Waste Water Practice Exam 2
with correct answers | Graded A+ |
Updated Version
QUESTIONS AND ANSWERS
What is the typical BOD removal efficiency in a primary clarifier ?. ANSWER -20-50%
What does the F in F/M ratio represent?. ANSWER -The food for the microorganisims
flowing into the aeration tank, in LBS/Day
Which of the following describes the appearance of healthy activate sludge ?. ANSWER -
Brown with a moderate amount of crisp ,white foam
What is used to control filamentous organisms?. ANSWER -Chlorine
What are commonly used to control chlorine feed rate for disinfection ?. ANSWER -Flow
and chlorine residual
Which toxic gas is commonly found in septic wastewater and smells like rotten eggs?.
ANSWER -hydrogen sulfide
What is the permissible exposure limit for chlorine gas vapor during a normal 8-hour
workday and a 40- hour workweek?. ANSWER -0.5 ppm
What is a vulnerability assessment ?. ANSWER -Contingency planning to determine the
vulnerability of the utility during various types of emergencies and identify corrective
actions to reduce the risks
What is the difference between the settling rate of activated sludge and raw sludge?.
ANSWER -Activated sludge settles much faster than raw sludge
What should be mostly found in healthy activated sludge?. ANSWER -Free-swimming and
stalked ciliates
, One to two percent of the digester gas in an anaerobic digester consist of:. ANSWER -
Hydrogen ,Nitrogen, hydrogen sulfide , and other gases
What is true during the colder winter months?. ANSWER -Modify operations to increase
solids under aeration to provide more microorganisms to treat the BOD
What type of sludge would you expect in an aeration tank if the content is dark and has low
DO?. ANSWER -Septic Sludge
What could happen if the volatile acid/alkalinity ratio starts to increase, and corrective
action is not taken immediately?. ANSWER -Carbon Dioxide content in the digester gas
will Increase
What are Screenings?. ANSWER -Pieces of wood, roots, rags and other large debris
What happens when there is more food in the influent to the aeration tank?. ANSWER -
More oxygen is required in the aeration tank
What impact does temperature have have on the reaction rate of microorganisms in
wastewater?. ANSWER -Reaction rate doubles with every 18* Fahrenheit increase in temp
until higher temps inhibits biological activity
What is commonly used to control the odor of hydrogen sulfide?. ANSWER -Chlorine
What is used to determine the amount of microorganisms in the aeration tank?. ANSWER
-Mixed liquor volatile suspended solids (MLVSS)
What could happen if the sludge line is isolated by closing the valves on each end for
several days?. ANSWER -Gas production could increase the internal pressure and cause
the line to fail
Which is true about Chlorine gas?. ANSWER -IT is 2.5 times heavier than air
with correct answers | Graded A+ |
Updated Version
QUESTIONS AND ANSWERS
What is the typical BOD removal efficiency in a primary clarifier ?. ANSWER -20-50%
What does the F in F/M ratio represent?. ANSWER -The food for the microorganisims
flowing into the aeration tank, in LBS/Day
Which of the following describes the appearance of healthy activate sludge ?. ANSWER -
Brown with a moderate amount of crisp ,white foam
What is used to control filamentous organisms?. ANSWER -Chlorine
What are commonly used to control chlorine feed rate for disinfection ?. ANSWER -Flow
and chlorine residual
Which toxic gas is commonly found in septic wastewater and smells like rotten eggs?.
ANSWER -hydrogen sulfide
What is the permissible exposure limit for chlorine gas vapor during a normal 8-hour
workday and a 40- hour workweek?. ANSWER -0.5 ppm
What is a vulnerability assessment ?. ANSWER -Contingency planning to determine the
vulnerability of the utility during various types of emergencies and identify corrective
actions to reduce the risks
What is the difference between the settling rate of activated sludge and raw sludge?.
ANSWER -Activated sludge settles much faster than raw sludge
What should be mostly found in healthy activated sludge?. ANSWER -Free-swimming and
stalked ciliates
, One to two percent of the digester gas in an anaerobic digester consist of:. ANSWER -
Hydrogen ,Nitrogen, hydrogen sulfide , and other gases
What is true during the colder winter months?. ANSWER -Modify operations to increase
solids under aeration to provide more microorganisms to treat the BOD
What type of sludge would you expect in an aeration tank if the content is dark and has low
DO?. ANSWER -Septic Sludge
What could happen if the volatile acid/alkalinity ratio starts to increase, and corrective
action is not taken immediately?. ANSWER -Carbon Dioxide content in the digester gas
will Increase
What are Screenings?. ANSWER -Pieces of wood, roots, rags and other large debris
What happens when there is more food in the influent to the aeration tank?. ANSWER -
More oxygen is required in the aeration tank
What impact does temperature have have on the reaction rate of microorganisms in
wastewater?. ANSWER -Reaction rate doubles with every 18* Fahrenheit increase in temp
until higher temps inhibits biological activity
What is commonly used to control the odor of hydrogen sulfide?. ANSWER -Chlorine
What is used to determine the amount of microorganisms in the aeration tank?. ANSWER
-Mixed liquor volatile suspended solids (MLVSS)
What could happen if the sludge line is isolated by closing the valves on each end for
several days?. ANSWER -Gas production could increase the internal pressure and cause
the line to fail
Which is true about Chlorine gas?. ANSWER -IT is 2.5 times heavier than air
