Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
40 Cards in this Set
- Front
- Back
|
Before treating suspected bulking you should confirm that the problem is actually bulking and not another cause. Which of the following best describes bulking? * (a) high sludge blanket in final; good settling sludge with clear superuanant; low SVI; and low solids concentration and the RAS* (b) filamentous organisms in sludge; low SVI and high sludge blanket in final * (c) filamentous organisms in sludge; high SVI and high solids concentration in the RAS * (d) low solids concentration in RAS; sludge settles good with clear supernatant; SVI higher than 150 and high sludge blanket in final |
Low solids concentration in RAS; sludge settles good with clear supernatant; SVI higher than 150 and high sludge blanket in final |
|
|
If nitrification is desired, why is a MCRT of about ten days a minimum amount of time required? |
To allow enough time for all the organisms to reach the endogenous stage |
|
|
The most important purpose for using the F/M process control method is: |
To ensure a proper balance between MLSS and organic loading |
|
|
Which of the following is the best method of reducing sludge bulking in an activated sludge plant? * (a) addition of small amounts of chlorine* (b) rapidly decreasing the sludge age * (c) reducing the F/M ratio * (d) slowly decreasing the pH * (e)lowering the nitrogen concentration |
* (a) addition of small amounts of chlorine
|
|
|
If the effects of nitrification becomes a problem, what operational changes should you make to solve the problem? |
Increase the F/M ratio (decrease sludge age) |
|
|
In the sludge settleability test, if the sludge rises in less than one hour, what process changes would most likely be needed? * (a) reduce sludge age or increase F/M ratio* (b) reduce sludge age or decrease F/M ratio * (c) increase sludge age or increase F/M ratio * (d) increase sludge age or decrease F/M ratio |
* (a) reduce sludge age or increase F/M ratio
|
|
|
Sludge bulking in the secondary clarifier is commonly caused by improper balance of BOD, MLSS concentration or: * (a) septicity* (b) low RAS concentration * (c) amount of chlorine * (d) decitrification |
* (b) low RAS concentration
|
|
|
If nitrification is an objective, then why would you use a trickling filter as a roughing filter? (the most important reason) * (a) to increase the MCRT* (b) to avoid recirculation * (c) to add "seed" to the activated sludge process * (d) to reduce the flow to the activated sludge process * (e) to remove carbonaceous wastes |
* (e) to remove carbonaceous wastes
|
|
|
The standard used in Chapter 17-6, F.A.C., for "high level disinfection", which is used to reduce fecal coliforms below detectable levels and uses chlorine as a disinfectant is: * (a) 1.0 mg/1 total chlorine residual after 30 minutes contact time at average daily flow* (b) 1.0 mg/1 total chlorine residual after 30 minutes contact time at maximum daily flow * (c) 1.0 mg/1 total chlorine residual aÍter 15 minutes contact time at maximum daily flow * (d) 0.5 mg/1 minimum total chlorine residual aÌter 30 minutes contact time at maximum daily flow * (e) 0.5 mg/l minimum total chlorine residual after 30 minutes contact time at average daily flow |
c) 1.0 mg/1 total chlorine residual aÍter 15 minutes contact time at maximum daily flow |
|
|
The carefully controlled use of digester supernatant to cure bulking sludge problems is successful because the supernatant: * (a) contains well-formed floc* (b) pH is higher * (c) DO is higher * (d) volatile solids content is lower than the sludge * (e) volatile solids content is higher than the sludge |
* (e) volatile solids content is higher than the sludge
|
|
|
In the use of lime in a digester, which of the following conditions takes place? * (a) the pH decreases* (b) the concentration of hydrogen ions increases * (c) the concentration of OH ions decreases * (d) the concentration of hydrogen ions decreases |
* (d) the concentration of hydrogen ions decreases
|
|
|
When starting up a new complete-mix plant, which is the most important step you would take to provide the most rapid start up? * (a) operate a maximum return sludge rate* (b) provide well-conditioned activated sludge as seed * (c) provide for maximum aeration to keep heavy solids from going septic |
* (b) provide well-conditioned activated sludge as seed
|
|
|
The following statements concern procedures to observe in the operation of an anaerobic digester. Which is not a good or acceptable procedure? * (a) maintain the percent solids of the raw sludge as high as is consistent with good operation* (b) add raw sludge slowly, at regular intervals * (c) check the pH frequently and maintain a pH of approximately 6.2 at all times * (d) maintain an ample amount of bacterially active sludge in the digester at all times |
