Stricter soil rules could stop sludge re-use

The long-awaited revisions to the EU Sludge Directive are likely to bring stricter limits on metals and other soil contaminants, making the re-use of sewage sludge in agriculture difficult if not impossible, the Chartered Institution of Water and Environmental Management has warned.

Such changes would strongly affect UK water companies, leaving them no other option but to incinerate biosolids, a process that is both costly and polluting, CIWEM said.

As a by-product of wastewater treatment, sewage sludge tends to concentrate heavy metals and potential pathogens such as viruses and bacteria, raising concerns about its use on agricultural land. But sludge is also rich in nutrients and organic matter, making it a cheap and effective soil improver and fertiliser.

Current EU legislation requires sludge used on farmland to be pre-treated, and imposes minimum time delays after which land can be used to grow fruit and vegetables or graze livestock. CIWEM argues that there is no case for the limits to be strengthened as no evidence exists of human health risk.

But the European Commission is taking a precautionary approach to potential effects on eco-systems in the on-going discussions, influenced by emerging research.

A French scientific paper published recently suggests that herbicides present in sludge could be toxic to eco-systems. CIWEM dismisses this type of research as presenting no real evidence and therefore “not helpful,” and calls on the UK Government to resist stricter controls.

In a letter to environment secretary David Millliband, CIWEM executive director Nick Reeves said: “CIWEM considers there to be no justifiable, risk-based reason for adopting such a restrictive course as appears eminently possible.

“To introduce legislation that would mean the only realistic option would be incineration is a tragic waste of resources and misdirection of expenditure, not only in the UK but in many other EU Member States. We urge the Government to argue against such a course of action.”

Goska Romanowicz