Chemicals in Treated Water

This article will only discuss on the chemicals used in the water treatment process. If you would like to know more on the water treatment process, please go to http://scienceray.com/biology/ecology/water-treatment-process/.

Have you ever wonder what do they add in our tap water during the water treatment process and what are the chemicals for?

The chemicals added to the water during the treatment process is are dependent on the quality of the raw water. The area with good quality of water need less chemicals than the area with bad quality of water. The common chemicals for water treatment process are:

1. Alum
2. Soda
3. Chlorine
4. Fluoride

Alum is the chemicals for the coagulation and flocculation processes. Flocculation and coagulation is the process to separate suspended solids from the water. In this process, the suspended solids will form a colloid that will become heavier and drop to the bottom of the water. Alum is normally dosed as Aluminum Sulphate (Al2SO4). Sometimes, dependent of the quality of raw water, polymer is also added as the coagulant aid. The type of commonly used polymer is polyacrylamides.

Soda is added for pH adjustment or increase the alkalinity of the water. Soda is dosed as Calcium Carbonate (CaCO3). In some area, the water is too acidic. Therefore, soda is added in order to adjust the pH of the water so that it will be almost neutral.

Chlorine is dosed as chlorine gas into the water system. The purpose of chlorine dosing is to disinfect the water mostly from bacteria so it is safe to be drank directly from the tap. Only of after the point of chlorine dosing is the water considered as treated water. Without the chlorine, the water is known as the clear water which is after the filtration process.

Fluoride is added for the purpose of dental protection which is specifically to prevent tooth decay. Fluoride is dosed as Sodium Silicofluoride (Na2SiF6) to the water system. However, it is not applied to all water treatment plant. In other words, it is an optional dosing which is dependent on the policy of the authorities at the location of the treatment plant.

In some locations, more chemicals need to be dosed to the water system dependent on the raw water quality. It is also dependent on the regulations of the state or country which the water treatment plant is located.