Mercerization is a process in the textile industry where the textile fibres under tensile stress are treated with caustic soda. These cotton fibres swell in the caustic solution thereby giving it a better luster, improved dyeability, dimensional stability and marginal increase in tensile strength.
Once the fabric is mercerized, the weak caustic liquor can be drained into the effluent treatment plant, which would create havoc in the ETP due to its highly alkaline nature. Due to high pH values, it will require lots of acid to neutralize, there by increasing the TDS of the effluent. A good Caustic Recovery Plant can turn a very large proportion of this weak lye into reusable concentrated caustic soda (strong lye). With proper filtration and purification processes in place, this recovered caustic soda of desired concentration can directly be used for mercerization again.