Water Flashcards
(12 cards)
What is potable water
Water that has been treated or is naturally safe for humans to drink
Is potable water pure
No
How is fresh water treated
-f…: a wire m… screens out large t… eg twigs, and then g…, and sand beds f… out any other s…
-s…: the water is sterilised to k… any harmful b… or microbes, this can be done by b… chlorine g… through it or using u… light
-filtration: a wire mesh screens out large things eg twigs, and then gravel, and sand beds filter out any other solids
-sterilisation: the water is sterilised to kill any harmful bacteria or microbes, this can be done by bubbling chlorine gas through it or using ultraviolet light
What chemical can be added to water supply which is good for teeth
Fluoride
What can distillation be used to do to sea water
Desalinate it
How can you distill water
-test the p… of the water using a pH m…, if the pH is too h… or low you m… it with a t…, use a pH m… rather than an i…
-test the water for s… chloride, to test for s… ions do a f… test on a small s…, if sodium ions are p… the flame will turn y…
-to test for c… ions add a few drops of d… nitric a… followed by s… nitrate solution
-if chloride ions are p… a w… precipitate will form
-to d… the water, pour the s… water into a d… apparatus
-h… the water until it b… leaving s… in the flask, the s… will c… back to water and be c…
-r… the distilled water for s… chloride, and retest the p…
-test the pH of the water using a pH meter, if the pH is too high or low you neutralise it with a titration, use a pH meter rather than an indicator
-test the water for sodium chloride, to test for sodium ions do a flame test on a small sample, if sodium ions are preset the flame will turn yellow
-to test for chloride ions add a few drops of dilute nitric acid followed by silver nitrate solution
-if chloride ions are present a white precipitate will form
-to distil the water, pour the salty water into a distillation apparatus
-heat the water until it boils leaving salt in the flask, the steam will condense back to water and be collected
-retest the distilled water for sodium chloride, and retest the pH
How can sea water be treated using reverse osmosis
-the s… water is passed through a m… that only allows water m… to pass t…
-i… and larger m… are t… by the membrane so are s… from the water
-the salty water is passed through a membrane that only allows water molecules to pass through
-ions and larger molecules are trapped by the membrane so are separated from the water
Disadvantages of distillation and reverse osmosis
-very expensive
-require a lot of energy
-not practical for producing large quantities of fresh water
Examples of things that produce waste water
-d… uses eg having a bath
-a… systems
-s… water has to be t…
-i… processes eg H… process
-domestic uses eg having a bath
-agricultural systems
-sewage water has to be treated
-industrial processes eg Haber process
Stages of sewage treatment
- The sewage is s…, removing l… bits of m…
- It’s allowed to s… in a s… tank and undergoes s…, the h… solids will s… and produce a s…, while the lighter e… floats to the t…
- The e… is removed and t… by biological a… digestion
—>where a… is pumped through the w… to encourage a… bacteria to b… down any organic m… - The s… from the bottom is r… and transferred to large t…, where it gets broken down by a… digestion
—>where the o… matter is broken down releasing m… gas in the process
—>which can be used as an e… source, and the remaining d… waste can be used as a f… - Waste w… containing t… substances have a… stages of treatment eg adding c…, UV r… or using m…
- The sewage is screened, removing large bits of material
- It’s allowed to stand in a settlement tank and undergoes sedimentation, the heavier solids will sink and produce a sludge, while the lighter effluent floats to the top
- The effluent is removed and treated by biological aerobic digestion
—>where air is pumped through the water to encourage aerobic bacteria to break down any organic matter - The sludge from the bottom is removed and transferred to large tanks, where it gets broken down by anaerobic digestion
—>where the organic matter is broken down releasing methane gas in the process
—>which can be used as an energy source, and the remaining digested waste can be used as a fertiliser - Waste water containing toxic substances have additional stages of treatment eg adding chemicals, UV radiation or using membranes
Does sewage treatment require more or less processes than treating fresh water
More
Does sewage treatment use more or less energy than treating saltwater
Less
