An evaluation of microplastics fate in the wastewater treatment plants: frequency and removal of microplastics by microfiltration membrane

Abstract

In this research, the fate and removal of microplastics (MPs) entering and leaving in wastewater treatment plant (WWTP) was investigated. Additionally, the application of microfiltration membrane technique for MPs removal were evaluated. In the first phase, the quantity, type and size of the MPs were studied from three different points of the WWTP. The results showed that the average amount of MPs entered into the WWTP, accumulated in thesludge matrix and discharged from the effluent were 206, 183 and 94 MP/L, respectively. The MPs were observed mainly in the forms of fiber, pellet, and fragment, with a proportion of 35%, 39, 22, and 34%, 22, 38, and 31%, 39%, 37.7% in the influent, effluent and sludge of the WWTP, respectively. It should be noted, a minor amount of foam (2%) and film (0.3%) was also observed. The particle size distribution of the MPs in the effluent of the system was almost identical (6–14% for 1–5,000 μm), while the influent mostly contained the particles within 1–100 μm (above 26%) with other particle sizes within 100–5,000 μm (8–17%). Particle size within a range of 500–5,000 μm was abundant in the sludge. In the second phase, a micro-filtration (MF) membrane with a pore size of 0.1 μm was applied to eliminate the MPs from the effluent of WWTP. It was observed the application of MF membrane technique could achieve MPs removal efficiency up to 98% in the effluent of the system.

Microplastics and the Water Industry

“…It has been estimated that typical microplastic removal rates range from 80% to 95%, with some plants achieving up to 99% removal (Kalčíková et al 2017, Mintenig et al 2017). It was observed that the application of microfiltration during wastewater treatment could achieve microplastic removal efficiency up to 98% (Yahyanezhad et al 2021).…”