Improved methodology to determine the fate and transport of microplastics in a secondary wastewater treatment plant. (15th April 2020)

• Record Type: Journal Article
• Authors: Raju, Subash; Carbery, Maddison; Kuttykattil, Aswin; Senthirajah, Kala; Lundmark, Anna; Rogers, Zoe; SCB, Suresh; Evans, Geoffrey; Palanisami, Thava
• Is Part Of: Water research. Volume 173(2020)
• Publication Date: 2020-04-15
• Subjects: Microplastics -- Wastewater -- Sludge -- Secondary treatment -- Methodology -- Glitter; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2020.115549
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: Wastewater treatment plants are a significant pathway of microplastics (MPs) to aquatic environments. To develop suitable management options and reduce microplastic emissions in treated effluent and sludge, we must first develop a reliable method to understand their transport and fate throughout the treatment process. An improved methodology was applied to determine the size, shape, polymer type and partitioning behaviour of MPs using a combination of oxidation treatment, fluorescent staining and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) to detect small MPs ≤20 μm in wastewater. The mean number of MPs (<5 mm) detected using this methodology was 11.80 ± 1.10 MP/L in raw sewage, 5.23 ± 0.25 MP/L in degritted wastewater, 7.91 ± 0.44 MP/L in waste activated sludge and 2.76 ± 0.11 MP/L in the final treated effluent. An increase in MPs following primary screening suggests that WAS is a sink for several stealth microplastics, including glitter, which is returned to the effluent during the treatment process. The estimated MP removal efficiency for the studied WWTP is relatively poor compared with global data for secondary WWTPs, which is likely due to the release of partially treated effluent into the Pacific Ocean via a second discharge point. The information generated through this study can be useful to; firstly, inform on-site wastewater management practices, and secondly, reduce MP concentrations in final treated effluents discharged to the marine environment. Graphical abstract: Image 1 Highlights: Improved methodology to reduce uncertainties in the detection of fine microplastics in wastewater. First study to reveal that glitter is abundant in waste activated sludge. First regional outlook of microplastics in an Australian secondary WWTP.