Microplastics extraction from wastewater treatment plants: Two-step digestion pre-treatment and application

Zhang，Ziqi1; Liu，Wenzong1; Gao，Qun2; Huang，Fang1; Kang，Yuanyuan1; Pan，Yusheng1,3; Luo，Gaoyang1; Zhou，Xu1; Fan，Lu4,5; Wang，Aijie1; Gao，Shu Hong1

2023-02-15

10.1016/j.watres.2023.119569

WATER RESEARCH   Impact Factor & Quartile

0043-1354

1879-2448

As the gathering place of urban wastewater, wastewater treatment plants (WWTPs) are indispensable for removing microplastics (MPs), one of the emerging contaminants of great concern, from cities into the natural environment. A reliable and efficient extraction method for MPs, especially in organic-rich matrices, such as sludge samples, is the basis for studying MPs contamination, while it is still lacking. The digestion process, which requires further optimisation, is the most important step during extraction. In this study, we developed and optimised a two-step digestion process to extract MPs and proposed a recommended dosage of digestion reagents based on the mixed liquid volatile suspended solids (MLVSS) level of the sample. Successive addition of 30% HO + 1 M HNO (v:v = 1:1, T = 60 °C, t = 5 h + 5 h) could efficiently extract MPs from sludge samples (over 90%), and the recommended dosage of digestion reagent was 100 ml 30% HO+100 ml 1 M HNO with the sample MLVSS lower than approximately 0.43 g. This new method was also applied to examine the characteristics of MPs in two typical WWTPs (anaerobic-anoxic-oxic and biofilter processes) in Shenzhen. The concentrations of MPs in the influent, effluent and dewatered sludge were approximately 114.00 n/L, 6.00 n/L, and 126.00 n/g (dry weight) in WWTP A, whereas 404.00 n/L, 22.00 n/L, and 204.00 n/g (dry weight) in WWTP B, respectively. Rayon and polyester were the dominant polymers in both the WWTPs. Fibers accounted for the largest proportion of the influent and effluent. Sizes between 0.20–0.50 mm were most detected. This study provides a new and efficient reference method to extract MPs from WWTPs samples, especially sludge sample, with less MPs loss and more beneficial to subsequent identification.

Characteristics Digestion and extraction Microplastics Sludge Wastewater treatment plants

SCI

English

NI Journal Papers

Others

National Natural Science Foundation of China["52070060","52230004","52293443"] ; Shenzhen Overseas High-level Talents Research Startup Program[20200518750C] ; Shenzhen Science and Technology Program[KQTD20190929172630447] ; State Key Laboratory of Urban Water Resource and Environment (Harbin Institute of Technology)[2021TS29]

Engineering ; Environmental Sciences & Ecology ; Water Resources

Engineering, Environmental ; Environmental Sciences ; Water Resources

WOS:000975203000001

PERGAMON-ELSEVIER SCIENCE LTD

ENVIRONMENT/ECOLOGY

2-s2.0-85146066225

Scopus

1.State Key Laboratory of Urban Water Resource and Environment,School of Civil and Environmental Engineering,Harbin Institute of Technology Shenzhen,Shenzhen,150090,China
2.State Key Joint Laboratory of Environment Simulation and Pollution Control,School of Environment,Tsinghua University,Beijing,100084,China
3.School of Chemistry and Chemical Engineering,Harbin Institute of Technology,Harbin,150090,China
4.Department of Ocean Science and Engineering,Southern University of Science and Technology,Shenzhen,China
5.Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou),Guangzhou,China

Zhang，Ziqi,Liu，Wenzong,Gao，Qun,et al. Microplastics extraction from wastewater treatment plants: Two-step digestion pre-treatment and application[J]. WATER RESEARCH,2023,230.

Zhang，Ziqi.,Liu，Wenzong.,Gao，Qun.,Huang，Fang.,Kang，Yuanyuan.,...&Gao，Shu Hong.(2023).Microplastics extraction from wastewater treatment plants: Two-step digestion pre-treatment and application.WATER RESEARCH,230.

Zhang，Ziqi,et al."Microplastics extraction from wastewater treatment plants: Two-step digestion pre-treatment and application".WATER RESEARCH 230(2023).