Modern miracle– from wastewater to fertiliser

The Eco Shop’s Sarah Williams with a new fertiliser made from wastewater.

Whangaparāoa’s Eco Shop is the first in the country to retail a sustainable new fertiliser with a unique point of difference – it’s made from Auckland’s treated wastewater.

The product, called Emerge, is a sandy, slow-release fertiliser made from struvite – a hard mineral better known as kidney stones. It utilises phosphorus and nitrogen which crystalise during the wastewater treatment process. 

The natural, renewable resource is extracted, sun-dried, sieved and sorted at Watercare’s resource recovery facility at Māngere Wastewater Treatment Plant.

It is odour and pathogen free and can be used on all plants, including turf and edibles like vegetables and herbs.

Watercare’s resource recovery manager Rob Tinholt, who leads product development, says the product represents a shift in thinking.

“We realised 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,” Rob says.

Eco Shop manager Sarah Williams, says the product is very different from the energy-intensive, imported fertilisers we mainly see in New Zealand that have a large carbon and environmental footprint. 

“There’s a lot of clay soil in Whangaparāoa that can be a challenge for gardeners so any organic products we can provide that add nutrients back to the land are beneficial,” she says.

Besides, she says, there’s a bigger picture for the zero-waste movement in getting on board with products made from recycled, treated wastewater.

“Currently New Zealand imports over 125 million tonnes of rock phosphate from overseas each year. Struvite is a clean, low-impact and locally sourced product in comparison. We need to start harvesting all the phosphorus from wastewater treatment plants around the country and getting this nutrient back to the land to maintain our soil fertility. Plants cannot grow without phosphorus so all New Zealand’s agriculture, horticulture and viticulture industries depend on this mineral – and we have a source of it right here on tap.”

Sarah adds that sales are going well and people are curious about the product and where it comes from.

“When they see it’s a nice clean sandy, odour and pathogen-free material and realise it has nothing to do with any kind of wastewater sludge, they are onboard with it.”

The Eco Shop is part of Whangaparāoa Community Recycling Centre, 637 Whangaparāoa Rd, Stanmore Bay. It is open Thursday to Monday, 10am-4pm.

Wendy Zhou

NEW at Recycling Centre • Rescued fruit and veg: The Eco-shop at the recycling centre now stocks fruit and vegetables from Perfectly Imperfect – a social enterprise based in Browns Bay that rescues produce from growers and importers that won’t make it for sale because of imperfections.  Around 45 percent of food is lost this way and Perfectly Imperfect wants to reduce that number by rescuing and selling or gifting it. There will be a stall at the Eco-shop on Thursdays, 1pm-4pm where locals will be able to purchase bags of fruit and vegetables, $15 for a bag. • Soft plastics, light bulbs, and coffee pods can also now be recycled at the Recycling Centre. All soft plastics will be taken directly to the Future Post factory in Waiuku where plastic fence posts and garden bed sleepers are manufactured. Unlike wooden posts, Future Posts last a lifetime and do not leach toxic chromium copper arsenic into the soil. There is a small charge for soft plastics – $1 per 10L and the light bulbs are $2 per long fluorescent tube and $1 per bulb. Coffee Pods are free. • Besides plastics, the recycling centre also accepts polystyrene, batteries, and all broken appliances for a charge.