What is a Wastewater Treatment System and How Does it Work?

What is a Wastewater Treatment System and How Does it Work?

Water treatment systems are often necessary since they ensure that discharge regulations are met, and safety precautions are observed by industrial companies producing wastewater as part of their process. The most pertinent industrial wastewater treatment system should assist the facility in avoiding causing harm to human health, the environment, and a facility's products or processes. This is why programs such as the Illinois wastewater certification program are designed to offer water operators comprehensive training on a diverse set of water treatment topics. 

When water operators are equipped with the necessary knowledge, facilities can avoid possible legal action and heavy fines, which are usually administered when wastewater is being improperly discharged into the environment or POTW (publicly owned treatment works).

What Is a Wastewater Treatment System

It is a system that is made up of multiple individual technologies which address specific wastewater treatment needs. Since treating wastewater is rarely a static process, a wastewater treatment system that is engineered to adapt to fluctuations in treatment needs will help avoid costly upgrades/replacements down the line.

A well-engineered and efficient water treatment system should handle:

  • Chemical volume adjustments
  • Process variations in flow and contamination
  • Possible changes in water effluent requirements
  • Variations in water chemistry requirements and needs

How Do Wastewater Treatment Systems Work


Although the specifics of wastewater treatment processes often vary, a typical wastewater treatment facility process should include the following steps:


This is the process where different chemicals are added to a reaction tank to eliminate the bulk suspended solids and other contaminants. Coagulation starts with an assortment of mixing one or two reactors which add specific chemicals to remove all the finer particles in the water by fusing them into bigger particles that settle out. Polyaluminum chloride and alum are the most widely used aluminum-based coagulates.


Post coagulation, the water flows into a flocculation chamber where the coagulated particles are cautiously stirred with long-chain polymers to create visible, settleable particles resembling snowflakes.


The sedimentation part of the wastewater treatment process involves a large circular device where water and flocculated material enter the chamber and circulate from the center out. The water rises to the top and overflows at the perimeter of the clarifier in a very slow settling process which allows the solid particles to settle down into a blanket-like layer of sludge at the bottom of the clarifier. After this, the solids are raked to the center of a clarifier then into a cylindrical tube, it is slowly mixed before the sludge is pumped out into a dewatering or sludge-handling operation.


After the dewatering operation, the water is run through gravity sand filters. These filters often contain two to four feet of sand that are jagged-edged, finely crushed silica sand.

When the water is run through this tightly packed filter, it traps the particles in the water. Ultrafiltration can also either be used in place of the gravity sand filter or after.


Chlorination or disinfection comes after running the water through the gravity sand filter. It helps kill the bacteria in the filtered water.


In case there is a need to reuse the water, it is then pumped into a holding tank where it can be used in a variety of industrial processes based on the demands of the facility. If the wastewater is reused for municipal use, it is often pumped into a water distribution system and various distribution and collection devices in a loop throughout the city.

Winding Up

Wastewater treatment is a complex process involving the use of reliable and high-tech equipment. An efficient wastewater treatment facility should have the necessary equipment and purification systems needed to clean, filter, and disinfect wastewater before it is sent back to flow into local waterways.

Wastewater is usually highly treated and then reused as reclaimed water. The primary reason for treating wastewater is to get water that can be safely disposed of or reused. Though, prior to treating wastewater, it is vital to consider whether the water is going to be reused or disposed of so that the proper treatment process is used on the wastewater.

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