Coagulants & Flocculants in water treatment

Coagulants & Flocculants is very important operation in various water and wastewater processing, because it decides follow-up process of run situation, eventually water of quality and run cost. The coagulation process can reduce water COD value, remove suspended real and colloidal particles in water, and also remove bacteria and virus in water. Besides, it has the role of phosphorus removal, decolorization, deodorant and mitigation of eutrophication in water.

Coagulant has inorganic and organic compounds. Inorganic compound mainly are water-soluble of bivalent or trivalent metal salts. Flocculant is organic polymer, most are high molecular weight and has particular electric and the charge density.



Commonly used inorganic flocculants are aluminum sulfate, alum, ferric chloride, ferrous sulphate, polyferric chloride is the new coagulant developed in the past half a century. Due to their combination of coagulation and flocculation functions, the efficacy can be multiplied compared with traditional pharmacy, it gradually become the mainstream pharmaceutical water treatment industry. Organic coagulant mainly are polyacrylamide, polyamine, etc.

Coagulation and flocculation are included in coagulation treatment. In condensed phases of water gel double layer is compressed and lose stability to form small particles; during flocculation stage such coalescence with each other to form larger particles Floc, these flocs can separate from the water removed in certain precipitation conditions.

In the practical application, as coagulants/flocculants are polymer materials, large and small molecules are in the same product, the so-called "molecular weight" is just an average concept. Therefore, when a wastewater treatment with a certain coagulant or Flocculent, "neutralization" and "bridge" are intertwined at the same time. Flocculation is the result of many factors, there are still some not to identify and solve problems at present.

As all we know, flocculation is related to coagulation agents molecular structure, molecular weight, charge density; also related to surface properties of suspended particles, particle concentration, surface area; related with medium (water) pH value, conductivity and other substances in the water, water temperature, agitation and other factors. In spite of theory and experience, select a flocculant by test is still indispensable. If you have interest in water treatment chemicals, please click here to get more!
Source: https://www.okchem.com/news/coagulants-flocculants-water-treatment.html