1. Environmental Education
Water Pollution

2. Content Types of Water Pollution Dissolved Oxygen and Oxygen Depletion
Petroleum Pollution
Indicators of Water Pollution
Water Pollution in Hong Kong
Water Quality Control in Hong Kong
Provision of Infrastructure

3. Types of Water Pollution [1]
Oxygen-demanding wastes
Diseases-causing agents
Thermal pollution
Sediments
Plant nutrients
Petroleum hydrocarbons
Inorganic chemicals and minerals
Synthetic organic compounds

4. Types of Water Pollution [2]
Oxygen-demanding wastes
All organic materials and wastes
Sources
Sewage from domestic and animals sources
Industrial wastes from food processing, papermills, tanning operations, meatpacking plants, etc
Decay of dead plant and animals
Broken down or decomposed by bacterial and other biological activity (biodegradation)
It consumes oxygen (oxygen demanding)
It causes oxygen depletion in water

5. Types of Water Pollution [3]
Importance of oxygen
Basic requirement of almost all plant and animal life-forms in water body
Insufficient amount of oxygen to support life and damage the ecosystem

6. Types of Water Pollution [4]
Disease-causing agents
Pathogenic microorganisms
Sources:
Wastes from human and other animals (hosts)
Spreading diseases through drinking water consumption or through other water contact activities
Indicators
Fecal Coliform Count
e.g. E. coli

7. Types of Water Pollution [5]
Thermal Pollution
Discharge of cooling water
Sources:
Industrial and commercial operations
Power Plants
Heating up the aquatic environment
Aquatic organisms may become physiologically stressed or even be killed
Interference of the natural life processes, e.g. reproduction, growth rates, distribution of species
Decreasing dissolved oxygen (DO) in water

8. Types of Water Pollution [6]
Sediments
Release of weathered sediments through runoff to water bodies
Sources:
Clearing and developments adjacent to water bodies
Natural weathering of soils
Sewage discharge
Littering in water bodies
Directly smother and kill aquatic life
Directly destroy habitats and spawning areas
Reduce the sunlight penetrating into water

9. Types of Water Pollution [7]
Plant nutrients
Phosphates, nitrates, potassium, etc.
Sources:
Fertilizers application in farming
Sewage treatment plant effluents
Leading to eutrophication and algal blooming

10. Types of Water Pollution [8]
Petroleum hydrocarbons
Crude oil, petroleum, gasoline, etc.
Sources:
Wastewater discharges, leaching,
Recreational boating,
Underground tank leakage
Underground water supplies, direct smothering, toxic effects, loss of habitat

11. Types of Water Pollution [9]
Inorganic chemicals and minerals
Heavy metal (cadmium, lead, mercury, copper, etc.), Cyanide, ammonia, hydrogen sulfide, etc.
Sources:
Industrial discharges, like eletroplating, bleaching and dyeing, gold milling
Marine sediments
Toxic (direct or long term)
Odour
Disease and Death
Carcinogenic

12. Types of Water Pollution [10]
Synthetic organic compounds
Pesticides, plastics, solvents, detergents, PCBs, paints, pharmaceuticals, etc.
Sources:
discharges of these compounds from domestic, agricultural, industrial and commercial operations, etc.
Resistant to biological breakdown and persist and accumulate in the environment
Directly toxic to aquatic life
Causing odours

13. Dissolved Oxygen and Oxygen Depletion [1]
Processes Affecting Dissolved Oxygen in Water
Photosynthesis
light
6 CO2 + 6 H2O  C6H12O6 + 6 O2
Respiration
C6H12O6 + 6 O2  6 CO2 + 6 H2O + Energy
Re-aeration
Decomposition

14. Dissolved Oxygen and Oxygen Depletion [2]
Factors Affecting Dissolved Oxygen in Water
Temperature
Light
Turbidity
Color
Salinity
Turbulence
Aquatic organisms

