Surfactant-assisted air flotation: A novel approach for the removal of microplastics from municipal solid waste incineration bottom ash

Jiaqi Chai; Yafei Shi; Yan Wang; Xiong Yang; Kewu Pi; Andrea R Gerson

doi:10.1016/j.scitotenv.2023.163841

Surfactant-assisted air flotation: A novel approach for the removal of microplastics from municipal solid waste incineration bottom ash

Sci Total Environ. 2023 Aug 1:884:163841. doi: 10.1016/j.scitotenv.2023.163841. Epub 2023 May 2.

Authors

Jiaqi Chai¹, Yafei Shi², Yan Wang¹, Xiong Yang¹, Kewu Pi³, Andrea R Gerson⁴

Affiliations

¹ Innovation Demonstration Base of Ecological Environment Geotechnical and Ecological Restoration of Rivers and Lakes, School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, Hubei 430068, China.
² Innovation Demonstration Base of Ecological Environment Geotechnical and Ecological Restoration of Rivers and Lakes, School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, Hubei 430068, China; National Engineering Research Center of Advanced Technology and Equipment for Water Environment Pollution Monitoring, Wuhan, Hubei 430068, China. Electronic address: yfshi@hbut.edu.cn.
³ Innovation Demonstration Base of Ecological Environment Geotechnical and Ecological Restoration of Rivers and Lakes, School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan, Hubei 430068, China; National Engineering Research Center of Advanced Technology and Equipment for Water Environment Pollution Monitoring, Wuhan, Hubei 430068, China.
⁴ Blue Minerals Consultancy, Wattle Grove, Tasmania 7109, Australia.

PMID: 37142027
DOI: 10.1016/j.scitotenv.2023.163841

Abstract

The potential for the presence of microplastics (MPs) in municipal solid waste incineration bottom ash (MSWI-BA) has not been fully explored. In this study, surfactant-assisted air flotation separation in aqueous media was used to examine the removal of MPs and other pollutants from different particle size fractions of MSWI-BA. The use of 1 mmol L^-1 sodium dodecylbenzene sulfonate (SDBS), at a liquid-solid ratio of 60:1, increased by 66 % the quantity of MPs floated from the MSWI-BA 0-0.3 mm fraction, as compared to pure water. The four most common shapes of the floated MPs were pellets, fragments, films and fibers, and the major polymers were polypropylene, polyethylene, polymethyl methacrylate, and polystyrene (approximately 450 μg g^-1 BA). The flotation of <10 μm MPs increased by up to 7 % using this method compared to flotation in saturated NaCl solution. Reuse of the flotation solution with the SDBS concentration maintained resulted in reduced MPs removal abundance by 22 % in the fourth use as compared to the first use. MPs removal correlated positively to SDBS concentration and negatively to turbidity. Precipitation from the fourth flotation solution was evaluated using polyacrylamide (PAM) and polyaluminium chloride (PAC) for the purpose of promoting the regeneration and recycling of the flotation solution. This treatment reduced MPs abundance, turbidity, and potential heavy metals in the recycled flotation solution. It is estimated that 3.4 kg of MPs could be removed from each ton of MSWI-BA. The findings of this study contribute to a better understanding of the redistribution of MPs during MSWI-BA pre-use treatment and provides a reference for the practical application of surfactant-assisted air flotation separation.

Keywords: Bottom ash; Flotation; Microplastics; Recycling; Surfactant.

MeSH terms

Coal Ash
Incineration
Lipoproteins
Metals, Heavy* / analysis
Microplastics
Plastics
Refuse Disposal* / methods
Solid Waste / analysis
Surface-Active Agents

Substances

Solid Waste
Coal Ash
Microplastics
Plastics
Surface-Active Agents
Metals, Heavy
Lipoproteins