Man-Made Fibre Industry
The major raw material for synthetic fibres is obtained from petrochemical feedstock and is commonly known as monomer whereas cellulose is the major raw material for viscose and acetate. The type and average consumption of major raw material for individual fibre are given in Table VI.
A large number of various chemicals, besides pulp or monomer, as the case may be, are required during the manufacture of each fibre. Ingredients include acetic acid, titanium dioxide, spin finish, catalyst, methyl acrylate or vinyl acetate, sulphuric acid, sodium hydroxide, carbon disulphide, Zinc, sodium sulphate, di-sodium sulphide, acetic anhydride, thermal stabilizer, light stabilizer, antioxidants etc.
Item |
Viscose | Nylon | Polyester | Acrylic | Polypropylene |
|---|---|---|---|---|---|
| Raw material | Cellulose Pulp | Caprolactum | DMT& EG | ACN | Propylene |
| Average Consumption | 1140 | 1100 | 1100 & 420 | 1000 | 1000 |
| Table VI: Major Material Consumption for Man-Made Fibre (Kg/ton product) | |||||
ACN is toxic and as a consequence stringent measure in an acrylic manufacturing plant is necessary to ensure that it does not contaminate liquid discharge. One of the major pollutants in viscose plant liquid effluent causing concern is the presence of zinc. The average consumption of zinc is in the range of 15 Kg/MT fibres. The zinc concentration in the effluent is on an average 15-40 mg/l [13].
| Parameter | Nylon | Polyester |
|---|---|---|
| Temperature (ºC) | 30 | 32 |
| pH | 7.25 | 8.55 |
| Total Suspended Solid (mg/l) | 1388 | 1736 |
| Total Dissolved Solids (mg/l) | 1600 | 1542 |
| BOD, 5 days, 20ºC, mg/l | 619 | 580 |
| Volatile Solids (mg/l) | 384 | 632 |
| COD, mg/l | 1459 | 1680 |
| Alkalinity (as CaCo3), mg/l | 350 | 730 |
| Table VII: Parameters of Waste Water Generated by Synthetic Fibre Industry | ||
The average consumption and parameters for liquid effluent discharged by nylon and polyester industries are given in Table VII. In India, for nylon and polyester, the wastewater generated is on an average of 170 m3/MT and for viscose 1200 m3/MT, respectively.