water treatment Flashcards
what is potable water?
water that been treated or is naturally safe for humans to drink. It is NOT pure, pure water only contains H2O molecules. whereas potable water still has many dissolved substances.
PH of salts in potable water?
6.5-8.5
Type of fresh water
Rainwater
when it rains water can collect as ………………………..
surface water from lakes, river
groundwater
source of fresh water depends on..
location.surface water dries up first so in warm areas domestic water is from groundwater
filtation
a wire mesh screens out large twigs and send bed filter out any other solid bits
sterilisation
the water is sterilised to kill any harmful bacteria or microbes through bubbling chlorine gas
in dry countries there is not enough..
surface water,or groundwater and so they must use sea water through deslination to provide potable water.
reverse osmosis is…
when sea water passes through a membrane that only allows water molecules to pass through.ions and larger molecules are trapped by the membrane. so are seperated from water.
potable water source(1)
having a bath, toilet, washing up etc. when you flush this water it goes through sewage treatment plants
potable water source2
agricultural systems from nutrient run off
sewage treatment step 1
the sewage is screened this involves removing large of material. e.g. twigs, plasticbags, grit
sewage treatment step 2
stands in settlement tank an goes through sedimentation the heavier suspended solids sink to the bottom to produce sludge whie the lighter effluent floats to the top
sewage treatment step 3
the effluent then is removed from the settlement tank and treated biological aerobic digestion( with oxygen). this is when air is pumped through the water to encourage aerobic bacteris to break down any organic matter and microbes.
sewage treatment step 4
the sludge from the settlement is then removed and transferred into large tanks, broken down by anarobic bacteria
