Removal of micro- and nanoplastics by filtration technology: Performance and obstructions to market penetrations

Micro- and nanoplastics (NPs/MPs), as a class of emerging pollutants, are being assumed as major environmental risk due to their unique characteristics, higher toxicity, low rate of degradation, and strong affinity to other contaminants. Notably, they can negatively impact aquatic, biotic, and even human life because marine species, animals, and humans can ingest MPs/NPs mistakenly. Regarding this, several treatment technologies, viz., adsorption, coagulation, photocatalysis, membrane bioreactor, filtration, and advanced oxidation, have been developed and used to eliminate MPs/NPs based pollution. From them, filtration technology is considered as an efficient treatment method to remove MPs/NPs from water and real sewage due to its many benefits such as higher pollutant removal, low environmental footprint, higher selectivity, ease of scalability, low operational and maintenance cost. In addition, plastic particles can be removed via sieving, straining, interception, adsorption, size-exclusive, cake-layer formation, electrostatic attraction/repulsion, concentration polarization, and standard blocking mechanisms. Hence, this thorough review is planned to discuss the elimination capability of MPs/NPs by filtration technology. Broadly, this review is also discussing for the first time the influence of critical factors (i. e., characteristics of MPs/NPs, membranes/filter media, and environmental medium) affecting removal performance of MPs and NPs by filtration technology. It was noticed that morphology and geometry of the filter media/ and membranes had a great influence on the elimination of MPs/NPs by filtration technology. Moreover, the current review also highlights the particle applications of membrane-based filtration technology in separating MPs/NPs from actual water samples. Notably, obstructions to market penetrations of filtration technology to eliminate plastic particles from real sewage have been critically discussed to better understand the execution of filtration-based technologies for the remediation of plastic particles pollution. It was noticed that pre-treatment, modifications, and integration techniques can significantly improve removal performance of MPs/and NPs by filtration technology. Finally, knowledge gaps and future recommendations have been elaborated precisely to improve filtration-based technology for removing MPs/NPs from sewage and, to assist scientific community for future explorations and to fight against plastic particles pollution.