water treatment Flashcards
where does groundwater come from and what does it contain
rocks that trap water underground which contains ions e.g Mg2+, Ca2+, Na+, K+ which from from minerals in the rock
what does rainwater contain
dissolved gases e.g CO2 and O2
what happens when CO2 dissolves in water
it lowers the pH of it
what pollutants can water contain and examples
man made: pesticides, fertilisers, household + industrial waste
natural pollutants: bacteria + viruses
why is fresh water crucial to humans and why is there a greater demand
drinking, farming and industry and because population is increasing
climate change also increases the risk of _________ which make ________ __________ more likely
droughts, water shortages
3 main stages for treatment of the public water so its safe for drinking
sedimentation, filtration, chlorination
what happens at sedimentation
large soluble particles in the water settle at the bottom of the water tank due to gravity
what happens after sedimentation and explain
filtration - where small insoluble particles are removed by filtering through layers of sand and gravel
what happens at chlorination
chlorine gas is bubbled through to kill harmful bacteria and other microbes
advantage of adding more fluoride ions to water supplies
strong evidence (reliable surveys of school children) that fluoride ions prevent tooth decay by strengthening enamel
disadvantages of adding fluoride ions to water supplies (3)
1) fluorosis
2) bone and stomach cancer
3) infertility
3 ways to reduce water consumption
1) take shorter showers/baths
2) turn off taps when not in use
3) ensure washing machines/dishwashers are full before use
