Texas Wastewater Class A Exam
Questions And Correct Answers
Seeding of BOD samples is necessary when samples
(All of the above) have a chlorine residual, have a previously been chlorinated, have
been subjected to high temperatures, contain high or low pH industrial wastes
When is blue-green algae the most dominant on a pond treatment system?
Summer
A 30-inch diameter wastewater interceptor is observed to be flowing half-full at about
two fps. The approximate volume of wastewater flowing through the pipe is 3.14x1.25
x 1.25 x 2 = 4.9 cfs x 449 = 2,200 gpm
c. 2,200 gallons per minute
A one-cylinder reciprocating sludge pump with a 10-inch bore and a 5-inch stroke
pumps at a rate of 50 cycles per minute. How many minutes must the pump be
operated to pump 5,000 gallons of sludge? 3.14x0.416 x 0.416 x0.416 x 50 x7.48 = 84.5
gpm 5000 gal = 59,2min 84.5 gpm b. 29
60 minutes
,If an existing centrifugal pump motor is replaced with a motor with 25 percent more
speed, the motor horsepower required will increase by 1.25 x 1.25 x 1.25 = 1.95
95 percent
When must TCEQ be notified about expansions of a treatment facility?
Before construction
In an anaerobic digester, the percentage of methane and carbon dioxide gas content
should be
70% methane, 30% carbon dioxide
The temperature of an anaerobic digester should be maintained at a minimum of
95° F
What type of wastewater treatment operates in the endogenous bacteria growth
phase?
Extended air
Why is recirculation needed in a trickling filter?
Keep the media wet Further reduce BOD All of the above (a, b, and c)
,What type of fire extinguisher would be used on an electrical control panel that has
been de-energized?
Class A Class C (a and d)
Disinfection with chlorine is the most effective at a pH of
6.0
The biomass on a normal functioning RBC has what appearance?
Grey to brown and 0.05 to 0.1 inch thick
The sludge from a primary clarifier should percent solids?
4% to 6%
What is eutrophication in a pond system?
Enrichment with nitrogen and phosphorous Causes algae blooms (b and c)
How often should pH meters be calibrated?
, Daily
In Texas, pH meters are required to be calibrated on how many buffers?
two
An industrial complex has a BOD discharge to the POTW of 500 pounds per day. The
population equivalent of this industry is 500 lbs = 2,941 0.17 lbs BOD person
2941
The parameters of the BOD test are
5 days at 20° Centigrade
Standard Dimension Ratio in pvc pipe is defined as
Ratio of OD pipe diameter to wall thickness
How should shoring be removed from a trench?
up from the bottom up
Questions And Correct Answers
Seeding of BOD samples is necessary when samples
(All of the above) have a chlorine residual, have a previously been chlorinated, have
been subjected to high temperatures, contain high or low pH industrial wastes
When is blue-green algae the most dominant on a pond treatment system?
Summer
A 30-inch diameter wastewater interceptor is observed to be flowing half-full at about
two fps. The approximate volume of wastewater flowing through the pipe is 3.14x1.25
x 1.25 x 2 = 4.9 cfs x 449 = 2,200 gpm
c. 2,200 gallons per minute
A one-cylinder reciprocating sludge pump with a 10-inch bore and a 5-inch stroke
pumps at a rate of 50 cycles per minute. How many minutes must the pump be
operated to pump 5,000 gallons of sludge? 3.14x0.416 x 0.416 x0.416 x 50 x7.48 = 84.5
gpm 5000 gal = 59,2min 84.5 gpm b. 29
60 minutes
,If an existing centrifugal pump motor is replaced with a motor with 25 percent more
speed, the motor horsepower required will increase by 1.25 x 1.25 x 1.25 = 1.95
95 percent
When must TCEQ be notified about expansions of a treatment facility?
Before construction
In an anaerobic digester, the percentage of methane and carbon dioxide gas content
should be
70% methane, 30% carbon dioxide
The temperature of an anaerobic digester should be maintained at a minimum of
95° F
What type of wastewater treatment operates in the endogenous bacteria growth
phase?
Extended air
Why is recirculation needed in a trickling filter?
Keep the media wet Further reduce BOD All of the above (a, b, and c)
,What type of fire extinguisher would be used on an electrical control panel that has
been de-energized?
Class A Class C (a and d)
Disinfection with chlorine is the most effective at a pH of
6.0
The biomass on a normal functioning RBC has what appearance?
Grey to brown and 0.05 to 0.1 inch thick
The sludge from a primary clarifier should percent solids?
4% to 6%
What is eutrophication in a pond system?
Enrichment with nitrogen and phosphorous Causes algae blooms (b and c)
How often should pH meters be calibrated?
, Daily
In Texas, pH meters are required to be calibrated on how many buffers?
two
An industrial complex has a BOD discharge to the POTW of 500 pounds per day. The
population equivalent of this industry is 500 lbs = 2,941 0.17 lbs BOD person
2941
The parameters of the BOD test are
5 days at 20° Centigrade
Standard Dimension Ratio in pvc pipe is defined as
Ratio of OD pipe diameter to wall thickness
How should shoring be removed from a trench?
up from the bottom up
