12.3.- DRINKING WATER TREATMENT

Drinking water is obtained after being subjected to a series of physical, chemical and biological treatments. Drinking water treatment plants (DWTP) are created thanks to this need for drinking water. The main stages or processes that are carried out in the DWTP are:

1. 1. Reception and homogenization of the water entering the system.
   2. Pretreatment or screening of coarse material: removal of solids that would cause damage to the installation.
   3. Reaction processes with addition of oxidants and coagulants. This stage removes odors, flavors, pathogens and inorganic matter (minerals) or organic matter (acids, nitrites, etc.). Depending on the contaminants, different techniques are used: aeration, potassium permanganate, chlorine, etc.
   4. The sedimentation removes solids of smaller size still contained in the water, normally using flocculants.
   5. The filtration finishes the clarification process after sedimentation.
   6. Conditioning. A pH adjustment is made, sometimes fluoridation and disinfection to kill pathogens. Iron and manganese are also removed. This step is critical because water must be analyzed after the treatments and it must be verified that water meets the legal requirements for the supply.
   7. Storage and supply of treated or purified water.

Currently, the laws are continually demanding greater quality in the purification of water, so continuous study and research of the processes and technologies for water treatment are necessary.