIR National Phosphorus Removal Trials in 2019 and was also a finalist in the Water Industry Awards for its innovative Filtration+ product in 2023.
We have now been invited to join the UKWIR Nitrogen Removal Trials in April 2026, being held at our existing NUTREM plant at Southern Water in Petersfield.
Get in touch today for more information.
Tel: 01420 590 400
Email: [email protected]
Web: www.plantworksystems.com