Impacts of Polylactic Acid Microplastics on Performance and Microbial Dynamics in Activated Sludge System

Mengbo Huang, Dongqi Wang (), Shengwei Zhang, Yuzhu Weng, Kailong Li, Renjie Huang, Yuan Guo, Chunbo Jiang, Zhe Wang, Hui Wang, Haiyu Meng, Yishan Lin, Mingliang Fang () and Jiake Li
Additional contact information
Mengbo Huang: National Demonstration Center for Experimental Water Resources and Hydro-Electric Engineering Education, Xi’an University of Technology, Xi’an 710048, China
Dongqi Wang: National Demonstration Center for Experimental Water Resources and Hydro-Electric Engineering Education, Xi’an University of Technology, Xi’an 710048, China
Shengwei Zhang: Department of Municipal and Environmental Engineering, Xi’an University of Technology, Xi’an 710048, China
Yuzhu Weng: Department of Municipal and Environmental Engineering, Xi’an University of Technology, Xi’an 710048, China
Kailong Li: Department of Municipal and Environmental Engineering, Xi’an University of Technology, Xi’an 710048, China
Renjie Huang: Department of Municipal and Environmental Engineering, Xi’an University of Technology, Xi’an 710048, China
Yuan Guo: Department of Municipal and Environmental Engineering, Xi’an University of Technology, Xi’an 710048, China
Chunbo Jiang: State Key Laboratory of Eco-Hydraulics in Northwest Arid Region, Xi’an University of Technology, Xi’an 710048, China
Zhe Wang: State Key Laboratory of Eco-Hydraulics in Northwest Arid Region, Xi’an University of Technology, Xi’an 710048, China
Hui Wang: Department of Municipal and Environmental Engineering, Xi’an University of Technology, Xi’an 710048, China
Haiyu Meng: Department of Municipal and Environmental Engineering, Xi’an University of Technology, Xi’an 710048, China
Yishan Lin: Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity, College of Urban and Environmental Sciences, Northwest University, Xi’an 710127, China
Mingliang Fang: Department of Environmental Science and Engineering, Fudan University, 220 Handan Rd., Shanghai 200433, China
Jiake Li: National Demonstration Center for Experimental Water Resources and Hydro-Electric Engineering Education, Xi’an University of Technology, Xi’an 710048, China

Sustainability, 2023, vol. 15, issue 19, 1-16

Abstract: A large number of microplastics (MPs) have been found in various stages of wastewater treatment plants, which may affect the functional microbial activity in activated sludge and lead to unstable pollutant removal performance. In this study, the effects of different concentrations of polylactic acid microplastics (PLA MPs) on system performance, nitrification and phosphorus (P) removal activities, and extracellular polymeric substances (EPS) were evaluated. The results showed that under the same influent conditions, low concentrations (50 particles/(g TS)) of PLA MPs had no significant effect on effluent quality. The average removal efficiencies of chemical oxygen demand, phosphate, and ammonia were all above 80%, and the average removal efficiencies of total nitrogen remained above 70%. High concentrations (200 particles/(g TS)) of PLA MPs inhibited the activities of polyphosphate-accumulating organisms (PAOs) and nitrifying bacteria. The specific anaerobic P release rate decreased from 37.7 to 23.1 mg P/(g VSS·h), and the specific aerobic P uptake rate also significantly decreased. The specific ammonia oxidation rate decreased from 0.67 to 0.34 mg N/(g VSS·h), while the change in the specific nitrite oxidation rate was not significant. The dosing of PLA MPs decreased the total EPS and humic acid content. As the concentration of PLA MPs increased, microbial community diversity increased. The relative abundance of potential PAOs (i.e., Acinetobacter ) increased from 0.08 to 12.57%, while the relative abundance of glycogen-accumulating organisms (i.e., Competibacter and Defluviicoccus ) showed no significant changes, which would lead to improved P removal performance. The relative abundance of denitrifying bacteria (i.e., Pseudomonas ) decreased from 95.43 to 58.98%, potentially contributing to the decline in denitrification performance.

Keywords: microplastics; activated sludge; nutrient removal; microbial activity; microbial community (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
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