Texas Wastewater A
What is TCEQ doing to control "point source" pollution of the Texas waterways? - ANS-
*Permitting of domestic wastewater plants
*Permitting of industrial wastewater plants
Describe proper design of force main wastewater lines. - ANS- Minimum two fps velocity
with the smallest pump operating alone. Minimum four inch diameter pipe with 150 psi
rating.
What is Standard Dimension Ratio? - ANS- Ratio of outside pipe diameter (OD) to wall
thickness (PVC)
Describe proper design of gravity wastewater lines. - ANS- Designed to flow half full
,under normal conditions, at a minimum of two fps and a maximum of ten fps.
Manholes should have a minimum opening of? - ANS- 24 inches and be at least 4 feet
wide.
pH meters should be calibrated how often? What standards should be used for
calibration purposes? - ANS- Daily with at least two buffers.
What is the standard chlorine residual and minimum contact time on Texas wastewater
permits? - ANS- 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
As the complexity of an organization increases, what management function becomes
most important? - ANS- Planning
What is the effective chlorine disinfecting agent? - ANS- Hypochlorous Acid (HOCl)
Does pH affect the chlorination process? Explain your answer. - ANS- 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.
What is the effluent chlorine residual in Texas that is standard on permits and the
minimum detention time? What is the maximum residual allowed? - ANS- 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.
, 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? - ANS- Formula
What activated process cannot nitrify in a single stage? - ANS- Contact Stabilization
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? - ANS- Formula
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? - ANS- Formulas
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? - ANS- Formulas
Anaerobic digester gas should contain? - ANS- 65-75% methane, 25-35% carbon dioxide
and 1-5% nitrogen.
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? - ANS- Formulas MCRT
What are some of the causes of filaments in the aeration basin? - ANS- a. low DO
b. low organic loading
c. septic wastes
d. nutrient deficiencies .
e. high sulfur content
Good sludge quality will have a predominance of what organisms in the MLSS? - ANS-
Ciliated protozoa
When an RBC is operating correctly, how will the slime appear on the media? - ANS-
Grey to brown 0.05 to 0.1 inches thick
According to design criteria, what are the minimum allowable diameters for a manhole? -
ANS- 24 inch opening and 48 inch inside diameter
What is TCEQ doing to control "point source" pollution of the Texas waterways? - ANS-
*Permitting of domestic wastewater plants
*Permitting of industrial wastewater plants
Describe proper design of force main wastewater lines. - ANS- Minimum two fps velocity
with the smallest pump operating alone. Minimum four inch diameter pipe with 150 psi
rating.
What is Standard Dimension Ratio? - ANS- Ratio of outside pipe diameter (OD) to wall
thickness (PVC)
Describe proper design of gravity wastewater lines. - ANS- Designed to flow half full
,under normal conditions, at a minimum of two fps and a maximum of ten fps.
Manholes should have a minimum opening of? - ANS- 24 inches and be at least 4 feet
wide.
pH meters should be calibrated how often? What standards should be used for
calibration purposes? - ANS- Daily with at least two buffers.
What is the standard chlorine residual and minimum contact time on Texas wastewater
permits? - ANS- 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
As the complexity of an organization increases, what management function becomes
most important? - ANS- Planning
What is the effective chlorine disinfecting agent? - ANS- Hypochlorous Acid (HOCl)
Does pH affect the chlorination process? Explain your answer. - ANS- 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.
What is the effluent chlorine residual in Texas that is standard on permits and the
minimum detention time? What is the maximum residual allowed? - ANS- 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.
, 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? - ANS- Formula
What activated process cannot nitrify in a single stage? - ANS- Contact Stabilization
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? - ANS- Formula
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? - ANS- Formulas
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? - ANS- Formulas
Anaerobic digester gas should contain? - ANS- 65-75% methane, 25-35% carbon dioxide
and 1-5% nitrogen.
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? - ANS- Formulas MCRT
What are some of the causes of filaments in the aeration basin? - ANS- a. low DO
b. low organic loading
c. septic wastes
d. nutrient deficiencies .
e. high sulfur content
Good sludge quality will have a predominance of what organisms in the MLSS? - ANS-
Ciliated protozoa
When an RBC is operating correctly, how will the slime appear on the media? - ANS-
Grey to brown 0.05 to 0.1 inches thick
According to design criteria, what are the minimum allowable diameters for a manhole? -
ANS- 24 inch opening and 48 inch inside diameter
