<prompt> Which of the following is purification of water at large scale - a Disinfection of well b Rapid sand filterc Slow sand filterd Household purificationbccacad  <response>: Purification of water Purification of water is of great importance in community.The method of treatment to be employed depends upon the nature of raw water, and the desired standards of water quality.For example ground water deep well, tube well and springs may need no treatment. On the other hand surface water river requires extensive treatment.Purification of water may be : -Purification on large scaleStorageFiltrationSlow sand Biological filterRapid sand mechanical filter 3. DisinfectionChlorinationOzonationUV irradiationPurification on small scaleHousehold purificationBoilingChemical disinfection 2. Disinfection of wells 