- Thesis topic: Investigation and Analysis of Microplastics in Taiwan wastewater treatment plant

- Doi: https://doi.org/10.6840/cycu202301516

- Abstract: 

        Microplastics (MPs) are emerging pollutants with particle sizes smaller than 5mm. In recent years, they have been widely detected and discovered in various environments. As carriers of organic pollutants, they pose ecological risks when collected and discharged through sewage systems, leading to the ingestion of MPs by aquatic organisms and subsequent harm to ecosystems. Therefore, this study aimed to investigate the abundance and characteristics of plastic microplastics in Taiwan's wastewater treatment plants during the summer months of July and August 2022, as well as in December 2022 during winter. Microscopic visual analysis, Microplastics diversity index, and correlation analysis were conducted to understand seasonal influences and regional differences. The results of the analysis revealed that the abundance of microplastics ranged from 17.6 to 136 n/L. The shapes of microplastics were fragments and fibers, accounting for 21.2% to 58.7% and 37.7% to 82.0% of the total, respectively. White was the primary color of microplastics, comprising 11.9% to 80.5% of all colors observed. Moreover, a significant correlation was found between white plastic microplastics and fiber plastic microplastics. In terms of size, microplastics ranging from 500 to 5,000 µm were the most prevalent, accounting for 14.7% to 46.9%. The microplastics diversity index indicated that the Taoyuan North District Wastewater Treatment Plant exhibited a more complex composition in the influent during summer, while the Kenting Wastewater Treatment Plant demonstrated a more complex composition in the influent during winter. The Guishan Wastewater Treatment Plant exhibited a relatively uniform composition in the influent due to the treatment of textile industry wastewater. The correlation analysis revealed that the factors influencing microplastics abundance, ranked from most to least influential, were regional GDP, population, temperature, rainfall, and influent volume. In terms of seasonal effects, the Taoyuan North District Wastewater Treatment Plant, Guishan Wastewater Treatment Plant, Daxi Wastewater Treatment Plant, and Fengshan Wastewater Treatment Plant exhibited higher plastic microplastics abundance during winter due to lower temperatures, with differences in abundance of 109 n/L, 34.0 n/L, 1.3 n/L, and 48.0 n/L, respectively. The Liukuaicuo Wastewater Treatment Plant and Kenting Wastewater Treatment Plant showed higher plastic microplastics abundance during summer due to less significant seasonal temperature differences and higher water consumption during that season, with differences in abundance of 16.9 n/L and 13.4 n/L, respectively. The MPs abundance increased with the daily processing capacity of the treatment plant. In the analysis of city type differences, higher regional GDP and population in the areas where wastewater treatment plants were located resulted in an elevated risk of microplastics pollution and increased levels of microplastics abundance. The analysis of differences between wastewater treatment plants in the northern and southern regions of Taiwan reveals variations in microplastics abundance levels due to differences in climate. In the analysis of differences in tourist areas, higher tourist populations are associated with higher levels of microplastics abundance. Therefore, it is important to assess the potential risk of microplastics pollution in relation to changes in tourist populations.

Keywords: microplastics, wastewater treatment plants, correlation analysis, seasonal influences, tourist area