Wastewater Exam Class C Questions and Answers Already Passed

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Wastewater Exam Class C Questions and Answers Already Passed The Activated Sludge Process: A. requires preaeration B. requires Activated Carbon C. is an aerobic biological process. D. Usually pr... ecedes primary sedimentation. E. Requires 50% by volume old sludge to work effectively. ✔✔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. ✔✔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? A. Aeration rate or resulting dissolved oxygen level. B. Influent or effluent. C. return sludge D. waste sludge E. all the above ✔✔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 ✔✔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. C. don't let the laboratory personnel influence you're judgement as to what the best solution is. D. standard textbooks in sanitary engineering are the best source of information. E. It is best to do nothing until the TNRCCC sends a violation notice. ✔✔A. there is almost always a good technical solution. It may require considerable experience and time to learn whaat it is. When the return sludge rate is too low, what happens? A. the aeration tank will not fill B. There will be insufficient organisms to treat the wast load entering the aeration basin C. the activated sludge in the aerator will starve. D. the sludge blanket in the secondary clarifier could become too high. E. B and D ✔✔E. B and D What factors affect how well the mixed liquor suspended solids settle in the final clarifier? A. flow velocity and or turbulence B. temperature C. quality of the mixed liquor solids D. Short circuiting E. All of the above ✔✔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. ✔✔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 E. Inhibit the growth of the nitrifying bacteria with chemicals. ✔✔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 ✔✔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 ✔✔B. Aeration tank mixed liquor. How many aeration tanks does a contact stabilization plant have? A. one, like all the others B. Four: contact, mix, reaeration and stabilization C. Two if you count the digester as an aeration tank D. a contact tank and a reaeration tank E. none of this makes any sense to me. ✔✔D. a contact tank and a reaeration tank Reducing the return sludge flow rate for an activated sludge system which has a good settling sludge will. A. Decrease the hydraulic detention time in the aeration basin B. Increase the solids concentration in the aeration basin C. cause the return sludge concentration to decrease D. have no effect on process performance. E. increase the RAS concentration ad the clarifier blanket thickness. ✔✔E. increase the RAS concentration ad the clarifier blanket thickness. What items would you check if an activated sludge plant becomes upset? 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. ✔✔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. ✔✔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. C. petroleum fats , oils and greases D. nitrogen and phosphorus compounds. E. B and C ✔✔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. ✔✔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 E. The F/M ratio is one tenth of the MCRT (Sludge Age) ✔✔C. When one increases the other decreases. Using results only from the settle-ability test and MLSS test of activated sludge solids the operator will be able to A. calculate the F/M ratio B. Set the doge for chlorinating the return activated sludge C. Calculate the MCRT D. Calculate the SVI E. A and C ✔✔D. Calculate the SVI Which of the following F/M ratios would be in the proper rage for a contact stabilization activated sludge plant? A. 0.08 B. 0.12 C. 0.30 D. 0.75 E. 1.25 ✔✔C. 0.30 Short circuiting in a final sedimentation process: 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. ✔✔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. ✔✔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 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. ✔✔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 ✔✔D. All of the above Who can sign the effluent Discharge Monitoring Report? ✔✔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 ✔✔False Pooling on a trickling filter can be caused by ✔✔Increased BOD strength entering the plant If the disinfection residual after 20 min is between 1mg/l and 4 mg/l but E.coli is exceeding the permitted value what could be the cause ✔✔Bacteria and algae sloughing off of the clarifier weirs Granular HTH is explosive or flammable when mixed with what? ✔✔Petroleum products When working on an open channel uv system one should? ✔✔Use Lock Out/ Tag Out procedures before beginning work What must you do before placing a pump back into service that has been locked out ✔✔Find the person that applied the LOTO and have him remove it once the pump is ready Effluent should be Neutralized so it does not adversely affect the aquatic life. What should the PH be A. 2 B. 4 C. 7 D. 10 E. 12 ✔✔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 ✔✔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 ✔✔C. At the Bottom Carbon Dixoide is hazrdous in a closed environment In an activated sludge plant this could ✔✔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 ✔✔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. ✔✔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 D. RAS too high ✔✔D. RAS too high What are some of the disadvantages of a manual bar screen? ✔✔Must be cleaned often Grease and oil can pass through a plant and cause? ✔✔Pumps too clog, collect on weirs, pass through the facility and endanger aquatic life. After collecting a 30 Min. set, what characteristics of a true bulking sludge would show? A. Settles fast with a cloudy supernatant B. Settles slowly with only a few milliliters of clear liquid at the top C. Sludge in bottom 1/3 with clear supernate D. Settles slowly with fluffy sludge E. Settles fast with clear supernate and pin floc ✔✔B. Settles slowly with only a few milliliters of clear liquid at the top Ponds should be designed to A. always be 10 feet deep B. Have an influent pipe with multiple outlets C. Maintain lots of vegetation on slopes D. Have trees to provide shade ✔✔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 ✔✔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 ✔✔E. All the above Analysis of dissolved oxygen must be performed how soon after collection? ✔✔Immediately Flow measuring devices must be calibrated where? ✔✔The 0" reading is at the bottom of the vnotch To improve accuracy of a flow measuring device one could? ✔✔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? ✔✔Protozoa Using alternating controls on lift pumps allows the operator to ✔✔Evenly wear pumps so they are ready for use. Floats in a lift station are designed to ✔✔Measure liquid levels and trigger pump controls Primary clarifiers can have a higher surface loading rate than secondary clarifiers because ✔✔The particles are heavier so they settle faster Treated sludge that is land applied is beneficial to he soil by adding ✔✔Nutrients When installing pipe underground which way should the bel be installed ✔✔Uphill What hazards would you find in an aeration tank? A. Hazardous/Toxic gases B. Drowning due to lack of buoyancy C. Waterborne diseases D. All of the above ✔✔D. All of the above The grit removal of inorganic from a wastewater plant helps with maintenance. What effects would they have on the plant ✔✔Oil and grease and clog pumps If a centrifugal pumps 100 gallons using 100 mps with a good impeller, what happens o the amps when a pump has a worn impeller? A. Amps increase B. Amps decrease C. Amps stay the same D. Amps can increase or decrease ✔✔A. Amps increase What causes corrosion in a collection system ✔✔Hydrogen sulfide The water in a wastewater collection line is septic, what are the characteristics ✔✔More gases than fresh raw wastewater A pump has a worn impeller the energy cost would be A. More B. Less C. The same ✔✔A. More [Show More]

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