Whether you’re farming fish or cows, the process will generate nitrate waste. Ngāire Scartozzi has experience in dealing with both livestock types and has developed technology that promises make dairying cleaner using tech she applied to fish farming. Richard Rennie reports.
Ngaire Scartozzi says as different as cows and fish obviously are, they have one thing in common: they both excrete significant amounts of ammonia into a concentrated area.
“Fish-farming barramundi on the Gold Coast, we relied upon having large volumes of reticulated water pumped around and around that had to be kept really, really clean to hold the high stocking densities we had.”
They used microbes and bacteria to clean the water of some of its ammonia before it was reused.
Combined with her hands-on experience on dairy farms, and research work with AgResearch, Scartozzi had always been aware of the potential for such cleaning technology on dairy farms, but had initially developed a system for cleaning up urban water with Christchurch City Council.
She spent the past year in the department of applied sciences and social practice lab developing her eClean Bioreactor for removing contaminants including nitrates, heavy metals and E.coli from urban waterways.
The research is conducted at the Ara Institution of Canterbury and Scartozzi is also a graduate student doing a research thesis on the technology and cultural monitoring at the University of Canterbury.
The bioreactor work was backed by te Ohaka Centre for Growth and Innovation, and HTK group, which specialise in working with Māori and indigenous groups.
“But we also found the technology was well suited to removing nitrates at even higher levels than the urban environments where nitrate levels were one to two parts per million. That compared to some parts of rural Canterbury where levels can vary from 10-25ppm.”
At the core of the technology sits a population or microbiome of bacteria capable of digesting nitrates and other contaminants. Scartozzi likens it to a massive stomach populated with suitable bacteria or nitrophytes that can be tuned in to deal with the particular waste profile.
“As an engineered system we know how to pull different levers. For example, if it’s acidic water, we can add in bacteria that will help increase the pH.”
The system’s flexibility is such that researchers can monitor the system’s clean-up in the field, and if it requires adjusting, take a sample, go back to the lab and adjust the bacteria mix.
“We also work to include indigenous de-nitrifying microbes in the populations, customising the biome to that area’s naturally occurring populations as much as possible.”
The first farm field trialled site is alongside a managed aquifer near Ashburton in the nitrogen red zone, an area facing the need to reduce nitrate levels by up to 30% by 2035 before heavy restrictions on fertiliser use come on.
The equipment will appear as a large container like box, with water flowing in one end and out the other. Proprietary media within the container house the bacteria.
“It’s like a massive spa for bacteria, they get all the food and water they need in there.”
Initial volume treated will be 150,000 litres a day, scaling up to 500,000 litres, then 1.0 million litres a day.
Initial lab results from the Ashburton trial are encouraging, with water going in at 15ppm of nitrates and coming out at 4-5ppm.
“We are also seeing a 50% removal of E.coli and 60% removal of heavy metals.”
The units require a power supply if there is insufficient water head, but power is relatively easy to arrange in Canterbury with its network of irrigation pump stations.
Scartozzi says farmer interest in the process has been intense, with irrigation co-operatives particularly keen to participate, aware of the need for nitrate reduction sooner rather than later.
On a commercial level, Scartozzi is ramping up her sales and marketing efforts mid-year under her eClean brand. Her business partner is the manufacturer of the units, which is capable of making them to bespoke size and capacity.
She sees the most likely placement of the units for dairy farmers as being at drainage points, or where water goes into effluent ponds.
“It’s really anywhere that represents a point source discharge for nitrates.”
Ideally the system is likely to be one per 400 cows, delivering a 10-15% reduction in nitrate levels to water, giving a healthy boost to achieving the 30% reduction target.
“And the beauty is the emission from the bacteria’s activity is straight inert nitrogen.”
She says there has been a strong level of investor interest, and she is about to embark of a funding round.
