Conventional wastewater treatment with primary and secondary treatment processes efficiently remove microplastics (MPs) from the wastewater. Despite the efficient removal, final effluents can act as entrance route of MPs, given the large volumes constantly discharged into the aquatic environments. This study investigated the removal of MPs from effluent in four different municipal wastewater treatment plants utilizing different advanced final-stage treatment technologies. The study included membrane bioreactor treating primary effluent and different tertiary treatment technologies (discfilter, rapid sand filtration and dissolved air flotation) treating secondary effluent. The MBR removed 99.9% of MPs during the treatment (from 6.9 to 0.005 MP L-1), rapid sand filter 97% (from 0.7 to 0.02 MP L-1), dissolved air flotation 95% (from 2.0 to 0.1 MP L-1) and discfilter 40-98.5% (from 0.5 - 2.0 to 0.03-0.3 MP L-1) of the MPs during the treatment. Our study shows that with advanced final-stage wastewater treatment technologies WWTPs can substantially reduce the MP pollution discharged from wastewater treatment plants into the aquatic environments.
Keywords: MBR; Microplastics; Tertiary treatments; Wastewater effluent.
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