Wastewater Treatment Class II Exam Prep FREE Sample Exam

A plant feeds 118 lb/day of chlorine (as chlorine) to a flow of 1.05 MGD. Using the feed records, what applied dose is the plant actually achieving?

112.4 mg/L, without checking whether the loading has actually changed

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13.48 mg/L

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1.35 mg/L

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16.83 mg/L

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After a new industry connects, a plant treats 1.35 MGD of wastewater with an influent BOD of 165 mg/L. How many pounds of BOD enter the plant each day?

223 lb/day

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1,376 lb/day

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2,228 lb/day

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1,858 lb/day

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Effluent ammonia is well within limits at average flow but spikes during each day’s peak-flow hours, and sludge age and DO are both adequate. Equalization volume is available. What adjustment addresses the pattern?

Waste heavily on peak days so the remaining sludge is younger and more active, because young sludge always nitrifies faster than an established population

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Raise the RAS rate only during the ammonia spikes and leave flow unaltered

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Use equalization to shave the peaks and feed flow forward steadily, restoring aeration detention time during the hours that now spike

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Lower the basin DO during peaks so the nitrifiers rest between surges

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MLSS has drifted slightly this week, but SVI is 95, the effluent is clear, and microscopic examination shows firm floc with many stalked ciliates and very few filaments. What is the best evaluation?

The sludge is young and dispersed, so wasting should stop until floc firms up

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Stalked ciliates signal an old, failing sludge, so wasting should double

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Filaments must be treated immediately even though few were seen before it can spread through the basin

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The biology is healthy and stable — hold the current RAS, WAS, and air setpoints and keep trending

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Nitrification is consuming alkalinity and the operator will feed an alkalinity chemical at 27 mg/L to a flow of 1.35 MGD. How many pounds per day of chemical (as the dosed compound) are required?

303.94 lb/day

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36.45 lb/day, found by multiplying flow by dose without the weight conversion

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253.3 lb/day

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364.7 lb/day

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A standby generator starts and runs smoothly through every weekly no-load exercise, but during a loaded transfer test it bogs down, frequency sags, and it nearly stalls. What does this evidence show?

The transfer switch is the only defective component in the standby system, and the engine's behavior under load is a normal characteristic that requires no further investigation

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No-load runs cannot prove generating capacity; the engine or fuel system is failing under real load and loaded exercising is what exposes it

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The generator is oversized for the plant and should be downsized

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The weekly exercise period should simply be lengthened at no load, running the engine for several hours unloaded until it is thoroughly warmed and able to accept the plant load

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An RBC shaft develops a rhythmic knock once per revolution and the shaft sits visibly lower at one bearing. Growth is even and drive current is normal. What is the most likely equipment finding?

The biomass has become too heavy for the shaft according to the gauge readings taken during the most recent rounds

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The trough water level is too high when checked against the performance baseline for this equipment

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The media discs are out of round from age under the loading conditions the unit has seen this operating week

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A worn or failing shaft bearing is letting the shaft drop

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A wet-well drawdown test on a centrifugal pump measures output about 18% below its commissioning value. Suction and discharge valves are verified fully open, the piping is unchanged, and discharge head reads the same as at commissioning. What is the best evaluation?

The discharge pressure gauge has drifted over time and should be recalibrated first, after which the drawdown result will likely return to its original value

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The pump is air-bound and only needs its casing vented

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The system head has increased because of changes elsewhere in the plant, and a larger motor must be installed before the pump can deliver its rated flow again

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Worn impeller and wear-ring clearances are allowing internal recirculation inside the pump

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An aerobic digester’s temperature has fallen steadily for two weeks. Air supply and mixing check out normal, volatile reduction is slipping, and the heat exchanger’s outlet temperature difference has narrowed. What is the best evaluation?

The digester blower is undersized for the tank and must be replaced with a larger unit, because the falling temperature shows the biology is no longer receiving enough air

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The temperature probe is the only thing that can produce this pattern

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The digester is being fed far too much volatile solids for its volume, and the excess feed is absorbing all the heat the exchanger can deliver faster than it can be replaced

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The heat exchanger is fouling and transferring less heat, so it is cleaned and its flows verified

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Seeded BOD bottles for a disinfected effluent show depletion in the valid range, but the seed control run beside them shows the seed alone consumed a large share of that oxygen. What must the analyst do before reporting the effluent BOD?

Report the bottle depletion as the effluent BOD without adjustment

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Discard the run, because seeded samples can never be reported

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Add the seed control depletion to each sample bottle depletion

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Correct each result for the oxygen uptake of the seed itself

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For the monthly report, a plant treated 900,000 gallons total, of which 117,000 gallons came from one industrial customer. What percent of the total flow came from that customer?

13%

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7.7%

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87%

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11.7%

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What does a supervisor verify when checking readiness of the chlorine emergency repair kit and breathing equipment stored for a gas leak?

Only that the kit box is present in the chlorine building and its lid is closed

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That the kit is the correct type for the containers in use, its contents are complete and undamaged, and the breathing equipment is inspected and ready for trained responders

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That the kit has been opened recently, because frequent opening proves the crew is familiar with it

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That one kit can serve both the chlorine and sulfur dioxide rooms regardless of container fittings

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Wastewater Treatment Class II Exam Prep FREE Sample Exam — Fixed Set

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