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Wu X, Zhao X, Chen R, Liu P, Liang W, Wang J, Teng M, Wang X, Gao S. Wastewater treatment plants act as essential sources of microplastic formation in aquatic environments: A critical review. WATER RESEARCH 2022; 221:118825. [PMID: 35949074 DOI: 10.1016/j.watres.2022.118825] [Citation(s) in RCA: 55] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 06/21/2022] [Accepted: 07/03/2022] [Indexed: 06/15/2023]
Abstract
According to extensive in situ investigations, the microplastics (MPs) determined in current wastewater treatment plants (WWTPs) are mostly aged, with roughened surfaces and varied types of oxygen-containing functional groups (i.e., carbonyl and hydroxyl). However, the formation mechanism of aged MPs in WWTPs is still unclear. This paper systematically reviewed MP fragmentation and generation mechanisms in WWTPs at different treatment stages. The results highlight that MPs are prone to undergo physical abrasion, biofouling, and chemical oxidation-associated weathering in WWTPs at different treatment stages and can be further decomposed into smaller secondary MPs, including in nanoplastics (less than 1000 nm or 100 nm in size), suggesting that WWTPs can act as a formation source for MPs in aquatic environments. Sand associated mechanical crashes in the primary stage, microbes in active sewage sludge-related biodegradation in the secondary stage, and oxidant-relevant chemical oxidation processes (light photons, Cl2, and O3) in the tertiary stage are the dominant causes of MP formation in WWTPs. For MP formation mechanisms in WWTPs, external environmental forces (shear and stress forces, UV radiation, and biodegradation) can first induce plastic chain scission, destroy the plastic molecular arrangement, and create abundant pores and cracks on the MP surface. Then, the physicochemical properties (modulus of elasticity, tensile strength and elongation at break) of MPs shift consequently and finally breakdown into smaller secondary MPs or nanoscale plastics. Overall, this review provides new insights to better understand the formation mechanism, occurrence, fate, and adverse effects of aged microplastics/nanoplastics in current WWTPs.
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Affiliation(s)
- Xiaowei Wu
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Xiaoli Zhao
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
| | - Rouzheng Chen
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Peng Liu
- Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China
| | - Weigang Liang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Junyu Wang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Miaomiao Teng
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Xia Wang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Shixiang Gao
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093, China
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Wang L, Wu WM, Bolan NS, Tsang DCW, Li Y, Qin M, Hou D. Environmental fate, toxicity and risk management strategies of nanoplastics in the environment: Current status and future perspectives. JOURNAL OF HAZARDOUS MATERIALS 2021; 401:123415. [PMID: 32763705 PMCID: PMC7345412 DOI: 10.1016/j.jhazmat.2020.123415] [Citation(s) in RCA: 248] [Impact Index Per Article: 82.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 06/23/2020] [Accepted: 07/04/2020] [Indexed: 05/19/2023]
Abstract
Tiny plastic particles considered as emerging contaminants have attracted considerable interest in the last few years. Mechanical abrasion, photochemical oxidation and biological degradation of larger plastic debris result in the formation of microplastics (MPs, 1 μm to 5 mm) and nanoplastics (NPs, 1 nm to 1000 nm). Compared with MPs, the environmental fate, ecosystem toxicity and potential risks associated with NPs have so far been less explored. This review provides a state-of-the-art overview of current research on NPs with focus on currently less-investigated fields, such as the environmental fate in agroecosystems, migration in porous media, weathering, and toxic effects on plants. The co-transport of NPs with organic contaminants and heavy metals threaten human health and ecosystems. Furthermore, NPs may serve as a novel habitat for microbial colonization, and may act as carriers for pathogens (i.e., bacteria and viruses). An integrated framework is proposed to better understand the interrelationships between NPs, ecosystems and the human society. In order to fully understand the sources and sinks of NPs, more studies should focus on the total environment, including freshwater, ocean, groundwater, soil and air, and more attempts should be made to explore the aging and aggregation of NPs in environmentally relevant conditions. Considering the fact that naturally-weathered plastic debris may have distinct physicochemical characteristics, future studies should explore the environmental behavior of naturally-aged NPs rather than synthetic polystyrene nanobeads.
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Affiliation(s)
- Liuwei Wang
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Wei-Min Wu
- Department of Civil and Environmental Engineering, William & Cloy Codiga Resource Recovery Center, Center for Sustainable Development & Global Competitiveness, Stanford University, Stanford, CA 94305-4020, USA
| | - Nanthi S Bolan
- Global Centre for Environmental Remediation, The University of Newcastle, Callaghan, NSW 2308, Australia
| | - Daniel C W Tsang
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Yang Li
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, China
| | - Muhan Qin
- School of Environment, Tsinghua University, Beijing 100084, China
| | - Deyi Hou
- School of Environment, Tsinghua University, Beijing 100084, China.
