Wastewater Treatment Exam Class C Questions and Answers Guide, Exams of Nursing

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The Activated Sludge Process: A. requires preaeration B. requires Activated Carbon C. is an aerobic biological process. D. Usually precedes primary sedimentation. E. Requires 50% by volume old sludge to work effectively. - Correct Answers ✅C. Is an Aerobic biological process A complete mix activated sludge plant has a fast settling sludge and high amounts of pin floc leaving the clarifier. One way to correct this problem is to : A. Increase the RAS Flow B. Reduce Wasting Rates C. Increase dissolved oxygen levels. D. Increase the F/M ratio by wasting more E. Increase the sludge age by wasting less. - Correct Answers ✅D. Increase the F/M Ratio by Wasting More Which of the following flow rates should be measured if the operator is to control plant properly?

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A. Aeration rate or resulting dissolved oxygen level. B. Influent or effluent. C. return sludge D. waste sludge E. all the above - Correct Answers ✅E. all the above During start up your aeration tank produces excessive amounts of billowing white foam. This can be corrected by: A. Doing nothing, it will go away in a few hours B. Increasing the sludge wasting rate C. Seeding the process with sufficient good quality sludge D. Spraying water on the foam until it is gone E. Taking a weeks vacation - Correct Answers ✅C. Seeding the process with sufficient good quality sludge In solving an operational problem at a treatment plant: A. there is almost always a good technical solution. It may require considerable experience and time to learn whaat it is. B. Human errors have to be corrected since the operator is at fault.

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C. quality of the mixed liquor solids D. Short circuiting E. All of the above - Correct Answers ✅E. All of the above The Active sludge process parameters which n operator can change directly are: A. aeration rates. B. waste rates. C. the ratio of free swimming to stalked ciliates. D. Return sludge rates. E. All the above except C. - Correct Answers ✅E. All the above except C. Which of the following would you use to increase the degree of nitrification in an activated sludge plant? A. increase the wast rates B. increase dissolved oxygen levels and increase the sludge age C. Remove excess alkalinity from the wastewater D. Maintain a thicker sludge blanket n the clarifier

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E. Inhibit the growth of the nitrifying bacteria with chemicals.

• Correct Answers ✅B. increase dissolved oxygen levels and increase the sludge age The Maximum change in the sludge wasting rates to maintain uniform operating conditions should be about A. 10- 20 % per day B. 20-40 % per day C. 40-60 % per day D. 60-80 % per day E. 100% per day - Correct Answers ✅A. 10- 20 % per day When operating an activated sludge plant, Which TSS concentration is most important for process control? A. Primary effluent B. Aeration tank mixed liquor. C. Return Sludge D. Digester. E. Plant influent - Correct Answers ✅B. Aeration tank mixed liquor.

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A. Influent temperature. B. Monthly average flow rates C. BOD loadings MLSS sludge settle-ability D.O. and oxygen uptake rate D. digester operation. E. Chlorinator settings. - Correct Answers ✅C. BOD loadings MLSS sludge settle-ability D.O. and oxygen uptake rate Causes of sludge bulking include: A. Low DO and presence of sulfides B. Air supply too low C. organic loading rate too high D. nutrient imbalance. E. All the above can cause bulking. - Correct Answers ✅E. All the above can cause bulking. Industrial waste materials which are usually not compatible with municipal treatment plants include: A. chemical oxygen demand B. Heavy metals.

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C. petroleum fats , oils and greases D. nitrogen and phosphorus compounds. E. B and C - Correct Answers ✅B. Heavy metals. Sludge is observed to accumulate in the final clarifier. This may be caused by : A. plugged sludge collectors return pumps or waste pumps B. too high a return rate. C. excessive solids wasting. D. hydraulically overloaded clarifier E. All of the above. - Correct Answers ✅A. plugged sludge collectors return pumps or waste pumps What is the relationship between the F/M ratio and the MCRT sludge age for a particular plant when the aerator detention time is a constant value. A. these to control parameters are unrelated. B. When one increases the other increases. C. When one increases the other decreases. D. it is a direct relationship

