TEXAS WASTEWATER
PRACTICE EXAM QUESTIONS WITH
CORRECT DETAILED ANSWERS |
ALREADY GRADED A+<RECENT
VERSION>
1. What is TCEQ doing to control "point source" pollution of the Texas
waterways? - answer *Permitting of domestic wastewater plants
*Permitting of industrial wastewater plants
2. Describe proper design of force main wastewater lines. - answer
Minimum two fps velocity with the smallest pump operating alone.
Minimum four inch diameter pipe with 150 psi rating.
3. What is Standard Dimension Ratio? - answer Ratio of outside pipe
diameter (OD) to wall thickness (PVC)
4. Describe proper design of gravity wastewater lines. - answer Designed
to flow half full ,under normal conditions, at a minimum of two fps and a
maximum of ten fps.
5. Manholes should have a minimum opening of? - answer 24 inches and
be at least 4 feet wide.
6. pH meters should be calibrated how often? What standards should be
used for calibration purposes? - answer Daily with at least two
buffers.
,7. What is the standard chlorine residual and minimum contact time on
Texas wastewater permits? - answer a. 1.0 mg/L for a minimum 20
minutes detention time at peak flow b. No chlorine residual needed if
detention time is greater than 21 days
8. As the complexity of an organization increases, what management
function becomes most important? - answer Planning
9. What is the effective chlorine disinfecting agent? - answer
Hypochlorous Acid (HOCl)
10.Does pH affect the chlorination process? Explain your answer. -
answer When using free chlorine the disinfectant is HOCl acid. As
such it is much more effective at pH's below 7.0. Above 7.0 pH the acid
begins to be neutralized.
11.What is the effluent chlorine residual in Texas that is standard on permits
and the minimum detention time? What is the maximum residual
allowed? - answer Texas standard is 1.0 mg/L for a minimum 20
minutes detention time at peak flow. Maximum residual allowed is 4.0
mg/L.
12.A treatment plant has a clarifier that is 60 feet in diameter and is 10 feet
deep. The weir is 2 feet inside the outer clarifier wall. The flow is 1.0
MGD. The weir and outflow channel is 3 feet deep. a. What is the
detention time in hours? - answer Formula
13.What activated process cannot nitrify in a single stage? - answer
Contact Stabilization
14.What is the GPM output of a piston pump with an 8-inch diameter piston
with a 10-inch stroke operating at 50 strokes per minute? - answer
Formula
15.A treatment plant has a clarifier that is 60 feet in diameter and is 10 feet
deep. The weir is 2 feet inside the outer clarifier wall. The flow is 1.0
MGD. The weir and outflow channel is 3 feet deep.
a. What is the detention time in hours?
, b. What is the surface loading in gal/ft2/day?
c. What is the weir loading in gal/linear ft/day? - answer Formulas
16.A primary clarifier has a flow of 3.0 MGD and has a diameter of 100 feet.
It is 12 feet deep and has 24 inches of freeboard. What is the detention
time in hours? - answer Formulas
17.Anaerobic digester gas should contain? - answer 65-75% methane, 25-
35% carbon dioxide and 1-5% nitrogen.
18.An activated sludge plant has an average daily flow of 3.5 MG. The
aeration tank capacity is 1.2 MG with a MLSS concentration of 3200
mg/L. The clarifier has a capacity of 400,000 gallons with a MLSS
concentration of 6,000 mg/L. The wasting rate is 40,000 gallons per day
with a MLSS concentration of 8, 000 mg/L. The effluent TSS is 18 mg/L.
Assuming volatile concentrations of 70%, what is the MCRT and what
type of activated sludge plant should this be? - answer Formulas
MCRT
19.What are some of the causes of filaments in the aeration basin? -
answer a. low DO
b. low organic loading
c. septic wastes
d. nutrient deficiencies .
e. high sulfur content
20.Good sludge quality will have a predominance of what organisms in the
MLSS? - answer Ciliated protozoa
21.When an RBC is operating correctly, how will the slime appear on the
media? - answer Grey to brown 0.05 to 0.1 inches thick
22.According to design criteria, what are the minimum allowable diameters
for a manhole? - answer 24 inch opening and 48 inch inside diameter
23.What activated sludge process does not achieve complete nitrification? -
answer Contact Stabilization
, 24.In the selection of forced main wastewater piping, what is the minimum
working pressure? - answer 150 psi
25.The oxygen depletion of BOD dilution water should not exceed -
answer 0.2 mg/L.
26.What is the minimum air gap when making water and wastewater
connections? - answer Minimum of one inch or twice the inlet pipe
size whichever is greater.
27.What is the minimum useful size pipe to prime a centrifugal pump? -
answer 1 inch
28.An anaerobic digester must maintain an average year round temperature
of - answer 95 degrees F.
29.How do you remove shoring from a trench? - answer From the bottom
up
30.Which of the following methods would you use to increase the degree of
nitrification in an activated sludge plant? - answer increase dissolved
oxygen levels and increase the sludge age
31.Which of the following are considered normal operator controls on an
activated sludge plant? - answer *aeration rates *return and wasting
rates
32.Reducing the return sludge flow rate for an activated sludge system
which has a good settling sludge will ________. - answer increase the
RAS concentration and the clarifier sludge blanket thickness
33.An extended air activated sludge plant has a fast settling sludge and high
amounts of pin floc leaving the clarifier. One way to correct this problem
is to ________. - answer * reduce the MCRT by wasting more
• increase the F/M ratio by wasting more
34.The primary causes of wastewater stoppages are ________. - answer
roots and grease
PRACTICE EXAM QUESTIONS WITH
CORRECT DETAILED ANSWERS |
ALREADY GRADED A+<RECENT
VERSION>
1. What is TCEQ doing to control "point source" pollution of the Texas
waterways? - answer *Permitting of domestic wastewater plants
*Permitting of industrial wastewater plants
2. Describe proper design of force main wastewater lines. - answer
Minimum two fps velocity with the smallest pump operating alone.
