Which chemical compound is used as a coagulant in wastewater treatment?

In wastewater treatment, alum, or aluminum sulfate, is effectively used as a coagulant due to its ability to promote the aggregation of fine suspended particles in water. This process, called coagulation, involves the neutralization of the negative charges on particles, allowing them to clump together and form larger aggregates, or flocs. Once these flocs are formed, they can be more easily removed from the water through sedimentation or filtration, vastly improving the quality of the effluent.

Alum is preferred in many treatment processes because it is cost-effective, widely available, and highly efficient in a variety of water conditions. Its ability to reduce turbidity and remove organic material contributes significantly to the overall efficiency of wastewater treatment systems, leading to cleaner and safer water before it is released back into the environment or reused.