Chapter 16The Water Issue• Cells in all living organisms are 60% water• Water has number of useful properties

– Molecules stick together– Great ability to separate other molecules– Heats and cools slower than most substances– Can be used to dissolve transport wastes

• However needs to be clean for us to drink it• 97% of Water is in oceans—saltwater• 3% is Freshwater

– 1.9% in ice and glaciers– 0.5% in groundwater– 0.02% in rivers and lakes– 0.01% in soil

Chapter 16• Potable water—unpolluted freshwater that

is of sufficient quality to drink

• Some areas of world will exhaust water supplies in future

• Water Pollution on a global scale renders 1.4 billion people without access to safe drinking water

• Water Quality remains an issue in US

Chapter 16Hydrologic Cycle

• Major processes are evaporation and condensation.– Evaporation is changing liquid to gas– Condensation is gas to liquid– Evapotranspiration is evaporation of moisture

from leaves after plants have pulled moisture from ground

– Solar Energy drives the process

Chapter 16Human Influences on Cycle• Irrigation/Cooling water from power plants

increase evaporation• Removing vegetation increases runoff and

decreases infiltration– Impervious cover increases this effect

– Flooding increases with imperviousness

– Creeks cease to flow in urban areas

• Overuse of water resources is same as mining if use is greater than recharge/recovery– Surface water and ground water

Chapter 16

• Use versus Consumption of water

• Use (Non-Consumptive)– lake-plant-you-toilet-wwtp-lake– Stays in local water cycle, used but not

consumed

• Consumption– Lake-pump-field-evaporation-condensation – Removed from local cycle– Rain falls elsewhere

Chapter 16• Water Use by Category• Domestic

– 90% provided by municipalities– Water is treated/disinfected– Use for drinking/bathing/washing/toilets/lawns– 70% non-consumptive 30% consumption

• Agriculture– Irrigation for fields 80% of consumption in N. Amer– Number of methods– Can use lots of energy for pumping

• Industry– 90% of water is non-consumptive use– Use-treat-discharge

• Similar quantity but not necessarily quality

Chapter 16

• In Stream Use– Non-Consumptive– Hydroelectric– Recreation– Navigation– May negatively effect waterway because of

changes in direction, time, volume of flow– Cold water releases from dams

Chapter 16• Kinds and Sources of Water Pollution

– Toxics• Kill organisms• Water unfit for consumption• Bio-accumulation

– Organic matter• Broken down by microbes• Use up DO• BOD• Taste and odors

– Pathogens• Disease causing organisms• Various bacteria• others

Chapter 16– Nutrients

• Nitrogen and phosphorus

• Increase growth

• Eutrophication

• DO

– Physical Particles• Sediment

• Destroy habitat

• Water clarity

• Abrasive

• Transport

Chapter 16• How clean is clean?

– Cannot eliminate all pollution– Law of Diminishing Returns?

$$ Cost $$

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Chapter 16Sources of Pollution• Point Sources

– Readily identifiable

– Discharge pipes

• Non-Point Source– Diffuse sources

– Much more difficult to ID and control

• Most point sources are identified and regulated.• Non-Point sources remain a difficult issue to

address

Chapter 16• Domestic Water Pollution

– Storm water

– Industrial waste

– Home and commercial waste

• Agricultural Water Pollution – Crops

– CAFOs

• Industrial Water Pollution– Easy to ID, well regulated, most under permits

– WWTP-- in house or use city’s

– Mining

Chapter 16

• Thermal Water Pollution– Use lake/river/ocean water to cool– Can affect organisms

• Marine Oil Pollution– Exxon Valdez spilled 11 million gallons– Much more is released by less visible sources– 2/3 of releases come from

• Runoff from streets

• Improper disposal

• Routine handling

Chapter 16Waste Water Treatment• Primary

– Physical process

– Remove larger particles with screens

– Smaller particles allowed to settle

– Still lots of organics

• Secondary– Biological process

– Uses water from primary and adds DO and organisms—eat organics and fall out

– Activated sludge

Chapter 16• Sludge Disposal

– Ocean dumping– Land application – Composting– Drying– Incineration– Landfilling

• Disinfection– Chlorination followed by dechlorination– Can also use UV light

Chapter 16

• Tertiary Treatment– Removes dissolved pollutants

– Used for nutrients

– Techniques • Wetlands

• Cropland, golf courses, etc

• Aquatic greenhouses

• In US most WWTP are at least Secondary plants-• Developing Countries?