Understanding Water Treatment Processes: Wastewater and Drinking Water

Water is a crucial resource for our survival and everyday lifestyle, but the water we use may contain harmful contaminants, pollutants, and bacteria that require removal. Water treatment processes are complex and critical to producing safe and clean water. That’s why we explore two common water treatment processes: wastewater treatment and drinking water treatment.

Wastewater Treatment Process

Wastewater is water mixed with waste matter from domestic, municipal, or industrial sources. It carries harmful contaminants that must be treated before it can be safely discharged or recycled. Wastewater treatment typically involves a combination of physical, chemical, and biological processes to remove solids, organic material, and nutrients.


Preliminary Treatment

The first step in wastewater treatment is preliminary treatment (or pretreatment), which removes large debris (cans, bottles, tree limbs, etc.) and heavy particles (sand, gravel, etc.) from the wastewater. This prevents damage to downstream pipelines and reaction basins.

Primary Treatment

The objective of primary treatment is to allow organic solids to settle to the bottom of the primary clarifier while simultaneously allowing greases and oils to rise to the surface. Once the organic solids settle, the sludge is then scraped from the bottom of the basin while the greases and oils are skimmed off the top.

Secondary Treatment

Secondary treatment aims to substantially remove and degrade the biological content of the wastewater. This is achieved by utilizing processes like attached growth systems or suspended growth systems. Attached growth systems include fixed film systems such as trickling filters, rotating biological contactors, and submerged fixed-film and moving-bed bioreactors. Suspended growth systems include activated sludge systems and sequenced batch reactors.

Tertiary Treatment

The tertiary treatment step, often referred to as advanced treatment or polishing, is used to provide a final treatment stage that will further improve the effluent quality of the water before it is discharged into the environment. Once the wastewater treatment process is complete, the water is most commonly released into a natural body of water or reused for applications such as irrigation. With the advancement of water technology, the water can also be processed more thoroughly to be reused as drinking water.

Drinking Water Treatment Process

Most drinking water comes from surface or groundwater sources and requires treatment before it can be safely consumed. Drinking water treatment processes involve a six-step process to remove undesirable contaminants.

Grit Removal

The first step in the drinking water treatment process is the removal of harsh grit particles (sand, gravel, cinder, etc.) and other large objects (cans, bottles, tree limbs, etc.). This step is necessary as it prevents damage to the pumps that transport the water between steps in the treatment process.


The second step in drinking water treatment is coagulation, which involves adding chemicals (like aluminum sulfate or ferric chloride) to the water to help particles clump
together and form larger, easier-to-remove particles. These particles in the water clump together and form larger particles called flocs.


The third step is sedimentation, where the flocs settle to the bottom of a basin or tank. The water is left undisturbed for several hours to allow the flocs to settle to the bottom. Tube settlers amplify the settling capacity of basins and clarifiers, efficiently reducing the particle distance to a flat surface, allowing heavy floc particles to gather and sink for easy removal by a sludge collector system. Clear water is then removed from the top of the basin or tank and sent for further treatment.


The fourth step is filtration, where the water passes through a filter to remove any remaining particles and impurities. The water is passed through layers of sand, gravel, and other materials that remove any remaining particles and impurities.


The fifth step is disinfection, where chemicals or physical methods are used to kill any remaining bacteria and viruses in the water. Chemicals like chlorine, ozone, or ultraviolet light are used to kill any remaining bacteria and viruses.


The final step is distribution, where the treated water is sent to homes, businesses, and other consumers through a network of pipes and other infrastructure. The treated water is distributed to consumers through pipes and other infrastructure, ensuring safe and clean drinking water for all. Water treatment is a complex and crucial process that ensures access to clean and safe water for consumption and other uses. With the increasing demand for water and the growing concern for environmental sustainability, the development of new technologies and innovative solutions to improve the efficiency and effectiveness of water treatment processes becomes more critical than ever. That’s why our team of engineers is constantly working on water and wastewater treatment innovations to ensure clean water for tomorrow.

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