Written evidence submission from Pär Larshans (NIT0045)

Nutrient production in wastewater treatment plants:

Additional information requested by the UK Parliament’s committee on Environment and Climate Change in the House of Lords, following an inquiry hearing session on 12 March 2025

Many waterways in the United Kingdom suffer from eutrophication caused by nutrients released by sewage treatment works. Treated effluent discharge generates 43 percent of the damage in rivers that do not achieve good ecological status today, more than any other man-made cause.[1] This needs to be remedied.

However, another factor in modernising UK wastewater treatment should be considered crucial: The opportunity to turn treatment plants into production facilities for nutrients such as phosphorus and nitrogen. These precious commodities, used in fertiliser and animal feed, can be recovered from sewage by modern methods, shifting the economics of the water system while countering climate change and reducing UK import dependency. The additional information below, as requested by the peers, should be viewed in the light of this opportunity.

1. Costs and savings associated with upgrading wastewater treatment facilities to recover more resources

The financial case depends on the current state of the wastewater treatment (WWT) facility. Importantly, seizing the opportunity to recover nitrogen requires transitioning from today’s nitrogen removal methods, where bacteria are employed to release nitrogen back into the atmosphere, towards chemical tapping or recovery methods. The Aqua2NTM technology, developed by EasyMining, a Swedish-based environmental company Ragn-Sells subsidiary, captures the nitrogen at the plant in a form immediately applicable to the fertiliser industry.[2]

Several factors impact the economics of applying such technology and start harvesting the nitrogen:

• New revenue. Turning WWT plants into circular production facilities adds revenue streams. Today, nitrogen fertilizer prices follow energy prices closely, as the standard production method (Haber-Bosch) involves burning fossil gas. In addition to creating almost one per cent of global greenhouse gas emissions[3] and keeping the UK and Europe dependent on Russian gas, this means that the potential revenue for WWT plants will vary. Of course, adding phosphorus recovery as well generates yet
• another source of income if done in scale by collecting incinerated sewage sludge from multiple wastewater treatment plants
• Energy costs. Bacterial methods require energy to create suitable temperature conditions, which is not the case for chemical technology such as Aqua2NTM. Again, exact financial implications depend on energy prices as well as the condition and location of the facility. But the higher the prices of energy become, the more income a WWTP will generate if it uses Aqua2NTM.
• Biogas production. If the plant also produces biogas, removing excess ammonia can improve the stability and efficiency of anaerobic digestion. High concentrations of free ammonia can inhibit methanogenic bacteria, leading to process upsets and reduced biogas yield. Chemical nitrogen recovery technologies like Aqua2N™ can selectively remove ammonium from digested sludge liquor, helping maintain optimal conditions for biogas production. While this doesn't directly increase the energy content of the feedstock, it can support higher organic loading rates and more stable operation, ultimately enhancing energy recovery and financial returns.
• Expansion challenges. Expanding WWT facilities to remove more nitrogen from sewage, as needed, for example, when cities grow, is often expensive due to space constraints in densely populated areas. Chemical nitrogen removal is very space-efficient.
• Emission costs. Bacterial methods cause large emissions of nitrous oxide (N2O). Also known as laughing gas, it contributes nearly 300 times more to climate change per tonne emitted than carbon dioxide. Increasing efforts to combat N2O emissions will likely create financial pressure on WWT plants. If such emissions are included in cap-and-trade systems, plants stand to face a very steep increase in operating costs. The Aqua2NTM solution can help eliminate the risk that N2O emissions even occur.

In summary, if a WWT facility needs to expand to handle the nitrogen load, a chemical solution adding nutrient recovery could be up to 100 million pounds less expensive than remodelling the plant. For a recently built WWT plant looking to increase energy production from biogas, bring down energy costs without emitting more N2O, and produce a nitrogen fertilizer, the technology investment is in the range of 3– 4 million pounds.

