1. Principles of Environmental Engineering and Sustainability
Lecture Nine: Water Resources and Water Pollution
Department of Environmental Engineering

2. OUTLINE Water Water Cycle Watershed Water Resources Management
Dams and Tapping Groundwater
Water Quality
Testing
Sources and terminology
BOD
EUtriphication

3. Water Resources Water Earth’s surface is covered by 71% water
Essential for life – can survive only a few days without water

4. Supply of Water Resources
Small fraction (0.014%) is readily
available for human use

5. Importance of Water Cooking Washing Use large amounts for:
Agriculture
Manufacturing
Mining
Energy production
Waste disposal
Use of freshwater is increasing

6. Properties of Water Composed of 2 Hydrogen and 1 oxygen
Exists as solid, liquid or gas
High heat capacity
Polar
One end has (+) charge, one end has (-) charge
Forms Hydrogen bond between 2 water molecules
H-bonds define water’s physical properties

7. Freshwater Terminology
Surface water
Precipitation that remains on the surface and does not seep into soil
Runoff
Movement of surface water to lakes, rivers, etc.
Watershed (drainage basin)
Land area that delivers water into a stream or river system
Groundwater
Freshwater under the earth’s surface stored in aquifers
Aquifer
Underground caverns and porous layers of sand, gravel and rock in which groundwater is stored

8. Evaporation and transpiration
Water Cycle – continuously collected, purified, recycled and distributed
Evaporation and transpiration
Evaporation
Stream
Infiltration
Water table
Unconfined aquifer
Confined aquifer
Lake
Well requiring a pump
Flowing
artesian well
Runoff
Precipitation
Confined
Recharge Area
Aquifer
Less permeable material
such as clay
Confirming permeable rock layer

9. Watershed
A watershed describes the total area contributing drainage to a stream or river
May be applied to many scales
A large watershed is made up of many small watersheds

10. Chehalis Basin

13. Global Water Problems
Amount of freshwater on planet CAN meet human needs
BUT, it is unevenly distributed and some places lack stable runoff
Problems:
Climate Change
Drinking Water
Population Growth
Sharing Water Resources Among Countries

14. Global Water Problems Water and Climate Change Drinking Water Problems
Climate change affects the type and distribution of precipitation
Potential issues:
Reduced snowfall will impact water resources downstream
Sea level rise will cause saltwater intrusion into drinking water supplies
Drinking Water Problems
Many developing countries have insufficient water to meet drinking and household needs
Population Growth
Increase in population means an increase in freshwater requirements
Limits drinking water available
Limits water available for agriculture (food)

15. Water Management Dams and Reservoirs
Main Goal: Provide sustainable supply of high-quality water
Requires humans to use resource carefully
Dams and Reservoirs
Water Diversion Projects
Desalinization
Dams and Reservoirs
Benefits:
Ensure year-round supply of water with regulated flow
Generate electricity
Provide recreational activities
Disadvantages
Alter the ecosystem
Reduce sediment load

16. Using Dams and Reservoirs to Supply More Water
Large losses
of water through
evaporation
Flooded land destroys forests or cropland and
displaces people
Downstream flooding is reduced
Downstream cropland and
estuaries are deprived of
nutrient-rich silt
Reservoir is useful for recreation and fishing
Can produce cheap electricity (hydropower)
Migration and spawning of some fish are disrupted
Provides water
for year-round
irrigation of
cropland

17. Groundwater Year-round use No evaporation losses Often less expensive
Potential Problems:
Water table lowering – too much use
Depletion – U.S. groundwater being withdrawn at 4X its replacement rate
Saltwater intrusion – near coastal areas
Chemical contamination
Reduced stream flows

18. The Ogallala Aquifer
The Ogallala Aquifer is an example of groundwater mining or depletion.
Water-level change in the High Plains aquifer (the Ogallala aquifer) through 2007, 2005–06, and 2006–07:
U. S. Geological Survey Scientific Investigations Report 2009–5019, 9 p., available at:
FIGURE 8.22 Water-level change in the High Plains aquifer through Source: McGuire, V. L., Water-level changes in the High Plains aquifer, predevelopment to 2007, 2005–06, and 2006–07: U. S. Geological Survey Scientific Investigations Report 2009–5019, 9 p., available at:

19. Desalinization Water Conservation
Removal of salt from ocean or brackish water
Two methods:
Distillation- salt water is evaporated, and water vapor is condensed into freshwater (salt left behind)
Reverse Osmosis- involves forcing salt water through a membrane permeable to water, but not salt
Very expensive
Water Conservation
Reducing Agricultural Water Waste
Agriculture is very inefficient with water
Microirrigation- irrigation that conserves waster by piping to
crops through sealed
systems
Also called drip or
trickle irrigation

20. Water Conservation Water Conservation Reducing Industrial Water Waste
Stricter laws provide incentive to conserve water
Recycling water within the plant
Water scarcity (in addition to stricter pollution control requirements) will encourage further industrial recycling
Potential to conserve water is huge!
Water Conservation
Reducing Municipal Water Waste
Gray Water
Can be used to flush toilets, wash car or water lawn
Water saving household fixtures
Government incentives

