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Wastewater Treatment
| Question | Answer |
|---|---|
| A 240gpm mixed media filter operated at a rate of 2gpm/ft2 is backwashed at a rate of 15gpm/ft2. The backwash lasts for 5min. How many gallons of washwater were used: | 9000g |
| A chlorine demand test will show the: | amount of chlorine required to give a desired residual after a given time |
| A horizontal centrifugal pump has rope" packing. When the pump is operating, water slowly drips from the packing gland. This indicates that the: | packing bolts or nuts on the packing gland are properly adjusted |
| A positive displacement sludge pump should never be placed into operation: | with the discharge valve closed |
| A pump runs continuously for 24 hrs at full speed and delivers 288,000 gal. The capacity of the pump is___g/min. | 200 gpm |
| A rotating biological contractor treats a flow of 2.2MGD with a BOD of 110mg/L. The surface area of the media is 550000ft2. What is the organic loading? | 3.7lbs BOD/1000ft2 |
| A settling tank that is 60ft long by 20ft wide and 12ft deep is used to treat a flow of 2.4MGD. What is the detention time? | 1.1hr |
| A single piston reciprocating pump has a 6in diameter piston with a 6in length stroke. If it makes 16 discharge strokes per minute, the pumping rate is____gpm. | 12gpm |
| A valve that allows water to flow in one direction only is a ___ valve. | check |
| Activated sludge generally ____ than raw sludge. | settles more slowly |
| An air–gap device is used to: | prevent contamination of potable water systems |
| An incubator for the BOD test should be controlled at ___ C. | 20 |
| Approximately how many gallons of wastewater would 600ft of 6in pipe hold? | 880g |
| Assuming a constant suction head, the discharge of a centrifugal pump: | decreases with an increase in discharge head |
| Before repairing a pumps electrical circuit, which of the following actions should you take: | disconnect the circuit breaker, place a red tag and lock out |
| Calculate pounds of BOD per day entering the trickling filter. influent wastewater flow is 1.5MGD influent wastewater BOD is 150mg/L There is a 30% reduction in BOD through primary treatment. | 1310lb/day |
| Calculate the weir loading for a primary settling tank that has an outlet weir that is 480ft long and recieves a flow of 5MGD. | 10420gpd/ft |
| Centrifugal pump parts include: | impeller |
| Chemical coagulation doses can be initially estimated by: | jar tests |
| Chloramines are: | combined chlorine |
| Chlorine gas is: | heavier than air |
| Chlorine is primarily used to: | disinfect |
| Chlorine residual may be determined using the reagent: | DPD |
| Common hydraulic detention times for primary clarifiers range from: | 2 to 3 hrs |
| Compute the lagoons detention time: Surface area = 6 acres Avg Depth = 3ft Avg Daily flow (Influent) = 0.25MGD | 24 days |
| Considering the layout and flow diagram for the complete treatment plant, oxidation ditch plants would be most similar to which of the following: | extended aeration |
| Controlling the sludge wasting rate by constant MLSS concentration involves maintaining a certain concentration of: | volatile suspended solids in the reactors (aeration tanks) |
| Decentralized authority describes the process of: | delegating power for decisions to lower levels |
| Disaster planning is: | useful in reducing confusion in the event of a disaster |
| Disaster plans should be developed to deal with which events? | floods |
| Exhaust from a chlorinator room should be taken from: | at floor level |
| Given the following data, calculate the average velocity in the channel. Data: 2.5ft wide channel flow depth is 1.4ft flow rate is 7.2MGD | 3.2ft/sec |
| Granular filter media used to filter wastewater can become coated with a biological slime due to the ___ in the wastewater. | soluble BOD and ammonia |
| How many pounds of chlorine gas are necessary to treat 4MGD of wastewater at a dosage of 2 mg/L: | 67lbs |
| How much does 7.5g of water weigh in lbs: | 62.5 lbs |
| Hydrogen sulfide gives off an odor similar to: | rotten eggs |
| If a fuse continues to blow, an operator should: | inspect the affected equipment to determine the cause |
| If chlorine costs $.21/lb, what is the daily cost to chlorinate 5MGD of wastewater to an initial concentration of 2.6mg/L? | $22.77 |
| If departments are defined based on jobs to be done, this is known as organization by: | function |
| If packing is not maintained properly,: | loss of suction will occur due to air being allowed to enter pump |
| If the bearings on horizontal centrifugal pumps are overlubricated, the most important effect is that the extra lubricant: | may cause overheating and possible failure of the bearings. |
| If the sewer rate is $25 for the first 500ft and all wastewater generated over that amount is billed at the rate of $2.50 per 100ft3, how much would a customer generating 1200ft2 of wastewater be billed? | $42.50 |
