Classic Chapter 11- Water Pollution

8/4/2019 Classic Chapter 11- Water Pollution

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Chapter 11- Water Pollution

11.1 Types of Water Pollution

Water pollution- any contamination of water that lessen its value to humans and other species- aquatic

and nonaquatic

recreation

unsuitable for irrigation

unsuitable for use in factories

unfit for domestic consumption

Affects both groundwater and surface waters

Surface water- bodies of water in direct contact with the atmosphere

Ground water- water found in the ground

In saturated soils

In aquifers

Classified by:

1. Sourcea. Point sourceb. Nonpoint source

2. Chemical typea. Sedimentb. Inorganic nutrientsc. Thermal pollutiond. Disease-producing microorganismse. Toxic organic chemicalsf. Heavy metalsg. Oxygen-demanding organic wastes

Point Source Water Pollution

Point source water pollution- has its source in a well-defined locationi.e. pipe through which a sewage treatment plant or factory discharges waste into either surface or

groundwater

Nonpoint Source Water Pollution

Nonpoint source water pollution- does not arise from distinct point sources; when pollutants are

washed into bodies of water from large areas

i.e. farmland where chemicals drain into groundwater or surface waters, pastures, construction

sites, cities, lawns, storm drains

11.2 Major Pollutants, Prevention, and Control

Two basic approaches for ensuring clean water supplies:

1. Water pollution controla. Pollution control devices- technologies that remove pollutants from the effluents of

factories and sewage treatment plants

i. Usually applied to point sourcesii. Pollutants are treated so they become less harmful, or are concentrated and

disposed of

1. Often in landfillsiii. Output controls- deal with the pollutant after is has been produced


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1. Expensive way of diverting pollution from one medium to another2. Pollution prevention- a variety of measures that eliminate the production of pollutants in

factories, water treatment plants, and nonpoint sources

a. Typically highly cost-effectiveb. Input controls- eliminates pollutants by adjusting inputsc. Throughput controls- alter the production of waste by adjustments of substances

flowing through a system

i. i.e. recycling wastes in another processSediment Pollution

Sediment- includes sand, silt, and clay-inorganic soil particles- eroded from soils

One of most destructive and costly water pollutants

1 billion tons/yr of sedimentaquatic ecosystems in US

Where Does Sediment Come From?

-Natural sources

i.e. Bank erosion

-Human sources- activities that lead to water and wind erosionFarmland

In under-vegetated, or disturbed watersheds, sediment pollution in surface waters can

reach elevated levels

Construction sites

Land is bare until building is completed 10x higher erosion rates than

cropland

Timber harvesting

Strip-mining

Harmful Effects

-$1 million/day in damage in US riversDamages turbines, clogs canals, fills navigable rivers

-Carry nutrient pollution and toxic chemicals

-Suspended sediment blocks sunlight

Kills photosynthetic base of many aquatic food chains

Reduces levels of dissolved oxygen in waters

-Smothers breeding grounds of fish and buries shellfish habitat

-Kills fish

-Problems for municipalities

-Threatens reservoirs

Control of Sedimentation

Input Control

-Proper application of erosion control strategies

Conservation tillage, strip cropping, contour farming, terracing

-Careful selection of construction sites

Avoid steep slopes

-Controls on land disturbance

Reducing denuded or bulldozed areas

Sodding and revegetating areas with a hydroseeder


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-Small dams places across drainage ditches

-Sediment fences

Output Control

-Direct muddy water to swamps and marshes

-Filter out the sediment

-Sedimentation ponds

-Dredging rivers

-Removed from drinking water by chemical coagulation and sand filtration

Inorganic Nutrient Pollution

Inorganic nutrient pollutants- nitrates and phosphates

Nitrogen and phosphorous are limiting factors- essential elements that play key role in growth of

individuals and populations

Essential in low concentrations, but become pollutants in large quantities

Nitrogen usually available in the form of NO3- ions or NH3 (ammonia)

