Our filter technology perfectly safe: IIT-M scientist

Developers of an arsenic water filter at the Indian Institute of Technology-Madras (IIT-M) are at pains to rubbish criticism that their device will require frequent replacement due to clogging and that the disposal of the used filters with trapped arsenic will pose environmental and health hazards in the long run.

They insist that their technology does not produce toxic waste as alleged. There is no clogging of the filters, nor does their filtering capacity get exhausted in days or weeks necessitating repeated substitution.

They contend that these and other “factually wrong” statements — and the “unwanted debate” that ensued — were based on incorrect understanding of the technology and tended to tarnish the image of the premier institute.

Arsenic is a toxic element and its contamination of groundwater is a major problem in northern and eastern India, Bangladesh and some other parts of the world.

A group at IIT-M, led by chemistry professor Thalappil Pradeep, had developed a filter based on nano-technology to make the water safe to drink by bringing down the arsenic content to an acceptable level.

Pradeep, whose startup recently received $18 million venture funding from a US company, is confident that his filter will make a big change.

“West Bengal has multiple installations of our filter; Punjab is getting ready to install them, and the states of Uttar Pradesh and Bihar have initiated plans,” Pradeep told this correspondent.

“Those who have concerns about our filter can go and see these for themselves,” he added.

For removing arsenic, Pradeep’s filter uses a nano-composite material (iron-oxyhydroxide) trapped inside tiny “cages” made of “chitosan”, a bio-material derived from seashells.

Sabyasachi Sarkar, a former chemistry professor at IIT-Kanpur and one of the critics, had said that chitosan, being biodegradable, will degrade and release the trapped arsenic once the used cartridge is thrown in a garbage pit. Random disposal of a large number of used filters may pose a health hazard, he had said.

Seconding this opinion, Ashok Gadgil, a professor of environmental sciences at the University of California-Berkely, had commented that arsenic will leach out “under the conditions of depleted oxygen” in the dump.

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