Water and Wastewater Treatment Operator Certification Exam Sample Questions, Exams of Nursing

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OIT SAMPLE TEST QUESTIONS AND ANSWERS

What unit is used to measure water pressure - Answers-Kilopascals Any space where hazardous gas can accumulate or an oxygen deficient atmosphere can occur - Answers-confined space 1 kpa raises water - Answers-10.2 cm Unit used to measure the total daily or monthly electrical usage - Answers- Kilowatt hours 4" pipe can carry ________________ of water as a 2" pipe (assuming same water velocity and pressure) - Answers-same volume Grease used to lubricate plant equipment should be - Answers-should be the same grade or exact equivalent as recommended by the equipment manufacturer 2500 L/sec is equal to what in m3/sec - Answers-2. What is the name given to the process used to kill pathogenic organisms in water treatment - Answers-Disinfection OIT not allowed to do - Answers-Be the operator with overall operational responsibility of the system Solution has a ph of 11 most effective way to neutralize - Answers-add an acid Rate of flow (in L/s) in a 300mm diameter pipe with a water velocity of 0.8m/s - Answers-57 L/s Chemical feeder will feed at max rate of 900 kg per day what is it in kg/min

• Answers-0. A treatment plant removes 97.4% BOD from wastewater. If BOD entering is 305 mg/L, what will the BOD in wastewater be leaving - Answers-7.9 mg/L

Example of cross connection - Answers-connection between boiler and domestic water line Most likely cause of noise and vibration in a valve - Answers-Backflow in a pipe Main reason wet wells for pumps pose safety hazard - Answers-subject to collection toxic gases How is water pressurized in a positive displacement pump - Answers-water is pushed by a screw, piston, gear or diaphragm Properties of chlorine - Answers-greenish/yellow gas with penetrating odour, heavier than air "head" in hydraulic systems - Answers-height or energy of water above a specified point Who is primarily responsible for your safety - Answers-you Why is methane gas dangerous - Answers-it is explosive What is BOD - Answers-Biochemical Oxygen Demand Sewage lagoon contains 224,000L of sewage, lagoon is 10 meters long and 14 meters wide, how deep is the sewage in the lagoon - Answers-1.6m What if liquid chlorine, alum, carbon dioxide or sulphuric acid was added to water - Answers-the ph would decrease Operator smells hydrogen sulphide in confined space - Answers-do not enter until no smell and only when all safety equipment is in place Chlorine is sometimes added to water because it is a strong oxidizer, what does this mean - Answers-chlorine will break down the organic material in water What will prevent the backflow of water in a water main or service pipe - Answers-check valve

Primary moving component of a centrifugal pump - Answers-impeller In 8 hours a lift station pumped 2000 L/min and next 16 hours 6500 L/min. If lift station serves 11000 people, what is the daily per capita production of sewage - Answers-773 L/d Primary moving component of a centrifugal pump - Answers-impeller Name of organisms used to indicate bacterial contamination - Answers- pathogens What property must a substance have to be a good coagulant - Answers- produce an insoluble floc What is indicated if the chlorine demand suddenly jumps from 0.9 mg/L in a well supply - Answers-more water is being pumped What is contact time - Answers-amount of time allowed for chlorine to react in water to provide disinfection What method of disinfections are known to produce trihalomethanes - Answers-ultraviolet light Why is alum added to water in the treatment process - Answers-it will help particles in water to combine together To calculate the amount of chemical needed, an operator must know the proper dosage required and the.... - Answers-rate of water flow What causes hardness in water - Answers-dissolved mineral salts Chlorine dosage is 3.8 mg/L, chlorine demand is 4.0 mg/L, what is the chlorine residual - Answers-0 mg/L Why is turbidity controlled - Answers-to remove particles which can shield microorganisms Order of processes in treatment plant - Answers-screens, filters flocculation, coagulation, chlorination

Course of action of e coli is detected in a sample - Answers-notify the ministry of the environment, medical officer of health, increase the chlorine dose and flush the system Firefighters use water causing water pressure to drop, what could it cause - Answers-water hammer due to water surges What is flushing - Answers-removing of deposits in a pipeline by high pressure, high velocity flow of water What is NOT one of the main purposes of distribution storage - Answers-to store a large volume of water for long periods of time Purpose of a thrust block - Answers-prevent the separation of water main pipes at bends When flushing a watermain, operators should ensure that the pressure in nearby areas does not drop below ... - Answers- 350 kpa Increased interior pipe roughness increases or decreases the carrying capacity of the pipe - Answers-decreases What is the purpose for maintaining a chlorine residual in a water distribution system - Answers-to ensure that bacterial/viruses do not reproduce After using a hydrant, the hydrant should be - Answers-closed slowly to reduce surges Which situation will most likely lead to poor drinking water quality in a distribution system - Answers-high flow rate, water containing 0.2 mg/l chlorine residual, corrosion of pipe within the distribution system, routine flushing of the pipes as required Name of valve that connects the customer service line to the municipal water line - Answers-curb stop After watermain installed or repaired and before reconnected to distribution system what is done to ensure customer safety - Answers-watermain should be super chlorinated

If a "boil water order" is given by a health unit in an emergency situation, how should customer disinfect the water - Answers-boil the water vigorously for 5 min Why is chorine residual useful in water systems - Answers-provides disinfecting ability after the chlorine is added What are devices used to measure the flow of water within a pipe called - Answers-meters Term "combined sewers" - Answers-storm water and sewage are collected in the same sewers What is a wet well - Answers-a chamber in a pumping station which collects wastewater Most common cause of sewer corrosion - Answers-hydrogen sulphide What is a "crown" - Answers-the inside top of a sewage pipe Why are gasoline or volatile solvents objectionable in a sewer - Answers- they produce a serious explosion hazard Which is a source of excessively clear water in a collection system - infiltration from a high water table, exfiltration from a high water table, excessive recirculation, inverted siphon - Answers-infiltration from a high water table Not a common method or equipment used to clean sanitary sewers - flushing, power rodding, addition of ammonia, high velocity jet cleaners - Answers-addition of ammonia What happens when a sewer is surcharged - Answers-hydraulically overloading a sewer A disease that can be transmitted through domestic wastewater - Answers- hepatitis Most common pump in pump station - Answers-centrifugal

Why should infiltration of ground water be avoided in collection systems - Answers-it can lead to a hydraulic overload of the sewer or treatment plant Why is a minimum wastewater velocity of 0.6 meters per second necessary in a gravity sewer - Answers-it will ensure that sewage has enough velocity to go up minor increases in sewer elevation The deposition of solids in a sewer line would most likely generate...... - Answers-hydrogen sulphide What may cause odours to escape from collection systems - Answers-low velocity wastewater **What is the main source of lead and copper in drinking water - Answers- corrosion of lead and copper in plumbing materials **what can cause over-heating of mechanical equipment - Answers-over- greasing **a total chlorine dosage of 6.9 mg/L is required for disinfection, if the effluent flow is 11700 m3/d and the hypochlorite used has 65% available chlorine how many kg/d of hypochlorite is required - Answers-124 kg/d **what part of a concrete pipe in a gravity sewer is most vulnerable to corrosion stemming from the effects of septic wastewater - Answers-crown **reviewing all aspects of the wastewater treatment plant to determine what would occur during various types of emergency situations is known as a ........ - Answers-vulnerability assessment