Flashcards
Water treatment
Flashcards do conjunto (15)
- 1Aims of water treatmentAbstract and treat water to potable quality.
- 2Quality of water from different sources-Rain water: reasonably clean, poss contamination from where its collected
-River water: poss high turbidity, poss contamination from pesticide and fertilizer runoff
-Reservoir water: sim to river ut storage reduces turbidity
-Groundwater: naturally filtered, high mineral content
-Seawater: high salt content - 3Water treatment processesScreening
Aeration
Sedimentation/filtration
Coagulation/flocculation
Clarification
Activated carbon filtration
Sterilisation
Fluoridation
Desalination
Storage of treated water - 4Water treatment processes: ScreeningMetal grids trap paper, plastics and other large objects to remove large solids.
- 5Water treatment processes: AerationBubbles of air or water sprays used to aerate water and ensure a high dissolved oxygen level. Those that are anaerobic may contain hydrogen sulfide which can make water smell. These are converted into insoluble so they can be filtered and removed.
- 6Water treatment processes: Sedimentation/ FiltrationWater allowed to remain static to let suspended solids, e.g. silt to settle. Filters used such as sand which traps any remaining suspended solids and bacteria.
- 7Water treatment processes: Coagulation/ flocculationClay particles don't settle in the sedimentation lagoons as the charges repel each other. These are neutralized by adding aluminum sulfate oir polyelectrolytes. This allows them to stick together.
- 8Water treatment processes: ClarificationIn the clarifier tank the clay particles that have coagulated sink in the still water.
- 9Water treatment processes: Activated carbon filtrationParticles of activated carbon are used to remove organic chemicals such as pesticides which adsorb onto the carbon particles. Caron has a large surface area.
- 10Water treatment processes: SterilisationChlorine, Ozone or UV is added to kill pathogens. Chlorine most common but if the water's from epaty sources ozone or UV should be used as the organic matter may react with the chlorine and produce toxic substances. Sterilisation with chlorine and make the water too acidic so the pH is adjusted by adding crushed lime.
- 11Water treatment processes: FluoridationFluorides added to reduce tooth decay in some areas.
- 12Water treatment processes: ION EXCHANGEToxic ions removed by ion exchange resins. Also used to remove calcium and magnesium ions to produce soft water.
- 13Water treatment processes: DesalinationAlso known as reverse osmosis. High salt content of seawater means not potable. Water filtered at very high pressure through partially permeable membranes and the freshwater that is collected is half the original volume. The salt molecules are too large to pass through.
- 14Water treatment processes: DistillationWater is boiled by heating and reducing the pressure. The steam produced is condensed and collected.
- 15Water treatment processes: Storage of treated waterPotable water is stored in a covered reservoir so it can't be contaminated.
Informações
- Descrição
- A level Environmental Studies FlashCards sobre Water treatment, criado por Mollie Munday em 29-01-2019.
- Criado por
- Mollie Munday
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