Chapter 21

Chapter 21Chapter 21

Water PollutionWater Pollution

Using Nature to Purify SewageUsing Nature to Purify Sewage

Ecological wastewater Ecological wastewater purification by a purification by a living living machinemachine.. Uses the sun and a series Uses the sun and a series

of tanks containing plants, of tanks containing plants, snails, zooplankton, snails, zooplankton, crayfish, and fish (that crayfish, and fish (that can be eaten or sold for can be eaten or sold for bait).bait).

WATER POLLUTION: SOURCES, WATER POLLUTION: SOURCES, TYPES, AND EFFECTSTYPES, AND EFFECTS

Water pollutionWater pollution is any chemical, biological, is any chemical, biological, or physical change in water quality that has a or physical change in water quality that has a harmful effect on living organisms or makes harmful effect on living organisms or makes water unsuitable for desired uses.water unsuitable for desired uses. Point sourcePoint source: specific location (drain pipes, : specific location (drain pipes,

ditches, sewer lines).ditches, sewer lines). Nonpoint sourceNonpoint source: cannot be traced to a single : cannot be traced to a single

site of discharge (atmospheric deposition, site of discharge (atmospheric deposition, agricultural / industrial / residential runoff) agricultural / industrial / residential runoff)

Major Water Pollutants Major Water Pollutants and Their Effectsand Their Effects


A fecal coliform A fecal coliform bacteria test is used bacteria test is used to indicate the likely to indicate the likely presence of presence of disease-causing disease-causing bacteria in water.bacteria in water.


Water quality and dissolved oxygen (DO) Water quality and dissolved oxygen (DO) content in parts per million (ppm) at 20content in parts per million (ppm) at 20°C.°C. Only a few fish species can survive in water less Only a few fish species can survive in water less

than 4ppm at than 4ppm at 2020°C.°C.

WaterQuality

Below 4

Below 4.5

DO (ppm) at 20°C

4.5–6.7

6.7–8

8–9

Gravelypolluted

Heavilypolluted

Moderatelypolluted

Slightlypolluted

Good

POLLUTION OF FRESHWATER POLLUTION OF FRESHWATER STREAMSSTREAMS

Flowing streams can recover from a Flowing streams can recover from a moderate level of degradable water moderate level of degradable water pollutants if they are not overloaded and their pollutants if they are not overloaded and their flows are not reduced.flows are not reduced. In a flowing stream, the breakdown of degradable In a flowing stream, the breakdown of degradable

wastes by bacteria depletes DO and creates and wastes by bacteria depletes DO and creates and oxygen sag curveoxygen sag curve..• This reduces or eliminates populations of organisms This reduces or eliminates populations of organisms

with high oxygen requirements.with high oxygen requirements.

Water Pollution Problems in StreamsWater Pollution Problems in Streams

Dilution and decay of degradable, oxygen-Dilution and decay of degradable, oxygen-demanding wastes and heat in a stream.demanding wastes and heat in a stream.

8 ppm

Biologicaloxygendemand

Dissolvedoxygen(ppm)

Types oforganisms

8 ppm

Recovery

ZoneSeptic ZoneDecomposition

ZoneClean Zone

Fish absent,fungi, sludgeworms,bacteria

(anaerobic)

Trash fish(carp, gar,leeches)

Clean Normal clean

water organisms

(Trout, perch, bass,

mayfly, stonefly)

Normal clean water

organisms

(Trout, perch, bass,

mayfly, stonefly)

Clean Zone

Trash fish(carp, gar,leeches)

POLLUTION OF FRESHWATER POLLUTION OF FRESHWATER STREAMSSTREAMS

Most developed countries have sharply Most developed countries have sharply reduced point-source pollution but toxic reduced point-source pollution but toxic chemicals and pollution from nonpoint chemicals and pollution from nonpoint sources are still a problem.sources are still a problem.

Stream pollution from discharges of Stream pollution from discharges of untreated sewage and industrial wastes is a untreated sewage and industrial wastes is a major problem in developing countries.major problem in developing countries.