Phosphorus usually available as PO4 -3 ions (phosphate)Phosphorous less abundant, limiting nutrient in most freshwater lakes, rivers

Three Major Sources:

1. Agricultural fertilizers- promotes crop production because they are rich in nitratesand phosphates

a. Commercial fertilizers- artificial, synthetic fertilizersb. Animal wastes- manure

Fertilizer not absorbed by crop roots washed by runoff waters into surface waters

Stimulate population explosion of aquatic plants in aquatic systems

2. Domestic sewagea.

Human wastes

b. Household detergents3. Livestock wastes

a. Feedlots- concentrated livestock facilities where animals are held forfattening before slaughtering

b. More animal waste is produced than human wastec. Farming practicesd. Domestic pets

Effects of Inorganic Nutrients on Aquatic Ecosystems

-Eutrophication- nutrient enrichment of an aquatic ecosystem

Natural occurs over a period of hundreds-thousands of years

Accelerated (cultural) sped up process due to release of excessive amounts of

nutrients into aquatic ecosystems as a result of human activities

80% N and 75% P entering surface waters in US

Eutrophication proceeding 100-1000 times faster than normal conditions

Classifying Lakes Based on Their Productivity

Three major types of lakes:

1. Oligotrophic- nutrient-poor


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a. Clear waterb. Deep basinc. Gravel or sandy bottomd. Plankton scarcee. Rooted vegetation scarcef. Low total biomass per unit volume of water

2. Mesotrophic- middle-nutrienta. Fertility, clarity, dissolved oxygen levels, total biomass are intermediateb. Good for swimming, boating, fishing

3. Eutrophic- nutrient-richa. Shallow basinb. Muddy bottom

i. Poor spawning surfacesc. Turbid waterd. Low dissolved oxygen content

i. Most from increased photosynthetic organisms released toatmosphere

e. Plankton abundantf. Rooted vegetation abundantg. Algal blooms- algal population explosions

i. Average concentration of soluble inorganic phosphorous exceeds.01 ppm

ii. Average concentration of soluble inorganic nitrogen exceeds .3 ppmiii. Destroy lake aestheticsiv. Impede recreationv. Reduce penetration of sunlightvi. Decomposing algae reduce DO levels

vii. Fills in lake bottomviii.

Give water bad taste and odor

ix. Piles of algae and rooted plants on shores1. Decompose giving off H2S gas (rotten egg odor)

x. Proliferation of blue-green algae1. Some release chemicals that are poisonous to fish and

humans

Stream Eutrophication

Naturally oligotrophic at headwaters, eutrophic at mouth

More easily reversed than lake eutrophication

Groundwater Pollution

Septic tanks contribute to nitrate and phosphate contamination in groundwater

Controls of Eutrophication

Output Measures and Controls:

-upgrade wastewater treatments plants to remove higher percentage of P and N

-Recycle wastes from wastewater treatment plants

-Use detention basins on feedlots

-Employ weed-cutting machines to remove excess vegetation from aquatic ecosystems

-Destroy plant growth in aquatic ecosystems with herbicides


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-Dredging the bottom sediment to remove nutrients

-Avoid dumping treated sewage in lakes in sensitive lakes

-Applying treated wastewater to grassy areas

-Treating wastewater biologically in artificially constructed wetlands

Input Controls in Urban Areas:

-Ban use of phosphate detergents

-Limit P content of detergents

-Use newly developed P-free detergents

-Impose excise tax on lawn and garden fertilizers to reduce volume of use

-Educate citizens to use less detergent and fertilizers

Input Controls in Rural Areas:

-Minimize use of fertilizers on cropland

-Inject liquid fertilizers directly into soil

-Postpone application of manure until spring melt of ice and snow

-Plant vegetative barriers between fields and waterways

-Implement soil erosion controls on farms to minimize surface runoff-Do not build concentrated livestock production areas in floodplains

Thermal Pollution

Thermal pollution- increase in the temperature of water that adversely affects organism living in it

