Water is the main running substances for wet processing of the textile industry as well as other manufacturing industry. The water which is in the environment that contains lots of impurities which required to purifying before use. By the purification, natural water becomes suitable for process.
Water for a textile plant may come from various sources. These include surface water from rivers and lakes, and subterranean water from wells. In most of the textile industries, they collect water from Underground. Natural and pretreated water may contain a variety of chemical species that can influence textile wet processing in general, and dyeing in particular.
The various salts present in water depend on the geological formations through which the water has flowed. These salts are mainly the carbonates (CO32-), hydrogen carbonates or bi-carbonates (HCO3-), Sulphates (SO42-) and chlorides (Cl–) of calcium (Ca2+), magnesium (Mg2+). Although calcium and magnesium carbonates in limestone are relatively insoluble in water. So in this reasons, water hardness can be divided into two ways. They are-
1. Temporary Hardness: Ca(HCO3)2 , Mg(HCO3)2 , Fe(HCO3)2.
2. Permanent Hardness: CaCl2, CaSO4, Ca (NO3)2, MgCl2, MgSO4, Mg (NO3)2.
Effect of Hard Water in Textile Industry: This water hardness causes some serious consequences in a textile dyeing and finishing industries and these are
- Precipitation of soaps.
- Redeposit ion of dirt and insoluble soaps on the yarn or fabrics being washed, this can cause yellowing and lead to uneven dyeing and poor handle.
- Precipitation of some dyes as calcium and magnesium salts.
- Scale formation on equipment and in boilers and pipelines.
- Incompatibility with chemicals in finishing recipes and so on.
Hardness expressed by parts per million (ppm) of CaCO3 which is standard hardness scale and it is also called American hardness. The hardness of raw water is 100 ppm or more. To use it in dyeing and in boiler this water must need to soft & foreign materials needs to remove.