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There are three main stages of the wastewater treatment process, aptly known as primary, secondary and tertiary water treatment.  Inside a huge a community, wastewater will always be present because it is the term used for the water that is contaminated by huge number of contaminants and heavy concentrations of pollutants. Sewage on the other hand is a more specific term for the wastewater that is contaminated with stools and urine.

Different treatment stages or combinations are adopted dependent on the original quality of the water and its intended final use.

The Primary Stage

For the primary stage, all the substances that are very easy to eliminate will be removed from the wastewater.  These are basically fats, oils, grease and other floating solids.  All the other solids like rocks and grit are strained from the water immediately to prevent the destruction of the wastewater treatment plant machines and other facilities.

Secondary Stage

Secondary treatment of wastewater works on a deeper level than primary and is designed to substantially degrade the biological content of the waste through aerobic biological processes. It is done in one of three ways:


Biofiltration uses sand filters, contact filters or trickling filters to ensure that any additional sediment is removed from the wastewater.


Aeration is a lengthy process which increases oxygen saturation by introducing air to wastewater.

Oxidation ponds

Typically used in warmer climates, this method utilises natural bodies of water such as lagoons, allowing wastewater to pass through for a set period before being retained for two to three weeks. Completing secondary wastewater treatment allows for safer release into the local environment, reducing common biodegradable contaminants down to safe levels.

Tertiary Stage

The aim of tertiary wastewater treatment is to raise the quality of the water to domestic and industrial standards, or to meet specific requirements around the safe discharge of water. In the case of water treated by municipalities, tertiary treatment also involves the removal of pathogens, which ensures that water is safe for drinking purposes. When correctly operated, the treatment works is guaranteed to produce an effluent in compliance with the Department of Water Affairs, South African General Standards. Special standard effluent can be produced if required.

Importance of water from Treatment Plants

The water produced by these plants may not be good for drinking, but they are usually used by people for other household chores to save drinking water. The water produced for drinking is actually like a treasure for various countries around the globe because it is the universal provider of life so instead of using it in watering your plants or cleaning your car, you can simply use the treated water from the treatment plants since they are very safe to use.