| Immediate first aid for burns is to: | flood with cold water |
| In certain situations, a supervisor encourages the employees to make their own decisions. this is considered to be: | highly desirable because it encourages employee growth and frees the supervisor for other tasks |
| In electrical circuits a ____ is used to reduce the voltage where necessary. | transformer |
| In the membrane filter method, the number of coliforms is estimated by the: | number of colonies grown |
| Industrial waste that can be treated by biological processes includes: | paper product waste |
| Information on preventive maintenance procedures, recommended maintenance frequencies and replacement parts for a specific piece of equipment installed at a plant can be obtained from: | manufacturer's operation and maintenance manuals |
| Jar tests may be used to determine the optimum dosage of: | polymer |
| Mechanical ventilation of a lift station is required to: | minimize the presence of harmful gases |
| Of the following, which is most likely cause of electric motor failure: | moisture |
| One method that generally is helpful in encouraging an employee to derive satisfaction from work is giving the employee a(n): | understanding of the relationship of the job to the work of the whole organization |
| One Opening has become available that would be an advancement to any one of three qualified eager employees. What is the best way to handle this situation? | talk to the three as a group, explain the situation, interview them individually, and make your selection, then notify all personnel of the change |
| Steel tanks may be protected from rusting by: | protective coating |
| The addition of chlorine, acid, carbon dioxide, or sulfuric acid will ____ the pH of wastewater. | lower |
| The amount of BOD in sludge entering a digester is an indirect measure of the: | "food" available for bacteria in the digester |
| The ash content remaining at the end of a VSS test is the same as the: | inorganic solids |
| The best approach to resolving complaints involving the operation of a wastewater plant is to: | explain the problem and proposed solution and offer to conduct a tour of the plant for those complaining |
| The gas most commonly associated with septic wastewater is: | hydrogen sulfide |
| The highest concentration of algae growth in a facultative lagoon is usually observed: | near the top |
| The part of the chlorine cylinder designed to melt at 150 to 162F to prevent the cylinder from exploding in the event of a fire is the: | fusible plug |
| The pressure against which a pump must operate is measured in terms of: | psi |
| The rock in a trickling filter is usually placed: | on a tile underdrain system |
| The rotational speed of air–driven rotating biological contactor (RBC) is controlled by: | air volume |
| The span of supervision is the: | number of subordinates for each manager |
| The weight of a chemical compound is 1/8 of the total weight of a chemical solution. the percent, by weight, of the chemical in solution is: | 12.5% |
| Three diseases potentially carried by wastewater are: | typhoid fever, dysentery, cholera |
| Turbidity in wastewater is caused by: | finely divided suspended material |
| Under ice and snow cover, the BOD level in ponds will normally: | increase slowly |
| Valves should be closed slowly to avoid: | water hammer |
| Wastewater is flowing through a 42in diameter pipe at a rate of 6.5ft/sec. What is the flow in ft3/sec? | 62ft3/sec |
| What is the purpose of heating and mixing a primary anaerobic digester: | to increase the digestion rate |
| What mixed liquor characteristics indicate a healthy activated sludge process? | brown color, frothy appearance, and musty odor |
| What organisms will be found in a balanced, good settling mixed liquor: | free swimming and stalked ciliate, some flagellates, and rotifers |
| What should be an operators top priority when making operational decisions? | protecting the public health |
| What term means that the employee reports to one specific supervisor and that the delegation of authority comes from one particular supervisor to the employee? | formal organization |
| What test is typically never performed on wastewater influent: | fecal coliform |
| When an employee breaks the rules and requires discipline, who is responsible for administering it? | supervisor |
| When chlorine reacts with hydrogen sulfide gas, the hydrogen sulfide is: | oxidized and made odorless |
| When high organic waste load reaches an activated sludge plant, the operators first indicator is a decrease in: | DO residual in the aeration tanks |
| When organic wastes are discharged to receiving water, oxygen is depleted by: | bacteria |
| When preparing for a public open house, what following in plant arrangements must be made: | visitor safety is ensured |
| Which activated sludge process could handle shock loads of dairy waste most effectively: | a complete mix system |
| Which gas is produced in anaerobic digesters and can be used as a fuel: | methane |
