INGENIEUR
POTENTIAL BOTTOM
ASH APPLICATIONS IN
MALAYSIA
FEATURE
By Shanmuga Kittappa, Noor Mohd Syeqqal Ismail, Sivapalan Kathiravale
Environmental Preservation and Innovation Centre Sdn Bhd (EPIC)
Haji Mohd Khairolden Ghani, Khairul Nizam Anuar Bashah
Construction Research Institute of Malaysia (CREAM)
Zuhairi Abd Hamid, Haji Razuki Haji Ibrahi
Construction Industry Development Board Malaysia (CIDB)
Fly Ash (FA) and Bottom Ash (BA) are by-products generated from the combustion process of power
plants, incinerators and boilers. The Malaysian Department of Environment (DOE) has classified BA
as a schedule waste (SW 104,) listed in Schedule Waste Regulation 2005 under the Environmental
Quality Act (EQA) 1974. It is expected that by December 2020, 657,000 tons of BA will be produced
by the industry in Malaysia exceeding the amount of previous years. Current regulations in the
country hinder the use of BA for commercial applications unlike FA, which is permitted for broader
usage.
This article focuses on BA, its physical-chemical characteristics, current global applications and
recommendations for future mass usage in Malaysia. The problems associated with BA utilisation
are assessed, where the understanding of BA is limited due to legal restrictions, improper
classification systems, wrong standards and codes applied to the material. A lack of awareness
of BA is the key factor leading to BA being registered as a hazardous and dangerous material.
Therefore, it is crucial to understand the detail physical and chemical composition of BA to
determine its correct nature. In a broader perspective, the industry needs to move forward through
further research and development in utilising BA in a more sustainable environment. In view of the
above and the vast possibilities that have been demonstrated at the global level, the Environmental
Preservation and Innovation Centre Sdn Bhd (EPIC), an institute dedicated to research, training and
consultation, together with CREAM and CIDB are embarking on enhancing the utilisation of BA in
Malaysia.
FA and BA are predominantly produced from
the incineration or combustion process of
coal in the energy industry. FA is the residue
collected in the Electrostatic Precipitator (ESP)
after the incineration of coal. It contains microsized
particles with the presence of silicon oxide
(SiO 2
), aluminium oxide (Al 2
O 3
), and calcium oxide
(CaO). Fly ash is alkaline in nature, spherical
in shape and grey in colour. BA is the residue
particles that fall to the bottom of a furnace during
the combustion process. A wet extractor rapidly
cools the ash and forms a wet BA but a more
efficient extractor generates dry BA.
BA consists of 15% of the total ash content
generated by a furnace and it is usually richer in
carbon content and heavy metals. BA grains are
62 VOL 82 APRIL-JUNE 2020