The two beakers illustrate how ClearTech separates farm dairy shed waste water into effluent and water able to be reused for yard washing.

A breakthrough in effluent technology that allows dairy farmers to treat dairy shed "green water" so it can be confidently reused as yard wash, could lift the dairy sector's effluent and water efficiency.

The emerging technology, known as ClearTech, was developed in a joint project between fertiliser co-operative Ravensdown and Lincoln University and looks to cut freshwater use, help existing effluent storage go further, and reduce the environmental and safety risk linked with farm dairy effluent.

The pilot project, which is installed at the Lincoln University Demonstration Farm, represents a $1.5 million investment so far by Ravensdown.

SUPPLIED ClearTech separates farm dairy shed waste water into effluent and water able to be reused for yard washing.

ClearTech will be available commercially later this year, once testing is complete, in a managed rollout.

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Ravensdown effluent technology manager Jamie Thompson said about a quarter of a dairy shed's fresh water use is used during yard washing, so the potential benefits were enormous of safely reusing treated water. "ClearTech will look to save 42 billion litres of freshwater a year - the equivalent of 17,000 Olympic-sized swimming pools through the reuse of safer water for dairy yard washing."

The technology, which binds effluent particles together in order to settle them out from the water, is installed between the dairy shed and the effluent pond. Effluent circulating in the system is automatically monitored and treated. The separation process kills up to 99 per cent of micro-organisms such as E. coli and reduces smell.

Farm dairy effluent is typically 99 per cent water and one per cent effluent particles.

ClearTech links to computer processors, controllers, tanks, pumps and pipes and can be retrofitted. Coagulants are used to bind effluent particles together which allows them to settle out from the water. The recycled water can then be reused on the farm for yard washing and the remaining treated effluent is stored in the existing effluent pond.

Thompson said 70 per cent of dairy farmers' environmental spending goes on effluent management. The technology would help dairy farmers save money by making their effluent storage go further and help to meet their compliance obligations.

Lincoln University professor of soil science Keith Cameron, joint lead on the ClearTech system with Professor Hong Di, said they were encouraged to see the willingness of dairy industry stakeholders collaborate with the project.

Colin Glass, chief executive of Dairy Holdings , a corporate which owns 59 dairy farms in the South Island, said the technology had the potential to transform the use of water in dairy operations and provided another tool for reducing nitrogen losses.