Water Treatment Flashcards
(10 cards)
What are the 2 stages of water treatment?
Filtering
Sterilising
How is water treated to make potable water?
Water is passed through a screen to remove any large objects
Settlement tank settles out sand and soil
Aluminium sulfate and lime is added to clump small particles together so they sink to the bottom of the tank
The water is then passed through a filter of fine sand and gravel to remove any mud or grit particles
Chlorine, UV light or ozone is added to kill bacteria
What is desalination
It is turning seas water into fresh water
What is reverse osmosis and what are some problems?
When water loves from an area of high concentration to a low concentration of water by using pressure to push the water through a membrane but not the salts or other impurities.
It can be expensive
Damage the membrane
Pumps corrode over time
Where does waste water come from and what is its proper name?
Domestic washrooms
Industry
Rainwater from roofs, roads etc
It is called sewage
What are the 4 stages of sewage treatment?
Screening
Primary treatment
Secondary treatment
Final treatment
What is the screening process for sewage?
The sewage passes through a metal grid to remove any large solid objects and grit
What is the primary treatment for sewage?
Solid sediment called sludge settles out as big paddles push it to the middle to be pipe off with the effluent above the sludge flowing to the next stage.
What is the secondary treatment for sewage?
Useful bacteria feed on organic matter and harmful organisms to break them down aerobically
What is the final treatment for sewage?
Useful bacteria settles out as sediment which is recycled to the secondary treatment or to the sludge. Now the water is safe to drink. It is piped back into the river but extra filtering or sterilising can be done if the river has a fragile ecosystem.