Animation: Stream PollutionAnimation: Stream Pollution

PLAYANIMATION

Global Outlook: Stream Pollution in Global Outlook: Stream Pollution in Developing CountriesDeveloping Countries

Water in many of Water in many of central China's rivers central China's rivers are greenish black are greenish black from uncontrolled from uncontrolled pollution by pollution by thousands of thousands of factories.factories.

Case Study: India’s Ganges River: Case Study: India’s Ganges River: Religion, Poverty, and HealthReligion, Poverty, and Health

Religious beliefs, cultural traditions, poverty, Religious beliefs, cultural traditions, poverty, and a large population interact to cause and a large population interact to cause severe pollution of the Ganges River in India.severe pollution of the Ganges River in India. Very little of the sewage is treated.Very little of the sewage is treated. Hindu believe in cremating the dead to free the Hindu believe in cremating the dead to free the

soul and throwing the ashes in the holy Ganges.soul and throwing the ashes in the holy Ganges.• Some are too poor to afford the wood to fully cremate.Some are too poor to afford the wood to fully cremate.• Decomposing bodies promote disease and depletes Decomposing bodies promote disease and depletes

DO.DO.

Case Study: India’s Ganges River: Case Study: India’s Ganges River: Religion, Poverty, and HealthReligion, Poverty, and Health

Daily, more than 1 Daily, more than 1 million Hindus in million Hindus in India bathe, drink India bathe, drink from, or carry out from, or carry out religious ceremonies religious ceremonies in the highly polluted in the highly polluted Ganges River.Ganges River.

POLLUTION OF POLLUTION OF FRESHWATER LAKESFRESHWATER LAKES

Dilution of pollutants in lakes is less effective Dilution of pollutants in lakes is less effective than in most streams because most lake than in most streams because most lake water is not mixed well and has little flow.water is not mixed well and has little flow. Lakes and reservoirs are often stratified and Lakes and reservoirs are often stratified and

undergo little mixing.undergo little mixing. Low flow makes them susceptible to runoff.Low flow makes them susceptible to runoff.

Various human activities can overload lakes Various human activities can overload lakes with plant nutrients, which decrease DO and with plant nutrients, which decrease DO and kill some aquatic species.kill some aquatic species.

Cultural EutrophicationCultural Eutrophication

EutrophicationEutrophication: the natural nutrient : the natural nutrient enrichment of a shallow lake, estuary or slow enrichment of a shallow lake, estuary or slow moving stream, mostly from runoff of plant moving stream, mostly from runoff of plant nutrients from the surrounding land.nutrients from the surrounding land.

Cultural eutrophicationCultural eutrophication: human activities : human activities accelerate the input of plant nutrients (mostly accelerate the input of plant nutrients (mostly nitrate- and phosphate-containing effluents) nitrate- and phosphate-containing effluents) to a lake.to a lake. 85% of large lakes near major population centers 85% of large lakes near major population centers

in the U.S. have some degree of cultural in the U.S. have some degree of cultural eutrophication.eutrophication.

POLLUTION OF GROUNDWATERPOLLUTION OF GROUNDWATER

Groundwater can become contaminated with Groundwater can become contaminated with a variety of chemicals because it cannot a variety of chemicals because it cannot effectively cleanse itself and dilute and effectively cleanse itself and dilute and disperse pollutants.disperse pollutants. The drinking water for about half of the U.S. The drinking water for about half of the U.S.

population and 95% of those in rural areas population and 95% of those in rural areas comes from groundwater.comes from groundwater.

Coal strip mine runoff

Polluted air

Deicing road salt

Pesticidesand fertilizers

Hazardous waste

injection well

Pumping well

Gasoline station

Water pumping well

LandfillSewer

Buried gasoline and solvent tanks

Cesspool, septic tank

Groundwater flow

Confined aquifer

Confined freshwater aquifer

Unconfined freshwater aquifer

Accidentalspills

Waste lagoonLeakage from faulty casing

Discharge


It can take hundreds to thousand of years for It can take hundreds to thousand of years for contaminated groundwater to cleanse itself of contaminated groundwater to cleanse itself of degradable wastesdegradable wastes.. Nondegradable wastesNondegradable wastes (toxic lead, arsenic, (toxic lead, arsenic,

flouride) are there permanently.flouride) are there permanently. Slowly degradable wastesSlowly degradable wastes (such as DDT) are (such as DDT) are

there for decades.there for decades.