Natural causes

Summer heating by sun

Human activities

Sources:

-Industries remove water to cool equipment or products and discharged as hot water

thermal plume- a heated body of water

Biological Effects of Thermal Pollution

-Reduction in Dissolved Oxygen

Warm water has lowered capacity to dissolve oxygen

Fish in warm water have increased oxygen requirements

-Interference with Reproduction

Body temperature of cold-blooded animals varies with temperature of environment

Thermal signals for spawning, nest building, migration disrupted

-Increased Vulnerability to Disease

-Direct Mortality

Cold-water fish may die from shock

-Undesirable Changes in Algal Populations

Three major groups of algae:

1. Diatomsa. Cool water

2. Green algaea. Warm water

3. Cyanobacteria (blue-green algae)a. Warm-hot waterb. Least desirable as aquatic animal food


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c. Give off toxic substances-Destruction of Organisms in Cooling Water

Affected by water turbulence, suction, and pressure

Controlling Thermal Pollution

-Install cooling towers- devices that transfer heat from the water to the atmosphere

Wet cooling tower-heated water is piped to the top of the tower as water flows

downward over a series of plates and meets cooling air flowing in from the bottom of

the tower

Cool water reused or discharged

Generate fog

Water permanently removed from aquatic ecosystem

Toxic chemicals used to prevent bacteria growth in pipes

Dominate skylines

Expensive

Beneficial Effects of Heated Water

Used to prevent ice from formingPrevent frost damage

Heat homes

Disease-Producing Organisms

Water contaminated with infectious microorganisms is responsible for more cases of human illness

worldwide than any other environmental factor

Cholera, typhoid fever, dysentery, polio, and infectious hepatitis

Caused by specific microorganism transmitted by water polluted with human or animal

wastes

Pfiesteria causes open sores and massive fish kills

Can cause human memory loss, confusion, skin gastro-intestinal, and respiratory problems

Protection Ourselves from Pathogens in Water Supplies

Good sewage treatment

Drinking water purification

Impossible to test for all pathogens

Pathogens- disease-causing bacteria

Law requires sampling of coliform bacteria

Coliform bacteria- extremely common form found in the intestines of humans

and warm-blooded animals

Indicators of potentially harmful bacteria and viruses

Chlorination- destroys bacteria during water treatment

Shift to an alternative available water source

Toxic Organic Compounds

Organic compounds- made primarily of carbon and hydrogen

Group of synthetic organic compounds sometimes released into ground and surface water are

toxic

i.e. Persistent organics are DDT (pesticide) and PCBs (industrial chemicals)

Released directly into surface or groundwater


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Poured into surface impoundments

Substances enter the atmosphere

Waste percolates into ground

Companies inject to deep wells

Groundwater Contamination

Virtually no natural cleansing mechanisms

Sources of toxic organic compounds that pollute groundwater:

1. Municipal and industrial landfills2. Percolating toxic chemicals from contaminated sites3. Deep injection wells4. Septic tanksAdverse Effects on Health

Numerous studies have linked groundwater contamination by toxic organic chemicals to serious

health effects

Disrupt normal enzyme function in living cells

Polluted well water rarely contains only a single organic contaminantPossible synergistic effects

Fetuses can be affected when mothers ingest chemicals

i.e. PCBs passed from mother to fetus cans cause:

delayed development

low birth weight

retarded reflexes

impaired memory

Preventing groundwater contamination requires preventative actions:

-Proper disposal or destruction of wastes

-Bans on evaporation ponds and burial of toxic wastes

-Hazardous waste recycling-Substitution of nonhazardous chemical processes

Heavy Metals Pollution

Heavy metals- highly toxic elements, not broken down by bacteria (persistent)

i.e. lead, mercury, selenium

Sources of Lead:

-Active and inactive mines

Release waters that have leached heavy metals

Mine tailings

Mine runoff

-Gaseous emissions of coal-fired power plants

-Garbage incineration

-Industrial facilities

Metal processing plants, dye-making firms, paper mills

-Lead leached from pipes

-Rain and snow

Effects of Lead:

