Fertiliser extracted from treated wastewater is officially launched

There’s a new, premium fertiliser in the New Zealand market with a uniquely local, Auckland point of difference.

EMERGE struvite is a sand-like, slow-release fertiliser that we produce from phosphorus and nitrogen that crystalises during the wastewater treatment process.

It’s a natural product that’s extracted, sun dried, sieved and sorted at a resource recovery facility at the Māngere Wastewater Treatment Plant.

Our resource recovery manager Rob Tinholt says it’s odour and pathogen free, making it ideal for growing plants and grass.

“We are taking something traditionally seen as waste and harnessing the good in it,” he says

“We have shifted our thinking of what it is we do from simply treating wastewater to realising we have one of the highest phosphorus and nitrogen concentrations in NZ right at our fingertips, so we are developing practical ways of extracting that nutrient value to return to soil.

“One of our key priorities as a company is to be fully sustainable, so it’s a natural progression to look at how we can apply circular economy principles to reimagine waste as a valuable resource.”

After conducting several trials and meeting the standards for being recognised as a normal fertiliser, according to the New Zealand Fertiliser Association Code of Practice, we made our first sale of the product to a turf management company earlier this year.

It’s now being applied to support turf growth on fields and help prepare grounds for winter sports seasons.
“This sale is a watershed moment on our resource recover journey and a positive step forward as part of our long-term plan to create a range of products from treated wastewater,” Tinholt says

Will Bowden, Manager of NZ Turf Management Solutions, who is an independent turf consultant, sees significant value in this approach and ethos.

He’s been involved with initial struvite trials and found it to be so successful that he’s recommending it for clients across a range of turf applications. He’s also looking at the fertiliser’s future potential to support pasture growth.

“When you think about some of the ethics and the carbon footprint of importing fertilisers - in in particular phosphorus - from overseas the value of using a locally-produced product like struvite is a no-brainer,” Bowden says.

“The added bonus is that struvite is also mitigating waste generation here in New Zealand.

“Regional governments and community stakeholders are more engaged than ever in the work we do to deliver quality sports surfaces and recreational facilities within a sustainable framework.

“The potential of using struvite as a supplementary amendment for turf nutrition aligns well with our commitment to researching sustainable products and specifying ‘better’ alternatives to the amenity sector.”

We have capacity to produce hundreds of tonnes of struvite a year and have plans to expand the product’s market reach over the next few months.

Proceeds from any sales are recovered by the resource recovery workstream in support of further investigations.

Tinholt is also experimenting with making an organic potting mix from treated biosolids – a major nitrogen-rich by-product of treating wastewater.

So far, he has successfully grown more than 10,000 seedlings in potting mixes with different ratios of pasteurised biosolids and other organic material like bark.

Once he’s perfected the mix, the next step is to find markets for the potting mix.

Currently, a few seedlings are sold, but most from the trials are given away for free to local marae, schools and community groups.