Fonterra's Maungatūroto dairy factory is recycling water through a natural wetland in an innovative project to reduce its water usage by up to 25 per cent.
The plant's environmental manager, Stuart Glen, said the initiative is a model that could be implemented at other manufacturing sites in New Zealand and worldwide.
Milk is made up of mostly water, with the factory extracting the rest of the components to be made into milk powder through an evaporation process.
The site had been considering options for saving water for many years, the issue becoming more pressing with several years of drought and a growing community nearby.
As a major water user in the area, Fonterra wanted to reduce its reliance on the Kaipara District Council supply.
"I started with the co-op a little over two years ago, and the idea for cleaning site water by using the wetland as a natural bioreactor had been looked at but faced a few challenges.
"It has required thinking outside of the box and a multi-faceted approach to overcome these challenges including maintaining the wetland's ecosystem, ensuring food safety quality, and not interrupting the site's efficiency to operate," he said.
Glen said the reclaimed water from processing was filtered through the natural wetland before being directed through the site's water treatment plant and reused.
The treated water was able to be used again in the processing plant as well as for drinking water.
The wetland recycling process is now producing about 500,000 litres a day and could produce up to 700,000 litres – representing about a quarter of the 2 million litres a day being used in the milk powder processing plants.
Glen spent about 18 years living in Australia where he was involved in several water-saving projects in the food industry, so has been able to apply his knowledge to this project.
"So much of this project has been about overcoming all the potential risks to our business. We had to be able to prove that we were not creating any risks to the site or the food we are making. We've gone through every aspect and managed to prove that it can work.
"It's taken about a year to go through everything and prove the concept,'' he said.
Glen said the evaporator condensate (water extracted from milk) was tested before it entered the wetland and again when it was brought back into the processing plant.
"The water quality monitoring is done in real time to make sure the water is as pure as possible at all stages in the process.
"The pumping system is set up to be able to divert water back to the Wairau River at the first sign of any flooding of the river. This is critical to protect the integrity of the water for the site,'' he said.
The wetland covers about 10,000sq m.
It was already well established with flaxes, reeds and trees with some additional planting done over the years.
"There is quite a bit of wildlife in there as well,'' he said.
"We've taken a holistic, circular and nature-based approach to look at how we could work in partnership with nature. Providing the right amount of nutrients for the native plants and habitat to thrive promotes greater biodiversity within the wetland.''
Glen said further water-saving measures were being introduced within the factory to try to get savings of up to 50 per cent.
"We've been looking at all processes on the site to make sure we are not using more water than we need to. This means more water is available for the community,'' he said.
The project has enabled Kaipara District Council to have more resilience in their water supply and has been seen as a great initiative by representatives of local iwi Te Uri o Hau and the Northland Regional Council.
The water-saving initiative is also a finalist in this year's Sustainable Business Awards, with the winner due to be announced in November.