a review on microplastics distribution in the persian gulf and oman sea and role of domestic wastewaters

The proliferation of microplastics in aquatic ecosystems has become an important environmental issue in recent years. the gradual disposal of plastic waste, the lack of standard diagnostic methods and the removal of microplastics have made it pervasive in the environment. methodology: in this research, water sampling was performed on both surface and deep forms of municipal wastewater of bandar abbas water treatment plant during one year (1399-1399), seasonally. the samples were passed through sieves with springs of 500, 300, 100 and 30 μm and then the organic matter in them was digested with hydrogen peroxide and the microplastics were separated by density-based separation method with sodium chloride salt and by stereomicroscope and ftir spectrometer investigated. the results showed that in all seasons, particles larger than 500 microns had the highest number in the sewage inlet, in other stations, the highest number was related to 300-500 micrometers and 100-300 microns. in all seasons of the year, the average number of macro and microplastics from wastewater to wastewater showed a decreasing trend. the decreasing trend of macroplastics was higher than microplastics particles, so that the effluent of municipal wastewater was not macroplastic (> 500 microns). in all stations (except the input station), the highest number of microplastics was related to particles with a size of 300-500 micrometers, and the reason could be due to the lack of a proper mechanism for removing microplastics. mand 2 showed higher efficiency in reducing and removing microplastics with the size of 300-500 and 100-300 microns than other stations. about 30% of the microplastic samples belonged to polyethylene and 30% to polypropylene. the rest of the identified microplastics belong to the family of polystyrene, polyester and polyacrylate, which are mostly due to the washing of textiles, disposable dishes and materials used in cosmetics. at present, treatment plant networks are not specifically designed to remove microplastics from wastewater, and in the process of treating treatment plants, the removal of microplastics depends on their density, because microplastics are low-density and can float superficially. deleted them. thus, considering the amount of microplastics in municipal wastewater, it is necessary to conduct research on the amount of microplastics released by the wastewater treatment plant and other possible sources of emission and their contribution to microplastic pollution in water sources.