Using ash from burnt trash to reclaim land

Audrey Tan The Straits Times AsiaOne 16 Mar 15;

Your trash could one day be used to reclaim land.

The National Environment Agency (NEA) has embarked on a project to study if ash left over from burnt rubbish can be used as land reclamation material.

This is part of its efforts to conserve landfill space and prolong the lifespan of Singapore's only landfill on Pulau Semakau, which is situated about 8km south of the mainland.

"If incineration bottom ash can be used as reclamation material, it would conserve the space available on Semakau Landfill for disposal of other non-incinerable waste," an NEA spokesman said.

The Semakau landfill contains non-incinerable waste as well as the ash from incinerable waste.

A combination of sand and approved fill material - such as excavated earth and material from construction - can be used for land reclamation.

With Singapore producing more waste, the landfill could be filled up by as early as 2035, a decade earlier than the projection of 2045 made in 1993.

In 2013, Singapore generated 7.85 million tonnes of waste, up from 7.27 million tonnes the year before. About 60 per cent of this is recycled, but the amount of waste going into the landfill is also going up.

NEA figures showed that 1,700 tonnes of incineration bottom ash was generated daily last year, up from the 1,600 tonnes in 2013 and 1,500 tonnes in 2012.

As part of the study, which began in 2013, the agency is looking at how the ash - which contains metals such as iron and aluminium - can affect the marine ecosystem.

The NEA has engaged researchers at Nanyang Technological University (NTU) to do a risk-assessment study, which will include the development of guidelines on how to use such ash as land reclamation material.

NTU is working with the Tropical Marine Science Institute as part of the project.

The research project is expected to end next year. It is the latest measure undertaken by the Government to recycle incineration ash to make Singapore's only landfill last longer.

Last year, the NEA awarded a tender to build a $15 million recovery facility to salvage metals from incineration bottom ash.
And in 2009, the Land Transport Authority carried out a trial using processed incineration bottom ash in the sub-base layer of two 50m sections of Tampines Road.

The trial showed that, in terms of performance, incineration bottom ash can be used for road construction, although it has not been used in any other roads here since.

This is due to the additional processing cost and uncertainty in projected demand for the material in road construction.

Asked if the NEA will face similar challenges in using the ash for land reclamation, its spokesman said the ongoing research will enable it to see if additional processing is needed to make the ash suitable as land reclamation material.