Large quantities of caustic soda (sodium hydroxide, NaOH) are utilized in the mercerizing process of cotton, be it woven fabrics, knits or yarn. Required is at least

240 g NaOH 100% per kg of cotton

mercerizing of

25'000 kg cotton per day

needs at least

12.8 metric tons
of 48 °Bé caustic solution per day

and this gives cost of

US$ 4500 for caustic per day

All this caustic soda is washed out of the cotton in the stabilizing and washing section
of the mercerizing machine and leaves as waste water, is lost, and needs
to be neutralized with acid, again causing expense

Such quantities of a valuable chemical must be
recovered from effluents and be recycled, if it is possible