Disinfection is one of the main processes in the water treatment plant. Disinfection is the process of killing pathogenic bacteria by various methods described below.
Different methods in disinfection
1. Boiling of water
Boiling of water is the most effective method of disinfection of water. It cannot be used for huge quantities of public water supplies. Boiling of water cannot take care of the future possible contaminations. It used only for domestic purposes in emergencies.
2. Treatment with excess lime
It effectively kills the bacteria, but cannot safeguard the future pollution. Enough lime is added to water to raise its Ph value to 9.5 or more, thereby most of the bacteria will be killed. Recarobonation is necessary. The process of removal of excess lime before it is supplied to the public is known as recarbonation.
Ozone is a more powerful disinfectant than chlorine. Ozone is more costlier than chlorine. It does not provide residual protection against recontamination. It is used for disinfection of water on a small scale such as for swimming pool waters
4. Iodine and bromine pills.
Compared to chlorine, iodine provides longer lasting protection against pathogens and reduced offensive tastes and odors. It is used for public water supply as it is costly.
5. Ultraviolet rays
Very costly technique and is an effective method for the disinfection of water. No residual effect is available for protection against recontamination. Adopted for water supply installations of private buildings, institutions, treating small quantities of water in hospitals, dispensaries for surgical use, swimming pools
5. Potassium permanganate
For disinfecting well water supplies which are generally contaminated with lesser amounts of bacteria. It can remove 100 percentage organisms causing cholera and it also oxidizes organic matter.
6. Silver or Electro Katadyn Process
It removes algae also and takes care of future pollution. It is costly.
Universally adopted for public waters supplies because it is capable of providing residual disinfecting effects for long periods. It satisfies all the requirements of an ideal disinfectant. It takes care of any possible future contamination. The only disadvantage is it imparts a bad taste
These are the various methods of disinfection in the water treatment process.
Read More: Properties of water