-Disrupt normal enzyme function in living cells


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-Lead poisoning

-Subtle adverse effect of low concentrations of lead in drinking water on embryonic

development, and learning and memory in children

Sources of Mercury:

-Direct industrial discharges

-Rain and snow

Coal-fired power plants and incinerators

-Bacteria convert innocuous mercury into methyl mercury

Accumulates in body tissues

Biomagnification- increasing concentration of toxins in body tissues as it moves up the

food chain

Sources of Selenium:

-Agriculture and irrigation

Controlling Heavy Metals Pollution

-Reduce discharges in air and water-Eliminate discharges in air and water

-Require industries to pretreat metal-laden waste

-Transported to certified hazardous waste dump

-Changes in types of pipes used

-Tighter controls on air pollution emissions

Cross-media contamination- when heavy metals in the environment originate as air

pollutants and then rain down on the land and water

Oxygen-Demanding Wastes

Excess biodegradable organic matter is consumed by bacteria

Deplete the dissolved oxygen content of the waterBacteria actively compete with other oxygen-demanding aquatic organisms

Levels of DO fall as bacteria populations increase

Oxygen-demanding wastes- organic wastes and human-produced wastes like sewage whose

decomposition consumes oxygen in aquatic ecosystems

Organic content of the water is expressed as the biological/biochemical oxygen demand (BOD)

BOD- measure of the amount of material that supports bacteria that demand oxygen

The more organic material, the more oxygen consumption

Only when assimilation capacity of the lake or stream is exceeded does severe oxygen

depletion occur

Rivers organic assimilation capacity determined by its rate of aeration- how fast

oxygen is replenished

Effects of High BOD on Aquatic Species

-Oxygen sag- dip in oxygen curve as measured further and further downstream from discharge

-Zone of declineimmediately below outfall

DO levels drop rapidly because of high organic component of waste

Cannot support more desirable fish species

Cannot support larvae of some insect species

-Damage zone- DO so drastically reduced that even more tolerant fish species cant survive


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Supports sludge worms

-Recovery zone- amount of oxygen removed by sewage bacteria is more than counterbalanced

by the oxygen entering the stream from the atmosphere or photosynthesis of aquatic plants

-Clean water further downstream where most organic material has been decomposed and DO

level rises to original value

Hormone Disruptors and Drugs

Hormone disruptors- chemical pollutants that when ingested by humans and other animals alter the

hormonal system of wild animals, affecting reproduction and other vital functions

Paper mills release estrogen-like compound (genistein)

Male fish develop sex organs of males and females unable to reproduce

Paper mills release dioxin

Carcinogenic

May suppress immune systems

Synthetic female sex hormones excreted

Shift in fish gender

Prescription drugs, antibiotics, painkillers, antidepressants pollute waterways

Trace amounts from urineLivestock

May have synergistic effects

11.3 Sewage Treatment and Disposal

Point sources discharge wastes into underground pipes

Pipes transport wastes to sewage treatment plants- facilities that remove wastes

Sewage Treatment Methods

Serve 70% of US population

Fall into one of three categories:

1.

Primary mainly a physical process to remove solids from wastewatera. Enters plantb. Travels through screenc. Passes into settling tanks

i. Suspended organic solids settle to the bottomd. Fluid that remains is chlorinated and discharged (in primary only treatment

plants)

e. Solids at the bottom of settling tanks pumped to sludge digesteri. Bacteria feed on the organic waste

1. Produces methane, which is sometimes recycled togenerate electricity

f. Removes 60% of suspended solidsg. Removes 33% of BOD

2. Secondary- primarily biological treatment that relies on aerobic bacteria to breakdown degradable organic materials and remove additional suspended solids

a. Two major methodsi. Activated sludge process

1. Fluid from settling tank piped to aeration tanka. Air is bubbled to provide oxygen


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b. Aerobic bacteria decompose organic compoundsrapidly

