The process of aggregating colloidal particles and tiny suspended solids in water through some method (such as adding chemicals). Coagulation includes two processes: coagulation and flocculation. Coagulation mainly refers to the process in which colloids destabilize and form tiny aggregates, and flocculation mainly refers to the process in which destabilized colloids or tiny suspended solids coalesce into large flocs.
Agents that can achieve corresponding coagulation and flocculation are collectively called coagulants. .
Common coagulants include polyaluminum chloride (PAC), ferrous sulfate, ferric chloride, polyacrylamide (PAM), etc.
The results of coagulation are affected by various conditions such as the composition of sewage pollutants, pH level, water temperature and water flow. Different coagulants are selected according to different situations. Generally, when the pH value is alkaline or weakly alkaline, the coagulation and precipitation effect is better.
pH (acid-base) neutralization: also known as pH adjustment, refers to adding a certain pH regulator to the sewage solution in order to achieve the expected pH value. Common pH adjusters include quicklime (calcium hydroxide), caustic soda (sodium hydroxide), various strong acids and citric acid, etc.