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Water Treatment OIT Test Questions with 100% Correct Answers | Latest Version 2024/2025 | Expert What units are used to measure water pressure? a) Kilowatts b) Kilopascals c) Horsepower d) Head units - Answer- b) Kilopascals Which of the following is NOT an example of PPE (Personal Protective Equipment)? a) Exhaust fan b) SCBA c) Face shield d) Traffic vest - Answer- a) Exhaust fan Which of the following are operators-in-training NOT allowed to do? a) There are no restrictions on the duties of an operator-in-training b) Any operational duties if not in the presence of another operator c) Anything which could effect the quality of the water/wastewater d) Be the operator with overall operational responsibility of the system - Answer- d) Be the operator with overall operational responsibility of the system Define the term "head" as used in hydraulic systems. a) The block of an internal combustions engine b) The ability of a piston pump to overcome the force of gravity c) The height or energy of water above a specified point d) The distance between the liquid level and the cover of a well - Answer- c) The height or energy of water above a specified point Which of the following statements accurately describes some of the properties of chlorine? a) I a colourless gas which is toxic to plants and animals; is flammable and explosive b) Is a greenish/yellow gas with a penetrating odour; is heavier than air c) Is a yellowish gas with an irritating odour; insoluble in water d) Is lighter than air; soluble in water and forms a salt which is lethal to microorganisms - Answer- b) Is a greenish/yellow gas with a penetrating odour; is heavier than air What happens when two or more different elements combine? a) chemical compound is formed b) atom is created c) molecule is formed d) concentration is created - Answer- a) chemical compound is formed What is the definition of a confined space? a) Any space which is not actively ventilated by an electrical ventilation system b) Any space from which exit by an injured worker is difficult c) Any space where hazardous gas can accumulate or an oxygen deficient atmosphere can occur d) Any space where the distance from floor to ceiling is less than 3 metres - Answer- a) Any space which is not actively ventilated by an electrical ventilation system The flow of electrical current is measured in a) Amperes a) Low organic material content b) High organic material content c) High level of inorganic suspended solids d) Low level of pathogenic bacteria - Answer- b) High organic material content Which of the following statements is the most accurate concerning a "Certificate of Approval" (C of A), issued by the Ministry of Environment? a) The terms and conditions stated in a C of A are legally enforceable b) The terms and conditions stated in a C of A are recommendations on how the facilities should be operated c) A C of A is only required for facilities built before 1965 d) Once a facility has been built the C of A is no longer required and can be discarded - Answer- a) The terms and conditions stated in a C of A are legally enforceable Coagulation is the mixing of coagulants with water to: a) disperse colloidal material b) form floc c) inactivate colloids d) suspend floc - Answer- b) form floc Trihalomethanes are produced when chlorine reacts with: a) inorganic materials b) chlorine dioxide c) organic materials d) ultra violet light - Answer- c) organic materials What is the chlorine residual in water? a) the amount of chlorine applied to the water daily b) low concentrations of chlorine gas c) chlorine salt which is left after water evaporates d) amount of chlorine that remains in water after disinfection - Answer- d) amount of chlorine that remains in water after disinfection The chlorine dosage of a town's water source is 4.0 mg/L. The chlorine demand for the water is 3.7 mg/L. What is the chlorine residual? a) 0 mg/L b) 0.3 mg/L c) 3.7 mg/L d) 4.3 mg/L - Answer- b) 0.3 mg/L Which of the following is the correct order of processes within a cognitional surface water treatment plant? a) screens, coagulation, flocculation, filters, chlorination b) screens, flocculation, coagulation, chlorination, filters c) chlorination, screens, filtration, coagulation, flocculation d) screens, filters, flocculation, coagulation, chlorination - Answer- a) screens, coagulation, flocculation, filters, chlorination What does the term 'contact time' mean? a) it is the amount of time a person is exposed to chlorine b) it is the amount of time allowed for chlorine to react in water to provide disinfection c) it is the amount of time a coagulant is exposed to water before flocculation occurs d) it is the amount of time it takes for chlorine to sterilize water - Answer- b) it is the amount of time allowed for chlorine to react in water to provide disinfection Backflow siphonage is caused by: a) positive pressure in the water main b) unprotected connections c) unprotected openings d) negative pressure in the water main - Answer- d) negative pressure in the water main When flushing a water main, operators should ensure that the pressure in nearby areas does not drop below _______. a) 60 kPa b) 140 kPa c) 350 kPa d) 550 kPa - Answer- b) 140 kPa Which of the following best describes the largest volume of water a distribution system would normally supply during a day? a) minimum demand (L/hour) b) average demand (L/hour) c) peak demand (L/hour) d) average demand per person (L/hour/person) - Answer- c) peak demand (L/hour) Distribution lines are flushed periodically to: d) grit channel, primary sedimentation, secondary sedimentation, aeration tank - Answer- c) grit channel, primary sedimentation, aeration tank, secondary sedimentation Secondary treatment typically removes ______ of the BOD and suspended solids. a) 20-39% b) 40-59% c) 60-79% d) 80-99% - Answer- d) 80-99% Water entering a wastewater treatment plant will pass through a bar screen. The bar screen is designed to remove which of the following items? a) dissolved solids b) grit and sand c) large objects d) nutrients - Answer- c) large objects Define the term 'supernatant' a) a solution which is supersaturated b) a substance used to reduce odour in polluted waters c) the liquid located above a sediment or precipitate d) an operator who is extremely proficient in fulfilling their duties - Answer- c) the liquid located above a sediment or precipitate A __________ is used to move wastewater from a wastewater lift station to an elevated gravity sewer: a) sewer lateral b) force main c) sanitary trunk main d) transmission main - Answer- b) force main What happens when a sewer is surcharged? a) infiltration of ground water into sewers b) flushing a sewer with clean water to clean debris away c) hydraulically overloading a sewer d) taxing a customer's water bill to pay for collection devices - Answer- c) hydraulically overloading a sewer Which of the following infectious diseases can be transmitted through domestic wastewater? a) hepatitis b) giardiasis c) cryptosporidiosis d) all of the above - Answer- d) all of the above What is meant by the term "combined sewers"? a) industrial sewage and domestic sewage are collected in the same sewers b) stormwater and sewage are collected in the same sewers c) the main sewer line which takes all of a city's sewage to the treatment plant d) a sewer which contains both gravity sewers and force mains - Answer- b) stormwater and sewage are collected in the same sewers Why is hydrogen sulphide gas a problem in sewers? a) results in an increase in rodent populations b) the gas can block the flow of sewage c) since it is odourless, workers will not know when they are exposed d) leads to corrosion of certain types of sewers - Answer- d) leads to corrosion of certain types of sewers Why is a minimum wastewater velocity of 0.6 m (2.0 feet) per second necessary in a gravity sewer? a) it will ensure that sewage has enough velocity to go up minor increases in sewer elevation b) it will prevent the growth of roots in sewers c) it will prevent the erosion of the bottom of the sewer d) it will prevent the build up of solids in the sewer - Answer- d) it will prevent the build up of solids in the sewer Which of the following is a source of excessively clear water in a collection system? a) infiltration from a high water table b) exfiltration from a high water table c) excessive recirculation d) inverted siphon - Answer- a) infiltration from a high water table Who is primary responsible for your safety? a) you b) employer c) MOE d) government - Answer- a) you