4.1.8 Water Treatment Process Exam
Questions and Answers
What are the three treatment processes described in the book - Answer-Primary
Secondary
Advanced wastewater
(Treatment Process) Primary wastewater process definition - Answer-is defined as
physical or at times chemical treatment for the removal of settable and floatable
materials
Primary wastewater treatment processes - Answer-Screening
Grit chamber
Comminuting devices
Flow measurement
Sedimentation tank
Screening - Answer-Removes large solids from the influent which would otherwise
clog/damage pumps or hinder the flow of wastewater through the plant
Raw wastewater passes through series of screening devices - rack and bar screens for
large debris, usually cleaned by hand AND perforated plates and fine screens
Grit chamber - Answer-The velocity (flow) of the wastewater is decreased to less than 1
foot per second so particles the size and density of sand and gravel (grit) can settle out
while permitting organic solids to float
Velocity is still rapid enough to allow organic material to remain in suspension
Open channel: Two basic types exists - manually cleaned chambers that require 2 grit
chambers to be operated AND automatically cleaned grit chambers
Aerated (grit chamber) - Answer-Diffused air is bubbled up from the bottom of the
channel to break up chunky wastes and release grit
Grit is removed by mechanical means or by air lifts. These are popular because tanks
are compact, grit is cleaner, and the dissolved oxygen creates aerobic conditions thus
reducing odor problems. Detention times vary from 1-3 minutes
Questions and Answers
What are the three treatment processes described in the book - Answer-Primary
Secondary
Advanced wastewater
(Treatment Process) Primary wastewater process definition - Answer-is defined as
physical or at times chemical treatment for the removal of settable and floatable
materials
Primary wastewater treatment processes - Answer-Screening
Grit chamber
Comminuting devices
Flow measurement
Sedimentation tank
Screening - Answer-Removes large solids from the influent which would otherwise
clog/damage pumps or hinder the flow of wastewater through the plant
Raw wastewater passes through series of screening devices - rack and bar screens for
large debris, usually cleaned by hand AND perforated plates and fine screens
Grit chamber - Answer-The velocity (flow) of the wastewater is decreased to less than 1
foot per second so particles the size and density of sand and gravel (grit) can settle out
while permitting organic solids to float
Velocity is still rapid enough to allow organic material to remain in suspension
Open channel: Two basic types exists - manually cleaned chambers that require 2 grit
chambers to be operated AND automatically cleaned grit chambers
Aerated (grit chamber) - Answer-Diffused air is bubbled up from the bottom of the
channel to break up chunky wastes and release grit
Grit is removed by mechanical means or by air lifts. These are popular because tanks
are compact, grit is cleaner, and the dissolved oxygen creates aerobic conditions thus
reducing odor problems. Detention times vary from 1-3 minutes
