Which method is NOT one of the ways to remove sludge from a settling basin?

Vacuum suction is not a method typically used for removing sludge from a settling basin. The other methods mentioned are all valid techniques employed in this process.

Mechanical rakes are commonly used to gather and move sludge towards a designated area for removal. They provide a systematic approach to collecting settled solids from the basin.

Drag chains also effectively remove sludge by using a chain system that drags along the bottom of the basin to scoop up the solids. This method is efficient for larger installations where manual removal would be impractical.

Traveling bridges serve a similar function by moving across the surface of the settling basin, equipped with rakes or other collection implements, to remove sludge efficiently.

Vacuum suction, while effective in some contexts, such as in clean-up scenarios or specialized applications, is not standard for sludge removal in typical settling basins due to the layout and physical properties of the material involved. This emphasizes the importance of selecting the appropriate technology based on the operational context, ensuring effective and efficient sludge management.