15. Dissolved Oxygen and Oxygen Depletion [3]
Oxygen Sag Curve

16. Dissolved Oxygen and Oxygen Depletion [4]
Natural Purification Process

17. Petroleum Pollution
Municipal and industrial wastewater discharges (31.1%)
Tanker operations (22%)
Other marine transportation (12.5%)
Tanker accidents (12.5%)
Atmospheric fallout (9.4%)
Natural seepage and erosion (7.8%)
Refinery wastewater discharges (3.1%)
Offshore oil production (1.6%)

18. Indicators of Water Pollution
Biochemical Oxygen Demand (BOD) Indicators
Amount of oxygen needed by aerobic decomposers to break down the organic materials in a given volume of water at a certain temperature over a specified time period.
Chemical Oxygen Demand (COD)
Amount of oxygen needed in the oxidation of chemicals in a given volume of water at a certain temperature over a specified time period.
Fecal Coliform Count (FCC)
Dissolved Oxygen (DO)
Total Inorganic Nitrogen (TIN)
Living organisms in the water

19. Water Pollution in Hong Kong [1]
Beach Water Quality
Beach Grading System
Situation in Hong Kong
Southern District
Sai Kung District
Islands District
Tuen Mun District
Tsuen Wan District

20. Water Pollution in Hong Kong [2]
River Water Quality
Improved steadily since the late 1980s
Significant increase in dissolved oxygen and decreases in suspended solids, aggregate organics, nutrients and metals
The number of E. coli bacteria in many of the rivers remains fairly high
(Source: EPD website, 16/4/2001)

21. Water Pollution in Hong Kong [3]
Causes
Multiplicity of Sources
Anthropogenic (household, industrial, commercial, farming, construction, etc.)
Natural
Lack of Infrastructure
Treatment facilities
Sewerage provision
Insufficient Control
Illegal connection of wastewater pipes

22. Water Pollution in Hong Kong [4]
Consequences
Economic Loss
Industries (tourism, mariculture), recreational facilities
Ecosystem Disruption
Ocean, rivers, streams
Coral, offshore habitats
Health Impacts
Food Poisoning

23. Water Quality Control in Hong Kong [1]
Legislation
Waste Pollution Control Ordinance (WPCO)
Water Control Zones (WCZs)
Water Quality Objectives (WQOs)
Technical Memorandum (TM)

24. Water Quality Control in Hong Kong [2]
Source: EPD website, 2001

25. Water Quality Control in Hong Kong [3]
Water Quality Objectives
Define
the maximum levels of pollutants which are acceptable
the minimum levels of essential constituents which are required if designated resources and uses are to be maintained in rivers and marine waters
The values of the WQOs vary among WCZs and depend upon
the resource
the use to be protected

26. Provision of Infrastructure [1]
Sewerage Master Plans (SMPs)
Source: EPD website, 2001

27. Treatment and Disposal
Source: EPD website, 2001

28. Provision of Infrastructure [3]
Strategic Sewage Disposal Strategy (SSDS)
Source: EPD website, 2001

29. Provision of Infrastructure [4]
Strategic Sewage Disposal Strategy (SSDS)
Source: EPD website, 2001

30. Discussion
What are the main types of water pollution in Hong Kong and what are the causes?
What is/are your opinion(s) about the pollution control carried out in Hong Kong?
With reference to the locations of beaches/streams, can you explain their differences of water quality?
Can you suggest other methods to improve the water pollution problem in Hong Kong?
According to the data from the EPD, the water quality in Hong Kong is improving, do you agree? Why?

31. Relevant Websites
Environmental Protection Department (EPD) Webpage (
Water Supplies Department (WSD) Webpage (

32. References
Schmitz, R.J., 1995, Introduction to Water Pollution Biology, Gulf Publishing Company, Houston, Texas, USA. ISBN
EPD, 2001 online, EPD Homepage – Water, EPD,