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Human impact on the Environment

Pollution II: Water pollution

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What is water pollution?

The pollution of water in the streams, rivers, lakes, and seas.

Pollutants

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Water pollutants

Agricultural:Manure, fertilizers, pesticides

Domestic:Sewage, detergents, rubbish

Industrial:Cyanides, heavy metals ions

Others:Crude oil and lubricant oil, hot water

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Group discussion

1. Manure

2. Fertilizers

3. Pesticides

4. Sewage

5. Detergents

6. Rubbish

7. Cyanides

8. Heavy metals ions

9. Crude oil

10. Hot water

You have to find out:Where does it from? (Sources)What is its effects to the environment? (Effect)How to minimize the problem? (Solutions)

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Agricultural waste - Manure

Source: Animals faeces from farms

Effects: Increase organic nutrients in water algae and bacteria to grow oxygen content decrease algae die and decomposed by bacteria toxic substances and bad smell producesCause diseases such as dysentery 痢疾

Solutions: Law enforcement to band illegal discharge of animal faecesCollect agricultural waste and treat

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Agricultural waste - Fertilizers

Source: Excess fertilizers leak from the farmland

Effects: Increase inorganic nutrients in water algae oxygen content decrease algae die and decomposed by bacteria toxic substances and bad smell producesCause diseases

Solutions: Avoid using excess fertilizers or using those not easy being dissolved in water to avoid leakage

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Agricultural waste - Pesticides

Source: washed from the farmland

Effects: causes death of animals and plants increase number of bacteria for decomposition toxic substances and bad smell produces

absorbed by animals or plants in the water accumulate in its body passed to another animals when being eaten accumulate in the food chain and attain a higher level in higher trophic level cause death of high predators

Solutions: avoid using man-made pesticides, using natural pesticides to minimize the effects

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Domestic waste – wastes from man

Source: Faeces and urine from man

Effects: Increase organic nutrients in water algae and bacteria to grow oxygen content decrease algae die and decomposed by bacteria toxic substances and bad smell producesCause diseases

Solutions: Law enforcement to band illegal discharge of wastesTreat waste water before discharged

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Domestic waste - Detergents

Source: from domestic washing process

Effects: contains phosphates ions promote algal growth in water oxygen content decrease algae died which promote the bacterial growth for decomposition toxic substances and bad smell produces

Cause diseases

Solutions: treat waste water before discharged

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Domestic waste - Rubbish

Source: dump from ships

Effects: bacteria grow on surface produce bad smell and cause health problems

cause damage to the engine of the ships when passing by

Solutions: Law enforcement for dumping of rubbish into rivers and seas

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Industrial waste - Cyanides

Source: from the industrial waste

Effects: highly toxic, only small amount can cause death of many animals and plants

contaminate drinking water and cause death to human

Solutions: Law enforcement to the industrial waste discharge

Collect industrial waste for chemical treatment before discharge

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Industrial waste – heavy metal ions

Source: from electroplating factories

Effects: Algae absorb heavy metal ions accumulate in algae passes to animals when being eaten accumulate in the food chain and attain a higher level in higher trophic level cause death or problem of high predators, especially human

Solutions: Law enforcement to the industrial waste dischargeCollect industrial waste for chemical treatment before discharge

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Crude oil and lubricant oil

Source: leakage from oil refineries and tankers; and illegal discharge of lubricant oil into river or sea

Effects: spread out in large area prevent oxygen dissolve in water cause death of plants and animals in waterstick onto feathers of water birds make them difficult to fly and cause body heat loss cause death of water birds

Solutions: Law enforcement to avoid illegal discharge of lubricant oil

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Hot water

Source: from cooling facilities of factories and power plant

Effects: Increase water temperature lower solubility of oxygen in water cause death of organisms in water because of suffocation

Solutions: Build the factories or power plant in area that are of less number of species of organisms, or shores with common species only to minimize the effect of biodiversity

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Waste water treatment

Divided into three main process:

Physical process – for large debrisBiological process – for organic mattersChemical process – for inorganic matters

Unfortunately, most of the countries, including HK, only do the first two processes, but not the chemical process. Although the water look clean and clear, is it really clean??????

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Physical process Biological process

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Screening and filteringRemove large debris from sewage

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SedimentationSolid particles are settles down to the bottom

forming sludge.

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FermentationOrganic matters in the sludge were broken dow

n by anaerobic bacteria. Methane gas 沼氣 will be produced burn as fuel. The solid remains will dried and can be used as fertilizers.

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DecompositionOrganic matters in the sewage will be

decomposed by decomposers. The liquid will passed through filter before discharged to remove microorganisms.

Air is pumped into the sewage, supply oxygen to the decomposers