Water PollutionWater Pollution

G. Tyler Miller’sLiving in the Environment

13th Edition

Chapter 19

G. Tyler Miller’sLiving in the Environment

13th Edition

Chapter 19

What is water pollution?What is water pollution?

Any chemical, biological, or Any chemical, biological, or physical change in water physical change in water quality that has a quality that has a harmfulharmful effect on living organisms or effect on living organisms or makes water makes water unsuitableunsuitable for for desired uses.desired uses.

Major CategoriesMajor Categories

1.1. Infectious AgentsInfectious Agents

2.2. Oxygen-Demanding WastesOxygen-Demanding Wastes

3.3. Inorganic ChemicalsInorganic Chemicals

4.4. Organic ChemicalsOrganic Chemicals

5.5. Plant NutrientsPlant Nutrients

6.6. SedimentSediment

7.7. Radioactive MaterialRadioactive Material

8.8. Heat (Thermal Pollution)Heat (Thermal Pollution)

Review Table 19.1!!

Common Diseases Transmitted Through Contaminated Drinking Water

Common Diseases Transmitted Through Contaminated Drinking Water

Type of Organism Disease

Bacteria Typhoid fever

Cholera

Bacterial Dysentery

Enteritis

Viruses Infectious hepatitis

Parasitic Protozoa Amoebic Dysentery

Giardiasis

Parasitic Worms Shistosomiasis

Effects of Yuck WaterEffects of Yuck Water• Premature death of 3.4 million

people worldwide each year• Diarrhea alone kills 2.1 million

people

How do we measure water quality?How do we measure water quality?

Fecal Coliform Test

Drinking Drinking waterwater

0 colonies 0 colonies per 100 mlper 100 ml

Swimming Swimming waterwater 200 200

colonies colonies per 100 mlper 100 ml

Presence or Absence of Harmful Pollutants

Concentration of Harmful Pollutants

HUMAN CONSUMPTION

RECREATION

How do we measure water quality?How do we measure water quality?• Measuring the level of Measuring the level of DDissolved Oxygen issolved Oxygen

(DO)(DO)Fig. 19-3 p. 485Fig. 19-3 p. 485

How do we measure water quality?How do we measure water quality?• Using Using DO + BOD measurementsDO + BOD measurements

• UsingUsing chemical analysis chemical analysis– Presence/Absence and concentrationPresence/Absence and concentration

• Using Using indicator speciesindicator species– macroinvertebratesmacroinvertebrates

Sources of Water PollutionSources of Water Pollution

• Point SourcesPoint Sources– Discharge of pollutants at specific

locations through pipes, ditches, or sewers into bodies of surface water.•Easier to control

• Non-Point SourcesNon-Point Sources– pollutants cannot be traced to any pollutants cannot be traced to any

single source of discharge, diffuse single source of discharge, diffuse sourcessources•Difficult to controlDifficult to control

Point and Nonpoint SourcesPoint and Nonpoint Sources

NONPOINT SOURCESNONPOINT SOURCES

Urban streets

Suburban development

Wastewater treatment plant

Rural homes

Cropland

Factory

Animal feedlot

POINT POINT SOURCESSOURCES

Fig. 19-4p. 486

Pollution of StreamsPollution of Streams DO + BOD Relationships DO + BOD Relationships

Fig. 19-5 p. 488

Oxygen Sag CurveOxygen Sag Curve

Pollution of LakesPollution of Lakes• Slow turnover

– Flushing and changing of water temp

• Thermal stratification– Little vertical mixing

• Biological Magnification• Increase in the concentration of chemicals in

organisms at successively higher trophic levels of a food chain

• Eutrophication• Natural nutrient enrichment of lakes

Water0.000002 ppm

Phytoplankton0.0025 ppm

Zooplankton0.123 ppm

Rainbow smelt1.04 ppm

Lake trout4.83 ppm

Herring gull124 ppm

Herring gull eggs124 ppm

Biomagnification

1. Eutrophication – enrichment of a body of water by inorganic plant and algal nutrients  Creates environmental problems as:

- excess nutrients enter water system- increases photosynthetic productivity - numbers of algae and cyanobacteria increase - water become cloudy (turbid) from population increase- populations die off and sink to bottom- become food for decomposers - decomposers BOD but DO in waters - fish die offother species take root in nutrient rich sediments and begin to fill in waters

 Lake said to be eutrophic! Cultural or artificial eutrophication can occur as nutrient levels are increased from sewage or agricultural runoff into waterways!