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Enfrin M, Lee J, Gibert Y, Basheer F, Kong L, Dumée LF. Release of hazardous nanoplastic contaminants due to microplastics fragmentation under shear stress forces. JOURNAL OF HAZARDOUS MATERIALS 2020; 384:121393. [PMID: 31740306 DOI: 10.1016/j.jhazmat.2019.121393] [Citation(s) in RCA: 168] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 09/27/2019] [Accepted: 10/03/2019] [Indexed: 05/22/2023]
Abstract
The presence of nanoplastics in water has become a major environmental concern in the last decade however the knowledge on the origin and formation of these emerging contaminants is lacking due to analytical challenges in detection and quantification techniques. The release of nanoplastics due to the fragmentation of microplastics extracted from a facial scrub and the resulting toxicity on aquatic species are reported here for the first time. The daily use of 4 g of facial scrub could release up to 1011 microplastics of 400 nm in size per litre of wastewater from household drains. Turbulences created by mixing or pumping induced the fragmentation of microplastics into nanoplastics smaller than 10 nm via a crack propagation and failure mechanism, increasing the number of particles in water by one order of magnitude. Compared to microplastics at a fixed concentration number of 6.8 × 108 part./mL, the generated nanoplastics initiated the death of 54% more cells in zebrafish by passive ingestion via skin diffusion which therefore pose a real threat for aquatic living organisms. These results stress the need to reduce the release of nano/microplastics in the aquatic environment to prevent the contamination of all trophic levels.
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Affiliation(s)
- Marie Enfrin
- Department of Chemical and Process Engineering, University of Surrey, Surrey, GU27XH, United Kingdom; Deakin University, Geelong, Institute for Frontier Materials, Waurn Ponds, Victoria, 3216, Australia
| | - Judy Lee
- Department of Chemical and Process Engineering, University of Surrey, Surrey, GU27XH, United Kingdom.
| | - Yann Gibert
- Deakin University, Geelong, School of Medicine, Waurn Ponds, Victoria, 3216, Australia; Department of Cell and Molecular Biology, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
| | - Faiza Basheer
- Deakin University, Geelong, School of Medicine, Waurn Ponds, Victoria, 3216, Australia
| | - Lingxue Kong
- Deakin University, Geelong, Institute for Frontier Materials, Waurn Ponds, Victoria, 3216, Australia
| | - Ludovic F Dumée
- Deakin University, Geelong, Institute for Frontier Materials, Waurn Ponds, Victoria, 3216, Australia
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Enfrin M, Dumée LF, Lee J. Nano/microplastics in water and wastewater treatment processes - Origin, impact and potential solutions. WATER RESEARCH 2019; 161:621-638. [PMID: 31254888 DOI: 10.1016/j.watres.2019.06.049] [Citation(s) in RCA: 245] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 05/30/2019] [Accepted: 06/19/2019] [Indexed: 05/22/2023]
Abstract
The presence of nano and microplastics in water has increasingly become a major environmental challenge. A key challenge in their detection resides in the relatively inadequate analytical techniques available preventing deep understanding of the fate of nano/microplastics in water. The occurrence of nano/microplastics in water and wastewater treatment plants poses a concern for the quality of the treated water. Due to their broad but small size and diverse chemical natures, nano/microplastics may travel easily along water and wastewater treatment processes infiltrating remediation processes at various levels, representing operational and process stability challenges. This review aims at presenting the current understanding of the fate and impact of nano/microplastics through water and wastewater treatment plants. The formation and fragmentation mechanisms, physical-chemical properties and occurrence of nano/microplastics in water are correlated to the interactions of nano/microplastics with water and wastewater treatment plant processes and potential solutions to limit these interactions are comprehensively reviewed. This critical analysis offers new strategies to limit the number of nano/microplastics in water and wastewater to keep water quality up to the required standards and reduce threats on our ecosystems.
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Affiliation(s)
- Marie Enfrin
- Department of Chemical and Process Engineering, University of Surrey, Surrey, GU27XH, United Kingdom
| | - Ludovic F Dumée
- Deakin University, Geelong, Institute for Frontier Materials, Waurn Ponds, Victoria, 3216, Australia.
| | - Judy Lee
- Department of Chemical and Process Engineering, University of Surrey, Surrey, GU27XH, United Kingdom
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