What condition is likely seen in the final clarifier when the aeration tank experiences high MLSS due to old sludge age?

High MLSS (Mixed Liquor Suspended Solids) due to old sludge age in the aeration tank tends to result in pin floc formation in the final clarifier. When the sludge age is too high, microorganisms in the system may become old and less viable, leading to poor settling characteristics. This creates small, lightweight flocs that do not aggregate properly and can remain suspended in the water column.

Pin floc is characterized by these small particles, which fail to settle effectively, resulting in a larger proportion of solids remaining in the supernatant. Consequently, the clarity of the effluent deteriorates, causing a cloudy appearance. The presence of pin floc reflects the inefficiency of the biological treatment process at this age and can lead to issues in the overall treatment process, including decreased effluent quality.

In contrast, stable floc formation indicates a healthy balance of microorganisms, which is not the case with high MLSS and old sludge. Enhanced sedimentation typically refers to a situation where the conditions are optimal, allowing for rapid settling of solids, which also would not occur under high MLSS conditions with old sludge age. The cloudy supernatant is a result of issues caused by pin floc and does not describe a singular condition