With the new capacity, revenue streams are added, energy costs go down, and the organisation is protected from rising emissions costs.

2. Policy and regulatory reform improving nutrient circularity

Wastewater treatment plants are a very good example of how society remains linear, despite efforts to make it more circular. They spend resources in the form of money, energy, and working hours on squandering resources in the form of nitrogen and phosphorus, creating greenhouse gas emissions in the process, while keeping the UK dependent on importing nutrients it already possesses.

The only way to change this destructive pattern is to transition from a waste focus, where society’s primary goal is to minimise and handle waste, to a resource focus, where the guiding principle is to provide raw materials sustainably, whether from labelled “waste” or not.

The following policy proposals are key to establishing nutrient circularity:

• Implement large parts of the European Union’s revised Urban Wastewater Treatment Directive. WWT facilities must become energy neutral, measure and mitigate nitrous oxide emissions, and recover phosphorus. Add mandatory nitrogen recovery from facilities serving more than 100,000 population equivalents.
• New nitrogen side stream removal solutions contributing to N2O emissions should not be allowed, and existing ones should be phased out over a timespan of 15 years.
• Revise legislation broadly to ensure a resource focus. Today, commodities produced from waste face significantly steeper market access barriers than their exact equivalents from virgin sources,
• counteracting circularity. An illustrative example is the phosphorus extracted from incinerated sewage sludge using EasyMining’s and Ragn-Sells’ Ash2PhosTM method.[4] Despite being of equal or higher quality than feed phosphate from sewage sludge, it is not permitted in animal feed in the UK or EU.[5] For nutrient circularity to be feasible, products must be evaluated on quality alone, regardless of origin.
• Always ensure detoxification and scale. Any WWT solution encouraged by the government should be able to separate out hazardous substances and remove them from circulation. Also, a potential pitfall lies in small-scale, local solutions; to set up true circular loops, financial viability requires large- scale solutions, just like the virgin production of nutrients today.
• Allow and facilitate the construction of material banks. Actively storing waste at a large scale until technology for extracting desirable raw materials from it has been developed means securing sustainable production for the future. An inspiring example is found in Copenhagen, where the public utility company BIOFOS has foresightedly stored incinerated sewage sludge for decades, creating Europe’s largest phosphorus bank.[6] (Quality matters! Volume matters! Reliability matters! … for Circular Economy)

3. UK dependence on phosphorus imports

Phosphorus is a key nutrient in agricultural fertiliser and feed. Without it, farmers could not produce enough food. It is a finite resource that can neither be replaced nor synthesised. The high qualities that are depleting today in the world are also the ones that are used as feed phosphate. They are also threatened by the interests of the battery industry, which needs the same quality. This was why China banned phosphorus exports in 2020, indirectly leading to the unrest in Sri Lanka.

However, the UK has no domestic source of phosphorus.[7] Instead, demand is covered by imports from countries like Morocco (Western Sahara) and Russia. The fact that a few overseas nations control the entire supply of phosphate rock has long been recognised as a vulnerability, a situation exacerbated by Russia’s war in Ukraine and China’s restrictions on phosphorus exports. One recent and evident effect is the rise of financial pressure on UK farmers and volatile food prices for consumers.[8]

A major obstacle to establishing circular, domestic production is the ban on phosphorus recovered from sewage in animal feed. As long as the feed market remains closed, the incentive for businesses to scale up circular methods for phosphorus production is severely reduced. This leads to innovation, investment, and marketing being directed towards countries that do not have such legislation. For example, the entire phosphorus output from Ragn-Sells’s first two Ash2PhosTM facilities will possibly be sold in Canada, even though the plants are being built in Germany and Sweden, respectively. Germany has been rightly lauded

for its foresight in 2017 legislation requiring WWT plants to recover most of the phosphorus from its sewage streams.[9] However, as the resulting product cannot be sold as feed in the EU or UK, it will benefit farmers overseas while Europe remains dependent on lower-quality imports.

27/03/2025