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Explora: Environment

and Resource

ORIGINAL RESEARCH ARTICLE
Enhanced inhibition of heavy metal leaching in

incineration bottom ash through accelerated
carbonation with ammonium carbonate

Suming Ye , Roy Ou Yong, Jie Bu, and Cun Wang*

Institute of Sustainability for Chemicals, Energy and Environment, A*STAR, Singapore

Abstract

The increasing generation of incineration bottom residues poses environmental risks due
to heavy metal leaching, while carbonation is one of the effective methods to immobilize
heavy metals. This study introduces a novel approach to mitigate heavy metal leaching
from incineration bottom ash (IBA) by accelerated carbonation with ammonium
carbonate solution. The effect of ammonium carbonate concentration on carbonation
efficiency and inhibition of heavy metal leaching was systematically investigated. X-ray
fluorescence was used to analyze the composition of IBA, and thermogravimetric analysis
(TGA) and inductively coupled plasma optical emission spectroscopy/mass spectrometry
were used to determine carbonation capacity and heavy metal leaching, respectively.
Results showed that maximum carbonation capacity was achieved at 8 wt% ammonium
carbonate concentration at a solid/liquid ratio of 1:5 for 1 h, but the increase in carbonation
efficiency slowed down when the concentration exceeded 4 wt%. Ammonium carbonate
*Corresponding author: accelerated carbonation effectively inhibited heavy metal leaching, particularly copper,
Cun Wang with an 89% inhibition rate at 10 wt% ammonium carbonate, while diminished effects
(wang_cun@isce2.a-star.edu.sg)
were observed with chromiun. The effect of the ammonium carbonate concentration
Citation: Ye S, Yong RO, Bu J, on heavy metal inhibition became less significant above 4 wt%, revealing a nuanced
Wang C. Enhanced inhibition of relationship between carbonation and heavy metal leaching inhibition. TGA and X-ray
heavy metal leaching in incineration
bottom ash through accelerated diffraction analyses confirmed the formation of insoluble CaCO during carbonation,
3
carbonation with ammonium elucidating neomineralization processes that immobilize trace heavy metals. In addition,
carbonate. Explora Environ Resour. the study explored the impact of carbonation on leachate pH, emphasizing the interplay
2024;1(1):4609.
doi: 10.36922/eer.4609 between pH reduction and heavy metal leaching inhibition.
Received: August 21, 2024
Accepted: October 14, 2024 Keywords: Municipal solid waste; Incineration bottom ash; Accelerated carbonation;
Heavy metal leaching; Ammonium carbonate
Published Online: November 8,
2024
Copyright: © 2024 Author(s).
This is an Open-Access article 1. Introduction
distributed under the terms of the
Creative Commons Attribution Incineration is one of the most effective technologies to reduce the volume and mass
License, permitting distribution,
and reproduction in any medium, of municipal solid waste (MSW). Despite its capacity to reduce MSW volume and
provided the original work is mass by up to 90% and 80%, respectively, the increasing generation of incineration
properly cited. residues, including incineration bottom ash (IBA) and incineration fly ash, poses
Publisher’s Note: AccScience a considerable challenge as they are usually disposed of to landfills. In Singapore, a
Publishing remains neutral with nation constrained by land availability, the sole landfill, Semakau Landfill, is projected
regard to jurisdictional claims in 1
published maps and institutional to reach its full capacity by 2035 if the current rate of waste generation persists. This
affiliations. underscores the urgency for innovative waste management strategies and sustainable

Volume 1 Issue 1 (2024) 1 doi: 10.36922/eer.4609