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22 Cards in this Set
- Front
- Back
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What is a sanitary sewer
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A pipe or conduit (sewer) intended to carry wastewater or waterborne wastes from homes, businesses, and industries to the treatment works
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Incineration or burial of skimmings from the clarifiers will prevent treatment plant operational problems
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True
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Algae in ponds produce oxygen for the other organisms to use
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True
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When are pump stations installed?
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When low areas of land must be sewered or where pipe depth under the ground surface becomes excessive
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How is oxygen provided for the organisms living in the biological slime that grows on the RBC (rotating biological contactor) media?
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The atmosphere surrounding the media
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What are the two major types of bacteria present in a digester?
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Acid formers and gas formers
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Why must the effluent from plants in some areas be dechlorinated or detoxified before discharge to receiving waters?
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To protect aquatic life
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What is disinfection?
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A process designed to kill or inactivate pathogenic organisms
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How can fluctuating flows from a large pump station be reduced
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By using variable speed pumps or short pumping cycles
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What is the purpose of flow measuring devices
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To measure and record the flow rates and volumes of the wastewater treated by the plant
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What is the purpose of pre-aeration?
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To freshen the wastewater and to help remove oils and greases
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Why is treated wastewater disinfected before it is discharged to receiving waters?
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To remove settleable and floatable materials
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Why are debris and trash usually removed from wastewater by a bar screen?
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To protect equipment and reduce any interference with in-plant flow
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Why are sewer pipes laid at a slope steep enough to maintain a wastewater flow of two feet per second
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To prevent grit from settling in the pipes
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Why should grit be removed early in the plant treatment process
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Because grit is abrasive and will rapidly wear out pumps and other equipment
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The exact amount of BOD removal in a clarifier depends on which factor?
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The amount of BOD contained in the settled material
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What happens when the clear surface water of the primary tank flows over the effluent weir at a high velocity?
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Particles settling to the bottom or those already on the bottom may be picked up and carried from the tank
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What is the purpose of disinfection?
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To destroy pathogenic microorganisms and thus prevent the spread of waterborne diseases
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What is the purpose of disinfection?
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To destroy pathogenic microorganisms and thus prevent the spread of waterborne diseases
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What is chlorine demand?
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Difference between the amount of chlorine added to wastewater and the amount of residual chlorine remaining after a given contact time
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Where is the most effective place for chlorine application for disinfection?
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After treatment and in a well-clarified effluent
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What is breakpoint chlorination?
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The addition of chlorine to wastewater until the chlorine demand has been satisfied
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