Particle balance and return loops for microplastics in a tertiary-level wastewater treatment plant

Thumbnail Image

Access rights

openAccess
publishedVersion

URL

Journal Title

Journal ISSN

Volume Title

A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
This publication is imported from Aalto University research portal.
View publication in the Research portal (opens in new window)
View/Open full text file from the Research portal (opens in new window)

Authors

Date

2021-07-01

Department

Department of Built Environment

Major/Subject

Mcode

Degree programme

Language

en

Pages

12

Series

Water Science and Technology, Volume 84, issue 1, pp. 89-100

Abstract

Microplastics (MPs) from households, stormwater, and various industries are transported to wastewater treatment plants (WWTPs), where a high proportion of them are captured before discharging their residuals to watersheds. Although recent studies have indicated that the removed MPs are mainly retained in wastewater sludge, sludge treatment processes have gained less attention in MP research than water streams at primary, secondary, and tertiary treatments. In this study, we sampled 12 different process steps in a tertiary-level municipal WWTP in central Finland. Our results showed that, compared to the plant influent load, three times more MPs circulated via reject water from the sludge centrifugation back to the beginning of the treatment process. Fibrous MPs were especially abundant in the dewatered sludge, whereas fragment-like MPs were observed in an aqueous stream. We concluded that, compared to the tertiary effluent, sludge treatment is the major exit route for MPs into the environment, but sludge treatment is also a return loop to the beginning of the process. Our sampling campaign also demonstrated that WWTPs with varying hydraulic conditions (such as the one studied here) benefit from disc filter-based tertiary treatments in MP removal.

Description

Keywords

enzymatic purification, microplastics, reject water, return loop, wastewater sludge, SEWAGE-SLUDGE, IDENTIFICATION, REMOVAL, FATE

Other note

DOI

10.2166/wst.2021.209

Citation

Salmi, P, Ryymin, K, Karjalainen, A K, Mikola, A, Uurasjarvi, E & Talvitie, J 2021, 'Particle balance and return loops for microplastics in a tertiary-level wastewater treatment plant', Water Science and Technology, vol. 84, no. 1, pp. 89-100. https://doi.org/10.2166/wst.2021.209

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-202107017908

Collections

[article-cris] Insinööritieteiden korkeakoulu / ENG