This study aims to detect how many microplastics and what kind are released from the wastewater treatment plant (WWTP) Skebäck, in Örebro. The study was limited to the analysis of three filters with 50 μm mesh size and one filter with 300 μm mesh size. The samples were taken at different times, two in the fall of 2019 and one in the spring of 2020. Visual characterization was used for the quantification of microplastics, and a lower and upper bound was used. The lower bound represents particles that were deemed identifiable as plastic with high certainty, while the upper bound also includes particles that may have been microplastic. An additional ATR-FTIR analysis was performed on selected microplastics >300 μm. The presence of microplastics in the effluent from Skebäcks WWTP could be confirmed. The quantity of microplastics per m3 (MP/m3) trapped on the 50 μm filters were quantified in a range between 0 MP/m3 to 291 MP/m3 for the lower bound, and 72 MP/m3 to 435 MP/m3 for the upper bound. The 300 μm filter had considerably less microplastics than the 50 μm filter with 1.8 MP/m3. The quantification of fibers on the 50 μm filter and 300 μm filters was not possible due to high blank contaminations. According to the concentration of 63 MP/m3 of the lower bound count on the 50 μm filters and the amount of water flowing through Skebäck in 2019, 17 818 935 m3, 1.1 billion microplastic particles were released into Svartån that year. In comparison the highest value of the upper bound count, 435 MP/m3, gave a release of 7.7 billion microplastic particles. Using the concentration of the 300 μm filter 1.8 MP/m3, 32 million microplastics/year were released from Skebäck in 2019. The amount of spheres 50-300 μm released in the effluent from Skebäck was estimated to be 3.7 kg in 2019.