What Are The Chemical Processes Involved In Waste Water Treatment?

25 April 2016
 Categories: Environmental, Blog

Water is perhaps the most valuable natural resource that human beings have at their disposal. This helps to explain why the modern being seems to be fixated on matters related to the conservation and recycling of water.

Recycling of waste water is often done through the use of various chemical processes. Below is a discussion on three of these processes for the benefit of environmental specialists in training.


Coagulation refers to the introduction of chemicals known as coagulants into colloidal waste water. Colloidal waste water contains impurities (suspended particles) that don't settle easily or those that don't settle at all. Failure of these particles to settle is explained by their possession of negative electric charges that limit their ability to aggregate and settle in the waste water.

Coagulants introduce a positive electric charge into the waste water, thereby neutralizing the negative electric charge from the suspended particles. The neutralization reaction result in the destabilization of these particles and this allows the suspended waste particles to aggregate and to finally settle.

Aluminium sulfate and ferric chloride are examples of coagulants commonly used in modern waste water systems.


This is perhaps the most widely used chemical process in the treatment of waste water. Precipitation is used for purification of water that contains dissolved and toxic metal particles as waste.

It involves the introduction of precipitation reagents into the waste water. The reaction brought about by the introduction of a precipitation reagent results in the formation of solid metal particles from the dissolved metallic waste. Once solid, the metal particles are filtered out of waste water.

Sodium and calcium hydroxide are examples of commonly used precipitation reagents in the treatment of waste water. It is important to point out that precipitation is often not the best chemical treatment process for waste water that contains a mixture of dissolved metals. The presence of different types of metals in the waste water limits the effectiveness of the precipitation reaction, which in turn limits the formation of solid metal particles within the waste water.


As the name suggests, oxidation is a chemical treatment process which employs the use of oxidizing agents to eliminate impurities in waste water.

When an oxidizing agent such as chlorine is introduced into waste water, its electrons flow into the waste particles. The reaction that follows alters the structure of the waste particles, thereby making them less harmful. Oxidation is the most commonly used chemical treatment process in the residential setting thanks to its non-complex nature.

For more information, contact Econocycle or a similar company.