Sustainability of Water Flashcards
Why is desalination used?
It is used to provide safe and reliable water to expanding populations, particulaly ones most affected by climate change. It is also drought-proof as the ocean will take forever to run out.
Describe irrigation
Irrigation, which is the artificial application of water to the land or soil, has been used by humans for thousands of years. It is estimated that around 50% of the world’s agricultural land uses some type of irrigation.
Describe drought-resistant crops
GM has been used on wheat to produce crops that are drought resistant. Farmers in drought-affected Kitui, Kenya, saw their yields more than double since they started using drought resistant crops grown from improved (GM) seed varieties. Also look back on your Food notes.
Name 3 modification processes
Conduct a water audit to determine actual levels of use
Reduce water pressure in pipework and flow regulators which reduces water loss when leaks do occur
Reuse and recycle grey (used) water on processes which do not require clean water
Name 5 methods of cleaning water
- Screening, to remove larger pieces of debris from surface water.
- Coagulation and flocculation involves the addition of a coagulant chemical that causes smaller particles to clump together, forming floc.
- Sedimentation, to allow the floc to settle out as sludge.
- Filtration, to remove bacteria, parasites and remaining suspended particles.
- Methods used in developed and developing countries are to be included.
- Disinfection, to kill pathogens. Methods used in developed and developing
countries are to be included
Describe 5 methods used in sewage treatment
- Preliminary treatment — screening to remove bulky solids, and grit removal.
- Primary treatment — sedimentation to remove remaining solids. Produces sludge and liquor; sludge is removed and treated, liquor passes to the next stage.
- Secondary treatment: biological oxidation using micro-organisms and aeration removes dissolved and suspended organic matter. Sludge is removed and treated, liquor passes to the next stage.
- Tertiary treatment: filtration, to remove remaining suspended matter and toxins from the liquor, which is now known as effluent.
- Discharge of effluent to river or sea
