Waste Water Treatment

Waste water is the water that comes from industries and other agricultural works which is contaminated and not fit for drinking or for any other purpose. Therefore this type of water is treated so that it doesn’t cause much harm to marine life, plants, animals and human beings.

Treatment of waste water involves the following steps:

Sewage Treatment:

This involves the removing of contaminates from waste water and household sewage. The three methods are physical, chemical and biological that are used to treat sewage water.
The main objective is to reuse it back into the environment.

Primary Treatment:

Sedimentation is the first step in the treatment of sewage water. Sewage water gets collected in large tanks in which the sludge settles and materials like oil and grease floats which can be taken off. This is the first step because this stage is used to produce similar liquids which is treated biologically and the sludge can be processed separately.

Secondary Treatment:

This is used to bring down the biological waste matter that comes from human, animals and other such sources. The municipal plant treats the sewage liquor using aerobic biological processes. The bacteria and protozoa consume biodegradable contaminates and bind the soluble fractions into floc.

Tertiary Treatment:

This treatment is used to provide a good quality before it is released into the environment. Tertiary treatment also involves various other steps like:

Constructed wetlands
Nutrient removal
Nitrogen removal


The actual purpose of disinfection is to remove micro-organisms in the water. Cloudy water may not be treated well enough since solid matter shields organisms from ultraviolet rays.


is the most important step in purifying waste water as it is not very expensive and is quite effective.


rays can be used instead of chlorine, iodine or other chemicals. Since no chemicals are used it is safe for other organisms that use this water. The ultraviolet rays destroy bacteria, viruses.


is used by passing oxygen through a high voltage resulting in third oxygen atom that gets attached and becomes O3. Ozone is unstable and reactive with other oxidises it comes in contact with and destroys many micro-organisms.

Odour removal:

During the process of purifying the water it tends to have produce smell. Hydrogen sulphide is the gas that involves a lot of smell therefore huge plants have a large tower to remove foul air and have air circulator.

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