What's next?

Regulatory standards for using sludge on farmland are only set to tighten. DEFRA completed a consultation on a review of the rules governing sludge for farming in Spring 2026 but has yet to publish the results. The review is in part in response to concerns about forever chemicals (PFAS) and microplastics in sludge entering the food system that have emerged in recent times.

Matt Taylor of Assured Biosolids says the BAS is also currently being reviewed for the first time in seven years to reflect developments in the water industry and agriculture. “There are lots of discussions around ensuring farmers as users of biosolids play their role in ensuring we are not polluting our watercourses and are making the best use of nutrients.”

As part of the review, there will be some “subtle” changes to testing requirements, Taylor says. The key focus will be on water company Hazard Analysis and Critical Control Points (HACCP) arrangements. HACCP systems are intended to control biological and chemical hazards throughout the production process. An update to the BAS standard is likely to come into force next Spring.

In the meantime, farmers will continue to look for ways to employ fertilisers not subject to international supply chains and price shocks, says Grant of the REA. One of the biggest benefits for agriculture would be to make biosolids and other biofertilisers more readily transportable and storable. “We might get to the stage where we can extract the nutrients and convert them into a more usable form, more like the synthetic fertilisers. That might mean pelletisation, or ammonia stripping, or there might be phosphate recovery from digestate.

“Some of the challenges around using digestate for farmers are the storage and spreading: it's liquid, there's a lot of water, it's expensive to transport. If we sort that, I think there’s further potential.”

Taylor agrees. “There’s a lot of work going on looking at the physical form of biosolids – whether pellets would be an improvement, and work considering extracting the nutrients, not just from biosolids but also from wastewater. Could you extract ammonium sulphate, produce high-ammonium material, and use it for agriculture or even industrial chemical processes? Struvite [a mineral composed of magnesium, ammonium, and phosphate], or other forms of phosphate extraction, there are investigations into that, too.”

With so much of the sludge in the UK already being used on farmland, there is limited scope for a widespread expansion. But extracting useful chemicals from the material or pelletising biosolids could make organic fertilisers more readily usable in parts of the country that aren’t close to water treatment works or urban centres. This would be welcome as farmers look to diversify their supply chains in a volatile world.

“If we can use more of the nutrients we’ve got here and not be reliant on manufactured or imported phosphate fertilisers, that can only be a good thing,” concludes Taylor.

For more information, contact Louise Ling: louise-ling@idexx.com