Wastewater Treatment B Test Exam Questions and Answers, Exams of Water and Wastewater Engineering

Download Wastewater Treatment B Test Exam Questions and Answers and more Exams Water and Wastewater Engineering in PDF only on Docsity!

The Wastewater Treatment B Test Exam Questions

and Answers

Lift stations at a treatment plant or those which discharge directly to a treatment plant with an average flow greater than 0.1 MGD shall have three or more pumps or have automatically controlled variable capacity pumps, these pumps should be adjusted to actual flow conditions and controlled to operate so as to: - Correct answer Minimize surges in the treatment in the treatment units. In the contact stabilization system of activated sludge treatment, the detention time in the contact zone is designed be _______ other types of activated sludge treatment. - Correct answer shorter than According to current TCEQ wastewater operator certification rules, an operator can renew a Class D Wastewater Treatment Plant Operator if he or she: A) Works only in a collection system B) Is an operator at an activated sludge plant? C) Is an operator at a trickling filter treatment facility with a permitted daily average flow of 0.15 MGD? D) Both A and C. E) None of the above - Correct answer none of the above If a Leak is suspected in an off-line, back-up, one-ton chlorine cylinder, after putting on proper safety equipment, the operator should first: - Correct answer Call appropriate emergency response personnel. The definition of an oxygen-deficient atmosphere is one that contains less than ________ percent oxygen. - Correct answer 19. A combustible atmosphere: - Correct answer contains oxygen and flammable gas, vapor, or dust All of the following EXCEPT ________ are damaging or irritating to the mucus membranes or lungs if inhaled: A) Ozone B) Lime Dust C) Chlorine Gas D) Carbon Dioxide E) Ferric Chloride Dust - Correct answer Ozone The Sludge Volume Index (SVI) is: - Correct answer the volume of settled sludge (30- minutes) in ml/L times 1000, divided by the concentration in mg/L of MLSS. Bio monitoring - Correct answer involves the use of aquatic life to test the toxicity of a wastewater treatment plant effluent.

A 24-Hour composite sample was tested for chlorine residual and found to contain none. These results indicate that: - Correct answer Residual chlorine was NOT present during the 24-hour period. In an activated sludge treatment plant, the 30 minute settle ability test indicates: A) The clarity of the effluent B) The influence of surface tension settling C) The current settling capabilities in the clarifier D) The ability of the organisms to flocculate and settle. E) All of the above - Correct answer E) All of the above Setting work goals for an individual works best - Correct answer Accompanied by an action plan One element of being an effective communicator is to: - Correct answer be a good listener An efficient primary clarifier is expected to remove _______ of the influent, settable solids. - Correct answer 90 percent or better Primary wastewater treatment facilities make use of - Correct answer the force of gravity and density differences between the water and the solids. If the inside diameter of the lift station wet well is 8 feet, and the vertical separation between "lead pump on" and "all pumps off" (low water line) is 4 feet 9 inches, the approximate storage in the wet well during a normal pump cycle is: - Correct answer 1,785 gallons Assume that both pumps shown in the exhibit are working. The function of float switch B is to turn: - Correct answer the lead pump on The extent of treatment necessary at a particular wastewater treatment plant depends upon: A) The treatment plant location B) Water quality standards set for the receiving stream C) Amount and final use of the treatment plant effluent D) The type and concentration of wastes received at the plant for treatment. E) All of the above - Correct answer All of the above In most pressure sewer systems, the plumbing units or grinder pumps at each residence are considered to be - Correct answer the integral part of the wastewater collection system Assume that a pumping unit with a 14 3/4 inch impeller has characteristics as described by the pump curve shown in the exhibit. If the pumping unit is working against a static

