River pollution solution tested on dairy farm in Wales

Reed channels filter animal slurry to produce clean water for cows to drink

A new system for treating animal waste from dairy farms promises to reduce river pollution and costs for farmers.

The college farm Coleg Sir Gâr Gelli Aur in Carmarthenshire converts the pulp into a solid agricultural fertilizer that is cheaper than imported counterparts.

The technology also filters waste to the point where it can be used by the farm as a source of clean water.

After five years of development, the process is ready to be rolled out commercially on farms across Wales.

John Owen, from the Tywi Farm Nutrient Partnership, said pulps are difficult and expensive to store safely.

They contain phosphates, a pollutant that can kill fish and aquatic life. Early data shows that the process reduces phosphates by 90%.

“It concentrates the liquid nutrients of the pulp into a solid form,” he explained. “Many farms will be able to extract the solid nutrients or use them on their own land as fertilizers.”

It could give farmers additional income at a time of dramatic increases in the cost of agricultural fertilizers and water shortages.

Pure water extracted from the pulp after the filtration process

The water extracted from the pulp is tested as drinking water for cows

It is even being tested as a potential drinking source for animals.

The process sees the remaining waste filtered through a series of reed grooves, leaving the water to now be used to wash yards and clean equipment.

“[The process] it cleans the water to a quality clean for the cows to drink,” Mr Owen said.

Cows in Gelli Aur

Cow waste at Gelli Aur college farm turned into solid fertilizer and clean water

Part processed pulp

Part processed pulp, which can be used as fertilizer.

The development team was supported by Welsh Government grants, European funding and a range of commercial companies.

Mr Owen said the system was now in operation at the college’s Gelli Aur farm, near Llandeilo, and could be rolled out to other farms at any time.

“Our trading partners are already talking to a number of farmers about implementing the process,” Mr Owen said.

“But we also want to explore the possibility of identifying treatment hubs so that not only medium to large-scale farmers can benefit, but also some of the smaller farms.”

Marc Williams in front of the equipment

Marc Williams from Natural Resources Wales says the project is extremely exciting

Marc Williams, agricultural policy adviser for Natural Resources Wales, said the Welsh Government agency was proud to be a project partner.

“Slurry is a pollutant in our waterways which, if managed incorrectly, can have a devastating effect on river quality,” Mr Williams said.

“It can cause significant fish kills.”

There were 167 incidents of agricultural pollution in Wales last year, he said, with the majority coming from the dairy sector.

He called the process extremely exciting, reducing the overall pulp volume, removing the water contained in the pulp and using the nutrients efficiently.

Farmers are invited to an open house at the Gelli Aur campus on September 15 to see the new system in action.

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