Wastewater Treatment: A Step-by-Step Process

Industrial Water Pipes

The wastewater from your everyday activities such as bathing, flushing, and washing goes down the drain and into your local sewer system. Wastewater is full of contaminants, like micro-organisms, chemicals, bacteria, toxins, and other pollutants. Water companies treat wastewater in several water treatment stages to reduce the contaminants in the water to an acceptable level that is safe enough to be released back to local waterways.

Two Types of Wastewater Treatment Plants

Chemical or Physical Treatment Plant

This wastewater processing plant has equipment that uses chemical reactions and physical processes to treat water. This is mostly used for factories, industries, and manufacturing firms because the wastewater that comes from these are highly toxic.

Biological Treatment Plant

Biological matter and bacteria are used to break down waste matter. This treatment is used for residential and business premises.

Wastewater Treatment Stages

Preliminary Treatment

First, cotton buds, diapers, rags, sanitary pads, tampons, leaves, and other large objects that can damage the wastewater process equipment are removed. Sand and grit that get washed into the sewer lines by rainwater are also removed. These solid wastes are sent to a landfill site for proper disposal.

Primary Treatment

This stage involves the separation of organic solid human waste from the wastewater. The water is allowed to settle, and the waste will settle at the bottom of the tank to form sludge. Large scrapers scrape them to the centre where they will be pumped away from the tanks for further treatment. The remaining wastewater is now ready for the secondary treatment.

Secondary Treatment

The wastewater is placed in rectangular tanks called aeration lanes. They pump air into the water to encourage bacterial growth. These bacteria will use oxygen and other micro-organisms for the breakdown of the remaining bits of sludge that escaped the primary stage.

Final Treatment

The wastewater goes through another settlement tank at this stage. It follows the same process of forming sludge at the bottom which will later be scraped and collected for treatment. Additional particles are removed when the water is allowed to flow through a bed of sand. At this point, the water is already free from chemicals and toxins that are harmful to the environment and is now ready to be released into the river.


Wastewater treatment is a very useful process that ensures that the environment is clean and free from chemicals that can cause an outbreak of waterborne diseases that can seriously harm people, plants, and animals.