Environmental breakthrough cleans truck wash wastewater at Mangonui
An environmental breakthrough that could have global implications has been officially unveiled at Doubtless Bay by the local environmental group and the school that proved it works.
Following the official presentation of the project results last week, Mangonui Haulage committed to installing an electro-coagulation (EC) unit that will clean its truck wash wastewater before it finds its way into the nearby Mangonui Harbour.
Lead scientist Andreas Kurmann said the two-year trial had shown the EC unit removed 80 per cent of nitrogen, more than 95 per cent of phosphate and more than 99.9 per cent of E.coli bacteria from polluted stock truck wash water.
“This is a stunning result,” he said.
Funding from the Ministry of Primary Industries’ Sustainable Farming Fund had enabled local group Clean Waters to the Sea to conduct the trial, and it was now calling for the technology to be trialled in larger sewage treatment and cowshed runoff scenarios, Mr Kurmann saying it offered a breakthrough opportunity for the genuine removal of faecal bacteria, nitrate and phosphate from a significant contributor to water pollution at its source.
With the science data in hand, and strong interest from Far North iwi, he wanted the Taipa sewage treatment plant, which he said was currently operating without consent, to host the next larger-scale trial.
He was also urging authorities to contribute to a major reduction in the pollution of waterways by lowering permitted levels of pollutants in wastewater before discharge.
The joint venture between Mangonui School, Mangonui Haulage and Clean Waters to the Sea showed how sustainable environmental changes could an be achieved when everyone worked together, Mr Kurmann said.
“This project is a first step in reducing pollution caused by water feeding into Mangonui Harbour and Doubtless Bay,” he added.
“Following a brainstorming session by Clean Waters to the Sea (CWTS), Tiger Tukariri, one of our trustees, sought approval from Mangonui Haulage to use their wastewater outflow for a trial. The water from stock and concrete trucks goes into a series of settling ponds, and the partly-cleaned water, which meets resource consent requirements, flows into Mangonui Harbour.
“The owner of Mangonui Haulage, Dennis Sparksman, was keen to support the project, and an opportunity was seen to involve Mangonui School children.
“Principal Dave Sedcole was keen to involve students in community projects that encourage them, as future users, to become kaitiaki of the Mangonui and Doubtless Bay area, and so a community partnership was born.”
Starting in March 2014, the project had involved three consecutive groups of Year 6 pupils, led by volunteers from CWTS.
Mr Kurmann said initial testing of the settlement pond water showed high levels of nitrates, ammonia, phosphates and bacteria, the students learning that there was pollution that was not visible to the eye. Two approaches were then considered, the use of wetland planting to filter out some of the pollutants, or trialling an electro-coagulation unit (which was expected to remove pollutants as the water across electrically-charged iron plates, forming a sediment that could be removed).
Mangonui Haulage preferred the second option, because it didn’t have space for the size of wetland needed.
The second group of pupils studied the EC unit in action, and tested the water before and after processing. finding that all pollutants had reduced to a level that made the water safe for recreational use.
Further trials established that treating the water with algae reduced nitrate levels even further, the algae being killed and “sedimented out” by the EC unit. The children were then trained as Water Watchers, learning the parameters needed for healthy streams.
The final group of pupils had had limited time to learn about the processing and testing of the water being focusing on making videos for last week’s presentation. They would train as Water Watchers later in the year.
Meanwhile, further laboratory testing by Mr Kurmann had validated the trial’s results.
He had found cost effective EC units that could be permanently installed by Mangonui Haulage, and was receiving requests from others who wanted to use this system now it had been proved effective, including a trial at the Taipa sewage plant.
“Our vision for the future is that similar cost-effective systems could eliminate much of the nitrate, ammonia, phosphate and bacteria flowing into our waterways,” Mr Kurmann said.
“This would stop the dangerous level of algal bloom evident at most of the river mouths in Northland. The Bay of Islands, for example, currently has a notake order on shellfish due to algal toxins caused by nutrient pollution.
“A reduction of the relevant pollutants allowed in resource consents from local councils for discharge into waterways would further support this vision.”