Pollution of LakesPollution of Lakes Cultural Eutrophication Cultural Eutrophication

Fig. 19-7 p. 491Fig. 19-7 p. 491

Oligotrophic WatersOligotrophic Waters Oligotrophic waters – have minimal levels of nutrients, unenriched, clear waters, small populations of aquatic organisms

Reducing Surface Water PollutionReducing Surface Water Pollution

Nonpoint SourcesNonpoint Sources Point SourcesPoint Sources

Reduce runoff Reduce runoff

Buffer zone vegetation

Buffer zone vegetation

Reduce soil erosion Reduce soil erosion

Clean Water Act Clean Water Act

Water Quality Act Water Quality Act

POLLUTION OF GROUNDWATERPOLLUTION OF GROUNDWATER

• It can take hundreds to thousand of years for contaminated groundwater to cleanse itself of degradable wastes.

– Nondegradable wastes (toxic lead, arsenic, fluoride) are there permanently.

– Slowly degradable wastes (such as DDT) are there for decades.

Groundwater Pollution: SourcesGroundwater Pollution: Sources

Coal strip mine runoff

Pumping well

Waste lagoon

Accidental spills

Groundwater flow

Confined aquifer

Discharge

Leakage from faulty casing

Hazardous waste injection wellPesticides

Gasoline station

Buried gasoline and solvent tank

Sewer

Cesspool septic tank

De-icing road salt

Unconfined freshwater aquifer

Confined freshwater aquifer

Water pumping well Landfill

Fig. 21-8, p. 502

Aquifer

Water well

Migrating vapor phase

Contaminant plume moveswith the groundwater

Free gasolinedissolves ingroundwater(dissolved phase)

Groundwaterflow

Watertable

Gasolineleakage plume(liquid phase)

Leakingtank

Bedrock

Groundwater Pollution PreventionGroundwater Pollution Prevention

•Monitoring aquifers•Leak detection systems•Strictly regulating hazardous

waste disposal•Storing hazardous waste

materials above ground

Water Break

Sewage TreatmentSewage Treatment

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

Sewage TreatmentSewage Treatment• Raw sewage reaching a municipal sewage

treatment plant typically undergoes:

– Primary sewage treatment: a physical process that uses screens and a grit tank to remove large floating objects and allows settling.

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

Sewage TreatmentSewage Treatment

• Primary and Secondary sewage treatment.

Fig. 21-16, p. 511

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

Primary TreatmentPrimary Treatment

PRIMARY removes suspended/floating particle screening and settling

Material removed called primary sludge

Secondary Treatment Secondary Treatment

Secondary TreatmentSecondary TreatmentSECONDARY microorganisms decompose suspended organic material 

trickling filters = water flows through aerated rock beds with bacteria to degrade organic materialactivated sludge process = aerated and circulated water with bacteria is allowed to settle out creating secondary sludgeNOW FREE OF SEWAGE!

Sewage TreatmentSewage Treatment• Advanced or tertiary sewage

treatment:– Uses series of chemical and physical processes

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

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

• TERTIARY bio/chem/phy process that removes dissolved minerals (N & P), metals, viruses, organic cmpds

Sludge Disposal OptionsSludge Disposal Options• Anaerobic digestion (need space and

time)• Convert to Fertilizer (Town of Cary) • Incineration (Carbon dioxide emissions

– ash disposal harmful)• Ocean Dumping – BAN in 1988/1991• Landfill Disposal

Advanced Sewage TreatmentAdvanced Sewage Treatment

Removes specific pollutants Removes specific pollutants

Fig. 19-18p. 505

Safe Drinking Water Act (1974)Safe Drinking Water Act (1974)

- set uniform standards for drinking water across US

- states had various standards prior to this date • EPA determined MCLs (maximum

contaminant levels)• EPA oversees program• Amended 1986 & 1996 • 1996 Amendment required disclosure to

citizens of contaminants in water

CLEAN WATER ACT (1977)CLEAN WATER ACT (1977)Amended 1981 & 1987-formerly known as Water Pollution Control ActTWO MAIN GOALS•eliminate discharge of pollutants•attain water quality for safe fishing and swimming

– CWA effective at improving water quality at point sources

– Point source discharges must obtain NPDES permits

•(National Pollutant Discharge Elimination System) to release untreated wastewater into waterways •Nonpoint Source discharges very difficult to control

CLEAN WATER ACTCLEAN WATER ACT• 1987 NPDES permit needed for nonpoint

source discharges• CWA not as effective at monitoring these

discharges due to lack of cooperation/coordination between govt, citizens, and industry

DRINKING WATER QUALITYDRINKING WATER QUALITY• Centralized water treatment plants

and watershed protection– can provide safe drinking water for city

dwellers in developed countries.

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

for 3 hours can kill infectious microbes.

2 million plastic bottles,dumped every 5 minutes.2 million plastic bottles,

dumped every 5 minutes.

Is Bottled Water the Answer?

Is Bottled Water the Answer?Is Bottled Water the Answer?• Some bottled water is not as pure as tap

water and costs much more.

• 1.4 million metric tons of plastic bottles are thrown away.

• Fossil fuels are used to make plastic bottles.– The oil used to produce plastic bottles in the U.S.

each year would fuel 100,000 cars.