**3. Conclusion**

Microplastic is a serious pollutant in our aquatic and terrestrial ecosystems. WWTPs play a major role in limiting the dispersal of MP in the environment. Nevertheless, as waste streams flow through WWTPs, these in turn become point sources of MPs, where MPs are released in the millions into rivers, lakes and lastly into the sea. Studies on different WWTPs around the world have given a good indication of the retaining efficiency of different wastewater treatment stages and methods. Usually, a large part of MP is retained in the preliminary and primary treatment stages. However, the amount of MP released in the final effluent is often a function of the tertiary treatment method used. In this regard, a further development of membranes and techniques used in combination with membranes for the filtration of MP seems of interest.
