Water project finds new use for slime

A pilot project on Lake Rotoiti could turn a nasty water infestation into a useful product - while cleaning up the Bay of Plenty’s lakes.

Representatives of Environment Bay of Plenty, New Zealand Trade and Enterprise (NZTE) which has helped fund the project and Aquaflow, the company providing the equipment, will officially open the algae harvesting project at the Ohau Channel which links Lakes Rotorua and Rotoiti on Thursday, 27 May.

The project is designed to investigate the possibilities of harvesting algae from some of Rotorua’s lakes where water quality is poor and algae and weed are growing because of excess nutrient flows.

And there are good uses for the harvest, such as making bio-fuels, fertiliser, animal and fish feed, valuable chemicals and products, including activated carbon used in filtration and absorption products. Algae used for activated carbon filtering can even be used to remove unpleasant flavours from drinking water – which can be caused by the presence of algae in the first place.

Environment Bay of Plenty Chairman John Cronin said the technology being tested could have many benefits for waterways in the region infested with algae and improve water quality in the region’s lakes and rivers.

“The Ōhau Channel is an ideal location to test the harvesting equipment, as it has a consistent flow of water from Lake Rotorua where water and algae can flow into the harvesting system. Algae concentrations at the Channel are high at times, and they worry lake residents and users,” he said.

NZTE, the Government’s economic development agency, is working on a number of projects to help New Zealand develop world-class industries based on new technologies. NZTE Director of Strategic Initiatives Chris Boalch said supporting the Lake Rotoiti project would help Aquaflow prove that its technology worked, which in turn could open up international markets for the company and boost New Zealand’s profile in the field of environmental technology.

“There is considerable international demand for technologies that can clean up waterways. New Zealand could become a leader in the application of new technologies to environmental management, and in the development of environmental solutions for problems associated with intensive agriculture,” Dr Boalch said.

The pilot project will run for three to six months. Technology for harvesting algae has already been tested on sewage treatment ponds in Marlborough. The low cost, short term trial at the Ohau Channel will allow practical and economic assessment of the process, and demonstrate the feasibility of algae harvesting to the local community.

The harvesting equipment can process raw water at 35 cubic metres an hour – a small fraction of the usual flow for the Channel. A safe water treatment chemical brings the algae particles to the surface to be harvested, and the cleaner, filtered water flows back into the lake.

Environment Bay of Plenty, Te Arawa Lakes Trust and Rotorua District Council are working together on the Rotorua Lakes Protection Restoration Programme, which aims to protect and restore water quality within the Rotorua district’s 12 lakes. The council has been working on this project with local trustees of the Waiatuhi Block. The project has also had the support of  representatives of Ngati Pikiao, the Lake Water Quality Association, Te Arawa Lakes Trust, and the local community on the project

Environment Bay of Plenty is also harvesting weed on Lake Rotoehu, with 3,000 tonnes of weed harvested last year. A small harvesting programme is also being undertaken on in Okawa Bay on Lake Rotoiti.

ENDS

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