A geotechnical fix for New Zealand’s phosphate-polluted lakes is struggling to find traction with the country’s authorities.
Lachie McKinnon, CEO of Australian stock exchange-listed Phoslock Environmental Technologies, says its products are an effective way of improving water quality.
The company has two products: Phoslock, which is primarily for treating lakes; and Phosflow, for flowing water. Phoslock was developed in the 1990s by Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) and later commercialised.
The product’s main ingredient is bentonite clay modified with lanthanum. It reacts with phosphorus to make it inert. Excessive phosphate pollution contributes to nutrient overload, excessive algal blooms and low water quality – a process known as eutrophication.
Last October, Phoslock Environmental Technologies (PET) carried out treatment at Auckland’s Chelsea Ponds, which were built as a water source for the Chelsea sugar refinery. McKinnon said that was a vote of confidence from Auckland.
“It was looking great, until the floods of course. That’s unfortunately brought a lot of sediment and nutrient pollution into that waterway.”
That was very disappointing and the results of the treatment and the impact from the floods have yet to be assessed, he said.
The worst lakes are in areas affected by farm runoff.
“I’m a farmer myself, so I’m careful with my words,” McKinnon said. “That’s where significant, particularly nitrogen but also phosphorus, pollution is arising.”
Although superphosphate fertilisers aren’t as commonly used as they once were, there is also significant phosphorus runoff from urban areas.
McKinnon said he doesn’t want to target any group or individuals – “I don’t want to be seen as a whingeing Aussie” – but NZ has been a frustrating place to crack beyond Chelsea Ponds.
The problem is not a distrust of Phoslock’s products but a lack of engagement by authorities, which includes councils and iwi organisations.
The work at the Chelsea Ponds was largely down to two people who were keen to try it out, McKinnon said. “You hope that you get some champions within groups who say, ‘This is worth looking at and this is worth considering.’”
McKinnon acknowledged that initial treatment is not cheap, but said it would work out as economical and efficient over the long term. Any further treatment would be to deal with new phosphate inflows, which would need a significantly reduced treatment.
Phoslock has been used in Europe and that is a very tough market to crack. “They’re pretty tight on the environment rules and they’re pretty tight on everything else, which is great.”
Last October, Phoslock met with the National Institute of Water and Atmospheric Research (NIWA) and is discussing carrying out trials in NZ with the research organisation. NIWA did not want to comment, as the proposal is at a very early stage.
Not all experts are convinced chemical treatment is the way to deal with NZ’s water pollution.
Mike Joy is a senior research fellow at Victoria University of Wellington’s Institute for Governance and Policy Studies and is an associate editor of the Marine and Freshwater Research Journal, published by Phoslock’s inventor, the CSIRO.
He said the sources of phosphate pollution need to be treated, rather than the symptoms. “[Phoslock] is not a solution to anything, rather it is an expensive avoidance option,” Joy said.
“My take is it is yet another ‘ambulance at the bottom of the cliff’ approach to a problem, which is something we seem to do for all our problems, environmental and social.”
Joy said NZ ships in loads of phosphates from overseas and called for a circular approach to such minerals. Phoslock represents a classic “swallowing a spider to catch a fly” mentality.
McKinnon responded that there is no doubt a total life-cycle approach to improving water quality is needed, but if all phosphorus pollution ceased today, there would still be waterways that needed to be cleaned due to legacy pollution and ongoing sediment release.
“It’s also nonsensical to say you wouldn’t use remediation tools to help fix a problem just because you want to stop the problem occurring in the first place.”
So far, the company has carried out more than 300 treatments around the world and has been cited in some 120 research papers in a list provided by PET.
One paper tested Phoslock in 18 lakes in the Netherlands, the United Kingdom, Germany and Canada, and states that phosphorus and nitrogen nutrient pollution in freshwater lakes has resulted in widespread ecological degradation worldwide.
The 17 authors looked at lake conditions in the two years before and after applying Phoslock to measure the changes in phosphorus levels. They also wanted to know whether the range and diversity of aquatic plant life improved and what the results meant for the use of La-bentonite in other lakes.
They found there were reductions in surface water phosphorus concentrations within two years of treatment, along with reductions in chlorophyll concentrations from reduced phytoplankton. There was an increase in aquatic plant species and their range in several of the lakes.
The research concludes that the “water quality responses reported across the lakes were the direct result of the La-bentonite applications”. However, the results were widely variable, and the paper cautions that the processes in each lake and its catchment need to be well understood to support such treatment.
A separate study of the Phoslock application in Lake De Kuil in the Netherlands found that no swimming bans were issued afterwards due to an improvement in water quality.
If NZ isn’t interested, Phoslock will take its business elsewhere. McKinnon said that, like any commercial organisation, it will focus its efforts on where they will bring results.