CHENNAI: Tamil Nadu, a major player in the country’s leather exports, and the first State to introduce zero liquid-discharge, is now taking a step further to ensure the tanneries in the State produce “zero waste”. Presently, to achieve zero liquid-discharge, the waste-water is subjected to reverse osmosis (RO) for water recovery and reuse in the leather industry.
The RO reject stream is evaporated to dryness and the solid residue (salt mixture comprising sodium chloride and sulfate) is stored, whose quantity now has reached several lakhs of tonnes. To address the ‘salt’ problem and turn it into wealth, scientists of the Central Leather Research Institute (CLRI) and Central Salt & Marine Chemicals Research Institute (CSMCRI) in Gujarat, have discovered a novel method that converts waste residual salt into saleable raw material.
KJ Sreeram, director, CLRI said that the increasing quantum of the stored salt mixture necessitated development and implementation of technology solutions for recovery of commercially acceptable materials, thereby minimizing the need for storage. He added that a five-to-seven-tonne-per-day capacity processing plant was being planned at Ranipet and the work is likely to commence next month.
A detailed project report was being prepared and Union Minister Nitin Gadkari has promised to lend financial aid. Gadkari on Tuesday inaugurated a Common Effluent Treatment Plant in Ranipet virtually from the CLRI campus. CSMCRI officials said laboratory trials have proven successful. “Within 18 months, we want to process the residue salt, separate sodium chloride and sell it to industries,” Sreeram said.