A survey of microplastics in wastewater from large-scale dairy farms and their surroundings in inner Mongolia of China

Microplastics (MPs), tiny polymeric particles resulting from the degradation of plastic waste and environmental erosion, pose significant threats to ecosystems, animal health, and human well-being. This study assessed MPs abundance in wastewater and surrounding environments from nine large dairy farms in Inner Mongolia, China, focusing on oxidation ponds. Using laser direct infrared spectroscopy (LDIR), MPs were detected in 42 samples, identifying 29 polymer types, with polyisoprene (22.69%), polyvinyl chloride (16.58%), and polyurethane (10.47%) being the most common. The results revealed a high abundance of MPs in oxidation ponds, while MPs removal efficiency remained unsatisfactory. To better understand the ecological risks posed by MPs, several pollution assessment indices were employed to evaluate their ecological impact. The assessment results indicated that current ecological risk levels were low, suggesting that the immediate threat of MPs to human health and the environment is relatively minor. Using a positive matrix factorization (PMF) model, the sources, composition, and distribution characteristics of MPs were thoroughly analyzed. Based on these findings, this study would provide insights for improving and innovating existing wastewater treatment technologies, with the goal of enhancing MPs removal efficiency and contributing to environmental protection efforts.