Aquifer

Water well

Migrating vapor phase

Contaminant plume moveswith the groundwater

Free gasolinedissolves ingroundwater(dissolved phase)

Groundwaterflow

Watertable

Gasolineleakage plume(liquid phase)

Leakingtank

Bedrock


Leaks from a number of sources have Leaks from a number of sources have contaminated groundwater in parts of the contaminated groundwater in parts of the world.world. According the the EPA, one or more organic According the the EPA, one or more organic

chemicals contaminate about 45% of chemicals contaminate about 45% of municipalmunicipal groundwater supplies.groundwater supplies.

By 2003, the EPA had completed the cleanup of By 2003, the EPA had completed the cleanup of 297,000 of 436,000 underground tanks leaking 297,000 of 436,000 underground tanks leaking gasoline, diesel fuel, home heating oil, or toxic gasoline, diesel fuel, home heating oil, or toxic solvents.solvents.

Case Study: Arsenic in Groundwater - Case Study: Arsenic in Groundwater - a Natural Threata Natural Threat

Toxic Arsenic (Toxic Arsenic (AsAs) can naturally occur at high ) can naturally occur at high levels in soil and rocks.levels in soil and rocks.

Drilling into aquifers can release Drilling into aquifers can release AsAs into into drinking water supplies.drinking water supplies.

According to WHO, more than 112 million According to WHO, more than 112 million people are drinking water with people are drinking water with AsAs levels 5- levels 5-100 times the 10 ppb standard.100 times the 10 ppb standard. Mostly in Bangladesh, China, and West Bengal, Mostly in Bangladesh, China, and West Bengal,

India.India.

Solutions

Groundwater Pollution

CleanupPrevention

Find substitutes for toxic chemicals

Install monitoring wells near landfills and underground tanksRequire leak detectors on underground tanks

Ban hazardous waste disposal in landfills and injection wells

Store harmful liquids in aboveground tanks with leak detection and collection systems

Pump to surface, clean, and return to aquifer (very expensive)

Pump nanoparticles of inorganic compounds to remove pollutants (may be the cheapest, easiest, and most effective method but is still being developed)

Keep toxic chemicals out of the environment

Inject microorganisms to clean up contamination (less expensive but still costly)

OCEAN POLLUTIONOCEAN POLLUTION

Oceans, if they are not overloaded, can Oceans, if they are not overloaded, can disperse and break down large quantities of disperse and break down large quantities of degradable pollutants.degradable pollutants.

Pollution of coastal waters near heavily Pollution of coastal waters near heavily populated areas is a serious problem.populated areas is a serious problem. About 40% of the world’s population lives near on About 40% of the world’s population lives near on

or near the coast.or near the coast. The EPA has classified 4 of 5 estuaries as The EPA has classified 4 of 5 estuaries as

threatened or impaired.threatened or impaired.

Fig. 21-10, p. 505

Healthy zoneClear, oxygen-richwaters promote growthof plankton and sea grasses,and support fish.

Oxygen-depleted zoneSedimentation and algaeovergrowth reduce sunlight,kill beneficial sea grasses, useup oxygen, and degrade habitat.

Red tidesExcess nitrogen causesexplosive growth of toxicmicroscopic algae,poisoning fish andmarine mammals.

FarmsRunoff of pesticides, manure, and fertilizers adds toxins and excess nitrogen and phosphorus.

Toxic sedimentsChemicals and toxic metals contaminate shellfish beds, kill spawning fish, andaccumulate in the tissues of bottom feeders.

