Exam (elaborations)
Texas Wastewater A (1)
- Module
- EDPNA - technical
- Institution
- EDPNA - Technical
Texas Wastewater A (1)
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Texas Wastewater AWhat is TCEQ doing to control "point source" pollution of the Texas waterways? - correct
answer-*Permitting of domestic wastewater plants
*Permitting of industrial wastewater plants
Describe proper design of force main wastewater lines. - correct answer-Minimum two fps
velocity with the smallest pump operating alone. Minimum four inch diameter pipe with 150
psi rating.
What is Standard Dimension Ratio? - correct answer-Ratio of outside pipe diameter (OD) to
wall thickness (PVC)
Describe proper design of gravity wastewater lines. - correct answer-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? - correct answer-24 inches and be at least 4
feet wide.
pH meters should be calibrated how often? What standards should be used for calibration
purposes? - correct answer-Daily with at least two buffers.
What is the standard chlorine residual and minimum contact time on Texas wastewater
permits? - correct 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
As the complexity of an organization increases, what management function becomes most
important? - correct answer-Planning
What is the effective chlorine disinfecting agent? - correct answer-Hypochlorous Acid (HOCl)
Does pH affect the chlorination process? Explain your answer. - correct 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.
What is the effluent chlorine residual in Texas that is standard on permits and the minimum
detention time? What is the maximum residual allowed? - correct 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.
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? - correct answer-Formula
What activated process cannot nitrify in a single stage? - correct answer-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? - correct answer-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? - correct answer-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? - correct
answer-Formulas
Anaerobic digester gas should contain? - correct answer-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? - correct answer-Formulas MCRT
What are some of the causes of filaments in the aeration basin? - correct answer-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? - correct
answer-Ciliated protozoa
When an RBC is operating correctly, how will the slime appear on the media? - correct
answer-Grey to brown 0.05 to 0.1 inches thick
According to design criteria, what are the minimum allowable diameters for a manhole? -
correct answer-24 inch opening and 48 inch inside diameter
What activated sludge process does not achieve complete nitrification? - correct
answer-Contact Stabilization
In the selection of forced main wastewater piping, what is the minimum working pressure? -
correct answer-150 psi
The oxygen depletion of BOD dilution water should not exceed - correct answer-0.2 mg/L.
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