2. Transferred to a settling tanka. Remaining suspended organic matter and bacteria

settle to bottom

b. Form sludgei. Drained to anaerobic digesterii. Activated sludge- the highly concentrated

mix of aerobic bacteria and organic matter

within the aeration chamber

3. Recycled back to aeration tanka. Provides bacteria seed population

4. Remaining sludge dried, incinerated, landfilled, or used asfertilizer

5. Remaining liquid chlorinated and discharged6. Reduces 90% BOD7. Removes 90% suspended solids8. 50% N and 70% P compounds still remain

a. Require tertiary treatmentii. Trickling filter- sewage is sprayed by arms of slowly rotating

sprinkler onto a filter bed made of stone or bark that are coated

with bacteria

1. Sewage trickles down through stones2. Bacteria consumes BOD3. Leftover solids pipe to settling tank

a. Transferred to sludge digester4. 80-85% of BOD removed5. Still contains P and N compounds

a.

Require tertiary treatment3. Tertiary- most advanced treatment process designed to remove most of remaining

pollutants (N and P compounds)

a. ExpensiveManaging Stormwater Runoff

In newer cities, stormwater and sewage pipe systems are separated

Stormwater delivered directly to streams

Combined sewer systems cause problems when heavy rainfall

Excess stormwater containing raw sewage piped directly into streams and lakes

CWA requires cities to create stormwater management programs

Septic Tanks

Septic tanks- underground sewage containers made of concrete or plastic into which all household

wastewater flows

Solids settle to the bottom to form sludge

Fluids flow into system of perforated pipes buried underground forming a leach field

Liquid waste passes through holes in pipes and percolates through soil

Soil acts as a natural filter

Organic material decomposed by soil bacteria


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Drawbacks:

-Cannot be used if water table is high

-Cannot be used if soil is relatively impermeable

-Easily overtaxed

-Limited lifespan

Alternative Treatment Methods

Holding Ponds, Indoor Biological Treatment Facilities, and Other Technologies

Direct sewage flow to specially built ponds of marshes

Holding ponds can serve as wildlife habitat or grow food

Indoor facilities consist of greenhouses with a number of tanks of aquatic plants,

microorganisms, and animals that degrade waste materials

Composting toilets

Specially built wetlands

Sewage Sludge: A Resource in Disguise

Use sludge as:-Fuel

Organic fuel called biogas released during anaerobic bacteria decomposition of organic

material in digester

Mainly methane

-Livestock feed supplement

Fair content of nutritional proteins, fats

-Soil conditioner and fertilizer

Improves ability of soil to retain nutrients, reduces erodibility and promotes the ability

of the soil to hold oxygen and moisture

-Make building materials

Mix sludge, clay and slateReduce soil erosion and visual pollution of clay mining

Slow rate that landfills are filling up

Reduce cost of sewage disposal

11.4 Legislating Water Pollution Control

1971- Federal Water Pollution Control Act amended 1977 as US Clean Water Act

US Clean Water Act:

Classifies surface waters according to their designated use:

-Drinking water

-Swimming and fishing

Most of nations surface waters

-Transportation and Agriculture

Establishes minimal water quality standards for nations waters

Deadlines for industries to reduce/eliminate waste discharges

US cities required to provide secondary water treatment

Control nonpoint water pollution

effluent trading policy

Monitoring provided by USGS National Ambient Stream Quality Accounting Network


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1974 Safe Drinking Water Act

