Abstract

Microplastics (MPs), and specifically microfibres (MPFs), are ubiquitous in water bodies, including wastewater and drinking water. In this work, a thorough literature review on the occurrence and removal of MPs, and specifically MPFs in WWTPs and DWTPs, has been carried out. When the water is treated, an average microfiber removal efficiency over 70% is achieved in WWTPs and DWTPs. These high percentages are still inefficient for avoiding the presence of a large number of microfibres in treated wastewater and also in tap water. RSF, DAF, oxidation ditch and CAS processes have been described as the most efficient treatments for eliminating MPFs from wastewater treatment. It is remarkable the wide range of the data reported on this topic; for example, treated wastewater contains between not detected and 347 MPFs/L, whereas tap water contains between not detected and 168 MPFs/L. Microfibres constitute more than half of the MPs found in treated wastewater and sewage sludge, whereas in DWTP effluents the percentage of MPFs is around 32%. Nevertheless, the relative amount of MPFs reported in tap water is notably higher (71%). Microfibres from WWTPs are discharged to the environment, being a source of MP pollution. Additionally, MPs released by DWTPs directly enter the drinking water lines, which constitute a direct route for MP human consumption, so that it has been estimated that an adult may ingest an average value of 7500 MPFs per year only via tap water. Thus, this review provides an update on the performance of WWTPs and DWTPs in removing MPs from water, which is an issue of great interest.

Highlights

  • Nowadays, Microplastics (MPs) can be considered ubiquitous in the environment.These microcontaminants can be originated from different sources

  • These pollutants can be emitted as ‘primary MPs’ or ‘secondary MPs’, which result from the breakdown of larger plastic items, such as those coming from industrial and agricultural activities, fishing activities, tyre wear or mismanagement of plastics [1,2,3]

  • Microfibres can be found in different aquatic environments—namely, oceans [8,9], lakes [10,11], wastewater [12,13], sea ice [14,15], the deep sea [16,17], rivers [18,19,20], drinking water [21,22,23], surface water [24], bays [25] and marine sediments [26,27,28]

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Summary

Introduction

Microplastics (MPs) can be considered ubiquitous in the environment. These microcontaminants can be originated from different sources. Microfibres can be found in different aquatic environments—namely, oceans [8,9], lakes [10,11], wastewater [12,13], sea ice [14,15], the deep sea [16,17], rivers [18,19,20], drinking water [21,22,23], surface water [24], bays [25] and marine sediments [26,27,28] This ubiquity notably contributes to the pollution of the environment, being a risk for fauna and flora [29,30], and for even humans. The vast majority of studies were carried out in Europe (48%) and Asia (43%); in particular, most of them were conducted in China (approximately 27% of the total studies reviewed)

Microplastics and Microfibres in WWTPs
Microfiber Occurrence in WWTPs
Technologies for Microfiber Removal in WWTPs
Microfibres Retained in Sludge
Analytical Methods Used to Analyse MPs from Wastewater and Sludge Samples
Microplastics and Microfibres in DWTPs
Microfiber Incidence in Tap Water
Findings
Future Prospects
Full Text
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