- Thesis topic: Microplastic Contamination in Sewage Sludge from Taiwan’s Domestic Wastewater Treatment Plant: Abundance, Risk Assessment and Potential Impacts on Food Chain

- Doi: 

- Abstract: 

        The widespread presence of microplastics in the environment has gravely harmed human health via the food chain system and had an extensive effect on ecosystems. This study investigated the characteristics of microplastic pollution during the summer (April) and winter (December) seasons in six WWTPs along Taiwan in order to better understand the seasonal variation in microplastics in sewage sludge, identify the sources of microplastic pollution, and discuss their migration characteristics. An investigation was conducted on the shape, size, color and polymer composition of microplastics. We also conducted a validation of organic matter removal before conducting microplastic extraction. 9 scenarios with variations in the number of samples to determine the optimal proportion in the digestion process or solid/liquid (S/L) ratio. Protocol 4 resulted in the highest organic matter removal of 88.04%. The sludge samples exhibited MP concentrations ranging from 32.79-85.06 × 103 items/kg dry weight, with an average of 48.35 ± 8.14 × 103 items/kg dry weight. Therefore, the concentration of sludge-based microplastic (MP) in Taoyuan WWTP was higher compared to other WWTPs and exhibited seasonal variations. Their colors, shape types, and size were mainly white (26.19%), fiber (43.25%), and 50-125 µm (54.15%), respectively. Both the hazard index (HI) and the pollutant load index (PLI) were utilized to carry out the risk assessment. Thereby, we provide possible transport to better understand the current conditions for microplastic-contaminated sludge and the potential effects to the food chain.

Keywords: Microplastic, Organic Matter Removal, Risk Assessment and Sewage Sludge