Biofilms on microplastic surfaces and their effect on pollutant adsorption in the aquatic environment

The extensive use of plastics has led to the widespread presence of a new type of pollutant called “microplastics (MPs)” in aquatic environments. MPs have large specific surface areas and strong hydrophobicity. In particular, MPs provide a new ecological niche for microorganisms in aquatic environments, which attach to and subsequently form biofilms on microplastic (MP) surfaces. This paper reviews the factors affecting biofilm growth on MP surfaces and the effect of biofilms on the adsorption of other environmental pollutants onto MPs as well as difference analysis. Biofilm formation is influenced by many factors related to the environment, MPs (e.g., type, particle size, and additives), and properties of microorganisms; environmental factors play an especially important role. Crucially, biofilms change the density of MPs and hydrophobicity of the surface of MPs and can attach new functional groups, charged sites, and other additives to MP surfaces. Primarily owing to this, biofilms affect the adsorption of environmental pollutants such as heavy metals, POPs, and pathogenic microorganisms. Notably, such adsorption is affected by MP particle size and additives. In particular, biofilms have a considerable effect on the interactions between MPs and pollutants. Further, this article suggests directions for revealing the influence of biofilms on pollutant adsorption to MPs. This review provides a reference for studying the formation of biofilms on MPs surfaces in aquatic environments and the effect of biofilms on contaminant adsorption onto MPs.