ENVIRONMENTAL TECHNOLOGY
From waste to HDB walls?

By Sharmilpal Kaur

THE walls inside new Housing Board flats here could be made from industrial waste in about two years' time.

Scientists at the Environmental Technology Institute have spent the past nine months working on a way to turn waste materials like marine clay - which covers most of Singapore - and sludge from the electronics sector into pellets that can be used in the construction of wall panels for homes. The clay and sludge would otherwise be used for landfills.

Said Dr Timothy White, a senior scientist at the institute, who is heading the research: 'Waste can also come from the petroleum industry, waste-water sludge, and incinerator ash.

'On their own, they are a problem, but put together, we can hopefully end up with a new material that is useful in its own right.'

He said the new 40-storey HDB blocks to be built will need to be constructed of lighter materials. If not, they will need a substantially stronger foundation, which costs a great deal.

Currently, materials like crushed granite are used to make wall panels. Lighter substitutes are available, but these can cost as much as 50 per cent more.

Another possible use for the new material is in land reclamation.

'It'll be safe if we get the chemistry right,' he said. But before combining the different waste materials, said Dr White, each one has to be understood.

To prepare the waste for commercial use, the materials will be blended and the mixture fired in a special kiln, that costs about $150,000.

The hardened mixture can then be added to other materials like cement, to make such items as cement blocks and wall panels.

Dr White said that the recycled products are likely be ready for commercial use in about two years' time, as there is still a lot of testing to be done, to make sure they are safe.

This is one reason why he has yet to approach the HDB with his proposal about the potential of recycled waste.

He said: 'We want to make sure we have a stable product first.'