Evolution of microplastics and changes in system performance in leachate biological treatment system

Abstract

This study systematically investigated the evolution of four microplastics (MPs) (polystyrene (PS), polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET)) in leachate treatment systems under aerobic and anaerobic conditions, employing surface morphology characterization (SEM) and microbial community analysis (16S rRNA sequencing) to unravel their degradation mechanisms and inhibitory effects on contaminant removal. The presence of MPs, particularly PS, PE, PP, and PET, significantly impeded the removal of chemical oxygen demand, ammonia nitrogen, and total phosphorus. Aerobic conditions resulted in initial inhibition, whereas anaerobic conditions exacerbated the degradation processes, including surface erosion and oxidation. Among the four types, PET aged more rapidly and visibly under the same conditions, while PS aged more quickly and prominently under aerobic conditions. Aerobic conditions initially suppressed microbial activity, while anaerobic conditions aggravated these effects. Changes in the microbial community, primarily composed of Proteobacteria and Bacteroidetes, reflected environmental preferences. The research emphasized the continuous need to explore MPs' evolution mechanisms within these systems to inform the development of effective pollution control strategies for practical applications. This understanding is crucial for mitigating the adverse effects of MPs on leachate treatment processes and protecting environmental health.