* (c) check the pH frequently and maintain a pH of approximately 6.2 at all times
|
|
|
Which of the following is not a correct long-term effect of BOD from a wastewater treatment plant on a receiving body of water? * (a) results in decreased DO demand* (b) results in rapid growth of algae * (c) accelerates eutrophication * (d) results in decrease of available DO * (e) results in increased DO demand |
* (a) results in decreased DO demand
|
|
|
How long should you allow an activated sludge process to react and stabilize after a major change: * (a) 1 week* (b) 2 days * (c) 1 day * (d) 12 hours * (e) 3 hours |
* (a) 1 week
|
|
|
In a conventional activated sludge treatment plant, if examination indicates that the free swimming ciliates have peaked and are reduced in relative dominance, and the effluent quality is deteriorating, what process change should be made? * (a) increase the RAS rate* (b) increase the MLYSS * (c) decrease the F/M ratio * d) reduce the MCRT * (e) decrease the WAS rate |
* (d) reduce the MCRT
|
|
|
A long MCRT or sludge age may cause ecdogenous decay. What is another important disadvantage? * (a) increased hydraulic washout* (b) higher sludge blanket height * (c) decreased pinpoint floc * (d) increased sludge production |
* (a) increased hydraulic washout
|
|
|
A contact stabilization plant's analysis indicated that the F/M ratio was 10 pounds BOD/100 pounds MLYSS. What would you do to improve the situation? * (a) reduce wasting to reduce F/M to 0.025 - O.50* (b) decrease the return activated sludge rate * (c) stop wasting of activated sludge * (d) increase wasting to increase F/M to 0.30 - 0.35 |
* (d) increase wasting to increase F/M to 0.30 - 0.35
|
|
|
In the winter the temperature of the wastewater applied to a trickling filter is lower than in the summer. This may cause: * (a) no change in the efficiency of the filter* (b) a decrease in the amount of BOD removed * (c) an increase in the amount of BOD removed * (d) an increased psychoda fly infestation * (e) a severe ponding condition |
* (b) a decrease in the amount of BOD removed
|
|
|
The following analysis was run on the mixed liquor of an anaerobic digester: pH 6.5; volatile acids 1,000 ppm; total alkalinity 1,000 ppm. It can he assumed that the digester was: * (a) dangerously close to being sour* (b) producing the best quality of supernatant that could be expected from an anaerobid digester * (c) probably able to handle a greater "raw" sludge input * (d) was hopelessly sour * (e) functioning very well, but cannot handle increased "raw" sludge input |
* (d) was hopelessly sour
|
|
|
Sludge wasting is done using the RAS, and the VSS of the RAS has increased. Then, in order to maintain a constant solids inventory, the: * (a) numbers of microorganisms in the aeration tank must be decreased* (b) sludge age (MCRT) will decrease * (c) WAS flow rate must be decreased * (d) MLVSS of the aeration tank is decreased, relative to the COD * (e) WAS flow rate must be increased to reduce the sludge age |
* (c) WAS flow rate must be decreased
|
|
|
A low PH following clarification (settling) in an extended aeration plant probably indicates: * (a) RAS rate too fast* (b) MLVSS too low * (c) sludge age too short (young) * (d) sludge age too long (old) * (e) MLSS too low |
* (d) sludge age too long (old)
|
|
|
The best control method for problems caused by a slug of restaurant grease in an activated sludge system is to: * (a) decrease the MCRT* (b) increase DO * (c) decrease RAS * (d) decrease WAS |
* (b) increase DO
|
|
|
Recirculation is utilized in a low-rate trickling filter plant in order to: * (a) maintain a constant hydraulic loading to prevent clogging* (b) allow solids to settle out more quickly * (c) reduce plant operating costs * (d) maintain a sufficient dosing rate during low flows * (e) provide adequate oxygen to the media |
* (d) maintain a sufficient dosing rate during low flows
|
|
|
A colored dye solution is added into the raw wastewater entering a primary settling tank, the dye color was noticeable in the effluent in 15 minutes, and all of the dye color had passed through the tank in 40 minutes. * (a) this tank has a design detention time of 55 minutes* (b) this tank bas a design detention time of 40 minutes * (c) such a test has no meaning to plant operation * (d) wastewater is passing through the tank so fast that settling is probably not effective |
* (d) wastewater is passing through the tank so fast that settling is probably not effective
|
|
|
The main purpose of treatment plant effluent chlorination is: * (a) sterilize the wastewater * (b) to help odor control by prevention of decomposition * (c) to aid in the settling of solids * (d) destruction of pathogenic organisms * (e) to lower the BOD and suspended solids in the plant effluent |
* (d) destruction of pathogenic organisms
|
|
|
