IIT Guwahati technology to remove microplastics from seawater

Researchers at the Indian Institute of Technology (IIT) Guwahati have come up with a microfiltration process to remove microplastics from seawater in order to prevent the inclusion of plastic residues in edible salt extracted from it.

Microplastics--plastic pieces smaller than one-fifth of an inch – are now found in almost all oceans and marine animals. Sea salt has been found to have considerable amounts of micro-plastic. Research performed in East Asia has shown that 90 percent of the table salt brands sampled worldwide has microplastics.

Microplastics ingested by human beings can disrupt hormones, leading to infertility, and cause nervous system problems, and even cancer, said the researchers.

"We have been able to remove 99.3 per cent of the microplastics present in seawater, without any reduction in the salt content. If this filtered water is used to extract salt, it would be free from microplastics,” the researchers said on Tuesday.

Kaustubha Mohanty and Senthilmurugan Subbiah, teachers at the IITG's chemical engineering department recently published the research findings in the journal, Environmental Technology and Innovation, in a paper co-authored by their research scholar, Naveenkumar Ashok Yaranal.

While there have been many studies to identify and quantify microplastics in various food products, including salt, there have been fewer attempts at finding ways to remove them.

"In our hollow fibre membrane filter, hundreds of tiny straw-like tubes are bundled together to create a filter matrix. The walls of these tubes are filled with microscopic pores, and when water is passed through the tubes, the microplastics are trapped inside, thus freeing water of this pollutant," Mohanty said in a statement.

Plastic pollution is rampant all over the world and while there is some level of awareness, the seriousness is not yet understood.

The hollow fibre membranes are already used extensively in daily life applications such as RO pre-treatment, industrial water/wastewater, juice processing, and other biotech applications, including in dialysis membranes used for kidney ailments. The hollow fibres are made of many kinds of materials and the ones used by the IITG team was made of polypropylene and a silk protein called sericin, the team team

However, the researcher clarified that the method could only remove microplastics from seawater before salt extraction, and could not remove microplastics that get added during salt production