New life for incinerated ash?

Every day, about 1,500 tonnes of incinerated bottom ash are produced in Singapore, according to the National Environment Agency 2018 data.

The reuse of incinerated ash is something that has been explored before but yet to be applied due to the risk of toxic heavy metals in the ash leaching into the environment.

Now there may be some headway in the safe reuse of burnt rubbish as construction materials, such as sand and stone, the Straits Times reports.

A research team from Republic Polytechnic (RP) has successfully created a chemical called GGBS-OPC liquid binders that can bind heavy toxic metals, like lead and arsenic, to incinerated bottom ash (IBA) so that they will not pollute the surroundings upon exposure to water, sunlight and open air. (IBA is the thicker and heavier component of incinerated ash.)

The polytechnic’s project was awarded SGD1.2 million in funding in April 2019, under the Closing the Waste Loop research and development initiative of the National Environment Agency (NEA). The SGD45 million fund was set up in 2017 to provide support to academic institutions, research institutes and companies developing the technology needed to convert waste to resources.

The same team had in 2014 developed a special chemical to encapsulate toxic heavy metals within incinerated fly ash—the lighter component of incinerated ash—to prevent leaching. RP has filed for a patent for its research, which is pending approval, and is collaborating with construction firm EnGro Corporation, which provides the raw materials for the chemical.

“The challenge of using the incineration ash in construction materials is that currently Singapore does not have its own standards or environmental guidelines for industry, and thus the adoption is quite limited,” said Dr Goh Chee Keong, the project’s principal investigator.

The NEA, he added, is currently working to develop environmental guidelines for using IBA in construction materials. and RP expects to expand the project to an industrial scale in three or four years. — Construction+ Online