Media Release

26 September 2008

From milk bottles to roof tiles – Waiheke set to be a leader in recycling

Clever thinking by University of Auckland Faculty of Engineering students is set to change the way milk bottles are recycled on Waiheke Island.

A team of three students plus two student volunteers has been working on developing a complete process to recycle used milk bottles into new products such as roof tiles or piping.

Clean Stream, the organisation that collects kerbside refuse on Waiheke, approached students from EPICS (Engineering Projects in the Community Service) to come up with an alternative to shipping used milk bottles off the island for recycling.

The key technology used by the students involves a machine called a rotating disc melt extruder that produces plastic rods from either shredded or half milk bottles and lids. These rods can then be turned into high-quality plastic pellets. These pellets can be fed into machines that produce shaped plastic articles, and natural fibres can be added to the mix to further reinforce the products.

The project was completed in the Faculty of Engineering’s Centre for Advanced Composites Materials at the Tamaki Campus. Mentors, Professor Debes Bhattacharyya and Dr Richard Lin, say the system incorporates existing and new technology, and creates a process that is extremely practical and useful for isolated communities.

“This is an excellent example of how the University can cooperate with community groups to develop sustainable ways of reducing waste,” Professor Bhattacharyya says.

Clean Stream Executive Director John Stansfield says the students have inspired his organisation by demonstrating there are alternatives to managing waste on the island.

More than 16 tonnes of used milk bottles are compressed into bales and transported by truck and ferry to the mainland at significant cost each year.

“The process we have at present is inefficient and expensive. By recycling the bottles locally, we can reduce shipping and petrol costs, provide jobs, and increase the monetary value of the used milk bottles by converting them into a value-added product,” Mr Stansfield says.

Clean Stream plans to adopt the technology in stages, with each stage providing additional savings and cash flow to make the next step possible.

The technology will be set up in a small mobile factory, so in the future it could be transported to other islands in the Hauraki Gulf to deal with plastic waste. It is also envisaged that it could be used in remote communities and in Pacific Island nations.

ENDS

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