Occurrence, fate and removal of microplastics as heavy metal vector in natural wastewater treatment wetland system. (15th March 2021)

• Record Type: Journal Article
• Authors: Sarkar, Dhruba Jyoti; Das Sarkar, Soma; Das, Basanta Kumar; Sahoo, Bigan Kumar; Das, Akankshya; Nag, Subir Kumar; Manna, Ranjan Kumar; Behera, Bijay Kumar; Samanta, Srikanta
• Is Part Of: Water research. Volume 192(2021)
• Publication Date: 2021-03-15
• Subjects: Microplastics -- Heavy metal -- Natural wastewater treatment system -- Freshwater wetlands -- Removal efficiency; MPs Microplastics -- CEC Contaminants of Emerging Concern -- EKW East Kolkata Wetland -- KMC Kolkata Municipal Corporation -- WWC Wastewater Canal -- TP Treatment Pond -- WWTP Wastewater Treatment Plant -- STP Sewage Treatment Plant -- ATR FT-IR Attenuated Total Reflection Fourier Transformed Infrared Spectroscopy -- PE Polyethylene -- PET Polyethylene Terephthalate -- PP Polypropylene -- PS Polystyrene; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2021.116853
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: Microplastics were dominantly found in natural wastewater treatment wetland system. Heavy metals load on extracted microplastics were 2.03 - 191.01 µg/g. Wetland biota were contaminated with microplastics and heavy metals. Floating microplastics were positively correlated with contamination in fish. Natural wetland system was capable of removing 50% of surface water microplastics. Abstract: Microplastics pollution in aquatic ecosystems is of great concern; however, systemic investigations are still lacking in freshwater wetland systems used for wastewater treatment. The present study discusses such freshwater wetland system in Eastern India to understand its microplastics transport mechanism, heavy metals association and microplastics removal efficiency. Microplastics (63 µm - 5 mm) were heavily found in surface water and sediments of treatment ponds (7.87 to 20.39 items/L and 2124.84 to 6886.76 items/kg) and associated wastewater canals (30.46 to 137.72 items/L and 1108.78 to 34612.87 items/kg). A high content of toxic metals (As, Cd, Cr, Cu, Ni, Pb and Zn) were found on the microplastics with polyethylene terephthalate and polyethylene as major plastics types which were also found in fishes and macroinvertebrates of treatment ponds. Machine learning algorithm revealed a close association between microplastics content in fishes and surface water, indicating risk associated with floating microplastics to the aquatic biota. The study also revealed that microplastics were acting as heavy metals vector and potentially causing fish contamination. Surface water microplastics removing efficiency of the treatment ponds was estimated to be 53%. The study bespeaks about transport of microplastics through wastewater canals and their retention in treatment ponds emphasizing sustainability maintenance of natural wastewater treatment systems especially considering microplastics contamination to the aquatic biota of freshwater wetland systems. Graphical abstract: Image, graphical abstract