Water and water purification

A plentiful supply of suitable water is essential for a dyeing and bleaching plant. Before modern methods of water purification were purification were available, the textile industries tended to congregate in areas where the natural water supply was plentiful and sufficiently pure. Water with a high degree of purity is rarely obtainable from natural sources. A knowledge of he impurities which will probably be present and how to remove them is, therefore, desirable. Supplies of water may be classified as follows: i) rain water ii) surface water, which consists of rain which has collected into streams, rivers, or lakes; iii) subsoil water, which has percolated a small distance into the ground. It is collected from shallow wells or surface springs; and iv) deep well waters, which have usually percolated through several strata. ➢ Rain water:- Rain, collected immediately after propitiation, is the purest of all natural waters. It may contain traces of gases dissolved out of the atmosphere, and possibly an almost infinitely small amount of finely divided solid matter derived from the air. In the neighborhood of towns rain may collect dissolved or suspended impurities such as soot, traces of sulphur dioxide, or sulphuric acid, and other by-products of industrialization. Rain water from such sources is improved by filtration through a bed of sand. Although the collection of rain for industrial purposes dose not warrant serious consideration, there are occasions when small quantities of it may be useful for special purposes. If storage is undertaken it is desirable to have some device which rejects the first few gallons which will be delivered from the collecting surface after a dry period, because they will contain all the solid matter which has been deposited from the atmosphere. Further purification,