Drinking Water Flashcards
(38 cards)
What is the purpose of a drinking water distribution system?
To deliver treated water from a treatment plant to consumers reliably and safely.
What are common materials used in water distribution pipes?
Ductile iron, PVC, HDPE, and steel.
What is water age and why is it important?
Water age is the time water remains in the system; long water age can lead to degradation of quality.
What is a typical residual chlorine concentration in distribution systems?
0.2 to 0.5 mg/L at the farthest point.
What are the main stages in a conventional drinking water treatment plant?
Coagulation, flocculation, sedimentation, filtration, and disinfection.
What is the goal of drinking water treatment?
To produce safe, palatable, and aesthetically acceptable water.
Why is pH control important in water treatment?
To optimize coagulation and prevent corrosion.
What is average daily demand?
The total water use divided by the number of days.
What is maximum day demand?
The highest average daily use over one 24-hour period in a year.
Why is future water demand forecasting important?
To ensure adequate design capacity and infrastructure planning.
What factors affect water demand?
Population growth, climate, industrial activity, and conservation measures.
What is the purpose of water storage facilities?
To balance supply and demand, provide pressure, and support emergencies.
What are the types of water storage?
Ground-level reservoirs, elevated tanks, and standpipes.
How does elevation affect water pressure in storage?
Higher elevation increases water pressure due to gravity.
What is sedimentation in water treatment?
The process of settling solids from water by gravity.
What factors affect sedimentation efficiency?
Particle size, flow velocity, detention time, and basin design.
What is the typical detention time for sedimentation basins?
2 to 4 hours.
What is surface overflow rate?
Flow rate divided by basin surface area; used to evaluate sedimentation performance.
What is coagulation?
The process of adding chemicals to destabilize particles.
What is flocculation?
The gentle mixing that encourages formation of larger flocs from destabilized particles.
What are common coagulants?
Alum (aluminum sulfate), ferric chloride, and polymers.
What affects coagulation efficiency?
pH, alkalinity, mixing intensity, and coagulant dose.
What are common membrane filtration types?
Microfiltration, ultrafiltration, nanofiltration, and reverse osmosis.
What is media filtration?
Water passes through porous media (e.g., sand) to remove particulates.