Construction sitesSediments are washed intowaterways, choking fish and plants, clouding waters, and blocking sunlight.

Urban sprawlBacteria and viruses fromsewers and septic tanks contaminate shellfish beds

Oxygen-depletedzone

Closedbeach

CitiesToxic metals and oil from streets and parking lots pollute waters;

IndustryNitrogen oxidesfrom autos andsmokestacks,toxic chemicals,and heavy metals in effluents flow into bays and estuaries.

Closedshellfish beds

OCEAN POLLUTIONOCEAN POLLUTION

Harmful algal blooms (HAB) are caused by Harmful algal blooms (HAB) are caused by explosive growth of harmful algae from explosive growth of harmful algae from sewage and agricultural runoff.sewage and agricultural runoff.

Oxygen Depletion in the Northern Oxygen Depletion in the Northern Gulf of MexicoGulf of Mexico

A large zone of A large zone of oxygen-oxygen-depleted water depleted water forms for half of forms for half of the year in the the year in the Gulf of Mexico Gulf of Mexico as a result of as a result of HAB.HAB.

Fig. 21-A, p. 507

Mississippi River

MississippiRiver Basin

Gulf of Mexico

Ohio River

Mississippi River

Missouri River

TX

MSLA

Depleted oxygen

LOUISIANA

Gulf of Mexico

Case Study: The Chesapeake Bay – Case Study: The Chesapeake Bay – An Estuary in TroubleAn Estuary in Trouble

Pollutants from six Pollutants from six states contaminate states contaminate the shallow the shallow estuary, but estuary, but cooperative efforts cooperative efforts have reduced have reduced some of the some of the pollution inputs.pollution inputs.

OCEAN OIL POLLUTIONOCEAN OIL POLLUTION

Most ocean oil pollution comes from human Most ocean oil pollution comes from human activities on activities on landland.. Studies have shown it takes about 3 years for Studies have shown it takes about 3 years for

many forms of marine life to recover from large many forms of marine life to recover from large amounts of amounts of crude oilcrude oil (oil directly from ground).(oil directly from ground).

Recovery from exposure to Recovery from exposure to refined oilrefined oil (fuel oil, (fuel oil, gasoline, etc…) can take 10-20 years for marine gasoline, etc…) can take 10-20 years for marine life to recover.life to recover.

OCEAN OIL POLLUTIONOCEAN OIL POLLUTION

Tanker accidents Tanker accidents and blowouts at and blowouts at offshore drilling offshore drilling rigs can be rigs can be extremely extremely devastating to devastating to marine life marine life (especially diving (especially diving birds, left).birds, left).

Reduce input of toxic pollutants

Solutions

Coastal Water Pollution

Prevention Cleanup

Use wetlands, solar-aquatic, or other methods to treat sewage

Require at least secondary treatment of coastal sewage

Sprinkle nanoparticles over an oil or sewage spill to dissolve the oil or sewage without creating harmful by-products(still under development)

Improve oil-spill cleanup capabilities

Recycle used oil

Regulate coastal development

Protect sensitive areas from development, oil drilling, and oil shipping

Ban ocean dumping of sludge and hazardous dredged material

Ban dumping of wastes and sewage by maritime and cruise ships in coastal waters

Separate sewage and storm lines

Require double hulls for oil tankers

PREVENTING AND REDUCING PREVENTING AND REDUCING SURFACE WATER POLLUTIONSURFACE WATER POLLUTION

The key to reducing nonpoint pollution – most The key to reducing nonpoint pollution – most of it from agriculture – is to prevent it from of it from agriculture – is to prevent it from reaching bodies of water.reaching bodies of water. Farmers can reduce runoff by planting buffers Farmers can reduce runoff by planting buffers

and locating feedlots away from steeply sloped and locating feedlots away from steeply sloped land, flood zones, and surface water.land, flood zones, and surface water.

