Seasonal variation and removal of microplastics in a central Asian urban wastewater treatment plant

• Published in: Marine pollution bulletin 2024-08, Vol.205, p.116597, Article 116597
• Main Authors: Zhaxylykova, Dana, Alibekov, Alisher, Lee, Woojin
• Format: Article
• Language: English
• Subjects: Central Asia; Microplastic removal; Polymer types; Seasonal variation; Urban wastewater treatment plant
• ISSN: 0025-326X; 1879-3363; 1879-3363
• DOI: 10.1016/j.marpolbul.2024.116597

This paper investigated the MP presence and removal in the urban WWTP in Astana, the capital city of Kazakhstan. MP concentrations in the 100–5000 μm size were analyzed across treatment stages with a modified treatment process scheme, and their removal efficiencies were evaluated. The WWTP effluent displayed a low MP concentration (4.06 ± 3.06 MP/L to 5.44 ± 3.51 MP/L), but considering the daily wastewater discharge (253,900,000 L/day), it can significantly contribute to the MP pollution of aquatic systems. Seasonal variation was observed in the influent, with higher abundance during summer, while no significant trend was observed in the effluent. The WWTP achieved an 88.6–93.0 % removal efficiency, with mechanical treatment and granular filtration being the most effective, followed by biological treatment and UV disinfection. Fragments were the most abundant among the observed shapes (53.9–59.9 %) and black MPs dominated (44.7–67.5 %). Polyethylene (PE) emerged as the most prevalent polymer type among the MPs analyzed (31.6–35.7 %). [Display omitted] •MP abundance, removal, and seasonal variation in an urban Kazakhstan WWTP were investigated.•Seasonally fructuating MP concentrations peaked in summer and were lowest in winter.•The dominant shape, color, and polymer type were fragments, black color, and polyethylene.•The MP removal was 88.6–93.0 %, with granular filtration being the most effective process.•Daily Astana WWTP discharge to aquatic systems was estimated as 52.7 ± 22.6 g/day.