The rise time test (along with the settleometer procedure) is used to monitor sludge behavior in the secondary clarifier of an activated sludge system. The test monitors the effect of the nitrification/denitrification process and aids the operator in determining optimum clarifier sludge detention time and, to some extent, optimum degree of oxidation in the aeration basin. Designed for individuals who have completed National Pollutant Discharge Elimination System (NPDES) level 1 laboratory training skills, this module provides waste water treatment plant operators with the basic skills and information needed to: (1) run and evaluate the test for sludge rise time; (2) record data; and (3) describe how nitrification/denitrification affects sludge rise time. The instructor's manual contains a statement of instructional goals, lists of instructor/student activities and instructional materials, and student worksheet (with answers). The student workbook contains objectives, prerequisite skills needed before the module is started, laboratory procedures, and worksheet. (Author/JN)