Membrane bioreactor (MBR) as an advanced wastewater treatment technology for removal of synthetic microplastics

Microplastics (MPs) pollutants are produced from macro plastic products and have harmful effects on our ecosystem. It can be generated as any form or shape such as chip, thread, and beads. Synthetic textiles materials such as polyester, nylon, rayon, and acrylic are used in used in clothing industry, which contribute about 70% of the clothing raw material globally. Synthetic microplastics are washed off from these products and contribute about 30–35% of primary microplastics polluting our environment and oceans. In a single laundry, approximately of 8 million microfibers are discharged into wastewater treatment plants, which cannot recover them and enter the marine environment. Microplastic pollution of the aquatic environment is most important distress in view of the devastating effect on the ecosystem. The application of highly developed wastewater treatment technologies is compulsory to avoid further spread of the emerging micro pollutants in the environment. MBR (membrane bioreactor) technology, as one of the modern wastewater treatment technologies, has many advantages over classical activated sludge treatment (CAS), with higher sludge ages, and higher sludge densities, thus giving enhanced properties to remove pollutants. MBR process facilitates to reach a more efficient elimination of microplastic particle contaminants from wastewaters. Treatment of waste waters through conventional method cannot able to eliminate microplastics (MPs) from the wastewater efficiently and final effluents can act as entrance path of MPs into the aquatic environments. Scientific reports concluded that almost 99% of MF particles can be retained by the activated sludge process and mainly through membrane bioreactors. The average concentrations decrease of microplastics from the primary to the final effluent 96.2% using MBR technique, indicating the importance of tertiary step to remove this emerging pollutant. In this present review, the present method of the detection, incidence and elimination of these microplastics pollutants in WWTPs were broadly appraised. Exclusively, the methods employed for sampling of microplastics from both wastewater and sewage sludge, and their pretreatment and characterization methods were analyzed. The key points concerning treatment microplastic pollutants trough MBR, total discharges, materials, and dimensions are discussed.