Coagulation And Flocculation Definition
Coagulation and flocculation in water treatment is essential in water and wastewater treatment. Coagulation refers to the addition of coagulation agents with positive ions in wastewater. A large number of positive ions exist between colloidal particles to eliminate the electrostatic repulsion between colloidal particles, so that the particles can coalesce. The process of coalescence of colloidal particles is called cohesion. Commonly used flocculants include aluminum sulfate, ferrous sulfate, alum, and ferric chloride.
Flocculation refers to adding a polymer coagulation agent to the wastewater. After the polymer coagulation agent is dissolved, a polymer is formed. The structure of this polymer is a linear structure. One end of the wire pulls a tiny particle, and the other end pulls another tiny particle. It acts as a bonding and bridging between the two particles far apart, making the particles gradually become larger, and finally form large-particle flocs (commonly known as alum blossom), which accelerates the particle settling. Commonly used flocculants include polyacrylamide (PAM) and polyaluminum chloride.
The process of combining coagulation and flocculation is the coagulation process. Coagulation is often used in experiments or engineering, such as adding ferrous sulfate and other agents in the water to eliminate electrostatic repulsion between colloidal particles, and then adding polyacrylamide(PAM) or polyaluminum chloride (PAC), making the particles gradually larger, forming visible alum flowers, and finally sedimentation.
Mechanism of coagulation and flocculation in Water Treatment
- The action mechanism of the coagulant used in water treatment is to compress the electric double layer and neutralize the electricity. According to the nature of the turbidity substance formed in the raw water, the appropriate pH value should be controlled.
- When the action mechanism of the coagulation and flocculation in water treatment is adsorption bridging, the types and control conditions of the coagulant used are more complicated.
- The action mechanism of the coagulant used in water treatment is adsorption bridging and snare roll. When the focus is on snare roll, the type of coagulant used and control conditions are extremely complicated. In short, the amount of coagulant is large and the pH value is high.
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