Recent advancement in microplastic removal process from wastewater - A critical review

• Microplastics are plastic particles having size <5 mm. • It can be remediated through physical, chemical, and biological methods. • Biochar filtration method is the most efficient way to remove microplastics. • Proper implementation of microplastic removal methods is highly required. Microplastics, small sized plastic particles having size <5 mm are formed through primary process including production of beauty products, microbeads and microfibres as well as secondary process including mechanical weathering, friction, aberration and fragmentation of large plastics. The major sources of microplastics are land-based and ocean-based sources. Microplastic pollution is a serious concern due to the persistent, low biodegradability and bio-accumulative behaviour. Microplastics can bioaccumulate in the food chain and can cause ecological and human health risk. Hence, it is important to remove from the aquatic ecosystems. Microplastics are removed from aquatic systems and wastewater through a series of processes such as physical, chemical and biological treatments. In the present articles, >250 articles are reviewed to collect the information regarding the various physical, chemical and biological methods for the removal of microplastics. Also, the probable control strategies to combat with plastic pollution were assessed. It was concluded that recent water treatment methods are efficient in removing microplastic pollution. The efficiencies to remove microplastic from the water ranged between 74 %-99.2 %, 65 %-99.20 % and 77 %-100 % for physical, chemical and biological treatment methods, respectively. Among the three treatment methods, physical methods especially the filtration of water from biochar is the most efficient way (efficiency up to 100 %) to remove microplastics. It was also concluded that creating public awareness, promoting reusing, recycling and reducing, and application of bioplastics can control the production of microplastics from plastic wastes. This review will be useful to add current knowledge regarding the abatement of microplastic pollution, and finding novel solution to control microplastics. This review will also help the policymakers to implement most effective and cost-efficient method to remove microplastics, and to find out new methods to reduce, reuse and recycle plastic wastes.