Science/Environment

This CLRI tanning technique leaves chromium hiding

Written by PaperDabba
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For a hundred years, leather tanneries have been polluting water bodies and soil by discharging billions of litres of highly toxic chromium contaminated water. This is because removing chromium from the waste water is expensive and the leather sector, dominated by small players, cannot afford it. But a cost-effective solution may finally be at hand to solve this problem.

A five-member team of scientists at CSIR’s Central Leather Research Institute (CLRI) in Chennai have come up with a path-breaking solution: Waterless Chrome Tanning Technology (WCTT).

WCTT, a process developed a couple of years ago, is seeing a rather gradual adoption in India. About 60 chrome-based tanneries (out of a total of 1,500) are using this patented technology even as it generates interest in Ethiopia, Sri Lanka, Vietnam, South Africa, the Netherlands, New Zealand, Vietnam and Brazil said J Raghava Rao, Chief Scientist, CLRI, who headed the five-member team.

Resistance to change

Resistance to change among traditional tanners is the main reason for the slow adoption, though those who have implemented the technology swear by it.

“This is the best technology for the industry. Our company annually saves about ₹25 lakh,” said AR Manikandan, Technical Manager at Bharat Enterprises in Ranipet, one of the first leather manufacturing units to adopt the WCTT.

“In fact, we recovered the licence fee of ₹ 2.5 lakh in the very first month of deploying the technology,” he added.

Chromium is the key to leather tanning. Of the 18 billion sq ft of leather produced globally every year, nearly 16 billion is made using chromium.

India produces about 2 billion sq ft of leather and the tanneries discharge about 20,000 tonnes of chromium.

More than salt and sodium sulphate, chromium is the most dangerous pollutant. When let out, the sludge forms a layer on the soil and prevent percolation of water. The WCTT completely eliminates chromium-bearing water discharge.

“This is the highlight of the WCTT,” says P Saravanan, Chief Scientist, CLRI. B Madhan Principal Scientist, CLRI, and Aravindhan Rathinam, a leather technologist, were the other two members of the team that invented WCTT process.

Annually, about 70,000 tonnes of basic chromium sulphate (BCS) is used. The average uptake (absorption) of chromium by leather pelts during tanning is only 65 per cent out of chrome tanning agent offered. This means, 24,000 tonnes of chromium tanning agent remains unabsorbed and gets discharged along with waste water.

Better absorption

According P Thanikaivelan, Principal Scientist, CLRI, in the WCTT the tanning is carried out without water but with ‘simple chemicals’ that ensure 100 per cent absorption of chromium by the hide.

“We are hopeful that more tanneries will use this technology. It’s just a matter of time,” said Rao of CLRI.

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