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A. is probably caused by mechanical failures. B. usually represents a hydraulic deficiency of design or operation C. Increases efficiency by facilitating rapid movement of treatment plant effluent D. has no effect on plant performance. E. All of the above. - Correct Answers ✅B. usually represents a hydraulic deficiency of design or operation An old, over oxidized sludge at an underloaded plant produces mixed liquor solids that A. settle slowly but produce a clear effluent B. Settle rapidly leaving a turbid supernatant. C. Cannot nitrify but turn septic readily in the final clarifier D. All the above E. None of the above. - Correct Answers ✅B. Settle rapidly leaving a turbid supernatant. The Correct operational response to a gently settling sludge which stays in the bottom two feet of the clarifier and produces a clear final effluent is to

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A. Increase return sludge flow rate B. Decrease return sludge flow rate C. Increase sludge wasting D. Decrease sludge wasting E. continue with past operating practices. - Correct Answers ✅E. continue with past operating practices. Certain violations at a WWTP require written notice within 5 days to the Executive Director of the TCEQ. What would be a reason? A. Exceed the permitted limit by more then 40% B. Endangers human health C. Operator bypasses treatment without prior authorization D. All of the above - Correct Answers ✅D. All of the above Who can sign the effluent Discharge Monitoring Report? - Correct Answers ✅Operator with signature authorization and an executive or official of the permittee True or False: Chlorine disinfection works better at a PH of 9 rather than 6 - Correct Answers ✅False

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C. 7

D. 10

E. 12 - Correct Answers ✅C. 7 A centrifugal pump running at 100% with restricted flow is registering 40 amps. If the pump is changed to run at 50% and the restriction is removed causing increased flow. What happens to the number of amps? A. Increase B. Decrease C. Stays the same D. Does not Change - Correct Answers ✅B. Decrease The chlorine room is required to have two air vents. One is a forced air fan at the top where should the vent on the opposite wall be placed? A. At the top B. Half way up the wall C. At the Bottom - Correct Answers ✅C. At the Bottom

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Carbon Dixoide is hazrdous in a closed environment In an activated sludge plant this could - Correct Answers ✅Makes up 3-4% of normal sludge gas The required detention time for a chlorine contact chamber is how many minutes? A. 5 B. 10 C. 15 D. 20 E. 25 - Correct Answers ✅D. 20 If a treatment plant has a high air flow rate and it is not overloaded with BOD, what could be the cause of low dissolved oxygen. - Correct Answers ✅Leaks in the air lines, and plugged diffusers The influent BOD is not high bu the plant appears to be overloaded. What could be causing the problem? A. High solids from thickeners to digester B. High solids in belt press C. Supernatant from digester to aeration

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B. Have an influent pipe with multiple outlets C. Maintain lots of vegetation on slopes D. Have trees to provide shade - Correct Answers ✅B. Have an influent pipe with multiple outlets The most accurate samples showing conditions through the day are? Samples collected at even intervals throughout the day i called a ____________ Sample - Correct Answers ✅Flow weighted composite When collecting E. Coli samples, one should? A. Not collect on rainy or windy days B. Do not touch the inside of the lid or bottle C. Use bottles sterilized in a laboratory D. Collect directly into the bottle when possible E. All the above - Correct Answers ✅E. All the above Analysis of dissolved oxygen must be performed how soon after collection? - Correct Answers ✅Immediately Flow measuring devices must be calibrated where? - Correct Answers ✅The 0" reading is at the bottom of the v-notch

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To improve accuracy of a flow measuring device one could? - Correct Answers ✅Clear algae or growth from sides to provide for even flow. What helps the process by removing small bits of bacteria and organics from the clarifier? - Correct Answers ✅Protozoa Using alternating controls on lift pumps allows the operator to

• Correct Answers ✅Evenly wear pumps so they are ready for use. Floats in a lift station are designed to - Correct Answers ✅Measure liquid levels and trigger pump controls Primary clarifiers can have a higher surface loading rate than secondary clarifiers because - Correct Answers ✅The particles are heavier so they settle faster Treated sludge that is land applied is beneficial to he soil by adding - Correct Answers ✅Nutrients When installing pipe underground which way should the bel be installed - Correct Answers ✅Uphill

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What causes corrosion in a collection system - Correct Answers ✅Hydrogen sulfide The water in a wastewater collection line is septic, what are the characteristics - Correct Answers ✅More gases than fresh raw wastewater A pump has a worn impeller the energy cost would be A. More B. Less C. The same - Correct Answers ✅A. More