Coagulants are treatment chemicals used in the process of wastewater treatment. These chemicals are used to destabilize the suspended solids and other impurities present in the wastewater, causing them to clump together and form larger particles, which can then be more easily removed from the water.
Coagulants work by neutralizing the negative charge on suspended solids and other particles in the water, which causes them to clump together and settle out. The most commonly used coagulants in wastewater treatment are aluminum sulfate (alum), ferric chloride, and polyaluminum chloride (PAC).
Alum is a popular choice because it is effective at low doses and is relatively inexpensive. However, it can increase the concentration of dissolved aluminum in the water, which can be harmful to aquatic life. Ferric chloride is more expensive than alum but can be more effective in removing certain contaminants, such as phosphorus. PAC is a newer coagulant that is becoming more widely used due to its efficiency and lower levels of residual aluminum in the treated water.
Coagulants are an important part of the wastewater treatment process, as they help to remove impurities from the water and make it safe for discharge back into the environment. However, it is important to use these chemicals carefully and in appropriate doses to avoid negative environmental impacts.