What operational action helps control TSS in an aeration basin?

• A. Amount of sludge wasted
• B. Increase aerator power
• C. Remove influent flow
• D. Add coagulant

Answer: (A)

Keeping the correct solids level in the aeration basin is essential for controlling TSS. In an activated sludge system, that means managing the mixed-liquor suspended solids (MLSS). Wasting sludge lowers MLSS, removing excess suspended solids from the basin, and directly reduces the total suspended solids in the mixed liquor and in the effluent. Increasing aerator power tends to keep solids in suspension and can even resuspend settled solids, which may worsen or fail to reduce TSS. Removing influent flow cuts the load but isn’t a targeted way to control TSS in the aeration basin, since it doesn’t directly adjust the MLSS to a desired level. A coagulant helps solids settle in downstream clarifiers rather than lowering TSS in the aeration basin itself.