21. Conserving at Home Install water-saving shower heads and faucets
Install low-flush toilets
Fix leaky fixtures
Purchase high efficiency appliances
Modify personal habits
Use the dishwasher instead of washing by hand

22. Testing Water Quality Water quality parameters often tested are:
Dissolved oxygen (DO)
Water temperature pH
Total Ammonia Nitrogen
Nitrite/Nitrate
Alkalinity/Hardness
Salinity
Water test kit

23. How water quality values are expressed
Parameter
Value
Dissolved oxygen
mg/L O2
Water temperature
C (Celsius) pH
------
Total ammonia nitrogen
mg/L N
Nitrite
mg/L NO2-
Nitrate
mg/L NO3-
Alkalinity/Hardness
mg/L CaCO3
Salinity (TDS)
g/L salt

24. Types of Water Pollution
Any physical or chemical change in water that adversely affects the health of humans and other organisms
Varies in magnitude by location
Major water pollution issue globally
Lack of disease-free water
Eight categories
Sewage, disease-causing agents, sediment pollution, inorganic plant and algal nutrients, organic compounds, inorganic chemicals, radioactive substances, and thermal pollution

25. Sewage The release of wastewater from drains or sewers
Includes human wastes, soaps, and detergents
Causes 2 serious environmental problems:
Enrichment
Fertilization of a body of water by high levels of plant and algal nutrients (nitrogen and phosphorus)
Increase in Biological Oxygen Demand (BOD)
Amount of oxygen needed by microorganisms to decompose biological wastes
As BOD increases Dissolve Oxygen (DO) decreases

26. Sewage- Eutrophication
Oligotrophic
Unenriched, clear water that supports small populations of aquatic organisms

27. Sewage- Eutrophication
Slow-flowing stream, lake or estuary enriched by inorganic plant and algal nutrients such as phosphorus
Often due to fertilizer or sewage runoff

28. Sediment Pollution Excessive amounts of suspended soil particles
Originates from erosion of agricultural lands, forest soils exposed by logging, degraded stream banks, overgrazed rangelands, strip mines, and construction
Problems
Limits light penetration
Covers aquatic animals and plants
Brings insoluble toxins into waterways

29. Inorganic Plant and Algal Nutrients
Chemicals such as nitrogen and phosphorus that stimulate the growth of plants and algae
Harmful in large concentrations
Sources:
Human and animal wastes, plant residues, atmospheric deposition, and fertilizer runoff
Causes:
Enrichment, bad odors, and a high BOD

30. Organic Compounds Chemicals that contain carbon atoms
Natural examples: sugars, amino acids, and oils
Human-made examples: pesticides, solvents, industrial chemicals, and plastics

31. Inorganic Chemicals
Contaminants that contain elements other than carbon
Examples: acids, salts, and heavy metals
Do not degrade easily
Lead
Found in old paint, industrial pollutants, leaded gasoline
Mercury
Mercury bioaccumulates in the muscles of top predators of the open ocean

32. Radioactive Substances
Contain atoms of unstable isotopes that spontaneously emit radiation
Sources
Mining
Processing radioactive materials
Nuclear power plants
Natural sources
Thermal Pollution
Occurs when heated water produced during industrial processes is released into waterways
Organisms affected
Temperature affects reproductive cycles, digestion rates, and respiration rates
Warm water holds less DO than cold water

33. Water Quality Today Two Types of Water Pollution
-Point Source Pollution
water pollution that can be traced to a specific origin
Discharge via pipes, sewage, and ditches
-Non-point Source Pollution
Pollutants that enter bodies of water over large areas rather than being concentrated at a single point of entry
Diffuse, but its cumulative effect is very large
Ex: runoff from agricultural fields or parking lots

34. Municipal Water Pollution

35. Water Pollution from Agriculture
Industrial Wastes in Water
Different industries generate different pollutants
Food processing plants- high BOD
Paper mills- High BOD and toxic compounds
Many industries recover toxins before they go into the waste stream
Water Pollution from Agriculture
Agriculture is leading source of water pollution in US
Animal wastes and plants residues have high BOD
Chemical pesticides can leach into groundwater
Almost all streams and rivers are polluted with agricultural pesticides

36. Biological Oxygen Demand (BOD)
As micro-organisms decompose (through respiration) organic matter, they use up all the available oxygen.
Biological Oxygen Demand (BOD) Amount of oxygen required to decay a certain amount of organic matter.
If too much organic matter is added, the available oxygen supplies will be used up.
It is most commonly expressed in milligrams of oxygen consumed per liter of sample during 5 days (BOD5) of incubation at 20°C and is often used as a robust surrogate of the degree of organic pollution of water

37. DO Sag Curve

38. Eutrophication
Eutrophic – well-fed, high nutrient (N and P) levels present in a lake or river
Oligotrophic – poorly-fed, low nutrient levels
Eutrophication arises from the oversupply of nutrients, which leads to over growth of plants and algae.
After such organisms die, the bacterial degradation of their biomass consumes the oxygen in the water,
hence increases BOD

39. Groundwater Pollution
Agricultural products
Underground storage tanks
Landfills
Septic tanks
others

40. End of Lecture Four