The settleometer test is used to indicate the solids-liquid separation (downtime) capability of sludge, most commonly on activated sludge entering the secondary clarifier and aerobic digesters. 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 the settleometer test to determine solids settleability; (2) accurately record data and observations; and (3) obtain consistent and reliable data from the test procedure. The instructor's manual contains a statement of instructional goals, lists of instructor/student activities and instructional materials, narrative of the slide/tape program used with the module, overhead transparency masters, and student worksheet (with answers). The student workbook contains objectives, prerequisite skills needed before the module is started, sources of settleometers, laboratory procedures, and worksheet. (Author/JN)