*water Flashcards
Sources of Waste Water
To avoid polluting our environment, we must treat waste water before releasing it into the environment. There are three main sources of waste water:
Agriculture
Nutrient run-off and slurry are two major sources of agricultural waste water.
Similarly to domestic waste water, organic matter and harmful microbes must be removed prior to releasing this water back into freshwater sources.
Industry
The Haber process is an example of an industrial process that produces lots of waste water.
Additional treatment stages are required for industrial waste water as it often contains harmful chemicals.
Domestic
Washing up, using the toilet, and having a shower are all activities which produce waste water.
Treatment removes the organic matter and harmful microbes found in this waste.
What are the two major sources of agricultural waste water?
1
Nutrient run-off
2
Slurry
Sewage Treatment
To avoid polluting our environment, we must treat sewage before releasing it into the environment. The steps in the sewage treatment process are:
Screening
Sewage is examined to remove grit and any large items such as plastic bags.
Sedimentation
This results in the separation of sewage into heavier sludge and lighter effluent.
Sludge vs effluent
The sludge is anaerobically digested by bacteria.
The effluent is aerobically digested by bacteria.
Which of the following does the process of screening remove from sewage?
Grit
why is it important to treat water befor putting it in environment?
To avoid pollution
Metal Ore Extraction
Metal ores are a finite resource and the availability of metal ores is rapidly decreasing. Mining is the traditional method used to extract ores from the ground, but this process causes significant environmental damage:
Pollution
Mining creates a lot of noise and air pollution.
Landscape scars
Large mounds of rock are left behind, scarring the landscape.
Habitat destruction
Habitats are destroyed by mining.
The destruction of habitats threatens biodiversity.
The supply of metal ores is..
finite
decreasing
Properties of Copper
Copper is a useful metal because it has the following properties:
Malleable
Copper is malleable, meaning it can be easily bent into a desired shape.
Unreactive
Copper does not react with water, meaning that it has good longevity (a long useful life).
Good conductor of what two things?
heat and electricity
Copper Overexploitation
Copper-rich ores (materials containing lots of copper) are in short supply because of historical overexploitation.
Consequently, we have had to find new ways to extract copper from low-grade ores and contaminated land.
Copper-rich ores (materials containing lots of copper) are in short supply because of historical overexploitation.
Alternative Methods of Extracting Copper
Phytomining is a technique that allows us to extract copper from contaminated land. A technique called bioleaching has improved our ability to extract copper from low-grade ores (that don’t contain much copper).
Phytomining
Plants growing on contaminated land absorb copper ions as they grow.
These plants are harvested and burned, producing ash that contains high concentrations of copper compounds.
Phytomining
Bioleaching
Bacteria are mixed in with low-grade ores.
The bacteria convert the copper into a solution rich in copper compounds called leachate solution.
A disadvantage of bioleaching is that the process is very slow.
Bioleaching
Bacteria are mixed in with low-grade ores.
The bacteria convert the copper into a solution rich in copper compounds called leachate solution.
A disadvantage of bioleaching is that the process is very slow.
In phytomining, what happens to the plants once they have been harvested?
Burned, ashes collected
Alternative methods of copper extraction
phytomining
bioleaching
Which of the following can copper not be extracted from?
waste water
What sources can copper be extracted from?
1 Copper-rich ores 2 Low-grade ores 3 Contaminated land
What is a disadvantage of bioleaching?
slow
Potable Water
We need to drink water to stay alive. However, water is often found with other substances dissolved in it. These substances can be harmful so we treat water to make it potable (safe for human consumption).
Not chemically pure
If water is potable, it does not mean that it has to be chemically pure (made up solely of H2O molecules).
Reduce concentrations of microbes
To make water potable, we need to drastically reduce the number of microbes found in it.
Reduce concentrations of dissolved minerals and salts
To make water potable, we need to reduce the concentrations of dissolved minerals and salts found in the water.
We do not eradicate the minerals and salts from the water completely.
Sources of Potable Water:
Potable water can be obtained from:
Fresh water
Fresh water only needs filtering and sterilising.
It is the easiest source to treat.
Seawater
Seawater is the most expensive source to treat because of the large amounts of energy needed to desalinate the water.
Waste water
Treatment of waste water involves many steps.
Less energy is used to treat waste water than to desalinate seawater.
Potable Water in Saudi Arabia
There are many methods for producing potable water. In Saudi Arabia, the conditions are very different to the UK and so a different method is used.
Seawater
Rainfall levels are low, and so fresh water supplies can’t be relied upon.
Seawater is used as an alternative to fresh water.
Treating seawater
Seawater must be desalinated (have the salt removed) to make it potable. There are 2 desalination methods:
Distillation: boiling seawater creates steam, which then condenses to give pure water.
Reverse osmosis: seawater is passed through a selective membrane that only allows water molecules through.
Cost of treating seawater
The major disadvantage of both desalination methods is that they need a high amount of energy, making them expensive.
Sources of Potable Water
Potable water can be obtained from:
Fresh water
Fresh water only needs filtering and sterilising.
It is the easiest source to treat.
Seawater
Seawater is the most expensive source to treat because of the large amounts of energy needed to desalinate the water.
Waste water
Treatment of waste water involves many steps.
Less energy is used to treat waste water than to desalinate seawater.
Natural Resources
Natural resources form without human assistance (involvement). They usually come from the Earth’s crust, oceans or atmosphere and are used for energy, building materials and food. We normally split natural resources into 2 categories:
Non-renewable
Non-renewable resources are regenerated at a much slower rate than we use them. Examples include:
Fossil fuels.
Nuclear fuels.
Metal ores.
Renewable
Renewable resources are regenerated at about the same rate as, or faster, than they’re used. Examples include:
Timber.
Fresh water.
Food.
Supplements to Natural Resources
The human population on Earth has increased rapidly in the last 100 years. This has forced us to find ways to supplement the Earth’s natural resources:
Agriculture
Agriculture is the main example of such supplementation.
Natural food products (e.g. beef, maize, wheat etc.) are now available in much larger quantities because of the organisation of agriculture.
Synthetic products
The development of useful synthetic products has reduced our reliance on natural products.
E.g. man-made polymers have gradually replaced rubber in tyres.
