Stabilisation/solidification of municipal solid waste incineration fly ash by phosphate-enhanced calcium aluminate cement

Liang Chen; Yan-Shuai Wang; Lei Wang; Yuying Zhang; Jining Li; Lizhi Tong; Qing Hu; Jian-Guo Dai; Daniel C W Tsang

doi:10.1016/j.jhazmat.2020.124404

Stabilisation/solidification of municipal solid waste incineration fly ash by phosphate-enhanced calcium aluminate cement

J Hazard Mater. 2021 Apr 15:408:124404. doi: 10.1016/j.jhazmat.2020.124404. Epub 2020 Oct 29.

Authors

Liang Chen¹, Yan-Shuai Wang¹, Lei Wang², Yuying Zhang¹, Jining Li³, Lizhi Tong⁴, Qing Hu⁵, Jian-Guo Dai¹, Daniel C W Tsang⁶

Affiliations

¹ Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
² Institute of Construction Materials, Technische Universität Dresden, 01062 Dresden, Germany. Electronic address: lei.wang1@mailbox.tu-dresden.de.
³ School of Environment, Nanjing Normal University, Nanjing, Jiangsu, 210023, China.
⁴ South China Institute of Environmental Sciences, Ministry of Ecology and Environment, 7 West Street, Yuancun, Guangzhou, 510655, China; School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China.
⁵ School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China.
⁶ Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China. Electronic address: dan.tsang@polyu.edu.hk.

PMID: 33153794
DOI: 10.1016/j.jhazmat.2020.124404

Abstract

Landfill disposal of municipal solid waste incineration fly ash (MIFA) presents significant environmental and economic burden. This study proposed a novel and high-efficiency approach for stabilisation/solidification (S/S) of MIFA by phosphate-modified calcium aluminate cement (CAC). Experimental results showed that the presence of Pb (the most leachable metal contaminant in the MIFA) retarded the early-stage reaction of CAC, resulting in an extension of setting time and a significant decline of compressive strength of CAC pastes. The incorporation of phosphate additives (10 wt% of binder), especially for trisodium phosphate, in CAC system effectively mitigated the negative impact of Pb on the CAC reaction and reduced the Pb leachability. Elemental mapping results illustrated that Pb²⁺ coordinated with phosphate to generate insoluble precipitates (e.g., Pb₃(PO₄)₂). The S/S treated MIFA samples fulfilled the compressive strength and leachability requirements for on-site reuse. Overall, this study demonstrated that phosphate-modified CAC is a promising binder for S/S of hazardous MIFA.

Keywords: Green and sustainable remediation; Hazardous waste treatment; High-alumina cement; Metal leachability; Phosphate additives.

Publication types

Research Support, Non-U.S. Gov't