Processes for drinking water

A combination selected from the following processes is used for municipal drinking water treatment worldwide:

• Pre-chlorination - for algae control and arresting any biological growth
• Aeration - along with pre-chlorination for removal of dissolved iron and manganese
• Coagulation - for flocculation
• Coagulant aids, also known as polyelectrolytes - to improve coagulation and for thicker floc formation
• Sedimentation - for solids separation, that is, removal of suspended solids trapped in the floc
• Filtration - removing particles from water
• Desalination - Process of removing salt from the water
• Disinfection - for killing bacteria.

There is no unique solution (selection of processes) for any type of water. Also, it is difficult to standardise the solution in the form of processes for water from different sources. Treatability studies for each source of water in different seasons need to be carried out to arrive at most appropriate processes.
The above mentioned technologies are well developed and generalised designs are available which are used by many water utilities (public or private). In addition to the generalised solutions, a number of private companies provide solutions by patenting their technologies.