Zero waste discharge proposed for Indian tanneries
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The southern India state of Tamil Nadu – a key player in the nation’s leather exports and the first state to introduce zero liquid discharge from its tanneries – is now working to ensure that these operations also produce no residue waste. At present, all waste water is subject to reverse osmosis (RO) for water recovery and reused within the leather industry. As part of the process, the RO reject stream is evaporated and the solid residue, which comprises a sodium chloride and sulphate salt mixture, is stored.
The quantity of this dried residue is said to now total several hundred thousand tonnes. To address this growing logistical problem, scientists at the Central Leather Research Institute (CLRI) and Central Salt and Marine Chemicals Research Institute (CSMCRI) in Gujarat have reportedly developed the technology needed to convert the waste residual mixture into saleable raw materials and therefore minimise the need for storage.
CSMCRI officials have stated that laboratory trials have proved successful, and CLRI director K J Sreeram hopes that within 18 months the process can be ready to produce materials to be sold for industrial applications. A plant capable of processing five to seven tonnes of the salt mixture per day is planned near the town of Ranipet.
Media reports suggest that financial assistance has been promised by government minister Nitin Gadkari, who recently inaugurated a common effluent treatment plant in Ranipet virtually from the CLRI campus.
This article was originally published on page 2 of the March 2021 issue of SATRA Bulletin.