Evaluation of microplastic removal efficiency of wastewater-treatment plants in a developing country, Vietnam

Environmental Technology & Innovation 29 (2023) 102994

Authors: Thi-Minh-Tam Le a,b, Tran-Nguyen-Sang Truong a,b, Phuoc-Dan Nguyen a,b,c,∗, Quang-Do-Thanh Le a,b, Quoc-Viet Tran a,b, Thanh-Tho Le d, Quoc-Hung Nguyen d, Thuy-Chung Kieu-Le b,e, Emilie Strady a,f,∗∗

a CARE, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Viet Nam b Vietnam National University Ho Chi Minh City, Viet Nam c Faculty of Civil Engineering, Ho Chi Minh City University of Technology (HCMUT), Viet Nam d CASE Center of Analytical Services and Experimentation, Ho Chi Minh City, Viet Nam e Faculty of Geology and Petroleum Engineering, Ho Chi Minh City University of Technology (HCMUT), Viet Nam f Aix-Marseille Univ., Universit. de Toulon, CNRS, IRD, MIO, Marseille, France

Accepted 21 December 2022

Available online 2 January 2023

Abstract. Wastewater-treatment plants (WWTPs) are considered significant point sources of microplastics (MiP) in the receiving waters; MiP release is poorly estimated in developing countries. MiP abundance, recovery efficiency and daily load to receiving waters were explored in treatment stage facilities of four WWTPs in Vietnam, located in Ho Chi Minh City, Thu Dau Mot, and Da Lat. MiP abundance varied from 1860 items m⁻³ to 125,000 items m−3 in influents and between 140 items m⁻³ and 813 items m⁻³ in the final effluents.

The MiP-removal efficiency was the highest in the Da Lat wastewater-treatment plant (DL WWTP), a tertiary treatment plant using trickling filters followed by aerated lagoon and maturation ponds for BOD and nitrogen removals. The lowest MiP-removal efficiency was observed in Binh Hung wastewater-treatment plant (BH WWTP), a combined sewer system using conventional activated sludge processes as secondary treatment.

The total daily MiP load to the receiving environment varied from 1,840,000 items d⁻¹ at the DL WWTP to 77,127,000 items d⁻¹ at the BH WWTP. Change in MiP abundance, morphology, and removal efficiency were discussed after each stage of the treatment process for the four WWTPs.