Wastewater Class B Certification Practice Quiz

Wastewater Class B Certification Practice Quiz

1. A common remedy for activated sludge system problems is to increase the waste activated sludge (WAS) flow rate. When would an increase of WAS rate NOT be correct?

A. When pin-point floc is observed on the clarifier surface B. When thick, scummy foam is seen on the aeration tank surface C. When the aeration system is critically under-loaded D. When straggler floc is present in clarifier and settleometer

2. PROBLEM: The chlorine residual is falling, and inspection of the 150-lb. cylinder and chlorine feed equipment shows ice forming on the chlorine regulator and feed lines. The BEST method to fix the falling chlorine residual is?

A. switch over to sodium hypochlorite solution B. place a second chlorine cylinder on-line C. roll the cylinder so liquid is feeding instead of gas D. place a 1500W space heater next to the cylinder to thaw the ice

3. Caution must be used when adding a caustic chemical to a digester. Lime can combine with carbon dioxide in the digester to form what problem?

A. Acid build-up B. Over-pressurization C. Struvite scale formation D. A dangerous vacuum

4. How many gallons will the single piston, reciprocating sludge pump discharge per minute if the piston bore (diameter) is 6 inches and the stroke length is 11 inches? The pump runs at 99 revolutions per minute. Select the closest answer.

A. 121 gpm B. 125 gpm C. 134 gpm D. 171 gpm

5. Operational data is given below for a conventional activated sludge treatment plant: Plant flow: 3.6 MGD Aeration tank volume: 5.0 MG MLSS: 2,350 mg/L WAS ss: 4,800 mg/L WAS flow: 150,000 gpd Effluent TSS: 15 mg/L

Calculate the MCRT

A. 1.5 days B. 15 days C. 23 days D. 45 days

6. Problem: There are high suspended solids in the water applied to the filters due to bulking sludge in the secondary clarifiers. Polymer is used as a filter aid chemical, but the effluent turbidity is worsening. What is the BEST method to correct the filter problem?

A. Add chlorine to the influent to control the bulking sludge condition B. Run jar tests to determine best polymer dosage C. Place additional chlorine contact tanks on- line D. Reduce the filter backwash frequency, increase the effluent chlorine feed

7. An advantage of a continuous-backwash, up-flow, deep-bed, sand filters is

A. Filters do not need to be taken out of service for backwashing B. Filters do not need coagulants C. Filter backwash does not need to be returned to the plant for treatment D. Filters do not need routine maintenance

8. The aeration tank DO has been running normal (1.5 to 2.0 mg/L) the whole month. Today's DO reading has spiked to nearly 6.0 mg/L in the aeration tank, and the clarifier and plant effluent are cloudy. What is the MOST likely cause of the rise in DO?

A. The aeration blowers were left on overnight B. A shock load of high organic strength waste has entered the plant C. A shock load of rain water has entered the plant D. A toxic shock load of cyanide has entered the plant

9. PROBLEM: Plant fecal coliform counts do not meet State standards. The chlorine supply is not the problem and there is adequate vacuum and chlorine feed. The chlorine contact tank has no solids buildup and the effluent flow is below design. What is the MOST likely cause of the poor fecal coliform kill?

A. High chlorine demand from excessive ammonia in effluent B. High chlorine demand from excessive nitrate in effluent C. High chlorine demand from excessive nitrite in effluent D. High chlorine demand from excessive polymer in effluent

10. The point, location or structure where wastewater discharges from a sewer, drain, or other conduit is called what?

A. Wetland B. Outfall C. Swamp-land D. Force main

11. How many pounds of anionic polymer will be used per day for the belt filter press operation if the polymer is dosed at 4.6 mg/L and the flow to the press is 50,000 GPD? Select the closest answer.

A. 1.9 lbs/day B. 9.2 lbs/day C. 19.2 lbs/day D. 38.4 lbs/day

12. The volatile acid to alkalinity ratio of a properly operating anaerobic digester is

A. 0.1 parts acid to one part alkalinity B. 0.4 parts acid to one part alkalinity C. 0.8 parts acid to one part alkalinity D. 1.0 parts acid to one part alkalinity

13. What is a disadvantage of running a digester in the thermophilic temperature range?

A. Nitrifiers become very sensitive to the struvite produced B. The sensitivity of the organisms to temperature change C. The higher costs of heating the digester with natural gas D. The long digestion time

14. Which condition of a surface water, river or stream will allow more DO saturation?

A. Warm water temperature B. Cold water temperature C. High pH D. Low pH

15. PROBLEM: Solids are washing out of the secondary clarifier of the activated sludge plant. Plant personnel increase the return activated sludge (RAS) flow rate, which slows the problem temporarily, but then it worsens after 30 minutes. What is the cause of the plant problem?

A. increasing the RAS flow increased the detention time in the clarifier B. Increasing the RAS flow caused the DO in the aeration tank to increase C. increasing the RAS flow increased the detention time in the aeration tank D. increasing the RAS flow decreased the detention time in the clarifier

16. Given the following data, what is the most likely cause of the upflow, continuous backwash, deep bed sand filter problem?

