Water Quality & Treatment Flashcards
6 cards from real ETC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Water Quality & Treatment flashcards as text
Which federal law establishes Maximum Contaminant Levels (MCLs) for drinking water contaminants and is enforced by the EPA?
Answer: Safe Drinking Water Act (SDWA)
The Safe Drinking Water Act (SDWA) authorizes the EPA to set and enforce MCLs and treatment technique requirements for public water systems to protect public health.
In wastewater treatment, what is Biochemical Oxygen Demand (BOD) a measure of?
Answer: The amount of oxygen consumed by microorganisms when decomposing organic matter in water
BOD measures the oxygen consumed by microorganisms as they biologically degrade organic matter in water over a standard 5-day incubation period (BOD5) at 20°C.
What is the primary treatment objective of coagulation and flocculation in a drinking water treatment plant?
Answer: To aggregate suspended particles and colloids into larger settleable masses
Coagulation (chemical destabilization) and flocculation (gentle mixing to form larger aggregates called floc) are the first treatment steps that convert fine suspended particles into settleable masses for removal by sedimentation.
Which water quality parameter, measured in mg/L as CaCO3, indicates the water's ability to resist changes in pH?
Answer: Alkalinity
Alkalinity measures the water's buffering capacity — primarily due to bicarbonate, carbonate, and hydroxide ions — expressed as mg/L CaCO3 equivalent, which resists acidification.
What is the purpose of the National Pollutant Discharge Elimination System (NPDES) permit program under the Clean Water Act?
Answer: To control point source discharges of pollutants into navigable waters of the United States
The NPDES program requires permits for any point source discharge (pipes, outfalls, ditches) of pollutants into waters of the US, setting specific effluent limits and monitoring requirements.
In a biological wastewater treatment system using activated sludge, what is the function of the aeration basin?
Answer: To provide oxygen and contact time for microorganisms to metabolize dissolved organic matter
The aeration basin supplies oxygen to a mixed liquor of wastewater and microorganisms (activated sludge), allowing aerobic bacteria to metabolize dissolved and colloidal organic pollutants.