Effect of modified diatomaceous earth on the heavy metal volatilization characteristics of aged refuse co-combustion

ABSTRACT

This paper investigated the adsorption performance of natural and modified diatomaceous earth (DE) for six heavy metal species (Cu, Zn, Ni, Cd, Pb, Cr) during the co-combustion of aged refuse (AR) and municipal solid waste (MSW) in a lab-scale tubular furnace. The aim was to examine the effects of temperature, sorbents, and modification methods on heavy metals’ adsorption performance. The capture rates of calcined diatomaceous earth (CDE) were higher than those of DE, especially for Ni at 700°C, whose capture rate increased to 78.6%. Modified sorbents with NaOH or Na₂CO₃ significantly reduced the volatility of six heavy metals at 700°C, with the volatilization rates (VR) of Ni and Zn decreasing by at least 50%. Meanwhile, for Cu, Pb, and Zn, the fixation of heavy metals in the bottom ash increased with rising the sorbents mass. However, when the combustion temperature was equal to or above 800°C, the effects of modification on the VR of Cd, Pb, and Zn diminished, except for 10 wt% DE and CDE-10%NaOH. Using NaOH-modified DE at higher temperatures increased the VR of Ni, Pb, and Zn, particularly for Ni whose VR increased by 21.13%. This work contributes to understanding DE’s control mechanism of heavy metals and investigates new heavy metal control strategies during the co-combustion of MSW and AR.

KEYWORDS:

• Aged refuse
• diatomaceous earth
• co-combustion
• heavy metal
• modified sorbent

Highlights

1. Usage of diatomaceous earth as sorbents for heavy metals capture during co-combustion of aged refuse and municipal solid waste was investigated.

2. Calcination modification at 850°C enhanced the efficiency of diatomaceous earth in capturing six heavy metals.

3. Na+ modified diatomaceous earth had great performance for Cu, Zn, Ni, Cd, Pb, and Cr capture at 700°C.

4. The effect of Na+ modification on the adsorption effect was diminished at 800°C and 900°C.

Acknowledgements

This work was supported by the Science and Technology Program of Guangzhou, China (202002030105) and Guangdong Basic and Applied Basic Research Foundation (2021A1515010497).

Disclosure statement

No potential conflict of interest was reported by the authors.

Author contibutions

Siqi Wang: Conceptualization, Methodology, Validation, Data curation, Writing -original draft, Writing – review & editing. Yuting Tang: Conceptualization, Supervision, Resources, Writing – review & editing, Supervision, Project administration, Funding acquisition. Yanhui Bin: Writing – review & editing, Methodology. Jiehong Tang: Writing – review & editing, Methodology. Fulong Wen: Writing – review & editing, Methodology. Xiaoqian Ma: Writing – review & editing, Funding acquisition.

Supplemental data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15567036.2023.2213174.

Additional information

Funding

The work was supported by the Science and Technology Program of Guangzhou, China ;Natural Science Foundation of Guangdong Province, China [202002030105; 2114050000829]; Science and Technology Program of Guangzhou, China; Guangdong Basic and Applied Basic Research Foundation [2021A1515010497].