Microplastic biofilm, associated pathogen and antimicrobial resistance dynamics through a wastewater treatment process incorporating a constructed wetland

Franciszek Bydalek, Gordon Webster, Ruth Barden, Andrew J. Weightman, Barbara Kasprzyk-Hordern, Jannis Wenk

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18 Citations (SciVal)


Microplastics in wastewater are colonized by biofilms containing pathogens and antimicrobial resistance (AMR) genes that can be exported into receiving water bodies. This study investigated establishment and changes in microplastic-associated biofilm and AMR during a conventional full-scale 2100 population equivalent wastewater treatment process combined with a free water surface polishing constructed wetland. Sequential microplastic colonization experiments were conducted at different stages of the wastewater treatment process, including in raw sewage, treated effluent and the constructed wetland. Two scenarios were tested in which the constructed wetland served as either (i) a polishing step or (ii) as primary recipient of sewage inoculated microplastics. Bacterial 16S rRNA gene sequencing was carried out for qualitative bacterial community analysis. qPCR was applied for quantitative analysis of AMR genes (sul1, ermB, tetW, intiI1), bacterial biomass (16S rRNA) and a human fecal marker (HF183). Microbial diversity on microplastics increased with incubation time. The initial sewage-derived biofilm composition changed more significantly in the wastewater effluent compared to the constructed wetland. Pathogen and AMR load decreased by up to two orders of magnitude after coupled conventional and constructed wetland treatment, while less impact was observed when sewage-inoculated microplastic material was directly transferred into the constructed wetland. Aeromonas, Klebsiella, and Streptococcus were key pathogenic genera correlated with AMR in microplastic-associated biofilms. Despite decreasing trends on human pathogens and AMR load along the treatment process, microplastic-associated biofilms were a considerable potential hotspot for AMR (intI1 gene) and accommodated Cyanobacteria and fish pathogens.

Original languageEnglish
Article number119936
Number of pages13
JournalWater Research
Early online date3 Apr 2023
Publication statusPublished - 15 May 2023

Bibliographical note

Funding Information:
Franciszek Bydalek was supported by a Natural Environment Research Council (NERC) studentship at the GW4 Centre for Doctoral Training in Freshwater Biosciences and Sustainability (GW4 FRESH CDT, Grant number NE/RO11524/1 ).

Data availability:
Data will be made available on request. Raw genetic sequencing data are available at NCBI repository https://www.ncbi.nlm.nih.gov/bioproject/940639 Accession: PRJNA940639


  • Antimicrobial resistance
  • Biofilm
  • Colonization
  • Constructed wetland
  • Microplastics

ASJC Scopus subject areas

  • Environmental Engineering
  • Civil and Structural Engineering
  • Ecological Modelling
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution


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