Test # 1 for Wastewater Treatment Plant Operators...
Information...
The Grade I examination contains questions regarding the following subjects: basic safety practices, hazards encountered
during wastewater treatment plant operations, sampling and simple analysis of wastewater constituents, operation and
maintenance procedures in preliminary and primary treatment unit processes, anaerobic sludge digestion and disinfection.
It also includes specific questions on the operation and maintenance of wastewater stabilization ponds and state
regulations regarding the classification of wastewater treatment plants and operator certification.
The Grade I examination also contains mathematical questions. Examinees may be asked to calculate a variety of problems
including chlorine demand/residual, overflow rates, removal efficiency (% removal), pumping rate, solids concentration,
detention time, hydraulic or organic loading rates and volume or surface area. The examinee should be familiar with typical
calculations related to the subject matter listed in paragraph 1.
6 True/False Questions
1 Point Each
4 Multiple Choice Questions
2 Points Each
5 Math Problems
4 Points Each
Total Points : 34
True / False Questions...
1. Hydraulic loading to a pond is generally expressed as gal/day/ft².
2. MCRT refers to the average number of days that a “cell” remains in an activated sludge system.
3. The major components of anaerobic digester gas are methane and hydrogen sulfide.
4. Raw influent settleable solids are measured in units of mL/L.
5. A trickling filter allows the flow to slowly trickle through a filtration bed in order to remove large particulates
by physically screening them.
6. In the wastewater field mg/L and ppM are considered to be equivalent.
Multiple Choice Questions...
7. Which one of the following statements is TRUE in regard to the concept of pH ?
a. pH indicates the amount of total alkalinity available.
b. A raw sludge sample with a pH of 6.5 is slightly basic.
c. Bacteria in wastewater generally function well at a pH near 7.0.
d. A pH meter gives the percent hydrogen ion concentration as its direct readout value.
e. Accurate pH measurements on raw wastewater require that a 24-hours flow-proportioned sample be collected.
8. Which one of the following statements regarding facultative ponds is TRUE ?
a. DO concentrations may often exceed 10 mg/L during the afternoon of a warm and sunny day.
b. The pH may fall as carbon dioxide is consumed by algae.
c. Aerobic bacteria produce oxygen that is consumed by algae.
d. A facultative pond has no anaerobic layer and no aerobic layer.
e. Facultative ponds are operated only in series, never in parallel.
9. The amount of chlorine used per day from a 1 ton chlorine cylinder is normally determined by :
a. Pressure gauges.
b. Rotometers.
c. Weighings.
d. Chlorine residuals.
e. Ammonia equivalents.
10. The total solids in wastewater would be a combination of :
a. Fixed solids and settleable solids.
b. Dissolved solids and volatile solids.
c. Dissolved solids and suspended solids.
d. Suspended solids and fixed solids.
e. Fixed solids and dissolved solids.
Math Questions...
11. What is the percent of BOD removed in a plant when the influent BOD is 245 mg/L and the effluent BOD is 22 mg/L ?
a. 91%
b. 86%
c. 35%
d. 13%
e. 9%
12. A plastic float is dropped into a wastewater channel and is found to travel 10 feet in 4.2 seconds. The channel is
2.4 feet wide and is flowing 1.8 feet deep. Calculate the flow rate of this wastewater in cubic feet per second.
a. 1.0 ft³/sec.
b. 2.3 ft³/sec.
c. 4.2 ft³/sec.
d. 5.7 ft³/sec.
e. 10.3 ft³/sec.
13. What is the detention time in a stabilization pond if the influent flow rate is 0.785 MGD, the pond depth is 4.5 feet,
and the pond covers 17 acres ?
a. 97 days.
b. 56 days.
c. 32 days.
d. 14 days.
e. 4.2 days.
14. What is the volume of water (in gallons) in an upright 25 foot diameter cylindrical tank with a water depth of 22 feet ?
a. 10,794 gallons
b. 13,750 gallons
c. 80,737 gallons
d. 90,022 gallons
e. 102,850 gallons
15. Thirty-four hundred and fifty (3,450) gallons of primary sludge is pumped to an anaerobic digester. How many pounds
of V.S. are pumped to the digester if the sludge contains 4.3% T.S. and 76% V.S. ?
a. 25,806 lbs.
b. 12,370 lbs.
c. 1,237 lbs.
d. 940 lbs.
e. 715 lbs.