PREVENTING AND REDUCING PREVENTING AND REDUCING SURFACE WATER POLLUTIONSURFACE WATER POLLUTION

Most developed countries use laws to set Most developed countries use laws to set water pollution standards, but such laws water pollution standards, but such laws rarely exist in developing countries.rarely exist in developing countries. The U.S. Clean Water Act sets standards fro The U.S. Clean Water Act sets standards fro

allowed levels of key water pollutants and allowed levels of key water pollutants and requires polluters to get permits.requires polluters to get permits.

EPA is experimenting with a EPA is experimenting with a discharge trading discharge trading policypolicy similar to that for air pollution control. similar to that for air pollution control.

Reducing Water Pollution through Reducing Water Pollution through Sewage TreatmentSewage Treatment

Septic tanks and various levels of sewage Septic tanks and various levels of sewage treatment can reduce point-source water treatment can reduce point-source water pollution.pollution.

Distribution box

Manhole cover(for cleanout)

Vent pipePerforated pipe

Drain field(gravel orcrushed stone)

Septic tank

Sludge

Wastewater

Gas

Scum


Raw sewage reaching a municipal sewage Raw sewage reaching a municipal sewage treatment plant typically undergoes:treatment plant typically undergoes: Primary sewage treatmentPrimary sewage treatment: a : a physicalphysical process process

that uses screens and a grit tank to remove large that uses screens and a grit tank to remove large floating objects and allows settling.floating objects and allows settling.

Secondary sewage treatmentSecondary sewage treatment: a : a biologicalbiological process in which aerobic bacteria remove as process in which aerobic bacteria remove as much as 90% of dissolved and biodegradable, much as 90% of dissolved and biodegradable, oxygen demanding organic wastes.oxygen demanding organic wastes.


Primary and Secondary sewage treatment.Primary and Secondary sewage treatment.

Raw sewagefrom sewers

Activated sludge

Disposed of in landfill or ocean or applied to cropland,pasture, or rangeland

Primary Secondary

Grit chamberBar screen Settling tank Aeration tank Settling tankChlorinedisinfection tank

Sludge drying bed

Sludge digester

Air pump

To river, lake,or ocean

(kills bacteria)

Sludge


Advanced or tertiary sewage treatment:Advanced or tertiary sewage treatment: Uses series of chemical and physical processes Uses series of chemical and physical processes

to remove specific pollutants left (especially to remove specific pollutants left (especially nitrates and phosphates).nitrates and phosphates).

Water is chlorinated to remove coloration and Water is chlorinated to remove coloration and to kill disease-carrying bacteria and some to kill disease-carrying bacteria and some viruses (disinfect). viruses (disinfect).


Sewage sludge can be used as a soil Sewage sludge can be used as a soil conditioner but this can cause health conditioner but this can cause health problems if it contains infectious bacteria and problems if it contains infectious bacteria and toxic chemicals.toxic chemicals.

Preventing toxic chemicals from reaching Preventing toxic chemicals from reaching sewage treatment plants would eliminate sewage treatment plants would eliminate such chemicals from the sludge and water such chemicals from the sludge and water discharged from such plants.discharged from such plants.

Sludge

Groundwater ContaminationHarmful chemicals and pathogens may leach into groundwater and shallow wells.

OdorsOdors may cause illness or indicate presence of harmful gases.

Livestock PoisoningCows may die after grazing on sludge-treated fields.

Dust ParticlesParticles of dried sludge carry viruses and harmful bacteria that can be inhaled, infect cuts or enter homes.

Surface RunoffHarmful chemicals and pathogens may pollute nearby streams,lakes, ponds, and wetlands.

ExposureChildren may walk or play in fertilized fields.

BUFFER ZONE


Natural and artificial wetlands and other Natural and artificial wetlands and other ecological systems can be used to treat ecological systems can be used to treat sewage.sewage. California created a 65 hectare wetland near California created a 65 hectare wetland near

Humboldt Bay that acts as a natural wastewater Humboldt Bay that acts as a natural wastewater treatment plant for the town of 16,000 people.treatment plant for the town of 16,000 people.• The project cost less than half of the estimated price of The project cost less than half of the estimated price of

a conventional treatment plant.a conventional treatment plant.


