What is the final step in the removal of suspended matter from water?

Filtration is the final step in the removal of suspended matter from water. During the filtration process, water passes through various layers of material, such as sand or activated carbon, which captures and removes remaining particles that are not settled during earlier processes like coagulation and sedimentation. This step is crucial for ensuring that the water is clear and free from particulate contaminants before it undergoes disinfection.

Coagulation, while essential in the overall treatment process, occurs earlier. It involves adding chemicals to destabilize particles, allowing them to clump together and form larger aggregates, or "flocs," which can later settle out of the water.

Disinfection follows filtration and is focused on eliminating pathogens in the water rather than the physical removal of suspended solids. Although disinfection is a critical step for ensuring the microbiological safety of the water, it doesn’t directly address the removal of suspended matter.

Decantation refers to the process of carefully pouring off liquid from the settled solids without disturbing them. While it can be part of the treatment process, it does not represent the final step in achieving the thorough removal of suspended materials from water. Thus, filtration is key as the last line of defense in producing clear, clean water before disinfection.