| Process |
Possible Pollutants |
Nature of Effluent |
| Desizing |
Starch, glucose, PVA, resins, fats and waxes do not exert a high BOD. |
Very small volume, high BOD (30-50% of total), PVA. |
| Kiering |
Caustic soda, waxes, soda ash, sodium silicate and fragments of cloth. |
Very small, strongly alkaline, dark colour, high BOD values (30% of total) |
| Bleaching |
Hypochlorite, chlorine, caustic soda, hydrogen peroxide, acids. |
Small volume, strongly alkaline, low BOD (5% of total) |
| Mercerizing |
Caustic soda |
Small volume, strongly alkaline, low BOD (Less than 1% of total) |
| Dyeing |
Dye stuff, mordant and reducing agents like sulphides, acetic acids and soap |
Large volume, strongly coloured, fairly high BOD (6% of total) |
| Printing |
Dye, starch, gum oil, china clay, mordants, acids and metallic salts |
Very small volume, oily appearances, fairly high BOD. |
| Finishing |
Traces of starch, tallow, salts, special finishes, etc. |
Very small volume, less alkaline, low BOD. |
PVA – Poly Vinyl Alcohol
BOD – Biological Oxygen Demand
COD – Chemical Oxygen Demand |
