Waste treatment cleans up

By SIMON COLLINS

Rotorua researchers have found a new method of treating pulp and paper effluent, which they believe could earn New Zealand more than $100 million.

Forest Research, the Rotorua crown-owned institute that developed the nitrogen-fixing process, has tested it at a local pulp mill and will start full trials at a Swedish mill in November before releasing it on to the market early next year.

Project leader Dr Trevor Stuthridge said the process cut the levels of nitrogen and phosphorous in pulp mill effluent by more than 90 per cent, reducing operating costs of effluent treatment by 25 to 35 per cent.

"The waste management industry for pulp and paper is worth US$2.2 billion [$4.7 billion] a year," he said.

"This could be a $100 million-plus opportunity for us at Forest Research - and a successful outcome of eight years' research."

Dr Stuthridge said the institute's key breakthrough in treating pulp mill effluent was solving the "nutrient paradox" - the fact that nutrients have had to be added to reduce pollution. "We are using a specialised group of bacteria to treat the wastewater which are capable of taking nitrogen from the air."

Forest Research has patented the technology and has formed a subsidiary, N-Fix Technologies, to market it.

"We are looking for investment partners and technical partners to help us roll it out," Dr Stuthridge said.

Although the technology does not need a large investment, the institute is working on a patented next-generation process that has the potential to produce biodegradable plastics out of wastewater. That technology could have huge market value, but would cost millions to develop.

In other work on pulp mill effluent, Forest Research has looked at the effects of all kinds of pollution on fish.

A team led by ecotoxicologists Dr Mike van den Heuvel of Forest Research and Dr Louis Tremblay of Landcare Research has started a $400,000 project with four regional councils to develop fish health tests that can be used to set consent conditions for industrial plants.

Dr van den Heuvel's research has found that trout exposed to effluent from the Norske Skog/Tasman pulp and paper mill at Kawerau produced eggs that were 10 to 20 per cent smaller than usual. There was no effect on the number of live offspring.

Fish fed on Rotorua's municipal sewage, which is spread on land in the Whakarewarewa Forest, produced more eggs than normal.

Dr van den Heuvel said the fish showed no physical deformities.

"The implications for humans are less clear because we don't tend to swim around in the receiving environments," he said.

Dr van den Heuvel said he would not hesitate to swim near Matata, where the Tarawera River from Kawerau meets the sea. "Given a good enough bet, I'd drink it."

But there were still toxic sediments at Matata, laid down before the Tasman mill installed secondary treatment in the 1970s, and it was unlikely that any modern mill would be allowed to discharge effluent into a river in such a populated area.

"They would never build a mill today with that receiving environment," Dr van den Heuvel said.

"It would never happen again given the rigour of the Resource Management Act."

Further reading:
nzherald.co.nz/environment