Engineers in New Zealand are using a sophisticated nanotech membrane to remove pollution-induced algae from one of the country's most renowned scenic lakes.

Lake Rotorua is the product of an immense volcanic explosion which occurred approximately 200,000 years ago, leaving a huge caldera around 16 kilometres in width which became host to a body of water after filling with rainfall.

In the modern era, the volcanic lake has become one of New Zealand’s most popular tourist destinations as a result of its pristine waters, yet they are now under threat as a result of the proliferation of algae blooms, which are nourished by effluent from adjacent farms and communities.

The local government has enlisted the help of sophisticated nano-engineering to deal with the besetting algae blooms, in the form of an advanced membrane which is capable of filtering out the unwanted microorganisms.

The engineers behind GE’s ZeeWeed Membrane Bioreactor used advanced nanotech methods to create tiny pores in the material, measuring a mere 40 nanometres in diameter.

Not only are these minute holes capable of filtering out the protozoa and bacteria which riddle the lake’s waters and stymie the growth of other aquatic organisms, they also serve to remove the phosphorus and nitrogen which is the underlying cause of the algae problem in the first place.

The membranes are arranged in sheets which are capable of undulating in the water like seaweed, thanks to a special synthetic resin which coats their exterior and confers them with enhanced flexibility.

The ZeeWeed membranes have been incorporated into the facilities of local treatment plant to radically enhance its ability to process waste water, thus dealing with the lake’s algae pollution problem at the source.

“The water being released by the previous treatment plant was still very high in nitrogen and phosphorus, and this was increasing the nutrient loads in the surrounding water courses,” said Chris Harpham of GE Power & Water for the Asia Pacific region. “We were able to retrofit the ZeeWeed membranes into the existing tanks on the treatment site. Now that it’s operating, it has led to a significant reduction in the nutrient load in the lake.”

The ZeeWeed membranes have already been deployed in other parts of Australasia, including the Queensland coastal towns of Cairns and Townsville, where they are helping to prevent urban and agricultural wastewater from adversely impacting the Great Barrier Reef.