Mechanisms of interaction between polystyrene nanoplastics and extracellular polymeric substances in the activated sludge cultivated by different carbon sources. (February 2023)

• Record Type: Journal Article
• Authors: Wang, Yaxin; Liu, Xiuhong; Liu, Runyu; Han, Weipeng; Yang, Qing
• Is Part Of: Chemosphere. Volume 314(2023)
• Publication Date: 2023-02
• Subjects: Microplastics -- Nanoplastics -- Activated sludge -- Extracellular polymeric substances -- Protein secondary structure -- Carbon source; MPs microplastics -- NPs nanoplastics -- MWWTPs municipal wastewater treatment plants -- EPS extracellular polymeric substances -- NaAc sodium acetate -- MeOH methanol -- GLC glucose -- PS-NPs polystyrene nanoplastics -- SBRs sequencing batch reactors -- DO dissolved oxygen -- pH potential of hydrogen -- MLSS mixed liquor suspended solids -- SRT sludge retention time -- MLVSS mixed liquor volatile suspended solids -- EDTA ethylenediamineetetraacetic acid -- LB-EPS loosely bound EPS -- TB-EPS tightly bound EPS -- PS polysaccharides -- PN proteins -- OTUs operational taxonomic units -- XPS X-ray photoelectron spectroscopy -- FTIR Fourier transform infrared -- 2D-CoS two-dimensional correlation spectroscopy -- LB-EPS + PS LB-EPS bound PS-NPs -- TB-EPS + PS TB-EPS bound PS-NPs; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2022.137656
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Nanoplastics (NPs) are ubiquitously present in wastewater treatment plants, which would be removed by the flocculation of extracellular polymeric substances (EPS) from activated sludge. However, the interaction mechanisms between NPs and EPS of activated sludge remain largely unexplored. This study investigated the interaction mechanisms between polystyrene nanoplastics (PS-NPs) and EPS with sodium acetate (NaAc), methanol (MeOH) and glucose (GLC) as carbon sources. The results showed that the functional group involved in the interactions between PS-NPs and EPS was the carbonyl of protein amide I region. The interaction between PS-NPs and EPS increased the β-sheets content, decreased the ratio of α-helix to (β-sheet + random coil), and changed the protein secondary structures to strong rigidity. This enhanced the flocculation of activated sludge cultivated by these three carbon sources. The flocculation between PS-NPs and EPS in activated sludge using NaAc as the carbon source was the strongest among these three carbon sources. Therefore, the degree of flocculation between NPs and EPS of activated sludge in wastewater treatment plants varies with carbon sources. This work provides a reference for the NPs removal mechanisms from wastewater, which will help to understand the migration behavior of MPs and NPs in wastewater treatment processes. Graphical abstract: Image 1 Highlights: The groups contained in the protein of EPS preferentially interacted with PS-NPs. The β-sheets played a vital role in the flocculation between EPS and PS-NPs. PS-NPs increased the contact surface area and promoted bioflocculation. NaAc had the best flocculation between EPS and PS-NPs among three carbon sources.