PE Environmental Qualitative Practice Exam 2026 - Free PE Environmental Practice Questions and Study Guide

Improving a secondary clarifier’s performance lies in controlling how the incoming flow is distributed and how long solids stay in the basin to settle. The inlet arrangement, including baffles, is key to dissipating jet energy and steering flow across the clarifier so you avoid short-circuiting and resuspension of settled solids.

Decreasing the depth of the inlet baffles would weaken their ability to intercept and redirect the incoming jet, allowing high-velocity flow to lag through the basin and promoting short-circuiting and disturbance of settled sludge. That makes settling less efficient, so this change would not improve performance.

In contrast, increasing the length of influent weirs spreads the flow over a longer area, reducing short-circuiting; adding chemicals helps flocculation and settling; and adding a third secondary clarifier increases capacity and residence time. All of these would generally enhance performance.