Friday, March 29, 2024

ClearTech an effluent game-changer

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Ravensdown says its new ClearTech dairy effluent treatment system will allow two-thirds of the water used to wash farm milking yards each day to be recycled. It removes up to 99% of E coli and phosphorus from the raw effluent water and cuts nitrogen concentration by about 70%.
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ClearTech’s promise, based on Lincoln University dairy farm results, convinced the judges at the South Island Agricultural Field Days to make Ravensdown the Agri Innovation Award winner.

“It’s a privilege for us to achieve this and the culmination of our partnership with Lincoln,” Ravensdown’s ClearTech product manager Carl Ahlfeld said. 

“We’re all excited. There’s been a lot of work and a lot of study, including three published papers on this.”

“We think it is a game-changer for dairy farm effluent inputs.”

The treated water can be reused in washing yards after a change in rules by the Ministry for Primary Industries. The approval still does not apply to the milking parlour and equipment, which still require fresh water.

As well as the pilot plant at Lincoln a ClearTech system is being installed at LIC’s innovation farm in Hamilton.

Ahlfeld is scoping dairy farms in Canterbury and is confident of signing-up business soon.

The system costs just under $90,000 to install.

The raw effluent, which is 99% water, is transferred to a second tank in which a coagulant works to tie up the phosphate, turning it into a slow-release form of phosphorus. After a two-to-three-hour process the clarified water is transferred out for reuse and the residue can be emptied into the farm storage pond.

The Lincoln experience since May last year shows the treated effluent can be applied to land in irrigation and is less likely to cause adverse environmental impacts on water quality than spreading untreated effluent.  

ClearTech is especially useful in the high-risk, low-demand period of August to November and when there is higher soil saturation in April and May, Ravensdown says.

In a research paper Lincoln professors and ClearTech science leaders Keith Cameron and Hong Di said an average 70 litres of water a day is used per cow to wash down the infrastructure after milking so a 400-cow farm uses an average 28,000 litres a day or 7.5 million litres over a milking season.

Public concern about water-use efficiency created an urgent need to find ways to reduce those volumes, they said.

The Lincoln farm had 555 cows generating about 58,000 litres of effluent a day. They found the ClearTech system was can clarify two 27,000-litre tanks a day so with two runs it can treat over 90% of all effluent produced there.

Ahlfeld said a lot of the equipment used in ClearTech can be bought off the shelf so scale can be built-up quickly.

“But it’s new tech and we will want to dot the is and cross the ts before we scale up.”

The judges described the ClearTech system as truly innovative and said it will enhance New Zealand’s clean, green image.

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