Sludge PFAS concerns spark call for environmental regulation

Sewage sludge, sometimes described as biosolids, is produced by treating sludge from the wastewater recycling process. In the UK, as in the US, sludge is commonly spread to agricultural land as a fertiliser.

However, in a recent report, the Independent Water Commission highlighted that existing regulations on use of sludge in England do not provide for the monitoring of the potential for substances such as microplastics and per- and polyfluoroalkyl substances (PFAS) – so-called ‘forever chemicals’ – being contained in sludge before it is spread on land.

PFAS is a class of approximately 10,000 fluorinated chemicals used in everything from beauty and healthcare products, to clothing, semiconductors, medical equipment, in food and drinks packaging, in cleaning chemicals, and in firefighting foam, among other things. Different chemicals serve different purposes – such as making products resistant to oil, water, or heat, for example. Some PFAS chemicals are known to degrade very slowly – data is not available on all of them – which has led to the colloquialism ‘forever chemicals’ being used to describe them.

While studies on this issue are ongoing, concern has been expressed about the risk PFAS poses to human health and the environment, particularly upon its entry to waterways and food systems. There have been calls for tighter regulation of PFAS around the world and examples of PFAS-related claims being raised in litigation are increasing in number. The Independent Water Commission said there is “evidence that sludge can contain contaminants including microplastics and forever chemicals”.

The Commission was tasked by the UK and Welsh governments with making recommendations on how the water sector regulatory framework could deliver eight desired outcomes – including improving public trust in the regulatory regime and achieving better environmental outcomes. The Commission issued its final report last week, with regulation of sludge just one of the issues it addressed.

In its report, the Commission recommended that the regulatory oversight of sludge practices be tightened, by bringing use of sludge within the scope of existing environmental permitting regulations., It also acknowledged that if sludge is not used in the same quantities in future by farmers as it is today and alternative uses of sludge are not found, water companies could be left with nowhere to store excess sludge they produce.

“We have heard there is concern from water companies that if farmers were to start refusing sludge, on the grounds of sludge containing both contaminants and nutrients in excess of crop and soil need, this could lead to the sludge supply chain starting to break down,” the Commission said. “Water and sewerage companies may have limited resilience to manage this with an average three months of self-storage across the sector.”

Recognising this problem, the Commission said the UK and Welsh governments should work with water companies and regulators “to develop a long-term strategy for managing sludge” in tandem with introducing a new environmental permitting regime.

“Introducing a permitting approach to sludge should enhance environmental protection and provide greater protection over the spread of modern contaminants contained within sludge by introducing a risk-based approach to regulation,” it said. “This should enhance trust both within the public and the farming community due to greater confidence that sludge use is being more tightly regulated and controlled.”

“However, an expansion of regulatory activity alone will not be sufficient. The UK and Welsh government should work [with] water companies and regulators to develop a long-term strategy for managing sludge, including the trial and adoption of new sludge treatment approaches, such as pyrolysis,” the Commission said.

Pyrolysis is a process that involves subjecting organic materials to high temperatures in an oxygen-free environment. Thames Water is currently leading a pilot project that is exploring how pyrolysis might be used to support the recycling of sludge.

According to the Commission, further research should be carried out into the impact of substances such as PFAS and on the effectiveness of treatment methods. The Commission also suggested that a monitoring framework requiring wastewater treatment plants to regularly test and report concentrations of PFAS, microplastics and other substances be introduced if the evidence and an assessment of the costs and benefits supports this.

Other potential reforms that the Commission urged the UK and Welsh governments to consider include enhancing the obligations of wastewater companies in relation to the treatment of sewage, as well as an update of current water quality standards.

The Commission further recommended that “legal mechanisms” be considered to “ensure ongoing surveillance and assessment of emerging threats present in the water environment”, such as PFAS.

Katie Hancock of Pinsent Masons, an expert in environmental litigation, said: “Water UK has previously publicly called for more research and trials of new uses for sludge, along with a ban for some products using PFAS and a national cleanup plan funded by manufacturers using PFAS. This recognises that removing PFAS from water is not a simple or cheap process and the removal of some types of PFAS comes with significant practical challenges.”

“However, the water industry has also warned that requiring water company customers to pay for expensive treatment for PFAS in water overlooks the exposures to PFAS from other sources such as furnishings and clothes. In its response to the Environmental Audit Committee’s recent call for evidence, Yorkshire Water argued that the most desirable approach would be the assessment of risks prior to market entry of PFAS,” she said.

“The proposal to bring sludge within the environmental permitting regime is not new. This was previously proposed by the Environment Agency in a report first published in 2020, which later became the subject of a judicial review when the deadline for new legislation was changed and then removed. Following this fresh call for change, all eyes will be on government to understand what happens next, and when,” Hancock added.