| Which are normal conditions for a manual control gas chlorination system: | line free of ice |
| Which causes the greatest pipe friction loss: | increasing the velocity of wastewater |
| Which devices is used to measure the flow of wastewater: | parshall flume |
| Which forms of plant life is necessary for the proper functioning of a stabilization or oxidation pond: | algae |
| Which is the most likely cause of rising sludge in clarifiers: | denitrification occurring |
| Which organisms should not be present in a healthy lagoon treatment system: | fungi |
| Which pieces of equipment should be calibrated daily at a treatment plant: | portable dissolved oxygen probe |
| Which process changes is most likely to improve the settling performance of primary settling tanks that are being operated at flows greater than their design flow | install flow equalization basins ahead of primary tanks |
| Which are normal conditions for a manual control gas chlorination system: | increase in organic matter |
| Why are check valves used in conjunction with centrifugal pumps: | to prevent wastewater in the discharge line from flowing back through the pump |
| Word has just come down from the top that operating funds are being cut. How should this be handled? | let the other personnel know what the situation is and ask for their help |
| Your systems billing is based on water usage rate. Calculate the bill to be received by a customer that uses 35000gal/quarter. Data:$1/1000gal for the first 10000gal $.75/1000gal for the next 15000gal $.50/100gal for more than 25000gal | $26.25 |
| Your wastewater treatment plant serves 1100 people. the flow avg is 80,000gpd. the approximate daily flow contribution per person is: | 73gpd/cap |
| When chlorine reacts with hydrogen sulfide gas, the hydrogen sulfide is: | oxidized and made odorless |
| When high organic waste load reaches an activated sludge plant, the operators first indicator is a decrease in: | DO residual in the aeration tanks |
| When organic wastes are discharged to receiving water, oxygen is depleted by: | bacteria |
| When preparing for a public open house, what following in plant arrangements must be made: | visitor safety is ensured |
| Where do the microorganisms in ponds - trickling filters and activated sludge systems come from? | They are naturally present in the influent |
| Which activated sludge process could handle shock loads of dairy waste most effectively: | a complete mix system |
| Which gas is produced in anaerobic digesters and can be used as a fuel: | methane |
| Which are normal conditions for a manual control gas chlorination system: | line free of ice |
| Which causes the greatest pipe friction loss: | increasing the velocity of wastewater |
| Which devices is used to measure the flow of wastewater: | parshall flume |
| Which form of plant life is necessary for the proper functioning of a stabilization or oxidation pond: | algae |
| Which is the most likely cause of rising sludge in clarifiers: | denitrification occuring |
| Which organism should not be present in a healthy lagoon treatment system: | fungi |
| Which piece of equipment should be calibrated daily at a treatment plant: | portable dissolved oxygen probe |
| Which pollutant is most likely to cause an algae bloom in a lake or river? | Phosphorus |
| Which process change is most likely to improve the settling performance of primary settling tanks that are being operated at flows greater than their design flow? | install flow equalization basins ahead of primary tanks |
| Which treatment processes would be considered a physical treatment process? | Grit basin |
| Which treatment processes would be considered biological treatment? | Activated sludge |
| Which technology are you likely to find a WRRF headworks? | Flow measurement |
| Why are check valves used in conjunction with centrifugal pumps: | to prevent wastewater in the discharge line from flowing back through the pump |
| Your wastewater treatment plant serves 1100 people. the flow avg is 80,000gpd. the approximate daily flow contribution per person is: | 73 gpd/cap |
| Which two methods of disinfection are most commonly used in domestic WRRFs? | Chlorine and UV light |
| Screenings and grit are typically: | Sent to a landfill |
| Primary sludge consists of | Unprocessed settleable organic and inorganic solids |
| Secondary sludge consists of | Microorganisms grown during treatment |
| This type of biosolids may be made available for public takeaway. | Class A |
| The vector attraction reduction requirement in the biosolids 503 regulations | Reduces the likelihood that rats and insects |
| Sludge thickening and biosolids dewatering are performed for this reason: | Reduces the total volume of sludge or biosolids |
| Anaerobic digester gas contains approximately: | 65% methane and 35% carbon dioxide |
| This piece of equipment rapidly spins biosolids to remove water. | Centrifuge |
Created by:
chymaiera
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