Plant Data: All filters operating Influent valves open 100% Effluent valves open 100% Filter level is normal Reject/washwater valves open 50% Poor filtrate quality

A. Effluent valve open too much B. Reject/washwater flow rate too low C. Too many filters on-line D. Influent valve open too much

17. When using lime to precipitate phosphorus from treated effluent, it is important to maintain the pH at or above

A. 6.0 B. 8.0 C. 9.0 D. 11.0

18. What is the upward force caused by groundwater on a sedimentation tank if the groundwater depth is 6 feet above the tank bottom? The tank is 80 feet wide and 157 feet long.

A. 400,700 lbs B. 1,572,000 lbs C. 2,300,000 lbs D. 4,700,000 lbs

19. PROBLEM: The luxury uptake method of phosphorus removal is failing to remove phosphorus to permitted levels. Indicators include:

? Influent phosphorus 8 mg/L ? Effluent phosphorus exceeds 1.0 mg/L ? Fermentation basin phosphorus 10 mg/L ? Aeration basin phosphorus 8 mg/L What is the MOST likely cause of the poor phosphorus removal?

A. Influent phosphorus exceeds permit B. Poor phosphorus release in aeration tank C. Secondary release of phosphorus in clarifiers D. Poor release of phosphorus in fermentation basin

20. Calculate the SVI for the activated sludge treatment plant:

30 minute settleability

675

60 minute settleability

420

MLSS, mg/L

3,650

MLVSS, mg/L

74%

A. 115 ml/g B. 155 ml/g C. 185 ml/g D. 540 ml/g

21. According to Chapter 62-600.440 (5) (f) FAC, regarding high level disinfection, any one sample shall not exceed how many fecal coliform values over a 30-day period?

A. 10 fecal coliform values per 100 ml sample B. 25 fecal coliform values per 100 ml sample C. 200 fecal coliform values per 100 ml sample D. 800 fecal coliform values per 100 ml sample

22. In the luxury-uptake method of phosphorus removal, organisms release phosphorus during which phase of treatment?

A. Aerobic phase B. Anaerobic phase C. Anoxic phase D. Bardenpho phase

23. PROBLEM: Plant effluent coliform count fails to meet required standards for disinfection. Chlorine residual is normal. Disinfectant supplies are not a problem. What is the most probable cause?

A. Contact time too short B. Too little solids in effluent C. Capacity of chlorinator too low D. Chlorine demand too high

24. Using the breakpoint chlorination method of ammonia removal, approximately how many parts of chlorine are needed to remove one part of ammonia?

A. 2 parts B. 5 parts C. 10 parts D. 25 parts

25. Using the data given below, calculate the new waste sludge flow rate to achieve the target MCRT.

Aeration tank capacity: 5.5 MG Plant flow: 9.7 MGD Aeration tank MLSS: 2,700 mg/L RAS ss: 7,000 mg/L Current waste flow rate: 200,000 GPD Effluent TSS: 15.0 mg/L Desired MCRT: 12 days

A. 0.170 MGD B. 0.175 MGD C. 0.180 MGD D. 0.225 MGD

26. Waste activated sludge is pumped into the aerobic digester at 77% volatile solids. After one week of digestion, sludge is applied to the drying beds at 70% volatile solids. What is the percent volatile solids reduction?

A. 3% B. 9% C. 30% D. 90%

27. What is the required brake horsepower (BHP) of the pump to move the water described below?

Feet of head: 1,450 feet Pump efficiency: 91% Flow rate needed: 5,000 gpm Pump impeller diameter: 11.5 inches Discharge pipe diameter: 12 inches

A. 150 BHP B. 200 BHP C. 1,500 BHP D. 2,000 BHP

28. How many gallons of treated effluent will be applied to a sprayfield if there are 7 acres in the zone and 4.5 inches of effluent are applied?

A. 114,340 gallons B. 122,200 gallons C. 855,300 gallons D. 10,263,000 gallons

29. When nitrification occurs in an aeration tank, the expected conditions at the end of the aerated zone would be:

A. A decrease in ammonium, nitrate and alkalinity, an increase in pH B. An increase in nitrate and nitrite, a decrease in alkalinity and pH C. A reduction of alkalinity and nitrate, an increase in ammonium and pH D. An increase in pH, alkalinity, nitrate and ammonium

30. Formation of material that is approximately round in shape, from pea-size to more than two inches in diameter, and forms in filter media from insufficient backwashing are called

A. Gravel media B. Denitrification zones C. Golf balls D. Mud balls

31. Measuring the water pressure above and below filter media is a way of determining

A. Unit Filter Run Volume (UFRV) B. Filtration rates (GPD/sq ft) C. Mudball production rate D. Head loss

32. The availability of which element or compound will reduce the efficiency of the denitrification process?

A. Free Oxygen (O2) B. Methanol (CH3OH) C. Acetic Acid (CH3COOH) D. Nitrate (NO3)

33. The preservative used for transport of the fecal coliform sample is:

A. 0.2% sulfuric acid B. 0.5% nitric acid C. Ice to 4?C D. Ice the sample for no less than 6 hours minimum

34. Which of the following suspended growth processes is not recommended for nitrification?

A. Complete mix B. Extended aeration C. Conventional/Plug flow D. Contact stabilization

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