Turning bottles into sand

Friday March 16, 2018 Written by Published in Environment
WATSAN staff member Hewett Paerau shows off a bin of sand produced from crushing glass bottles. Glass can be crushed into extremely fine particles and substituted for sand in making concrete. 18031509 WATSAN staff member Hewett Paerau shows off a bin of sand produced from crushing glass bottles. Glass can be crushed into extremely fine particles and substituted for sand in making concrete. 18031509

Work now being done at WATSAN (Water, Waste and Sanitation) division of Infrastructure Cook Islands (ICI) could see most of Rarotonga’s empty glass bottles end up as sand.

A cost-benefit analysis of glass crushing is one of three projects being undertaken by WATSAN’s first dedicated waste programme coordinator, Hilary Boyes, who hails from Wanaka in New Zealand and will be with ICI for the next six months.

Boyes has been involved in waste management all over the world, most notably in Vancouver, Canada, where she helped set up organic waste collection for composting purposes. She also worked as an on-site coordinator during the construction of a large natural gas project site in Australia.

“By crushing glass into the particle size of sand, the glass can be substituted for sand in concreting and leave the sand where it belongs,” says Boyes.

“Speaking with experts in concreting they advise that coral sand isn’t actually ideal for concreting and crushed glass is the preferred option.”

A side benefit of recycling glass bottles by crushing them into sand is that it also saves sand being mined for construction purposes.

The rate of natural production of sand is much slower than extraction, which means using sand as aggregate in concrete is unsustainable, especially on small islands. And sand mining can also have other undesirable effects, says WATSAN director Jaime Short.

“The continued mining of sand with the holes being filled with soil and worse still, hazardous waste that is often reported dumped in these holes, will have disastrous effects on lagoon and human health.”

In the 2018/19 budget bidding, ICI is vying for an industrial glass crusher and the findings of Boyes’ cost-benefit analysis will ensure the correct size of crusher is purchased - and that parts are easily obtainable.

“The long-term view is to have this operation taken over by the private sector and we do hope that it can be a profitable venture to attract a private-sector operator,” says ICI secretary Ngametua Pokino.

“We also hope that it will create more attention and action on realising that waste actually is a resource.” ICI now asks the public to separate glass bottles when putting them out for collection, but the glass cannot actually be sent off the island as its international value is too low. Instead, the bottles are used as cover for the landfill and crushed glass from a small single-bottle feed crusher is used as fill on driveways.

The industrial crushing idea has been floating around for some time and there are already private-sector initiatives out there. For example, Brad and Ngere from Brad’s Auto Body Repairs have their own crusher and use cullet-sized crushed glass in pavers – and in the construction of their home.

Andy Olah of Timberland also approached ICI about glass crushing and has been a longtime proponent of the repurposing of glass bottles.

All these local real-life examples for glass crushing will contribute to the analysis, and Malcolm Sword of General Transport is also providing some technical advice for the project.

            - Release/SB

Leave a comment