Minimum four inch diameter pipe with 150 psi rating.
3. What is Standard Dimension Ratio? - answer Ratio of outside pipe
diameter (OD) to wall thickness (PVC)
4. Describe proper design of gravity wastewater lines. - answer Designed
to flow half full ,under normal conditions, at a minimum of two fps and a
maximum of ten fps.
5. Manholes should have a minimum opening of? - answer 24 inches and
be at least 4 feet wide.
6. pH meters should be calibrated how often? What standards should be
used for calibration purposes? - answer Daily with at least two
buffers.
,7. What is the standard chlorine residual and minimum contact time on
Texas wastewater permits? - answer a. 1.0 mg/L for a minimum 20
minutes detention time at peak flow b. No chlorine residual needed if
detention time is greater than 21 days
8. As the complexity of an organization increases, what management
function becomes most important? - answer Planning
9. What is the effective chlorine disinfecting agent? - answer
Hypochlorous Acid (HOCl)
10.Does pH affect the chlorination process? Explain your answer. -
answer When using free chlorine the disinfectant is HOCl acid. As
such it is much more effective at pH's below 7.0. Above 7.0 pH the acid
begins to be neutralized.
11.What is the effluent chlorine residual in Texas that is standard on permits
and the minimum detention time? What is the maximum residual
allowed? - answer Texas standard is 1.0 mg/L for a minimum 20
minutes detention time at peak flow. Maximum residual allowed is 4.0
mg/L.
12.A treatment plant has a clarifier that is 60 feet in diameter and is 10 feet
deep. The weir is 2 feet inside the outer clarifier wall. The flow is 1.0
MGD. The weir and outflow channel is 3 feet deep. a. What is the
detention time in hours? - answer Formula
13.What activated process cannot nitrify in a single stage? - answer
Contact Stabilization
14.What is the GPM output of a piston pump with an 8-inch diameter piston
with a 10-inch stroke operating at 50 strokes per minute? - answer
Formula
15.A treatment plant has a clarifier that is 60 feet in diameter and is 10 feet
deep. The weir is 2 feet inside the outer clarifier wall. The flow is 1.0
MGD. The weir and outflow channel is 3 feet deep.
a. What is the detention time in hours?
, b. What is the surface loading in gal/ft2/day?
c. What is the weir loading in gal/linear ft/day? - answer Formulas
16.A primary clarifier has a flow of 3.0 MGD and has a diameter of 100 feet.
It is 12 feet deep and has 24 inches of freeboard. What is the detention
time in hours? - answer Formulas
17.Anaerobic digester gas should contain? - answer 65-75% methane, 25-
35% carbon dioxide and 1-5% nitrogen.
18.An activated sludge plant has an average daily flow of 3.5 MG. The
aeration tank capacity is 1.2 MG with a MLSS concentration of 3200
mg/L. The clarifier has a capacity of 400,000 gallons with a MLSS
concentration of 6,000 mg/L. The wasting rate is 40,000 gallons per day
with a MLSS concentration of 8, 000 mg/L. The effluent TSS is 18 mg/L.
Assuming volatile concentrations of 70%, what is the MCRT and what
type of activated sludge plant should this be? - answer Formulas
MCRT
19.What are some of the causes of filaments in the aeration basin? -
answer a. low DO
b. low organic loading
c. septic wastes
d. nutrient deficiencies .
e. high sulfur content
20.Good sludge quality will have a predominance of what organisms in the
MLSS? - answer Ciliated protozoa
21.When an RBC is operating correctly, how will the slime appear on the
media? - answer Grey to brown 0.05 to 0.1 inches thick
22.According to design criteria, what are the minimum allowable diameters
for a manhole? - answer 24 inch opening and 48 inch inside diameter
23.What activated sludge process does not achieve complete nitrification? -
answer Contact Stabilization
, 24.In the selection of forced main wastewater piping, what is the minimum
working pressure? - answer 150 psi
25.The oxygen depletion of BOD dilution water should not exceed -
answer 0.2 mg/L.
26.What is the minimum air gap when making water and wastewater
connections? - answer Minimum of one inch or twice the inlet pipe
size whichever is greater.
27.What is the minimum useful size pipe to prime a centrifugal pump? -
answer 1 inch
28.An anaerobic digester must maintain an average year round temperature
of - answer 95 degrees F.
29.How do you remove shoring from a trench? - answer From the bottom
up
30.Which of the following methods would you use to increase the degree of
nitrification in an activated sludge plant? - answer increase dissolved
oxygen levels and increase the sludge age
31.Which of the following are considered normal operator controls on an
activated sludge plant? - answer *aeration rates *return and wasting
rates
32.Reducing the return sludge flow rate for an activated sludge system
which has a good settling sludge will ________. - answer increase the
RAS concentration and the clarifier sludge blanket thickness
33.An extended air activated sludge plant has a fast settling sludge and high
amounts of pin floc leaving the clarifier. One way to correct this problem
is to ________. - answer * reduce the MCRT by wasting more
• increase the F/M ratio by wasting more
34.The primary causes of wastewater stoppages are ________. - answer
roots and grease
