4.9 Managing pollution of fresh water

Question 1

strategies for improving
water quality

Answer 1

• improved sanitation
• treatment of sewage
• pollution control and legislation

Question 2

Improve sanitation:

Answer 2

separates human excreta from contact with humans, achieved by toilets and latrines

Question 3

Waste can be removed by:

Answer 3

Connection to a system of sewer pipes or sewerage, that collects human faeces, urine and waste water.
Connection to a septic system, which consists of an underground, sealed settling tank.

Question 4

Examples of toilets:

Answer 4

1) Flush toilet
3) Pit latrine
4) Composting toilet:

Question 5

sewage treatment process

Answer 5

• Screening tank: large objects are removed from the waste using a coarse grid.
• Primary treatment, first settling tank: solid organic matter, mainly human waste, settles at the bottom of the tank (sludge), which is treated in a sludge digester.
  Clean water then overflows the sides of the tank and is taken to the next stage.
• Sludge digester: oxygen-free conditions are created that encourage the growth of bacteria which can break down the sludge, releasing methane, that can be burnt.
• Secondary treatment, oxidation: water is pumped into a tank where oxygen is bubbled through it.
  This encourages the growth of bacteria and other microbes that break down organic matter.
• Secondary treatment, second settling tank: water enters, where bacteria settle to the bottom, forming more sludge.
  This cleaner water overflows the sides of the tank as effluent, usually discharged into a river.
• Tertiary treatment: further filtering out of its effluent or its chlorination which produces even cleaner effluent that protects the habitat in which it is released.

Question 6

what other ways are water treated except sewage?

Answer 6

Water is made potable by undergoing coagulation treatment, Chlorination, being filtered and disinfected.

Question 7

process of Chlorination and coagulation treatment

Answer 7

• Coagulation: Particles in the water are stuck together and settle to the bottom of the container.
  Water is then filtered through sand.
• Chlorination: to kill remaining pathogens, chlorine is added as a disinfectant.

Question 8

Pollution control and legislation:

Answer 8

• puts pressure on polluters to find ways to reduce pollutants.
• Industries are required to monitor the pollution they cause and keep it within set level.

Question 9

examples of laws for pollution control

Answer 9

• Fines for exceeding set limits.
• Companies may be prosecuted and in extreme cases, forced to shut down.
• Companies may need government agreement on strategic plans to reduce pollution levels.
• Incentives may be used to encourage companies to take part, such as grants or tax relief, for those that do achieve a reduction in pollution.