Establishes EPA as main regulator of drinking water quality

Establish regulations for pollutants in drinking water

Ensure that drinking water from public supplies was filtered and disinfected

1986 Emergency Planning and Community Right-to Know Act

Toxics Release Inventory- pollution accounting system

Watershed Management Plans

Watershed management can regulate nonpoint water pollution

Reduce nonpoint sources in watershed

Reduce fertilizer use

Reduce surface runoff

Protect/increase vegetative ground cover

Reduce impervious surfaces

Buffer zones- vegetative strips along streams, rivers, lakes to reduce surface flow into

waters and filter runoff

Set aside open spaces

Stormwater retention pondsEducation programs

Watershed protection plans

11.5 Pollution of Oceans

FWPCA sets standards and regulates the discharge of pollution into US waters, many of which flow into

oceans

Laws ban or regulate disposal of waste into ocean

Enforcement set to Coast Guard and Army Corp of Engineers

UN programs

International Maritime Organization- aimed at reducing ocean pollution

International Seabed Authority- regulates mining in oceans

Sewage

Often dumped into neritic zone along US coastline

Adverse effects:

-High BOD lowers DO levels

-Fish kills

-Toxic metals reached high levels in fish

-Harmful mutations in aquatic organisms

1988 Ocean Dumping Act- banned all ocean garbage dumping

Dredge Spoils

80% of waste in US coastal waters is dredge spoil

Dredge spoil- sediment scooped from harbor and river bottoms to deepen channels for

navigation

15% of this material is disposed of in ocean

1/3 tons of dredged spoil in contaminated with urban and industrial waste and runoff pollutants

Enter aquatic food chainshuman consumption

Plastic Pollution


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Plastic materials kill seabirds, whales, porpoises, seals when ingested or entangled

1. Cannot be digested nor voided once ingested2. Entanglementdrowning3. Entanglementstarvation

a. Cannot search for or swallow foodSources:

-Manufacturers

-Human litter

-Litter from fishing boats or barges

Plastic materials cannot be broken down by bacteria (nonbiodegradable)

Plastic items are buoyant

Control of Plastic Pollution

1972 London Dumping Convention- agreement to regulate disposal from trash-hauling ships

1973 Marine Pollution Convention- bans ships from dumping trash

Recycle more

Do not manufacture plastic

Oil Pollution

91% of oil in oceans is from human activities

Oil Tanker Spills

5% of oiloceans per year

Damage of spill exacerbated if:

-Protected waters close to land

-Cleanup is delayed

-Cold waters

-Biologically rich waters

Routine Ship Maintenance

20% of oil oceans per year from:

-Loading and discharging oil

-Tank cleaning

-Oil ballast discharge

Offshore Oil Well Accidents

Contribute less oil than tanker spills on annual basis but can be more devastating

Land Sources of Oil Pollution

>50% of oil oceans per year comes from inland and coastal communities

Service stations

Motor vehicles

Factories

storm and sewage drains

runoff

Air Pollution

Airborne hydrocarbons rain down on oceans


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13% of oiloceans per year

Adverse Effects of Oil Pollution

Depends on:

-Type and amount of oil

-Proximity of spill to biologically sensitive areas

-Season of year

-Weather

-Ocean currents

-Wind velocity

Greatest impact closest to shore

Oil can kill or contaminate sea life

Economic effects on locals who makes living from harvesting sea

Mimic chemicals that guide marine animals during mating, feeding, homing, and migrating

Carcinogens in oil

Devastate beaches and recreation

Costly cleanup

Control of Oil Pollution

Oil Pollution Act of 1990- established new provisions for new tanker structural design,

retirement of outdated fleet, improved spill response strategies, more rigorous inspection,

clearly defined financial responsibility and liability

Controls after spill has occurred include:

1. Physical cleanupa. Machines, absorbent pads, hot water, skimmers

2. Decomposition of oil by bacteria3. In-situ burning

a. Controlled burn rapidly removes oilb.

Highly visible smoke

i. Air pollutionc. Localized temperature elevations

i. Harm or kill wildlife11.6 World View of Water Pollution

Water pollution problems in less developed countries are much worse than US

-Lack of education and training

-Lack of funding for treatment plants

-Lack of tough pollution control legislation

-Lack of enforcement

1980 UN International Drinking Water and Sanitation Decade

Impeded by population increase, resource demand, and industrial ouput

Classic Chapter 11- Water Pollution

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