7 Wastewaster Treatment Process Steps and Stages

Wastewater treatment is processing water from household and industrial use to make it safe to reintroduce into the ecosystem. From your drainpipes it it transported through sewage systems to the water treatment plant operator who undergoes a serious of processes before it is recycled or disposed of. In a combined sewage system it can also include storm water runoff.

Wastewater Treatment
There are three main stages of the wastewater operations, aptly known as primary, secondary and tertiary water treatment. In some applications, more advanced treatment is required, known as quaternary water treatment. This stage deals with part per million to part per billion levels of contamination and often involves oxidation or fine filtration processes. Each of these stages tackles different pollutants, with water becoming cleaner as it moves through the phases.

Wastewater treatments systems are available for companies that have contaminated effluent or run-off water and would like to treat it and reuse it. These systems can be very compact to fit in small areas and are easily transported. They can also be quite large for treating huge amounts of greywater every day.

There are the Basic Steps for Wastewater Treatment are:

  • Pre-treatment that removes large pieces and debris such as branches.
  • Screening also removes large pieces. That are smaller than the debris removed in pre-treatment including plastic packets, cans, rags and sticks. This is usually done with a raking bar but can be done manually.
  • Removal of grit includes removing sand, small stones and broken glass. This is mainly done in large systems, because in small systems the grit may be removed during the screening.
  • In larger systems fat and grease is removed with skimmers that collect what is floating on the surface. This is done in most plants with mechanical surface skimmers as primary clarifiers.
  • The solids that fall to the bottom of the clarifier are know as sludge and pumped out regularly to ensure it doesn’t impact the process of separation. The sludge is then discarded after any water is removed and commonly used as fertilizer.f
  • Primary water treatment is used to settle sludge through sedimentation. There are scrapers that drive the settled sludge towards a container for further treatment.
  • Secondary treatment is to degrade the biological content from sewage that comes from human and food waste as well as soap and detergents. There are several types of secondary treatment systems.

Wastewater Treatment Operations
If the wastewater is to be discharged into a fragile ecosystem such as coral reefs, low-flow rivers or estuaries, there is a tertiary treatment after secondary treatment to disinfect the water chemically or physically. If it is satisfactorily purified, it can be used to recharge groundwater or irrigate crops.


Choice Water Solutions has over 25 years of experience designing and manufacturing wastewater treatment systems. So please feel free to reach out to us with your questions. We can walk you through the steps for developing the proper solution and realistic cost for your wastewater treatment system needs.