When operating an activated sludge plant, which is the most important suspended solids test for operational control? * (a) raw suspended solids test* (b) final secondary clarifier effluent mixed liquor * (c) aeration tank mixed liquor * (d) primary settling tank effluent BOD * (e) return sludge from the primary settling tank |
* (c) aeration tank mixed liquor
|
|
|
If the chlorine in an effluent sample was not removed before a BOD test was set up, what results would you expect to find after five days? * (a) the measured BOD of the sample would be lower* (b) the DO of the sample would be increased * (c) the measured BOD of the sample would be higher * (d) the test is not affected by the presence of chlorine * (e) none of the above |
* (a) the measured BOD of the sample would be lower
|
|
|
Which of the following is not an advantage of recirculation in a trickling filter plant? * (a) minimizes odor, ponding and filter fly breeding* (b) saves on plant energy tests * (c) improves distribution of wastewater over the filter surface * (d) prevents biological growth from drying out during low flows * (e) minimizes hydraulic and organic loading variations |
(b) saves on plant energy tests |
|
|
Generally, treatment of domestic wastewater is performed to: * (a) prepare wastewater for safe disposal* (b) remove suspended solids * (c) remove pathogenic bacteria * (d) remove organic matter * (e) all of the above |
* (e) all of the above
|
|
|
The purpose of a sludge drying bed is to: * (a) stabilize secondary sludge* (b) provide for the aerobic digestion of sludge * (c) convert primary sludge into fertilizer * (d) provide for the dewatering of digested sludge * (e) provide storage space for digested sludge |
* (d) provide for the dewatering of digested sludge
|
|
|
If polymer is used in a sludge, gravity thickening process, more polymer dosage will be required when: * (a) the solids loading rate is about 0.4 lbs./sq. ft./hr* (b) the hydraulic loading rate exceeds 30 gals/sq. ft./hr * (c) the solids loading to the unit decreases * (d) the hydraulic loading to the unit decreases * (e) the SVI in the feed sludge becomes higher |
* (e) the SVI in the feed sludge becomes higher
|
|
|
Which of the following modifications of the activated sludge process has the longest total detention time: * (a) extended aeration* (b) conventional activated sludge * (c) step aeration * (d) contact stabilization * (e) trickling filter |
* (a) extended aeration
|
|
|
In the activated sludge process, if the results of a mixed liquor settling test indicate that the supernatant of the mixed liquor sample is clear and the supernatant of the plant effluent sample is turbid. In which tank are problems occurring? * (a) chlorine contact tank* (b) secondary settling tank * (c) primary settling tank |
* (b) secondary settling tank
|
|
|
Chapter 17-19, Florida Administrative Code, specifically states that the plant effluent sampling point is: (SELECT THE BEST ANSWER) (2 points) * (a) after chlorination but before tertiary treatment* (b) immediately before discharge to surface or groundwaters * (c) immediately after chlorination * (d) before chlorination but after the clarifier |
* (b) immediately before discharge to surface or groundwaters
|
|
|
Which of the following statements relative to F/M ratio is not true? * (a) F/M indicates the range of organic loading* (b) oxygen demand test proved crude approximations of COD removed * (c) MLSS results approximates the microorganism concentration * (d) F/M data should be based on a five day moving average * (e) F/M is based on MLVSS |
* (b) oxygen demand test proved crude approximations of COD removed
|
|
|
Excessive wasting can create a young unstabilized sludge with _____ , which could lead to excessive filamentous microorganisms. * (a) stalked ciliates* (b) a pin point floc * (c) an excessive MCRT * (d) a low F/M ratio * (e) a high oxygen uptake rate |
* (e) a high oxygen uptake rate
|
|
|
The two most important operational factors in well operated aerobic digestion: * (a) DO and volatile solids* (b) pH and temperature * (c) alkalinity-volatile acid relationship * (d) proper mixing and DO * (e) pH and DO |
* (d) proper mixing and DO
|
|
|
The return activated sludge in a contact stabilization plant must be: * (a) reduced during the night* (b) maintained at a rate of 10% of plant flow * (c) cycled "on and off" as the solids in the reaeration tank get too high or low * (d) stopped once or twice each day to settle sludge * (e) returned 24 hours/day |
* (e) returned 24 hours/day
|
|
|
In the activated sludge process, if the results of a mixed liquor settling test indicate that the supernatant of the mixed liquor sample is clear and the supernatant of the plant effluent sample is turbid, in which tank are problems most likely occurring? * (a) primary settling tank* (b) aeratîon tank * (c) secondary settling tank * (d) chlorine contact tank |
* (c) secondary settling tank
|
