Uisce Éireann is running out of space to spread sewage sludge and may look to use it on golf courses and race courses.
The water company spreads 70,000 tonnes of “biosolids” – dried, sterilised and granulated faeces, fats and grease from toilets and sinks – on farmland each year.
Volumes are expected to increase significantly in the coming years as the population grows.
Documents published as part of a public consultation on the issue show just 130 farms are spread with the waste.
RM Block
Options for using more farmland are limited as most farms already have large quantities of animal manures spread on them in the form of slurry.
Bord Bia will not allow its approved farm certification to be displayed on food produced on farms where waste is spread.
The documents show other ideas being considered are spreading on landfills, in mine restoration projects or in forests.
The biosolids could also be mixed with cement, incinerated or added to anaerobic digesters with farm waste to make biogas.
Uisce Éireann says it is looking for public input to its new National Bioresources Strategy to decide a “long-term vision for the sustainable management of wastewater sludge”.
“Advances in research, innovation and technology are increasing the potential to recover energy and valuable resources from wastewater sludge treatment processes,” said Aoife Kyne, asset planning bioresources manager at the company.
The volume of treated wastewater sludge that needs to be disposed of is small by comparison with the 40 million tonnes of animal manures spread on land each year. But it is expected to rise by more than one-third, to 96,000 tonnes, by 2040.
The human and food waste that makes up the sludge contains phosphorus, potassium, ammonia and nitrogen that can be used as fertilisers.
But Uisce Éireann said it can also contain “contaminants of concern” such as microplastics, pharmaceuticals, viruses, bacteria, heavy metals and so-called forever chemicals – persistent organic pollutants and polyfluoroalkyl substances (PFAS).
“We recognise the need to monitor source control to protect wastewater sludge quality,” the company said.
“Monitoring is also carried out on treated biosolids before reusing in agriculture.”
It said, however, there were currently no limits for levels of organic pollutants in treated biosolids used in agriculture.
“It is proposed that research and recommendations in this area are reviewed regularly, and we will undertake additional analysis as needs emerge to mitigate against any risk to soils or health,” it said.
