2.3 and 2.4 Water Treatment/Water Issues Flashcards
Name the order of processes the of water treatment
- sedimentation
- filtration
- disinfection
What can be used to improve the taste of water?
Water filters
Why is disinfection important?
It kills microbes in the water
What is often used to kill microbes in drinking water?
Chlorine
What 2 things do water filters usually contain?
- carbon
* an ion exchange resin
Why is the ion exchange resin important in water filters?
Removes some soluble substances and silver or another substance to prevent the growth of bacteria
How can pure water be made?
Distillation
Explain why distillation is not used to treat mains tap water
It requires a large amount of energy to boil the water so would be very expensive to do on a large scale
What must drinking water not contain to be classified as drinking water?
Doesn’t have to be pure but must not contain anything that will harm us
What does sedimentation do for water treatment?
Removes insoluble particles, like twigs and leaves
What does filtration do in water treatment?
Removes smaller particles, like mud and dirt
What does chlorination/disinfection do in the water process?
Adds chlorine to kill bacteria so it is safe for humans
Why do we use distiller water in experiments?
So there are no other ions to interfere with the experiment
Name 2 alternatives for chlorination
- use uv lights
* use ozone instead
Why do some people dislike the idea of chlorination?
It is a risk to their health as too much chlorine is poisonous
What can we buy to remove chlorine before it leaves the tap?
Filters that absorb the chlorine
Name 5 advantages to fluoridation of the water supply
- no harmful effects except fluorosis
- 30% reduction in cavities in teeth
- helps protect teeth of people with bad dental hygiene
- bacteria for tooth decay causes heart disease so fluorine prevents that too
- only added in tiny amounts
Name 5 disadvantages of fluoridation of the water supply
- causes fluorosis (white porous streaks on teeth) which is reflected in your bones
- no significant benefit so why take risks
- ethically wrong to give people treatments they haven’t consented to
- excess fluorine affects brain and causes learning difficulties and Alzheimer’s
- can’t control people’s intakes
What should drinking water contain low levels of?
Dissolved salts and microbes