head of 47 feet, and the force main on the discharge side has a total friction loss of 4 feet, the approximate pump discharge should be - Correct answer 1550 gallons per minute Assume that a pumping unit with a 13 1/4 inch impeller has a characteristics as described by the pump curve shown in the exhibit. If the pumping unit has a total dynamic head of 38 feet, the approximate pump discharge should be: - Correct answer Proper operation of a facultative pond system requires that - Correct answer adequate DO be maintained at the surface at all times. In a washing grit remover, the grit is moved slowly by screw conveyers up an inclined channel in order to - Correct answer decrease the amount of organic matter in the grit. The amount of organic matter removed by a trickling filter is dependent of the recirculation ratio - Correct answer True The purpose of returning the solids from the bottom of the clarifier to aeration tank in the activated sludge process is to: - Correct answer Remove the solids that accumulate in the clarifier, and to reseed the aeration tank with biologically active solids. In the extended aeration activated sludge process, the biological mass is kept. - Correct answer within the endogenous phase The extended air activated sludge treatment process - Correct answer is the simplest activated sludge process, and easier to operate than most other activated sludge processes. Microscopic examination of a good settling sludge should show a predominance of - Correct answer free swimming and stalked ciliates with few rotifers and flagellates. In an activated sludge treatment plant, a SVI of 180 would indicate: - Correct answer A "bulky" sludge. If nitrification is desired in an activated sludge system, then the DO should be maintained above 2 mg/l because: - Correct answer excessive oxygen speeds up the nitrification process. The white, thick billowing foam common during the startup of an activated sludge wastewater treatment plant results from high MLSS - Correct answer False In an activated sludge process, the results of a mixed liquor settling test indicate that the supernatant of the mixed liquor sample is clear, but the supernatant of the plant effluent sample is turbid. These test results indicate that the problem is occurring in the - Correct answer Secondary settling tank (Clarifier)

If released to atmospheric pressure, one part liquid chlorine will to about - Correct answer 450 parts gas chlorine Besides disinfection, chlorination can be used in wastewater treatment process to: A) Perchlorate influent for control of hydrogen sulfide B) Remove nitrogen by breakpoint chlorination C) Dose RAS for control of bulking or foaming D) Reduce ponding in a trickling filter E) All of the above - Correct answer E) All of the above One indication that anaerobic digestion facility is improving would be: - Correct answer a decrease in the carbon dioxide content of the gas produced, and a corresponding increase in the methane content. Sludge from a digester should be slowly drawn to a drying bed in order to - Correct answer avoid thinning of the sludge during the drawing operation. The terms "low rate" and "high rate" when used in reference to the anaerobic digester refer to the rate of stabilization of the raw sludge. - Correct answer False Direct aquifer recharge of treated effluent can be used to: A) Replenish groundwater B) Reduce ground subsidence C) Prevent salt water intrusion D) All of the above - Correct answer All of the above Activated carbon is used in physical-chemical treatment of wastewater to remove primarily: - Correct answer Chlorine Anaerobically digested sludge should applied to a drying bed to a depth of about: - Correct answer 4 to 6 inches The maximum design organic loading for stabilization ponds is 35 pounds of BOD per acre per day. A city with a 10 acre stabilization pond currently receives a daily flow of about 125,000 god with an average of 240 mg/l. The city has an application from an industry to construct a plant which will add a flow of 50,000 god with an average BOD of 450 mg/l. In order to accommodate the combined flows, the city's pond area must be expanded by a minimum of: - Correct answer 2.5 acres A sewer construction project in rocky ground will require a 2 feet wide by 350 foot long trench with an average depth of 10 feet. The new pipe and select bedding material (hauled in) will occupy the bottom third of the trench. Assuming that the rest of the soil from the trench can be used for backfill, the cubic yards of spoil dirt which must be hauled away will be about: - Correct answer 86 cubic yards

Both pumps in a two pump lift station have a rated capacity of 100 gym, and the storage in the wet-well between "lead pump on" level and "all pumps off" level is 850 gallons. If it takes 11 minutes and 30 seconds for a single pump to draw the wet-well down to the low-water line, the average inflow to the station during that time period was about: - Correct answer 26 gym At a flow of 1.7 MGD, a 50- foot diameter clarifier has overflow rate of about: - Correct answer 866 gallons per square foot. (On the WWTP Example Permit) The daily flows indicate? - Correct answer a violation of the daily-average limit (On the WWTP Example Permit) The ammonia nitrogen values indicate? - Correct answer a violation of the daily maximum value (On the WWTP Example Permit) The dissolved oxygen values indicate? - Correct answer a violation of a grab sample limit