Effect of anaerobic sludge microbial treatment on the surface properties of microplastics.

Waste sludge produced from wastewater treatment has been regarded as a potential reservoir of microplastics. In order to investigate the effect of sludge microbial decomposition on the microplastics, polypropylene, polyethylene, polyvinyl chloride, and tire microplastics are chosen to investigate changes in their surface properties during anaerobic sludge treatment process. The results show that the intensity of oxygen-containing functional groups such as carbonyl and hydroxyl exhibits an increasing tread with anaerobic sludge microbial treatment time, indicating an enhanced hydrophilicity of microplastic surface, which is further confirmed by contact angle results. Correlation results show that carbonyl index can favorably reflect the impact of anaerobic sludge microorganisms on the surface properties of polyethylene and polyvinyl chloride microplastics, while the surface changes of polypropylene and styrene butadiene rubber tire microplastics can be characterized with the absorption peak areas in wavenumber range of 1 300 to 1 500 cm^-1. This study can provide theoretical basis for further investigating the sludge microorganism-driven decomposition and reaction behavior of microplastics. [ABSTRACT FROM AUTHOR]