From landfill ash to road material

NEA studying feasibility of setting up a plant to recycle Pulau Semakau's burnt waste
Goh Chin Lian, Straits Times 7 Mar 10;

Ash can be recycled too, and the bonus is Singapore's only landfill will last longer.

A study is being done to see if it makes sense to build the country's first commercial plant to recycle the waste ash currently being dumped at the Pulau Semakau landfill.

By reducing the amount of waste that ends up at the landfill, its lifespan can be extended beyond its projected 2045.

The National Environment Agency (NEA) wants to know if the residue from its incinerators - known as incineration bottom ash - can be converted here into useful material for construction work.

A consultant will do a cost-benefit study.

The technology is there. The NEA told The Sunday Times that several countries, including the Netherlands, Denmark, Germany and Britain, have already used recycled ash for road construction.

The consultant will also look at a regulatory regime for the recycling plant, NEA tender documents obtained by The Sunday Times reveal.

The idea is for a private sector company to develop, build and run the plant - as well as sell and market the processed ash.

The NEA said: 'A decision on setting up a recycling plant for incineration bottom ash will be made only after the completion of the study.'

It declined to say when a decision will be made, but the agency has set aside eight months for the submission of reports on the costs and benefits, technology and regulatory regime.

It also allocated seven months for tender documents to be submitted for the plant and for bids to be evaluated.

The NEA said that if a go-ahead is given, the plant will likely be located on the mainland to avoid double handling and to minimise transport cost.

Waste ash here comprises mainly inert substances like silica, ceramics, glass, stones and trace amounts of heavy metals and organic material.

In 2008, about 1,605 tonnes of waste ash were produced daily here.

Singapore Environment Council executive director Howard Shaw lauded the study, saying it was important to find innovative ways to recycle the ash.

'Semakau's lifespan is limited and the waste material can't be exported.

'So, rather than dump the ash on Semakau, finding ways to commercialise it would be a good thing for Singapore,' he said.

The Land Transport Authority (LTA) has tried using ash as the foundation layer for new roads. Typically, raw material such as granite is used.

Ash was used successfully on a 150m section of Jalan Buroh in Jurong in 2002, but a recent trial involving a 200m stretch of Tampines Road between Hougang Avenue 7 and Defu Avenue 2 has run into some hiccups.

The trial, announced in March last year, was to have lasted six months. If successful, the ash would have been used to build other roads.

The LTA told The Sunday Times that while there were some positive results, more tests and evaluation were needed before it could conclude if such recycled material was feasible and practical for all roads.

The NEA also announced last month that it is funding a Nanyang Technological University research project to use the ash to cover, line and stabilise landfill sites to enable large structures to be put up.

The landfill sites, when filled up and no longer able to accept any waste, can then be redeveloped in 10 to 15 years, instead of the usual 30 to 40 years.