Operation of Wastewater Treatment Plants (Level 1 Exam Prep)

An Imhoff cone is used to measure________solids. A. suspended B. colloidal C. volatile D. settleable - Answer - D. settleable (Operation of Wastewater Treatment Plants, Volume 1 by Kenneth D. Kerri) A _____ flume is widely used for measuring wastewater flow. - Answer - Parshall (Operation of Wastewater Treatment Plants, Volume 1 by Kenneth D. Kerri) Velocity of flow in a grit channel must be reduced to a range of ____ to _____ fps in order for grit to properly settle. - Answer - .7 to 1.4 fps (Operation of Wastewater Treatment Plants, Volume 1, 3.33 by Kenneth D. Kerri) With respect to grit removal systems, grit is traditionally defined as particles larger than 0.21mm (0.008 in) (65 mesh) and with a specific gravity of greater than ______. - Answer - specific gravity of grit is 2.65 or greater (EPA Wastewater Technology Fact Sheet, Screening and Grit Removal) Mechanically cleaned bar screens feature bars set at _____ to _____ degrees from vertical. - Answer - Bars set at 0 to 30 degrees from vertical. (EPA Wastewater Technology Fact Sheet, Screening and Grit Removal) Manually cleaned bar screens feature bars set at _____ to _____ degrees from vertical to facilitate cleaning. - Answer - Bars set at 30 to 45 degrees from vertical to facilitate cleaning. Primarily used in older or smaller treatment facilities, or in bypass channels. (EPA Wastewater Technology Fact Sheet, Screening and Grit Removal) The BOD test measures the amount of oxygen that is consumed while a sample of wastewater is incubated in the dark at a temperature of _____ °C for _____ days (± _____ hours) - Answer - The BOD test measures the amount of oxygen that is consumed while a sample of wastewater is incubated in the dark at a temperature of 20 °C for 5 days (± 3 hours) (USGS Book 9-A7 (Third Edition) Five-Day Biochemical Oxygen Demand) What do we mean by Total Dissolved Solids (TDS) in wastewater? - Answer - All the solids that cannot be filtered out of the water (New Mexico Wastewater Systems Operator Certification Study Manual)