36 Questions
What does MCRT refer to in an activated sludge system?
The average number of days a cell remains in the system
Is activated sludge an anaerobic process?
No
What is the main purpose of secondary treatment in wastewater treatment?
To remove the organic content of the wastewater
What does SVI measure in a wastewater treatment system?
The sludge volume that needs to be wasted
Is it true that most bacteria in untreated wastewater are harmful to humans?
No
What does BOD measure in wastewater?
The organic content of wastewater
Are ppm and % considered roughly equivalent for wastewater treatment calculations?
No
Does a one acre wastewater treatment pond, operated at a depth of 3 feet, hold approximately 1 million gallons?
Yes
Are trickling filters easily upset by shock loads when compared to activated sludge?
Yes
What causes ponding on the surface of trickling filters?
Plugging of underdrains immediately below the point of ponding
What test is used to determine the organic matter found in the mixed liquor?
MLVSS
The four (4) basic components of every activated sludge treatment system are:
Aeration, clarification, return sludge and waste sludge
Which of the following statements is not true regarding a wastewater collection system:
A sewer is designed to allow the waste to flow at a rate of approximately 1 ft/sec.
Velocity of flow in sewers is usually expressed in terms of
Feet per second
One of the reasons that air should be excluded from anaerobic digesters is because:
the entrance of air mixed with the gas produced in the digester could create an explosive mixture
The fundamental purpose of disinfection is to:
Destroy pathogenic organisms
The difference between the amount of chlorine added and the amount of chlorine remaining after the contact period is referred to as:
the chlorine demand
TKN is the measure of:
Ammonia/Ammonium+Organic Nitrogen
Sludge with a specific gravity of 1.1 will weigh:
9.17lbs/gal
What problem is associated with trickling filters?
Bulking
What is the primary organism responsible for treating wastewater in the trickling filter process?
Aerobic bacteria
What does 'sloughing' refer to in the context of a trickling filter?
The periodic discharge of large quantities of slime growth with the filter effluent.
What is the surface area of a cylindrical tank 80 feet in diameter and 25 feet in height? (Cylindrical part surface area only)
1,570 sq. ft
Calculate the VS loading to the digester in lbs/day if 10,000 cu. ft of sludge containing 4.8% TS with an average VS content of 82%.
30,987 lbs/day
Calculate the weir loading for a sedimentation tank with an outlet weir 480 ft long and a flow of 5 MGD.
10,420 gpd/ft
What is the hydraulic loading on the trickling filter in gpd/ft2 if a 90 feet diameter trickling filter treats a 540,000 gpd primary effluent flow with a recirculated flow of 120,000 gpd?
104 gpd/ft2
What is the detention time of a wastewater treatment pond that is 40 acres and receives a flow of 0.6 MGD?
87 days
Calculate chlorine demand if chlorine is being fed at the rate of 200 pounds per day, with a plant flow of 4 MGD and a chlorine residual of 3 mg/L.
3 mg/L
Calculate SVI for a mixed liquor sample if a sludge settleability test shows a reading of 220 ml after 30 minutes of settling in a one liter graduated cylinder, with MLSS concentration of 1850 mg/L and MLVSS concentration of 1440 mg/L.
119
Ponding is typically caused by plugging of media by zoogleal mass and not by plugging of the underdrains. Is this statement true or false?
True
Series operation of trickling filter is the preferred mode during very low temperature conditions during winter. Is this statement true or false?
False
Hydrogen sulfide gas in a moist atmosphere can result in corrosion of concrete structures. Is this statement true or false?
True
It is common for primary clarifiers to remove 80-85% of the BOD and 90-95% of the TSS. Is this statement true or false?
False
Detention time is the time required to fill a tank at a given flow. Is this statement true or false?
True
Fresh wastewater is characterized by a blackish color, foul and unpleasant odors with floating materials and suspended solids. Is this statement true or false?
False
Algae is primarily responsible for the effective working of an anaerobic pond. Is this statement true or false?
True
Test your knowledge about activated sludge treatment systems with this quiz. Explore topics such as outlet weirs, density of sludge, flow distribution, and testing for organic matter in mixed liquor.
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