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Desalination by Mind Map: Desalination

1. Ocean Background

1.1. Can be transformed into freshwater

1.2. Cannot drink saline water

1.3. Ocean water could contain 50 quadrillion tons of TDS

1.4. Water came from inside of Earth

1.5. Got salt from eroding rocks/minerals

1.6. Average ocean salinity is 45%

1.7. Oceans are 97% of world's water

1.8. Seawater has TDS of about 35000mg/L

2. Desalination Background

2.1. Plants being created, research being done

2.2. Can produce 11 billion gallons of water

2.3. Two main types: Distillation, RO

2.4. Helps areas with little freshwater

2.5. Generally has high operation cost

2.6. Where needed, equipment needed is not produced locally

2.7. Lack of freshwater hurts living standards/economy

2.8. After desalination, local authorities sometimes add minerals

2.9. Most desalination plants are: too expensive, make false claims, badly designed, placed incorrectly

2.10. Very energy intensive

2.11. Plants built by private companies

3. RO Info

3.1. Pressure driven

3.2. Most effective with brackish water

3.3. Water pumped into container against membrane

3.4. Water is pushed through by pressure, restraining solids

3.5. Membrane is selectively permeable

3.6. Can also remove heavy metal from water

3.7. Portions of reject water must be removed from time to time to reduce effort needed to filter

3.8. Over time, membrane becomes clogged or "fouled"

3.9. Pre-filters needed to remove larger particles to not damage membrane

3.10. 40% drinking water, 60% reject brine

3.11. Chemicals added after treatment to stabilize water

3.12. High efficency

3.13. High operation cost

3.14. Energy intensive

3.15. Problems with disposal

3.16. Osmosis attempts to equalize substance concentration, reason why dehydration occurs

4. Distillation Info

4.1. Uses evaportation to extract fresh water

4.2. Recondenses vapor into fresh water

4.3. Pressure inside of devices makes it difficult to maintain

4.4. High heat cost

4.5. To save money, plants use heat generated from other sources

4.6. Disposal of leftover brine is difficult

4.7. Uses chemicals that must be handled carefully

4.8. Very high quality water

4.9. Multi-stage flash distillation sends water through chambers, flashing water into vapor

4.9.1. Uses vapor from previous stage to heat water in next stage

4.10. 56% of desalination plants are MSFD

4.11. As water passes through MSFD chambers, water becomes more and more concentrated, more difficult to flash into vapor

5. Other methods

5.1. Nano-filtration is similar to RO

5.1.1. Both use hydrostatic pressure

5.1.2. Both use membrane

5.1.3. Removes TDS

5.1.4. Higher net water recovery than RO

5.2. Clathrate

5.2.1. aggregation of water surrounding a molecule that isn't water, forming an ice crystal

5.2.2. invented in 1960s/70s by U.S Dept Interior

5.2.3. More cost effective than RO

5.2.4. Ice can be scraped off top, creating freshwater

6. Concequences

6.1. High operation cost

6.2. Disposal of reject water is problematic

6.3. RO has delicate membranes

6.4. Distillation has pressure

6.5. Not enough research done on environmental

6.5.1. Plants claim to be doing fine

6.6. Cannot be produced with local materials

6.7. Only economically viable when alternatives are also expensive

6.8. Some plants use wind turbines for power

6.9. RO membranes are not ideal

6.10. Salt forms bonds to water, hard to break

6.11. Sea life can be killed