Water pollution laws have significantly Water pollution laws have significantly improved water quality in many U.S. streams improved water quality in many U.S. streams and lakes but there is a long way to go.and lakes but there is a long way to go.

Some want to strengthen the U.S. Clean Some want to strengthen the U.S. Clean Water Act (CWA) to prevent rather than Water Act (CWA) to prevent rather than focusing on end-of-the-pipe removal.focusing on end-of-the-pipe removal.

Many farmers and developers see the CWA Many farmers and developers see the CWA as limiting their rights as property owners to as limiting their rights as property owners to fill in wetlands.fill in wetlands.

DRINKING WATER QUALITYDRINKING WATER QUALITY

Centralized water treatment plants and Centralized water treatment plants and watershed protection can provide safe watershed protection can provide safe drinking water for city dwellers in developed drinking water for city dwellers in developed countries.countries.

Simpler and cheaper ways can be used to Simpler and cheaper ways can be used to purify drinking water for developing countries.purify drinking water for developing countries. Exposing water to heat and the sun’s UV rays for Exposing water to heat and the sun’s UV rays for

3 hours can kill infectious microbes.3 hours can kill infectious microbes.

Using Laws to Protect Drinking WaterUsing Laws to Protect Drinking Water

While most developed countries have While most developed countries have drinking water quality standards and laws, drinking water quality standards and laws, most developing countries do not.most developing countries do not.

The U.S Safe Drinking Water Act requires the The U.S Safe Drinking Water Act requires the EPA to establish national drinking water EPA to establish national drinking water standards (standards (maximum contaminant levelsmaximum contaminant levels) ) for any pollutant that may have adverse for any pollutant that may have adverse effects on human health.effects on human health.

Using Laws to Protect Drinking WaterUsing Laws to Protect Drinking Water The U.N. estimates that 5.6 million The U.N. estimates that 5.6 million

Americans drink water that does not meet Americans drink water that does not meet EPA standards.EPA standards.

1 in 5 Americans drinks water from a 1 in 5 Americans drinks water from a treatment plant that violated one or more treatment plant that violated one or more safety standard.safety standard.

Industry pressures to weaken the Safe Industry pressures to weaken the Safe Drinking Act:Drinking Act: Eliminate national tests and public notification of Eliminate national tests and public notification of

violations. violations. Allow rights to pollute if provider cannot afford to Allow rights to pollute if provider cannot afford to

comply.comply.

Is Bottled Water the Answer?Is Bottled Water the Answer?

Some bottled water is not as pure as tap Some bottled water is not as pure as tap water and costs much more.water and costs much more. 1.4 million metric tons of plastic bottles are 1.4 million metric tons of plastic bottles are

thrown away.thrown away. Fossil fuels are used to make plastic bottles.Fossil fuels are used to make plastic bottles.

• The oil used to produce plastic bottles in the U.S. each The oil used to produce plastic bottles in the U.S. each year would fuel 100,000 cars.year would fuel 100,000 cars.

• Prevent groundwater contamination

Solutions

Water Pollution

• Reduce birth rates

• Reduce poverty

• Reduce air pollution

• Practice four R's of resource use (refuse, reduce, recycle, reuse)

• Work with nature to treat sewage

• Find substitutes for toxic pollutants

• Reuse treated wastewater for irrigation

• Reduce nonpoint runoff

What Can You Do?

Water Pollution

• Fertilize garden and yard plants with manure or compost instead of commercial inorganic fertilizer.

• Minimize your use of pesticides.

• Do not apply fertilizer or pesticides near a body of water.

• Grow or buy organic foods.

• Do not drink bottled water unless tests show that your tap water is contaminated. Merely refill and reuse plastic bottles with tap water.

• Compost your food wastes.

• Do not use water fresheners in toilets.

• Do not flush unwanted medicines down the toilet.

• Do not pour pesticides, paints, solvents, oil, antifreeze, or other products containing harmful chemicals down the drain or onto the ground.

Chapter 21

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