Coagulants for Wastewater Treatment

Coagulants for wastewater treatment play a vital role in the process, allowing for solids removal and dewatering, water clarification, lime softening, and sludge thickening.

With the help of other specialized chemicals and mechanical filtration methods, coagulants help companies maintain a consistent and reliable source of clean water to support their industrial processes.

Rather than having to pay another company for costly water treatment, coagulants enable efficient, on-site water treatment, providing:

  • Long-term process sustainability
  • High water reclamation with near closed-loop systems
  • Significant cost and efficiency savings

Learn more about Coagulants and Coagulation

Coagulants In Water Treatment?

In order to use coagulation in your water treatment, you have to apply coagulants to chemically initiate the process. These specialty chemicals should be formulated to meet your specific water quality application based on a particle analysis of your dissolved/suspended solids.

Chemical coagulants used in wastewater treatment fall into two main families: organic and inorganic.

Coagulants play a crucial role in wastewater treatment by aiding in the removal of suspended particles, colloids, and other impurities from wastewater, making it clearer and cleaner. Wastewater typically contains a mixture of solid particles, organic matter, and other contaminants that need to be separated and removed before the water can be safely discharged into the environment or reused.

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Coagulants are chemicals that are added to wastewater in order to facilitate the aggregation and clumping together of these fine particles and colloids. The process involves creating larger, heavier particles called flocs, which settle more readily under the force of gravity or can be more easily separated using filtration or other mechanical methods.

Here’s how coagulants work in wastewater treatment:

  1. Coagulation: Coagulants are added to the wastewater, and they carry a positive or negative charge. The choice of coagulant depends on the nature of the contaminants present. Positively charged coagulants are often used to neutralize the negative charges on suspended particles, while negatively charged coagulants are used to neutralize positively charged contaminants. This charge neutralization reduces the repulsive forces between particles, allowing them to come closer together.
  2. Flocculation: Once the coagulants have neutralized the charges and destabilized the suspended particles, flocculants are introduced. Flocculants are polymers that help the destabilized particles aggregate into larger flocs. These flocs are more easily and quickly removed from the wastewater through sedimentation or other separation processes.
  3. Sedimentation: The wastewater with formed flocs enters a settling basin or tank, where the flocs are allowed to settle under the influence of gravity. The larger and heavier flocs settle at the bottom of the tank, forming a sludge layer, while clearer water rises to the top.
  4. Clarification: The settled water at the top of the tank, also known as the supernatant, is carefully decanted or siphoned off, leaving the settled sludge at the bottom. This clarified water now contains significantly reduced levels of suspended solids and other impurities, making it suitable for further treatment or discharge.

It’s important to note that the efficiency of coagulation and flocculation depends on various factors, including the type of coagulant and flocculant used, their dosages, the pH of the wastewater, the nature of contaminants, and the mixing intensity during the process. Improper coagulant dosage or inadequate mixing can result in poor flocculation and incomplete particle removal.

Commonly used coagulants include aluminum-based compounds (like aluminum sulfate or alum) and iron-based compounds (like ferric chloride or ferrous sulfate). The choice of coagulant depends on factors such as the characteristics of the wastewater, cost considerations, and local regulations.

Coagulant Products


Organic coagulants consist in liquid chemicals which have a high coagulant efficiency mainly focused on its polymer structure and on the strength of the cationic charges.


Inorganic coagulants are both cost-effective and applicable for a broad variety of water and wastewater. Inorganic coagulants are particularly effective on raw water with low turbidity and will often treat this type of water when organic coagulants cannot.

Coagulant Applications

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