Environmental Engineering Reference
In-Depth Information
5.4 ChaPTer revieW QuesTions
5.1
While making rounds of the bar screens, you detect the smell of
rotten eggs. What does this indicate?
5.2
What is the purpose of preliminary treatment?
5.3
What is the purpose of the bar screen?
5.4
What two methods are available for cleaning a bar screen?
5.5
Name two ways to dispose of screenings.
5.6
What is a Parshall flume used for?
5.7
What must be done to the cutters in a comminutor to ensure
proper operation?
5.8
What controls the velocity in a gravity-type grit channel?
5.9
A plant has three channels in service. Each channel is 3 ft wide
and has a water depth of 2.5 ft. What is the velocity in the chan-
nel when the flow rate is 9.0 MGD?
5.10 A section of sprocket chain is broken on the mechanically
cleaned screen. To ensure your safety while replacing the chain,
you should first secure all energy sources to the machine. What
should you do next?
5.11 List three reasons why you might wish to include preaeration in
the preliminary treatment portion of your plant.
5.12 Name two reasons why we would want to remove grit.
5.13 How slow should the flow of wastewater be in order to settle the
grit?
5.14 Below what velocity will grit settle in the screening channel?
5.15 An empty screenings hopper 4 ft by 6 ft is filled to an even depth
of 24 in. over the course of 64 hr. If the average plant flow rate
was 4.0 MGD during this period, how many cubic feet of screen-
ings were removed per million gallons of wastewater received?
5.16 The decomposition process that results in the production of
methane gas is known as
decomposition.
5.17 A V-notch weir is normally used to measure
.
5.18 If untreated organic wastes are discharged to a stream, the dis-
solved oxygen level of the stream will
.
5.19 The main purpose of the grit chamber is to
.
5.20 The main purpose of primary treatment is to
.
5.21 List four applications for chemical addition as a preliminary
treatment process.
5.22 Calculate the weir loading for a sedimentation tank that has an
outlet weir 500 ft long and a flow of 4.5 MGD. Your answer should
be in gpd/ft.
 
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