The difference between coagulant and flocculant

In sewage treatment and water treatment, coagulant and flocculant are two commonly used technical means, they play different roles in the water treatment process. Although they are all part of the coagulation/flocculation technology, there are significant differences in the principle of action, application, and treatment effects. This article will analyze the difference between coagulant and flocculant in detail to help readers better understand the applicability and characteristics of these two technologies.

Principle and Characteristics of 1. Coagulant

coagulant, the full English name is Aied Coagulation Agent, Chinese is often translated as coagulant. Its main function is to help the dissolved impurity particles in the water gather together through chemical reaction or condensation to form larger precipitation particles, thereby improving the precipitation efficiency.

1. chemical reaction principle coagulants usually exist in the form of chemical substances, such as iron salts (iron sulfate, iron chloride, etc.). These substances will react with certain ions in the water (such as calcium ions, magnesium ions) to form a precipitate. For example, the three salts of iron will react with calcium ions in water to form ferric hydroxide colloids, which agglomerate the impurity particles.
2. physical condensation principle: Some coagulants use physical condensation, such as polypropylene electrolytic gel(polypropylene electro gel, referred to as PEG), which can enhance its ability to attract suspended particles through electrolysis.
3. Features: Coagulants are usually low-cost, easy to obtain, and perform well in the treatment of high-turbidity industrial wastewater and high-concentration water. However, due to the nature of its chemical reactions, the effectiveness of the treatment may be affected by the complexity of the water quality.

The action principle and characteristics of 2. flocculant

flocculant, English full name is Flocculation Agent, Chinese is often translated as flocculant or precipitation promoter. Its main function is to gather the suspended impurity particles in the water through physical action to form larger floc particles and accelerate the precipitation process.

1. mechanism of action: Flocculants usually exist in the form of cations and can absorb suspended particles in water through electrostatic attraction. For example, polypropylene electrolytic gel(PEG), after forming microcolloids in water, can adsorb more suspended particles and make them form flocculent structures.
2. Features: The treatment effect of flocculant is usually better than coagulant, but its cost is higher. In addition, the flocculant has strong adaptability to water quality and can treat water with medium and low turbidity.

3. The main difference between coagulant and flocculant

although both coagulants and flocculants belong to coagulation/flocculation technology, there are significant differences in the principle of action and application.

1. Principle of action coagulants mainly improve precipitation efficiency through chemical reaction or coagulation, while flocculants promote particle aggregation mainly through physical effects (such as electrostatic attraction).
2. treatment effect: Under the same conditions, the treatment effect of flocculants is usually better than coagulants. Coagulants are suitable for water with high turbidity, while flocculants are suitable for water with medium and low turbidity.
3. Cost and applicability: The cost of coagulant is low, and it is suitable for treating high turbidity water with complex water quality; the cost of flocculant is higher, but the treatment effect is better, and it is suitable for medium and low turbidity water with clearer water quality.

4. When to choose coagulant or flocculant

in practical applications, the selection of coagulants and flocculants depends on the specific water quality and treatment objectives. For example:

• high turbidity water treatment: Coagulant is selected because it can quickly improve the precipitation efficiency.
• Medium and low turbidity water treatment: Choose flocculant because it can provide better treatment effect and finer sedimentation control.
• complex water quality treatment: For water with complex water quality and difficult to precipitate substances, coagulant and flocculant can be used at the same time to achieve the best treatment effect.

Summary

coagulant and flocculant are two commonly used coagulation/flocculation technologies, and there are significant differences in the principle of action, treatment effect and applicability. The coagulant improves the precipitation efficiency through chemical reaction or coagulation, and is suitable for complex water quality with high turbidity; the flocculant promotes particle aggregation through physical action, and is suitable for water quality with medium and low turbidity. Choosing a suitable coagulant or flocculant can significantly improve the effect of water treatment and meet different water quality and treatment needs.