PRINCIPLES OF ENVIRONMENTAL ENGINEERING AND SUSTAINABILITY LECTURE NINE

PRINCIPLES OF ENVIRONMENTAL ENGINEERING AND SUSTAINABILITY LECTURE NINE: WATER RESOURCES AND WATER POLLUTION DEPARTMENT OF ENVIRONMENTAL ENGINEERING

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

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

Supply of Water Resources Small fraction (0. 014%) is readily available for human use 4

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

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 6

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 7

WATER CYCLE – CONTINUOUSLY COLLECTED, PURIFIED, RECYCLED AND DISTRIBUTED Flowing artesian well Precipitation Well requiring a pump Evaporation and transpiration Evaporation Confined Recharge Area Runoff Aquifer Infiltration Stream Water table Infiltration Lake Unconfined aquifer Less permeable material such as clay Confined aquifer Confirming permeable rock layer 8

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 9

Chehalis Basin 10

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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 13

Global Water Problems • Water and Climate Change • 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) 14

Water Management • 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 15

USING DAMS AND RESERVOIRS TO SUPPLY MORE WATER Large losses of water through evaporation Flooded land destroys forests or cropland displaces people Downstream cropland estuaries are deprived of nutrient-rich silt Downstream flooding is reduced 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 16

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 4 X its replacement rate • Saltwater intrusion – near coastal areas • Chemical contamination • Reduced stream flows 17

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: http: //pubs. usgs. gov/sir/2009/5019/. 18

Desalinization • 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 19

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 20

Conserving at Home üInstall water-saving shower heads and faucets üInstall low-flush toilets üFix leaky fixtures üPurchase high efficiency appliances üModify personal habits üUse the dishwasher instead of washing by hand 21

TESTING WATER QUALITY Water quality parameters often tested are: üDissolved oxygen (DO) üWater temperature üp. H üTotal Ammonia Nitrogen üNitrite/Nitrate üAlkalinity/Hardness üSalinity Water test kit 22

HOW WATER QUALITY VALUES ARE EXPRESSED Parameter Value Dissolved oxygen Water temperature p. H mg/L O 2 C (Celsius) ------ Total ammonia nitrogen mg/L N Nitrite mg/L NO 2 - Nitrate mg/L NO 3 - Alkalinity/Hardness Salinity (TDS) mg/L Ca. CO 3 g/L salt 23

Types of Water Pollution • 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 24

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 25

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

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

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 28

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 29

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

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 bioaccumulates in the muscles of top predators of the open ocean 31

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 32

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 33

Municipal Water Pollution 34

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 35

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 (BOD 5) of incubation at 20°C and is often used as a robust surrogate of the degree of organic pollution of water 36

DO SAG CURVE 37

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 38

GROUNDWATER POLLUTION • Agricultural products • Underground storage tanks • Landfills • Septic tanks • others 39

END OF LECTURE FOUR