Water Pollution

Chapter 22APES

Ms. Miller

Key Concepts

Types, sources, and effects of water pollutants

Major pollution problems of surface water

Major pollution problems of groundwater

Reduction and prevention of water pollution

Drinking water quality

Types and Sources of Water Pollution

Point sources

Nonpoint sources

Biological oxygen demand

Biochemical oxygen demand is a measure of the quantity of oxygen used by microorganisms (e.g., aerobic bacteria) in the oxidation of organic matter. Natural sources of organic matter include plant decay and leaf fall.

Water quality

WaterQuality

Good 8-9

Do (ppm) at 20˚C

Slightlypolluted

ModeratelypollutedHeavily

pollutedGravelypolluted

6.7-8

4.5-6.7

Below 4.5

Below 4

Fig. 19.2, p. 478

Pollution of Streams Oxygen sag curve Factors influencing recovery

Clean Zone DecompositionZone

Septic Zone Recovery Zone Clean Zone

Normal clean water organisms(Trout, perch, bass,

mayfly, stonefly)

Trash fish(carp, gar,Leeches)

Fish absent, fungi,Sludge worms,

bacteria(anaerobic)

Trash fish(carp, gar,Leeches)

Normal clean water organisms(Trout, perch, bass,

mayfly, stonefly)

8 ppmDissolved oxygen

Biological oxygendemand

Oxygen sag

2 ppm

8 ppm

Con

cent

ratio

nTy

pes

ofor

gani

sms

Time of distance downstream

Direction of flow

Point of waste orheat discharge

Fig. 19.3, p. 479

Pollution of Lakes

Eutrophication

Slow turnover

Thermal stratification

Discharge of untreatedmunicipal sewage

(nitrates and phosphates)Nitrogen compounds

produced by carsand factories

Discharge of treatedmunicipal sewage

(primary and secondarytreatment:

nitrates and phosphates)

Discharge of detergents

( phosphates)

Natural runoff(nitrates andphosphates

Manure runoffFrom feedlots(nitrates andPhosphates,

ammonia)

Dissolving of nitrogen oxides

(from internal combustionengines and furnaces)

Runoff and erosion(from from cultivation,mining, construction,

and poor land use)

Runoff from streets,lawns, and construction

lots (nitrates andphosphates)

Lake ecosystemnutrient overload

and breakdown of chemical cycling

Fig. 19.5, p. 482

Case Study: The Great Lakes

Great Lakes drainage basinMost polluted areas, according to the Great Lakes Water Quality Board“Hot spots” of toxic concentrations in water and sedimentsEutrophic areas

CANADA

WISCONSIN

MINNESOTA

IOWA

ILLINOIS INDIANA OHIO

PENNSYLVANIA

NEW YORKMICHIGAN

MICHIGAN

Nipigon BayThunder Bay

Silver Bay

St. Louis R.

Jackfish Bay

St. Mary’s R.Spanish R.

Penetary Bay

Sturgeon Bay

SaginawBaySaginaw R.

SystemSt. Clair R.

Detroit R.Rouge R.Raisin R.

Maumee R.Black R.Rocky R.

Cuyahoga R.Ashtabula R.

Thames R.

Grand R. Niagara FallsNiagara R.

Buffalo R.

St. Lawrence R.

Fig. 19.7, p. 484

Groundwater Pollution: Sources

Low flow rates

Fewbacteria

Colder Temps

Waste lagoon,pond, or basin

Miningsite

Pumpingwell

Waterpumping

wellSewer

Cesspoll,septictank

Hazardous wasteinjectionwell

Buried gasolineand solvent

tanksLandfill

Roadsalt

Unconfined freshwater aquifer

Confined freshwater aquifer

Confined aquifer Discharge

Leakagefrom faultycasingGroundwater

Groundwater flow

Fig. 19.9, p. 487

Groundwater Pollution Prevention

Monitoring aquifers

Leak detection systems

Tyco Thermal Controls provided the solution with its cable-based TraceTek leak detection system using TT5000 sensing cable which contains a hydrocarbon

scavenging material. Installed within PVC conduit in the soil beneath fuel tanks it offers a system capable of quickly detecting fuel leaks. Any spillage is drawn into the conduit by capillary action and contact is absorbed by the cable jacket which swells and as contact is made with the electrodes in the cable core leak detection is achieved. TraceTek systems are offered with continuous monitoring equipment for

very quick detecting, precise locating and triggering alerts.

Strictly regulating hazardous waste disposal

Schematic diagram of a secure hazardous-waste landfill with a double leachate collection system

Storing hazardous materials above ground

Groundwater contamination occurs when man-made products such as gasoline, oil, road salts and chemicals get into the

groundwater and cause it to become unsafe and unfit for human use. Some of the major sources of these products, called

contaminants, are storage tanks, septic systems, hazardous waste sites, landfills, and the widespread use of road salts, fertilizers,

pesticides and other chemicals.

IndustryNitrogen oxides from autosand smokestacks; toxicchemicals, and heavymetals in effluents flowinto bays and estuaries.

CitiesToxic metals andoil from streets andparking lots pollutewaters; sewageadds nitrogen andphosphorus.

Urban sprawlBacteria andviruses from sewersand septic tankscontaminate shellfishbeds and closebeaches; runoffof fertilization fromlawns adds nitrogenand phosphorus.

Construction sitesSediments are washed into waterways,choking fish and plants, cloudingwaters, and blocking sunlight.

FarmsRun off of pesticides, manure, andfertilizers adds toxins and excessnitrogen and phosphorus.

Red tidesExcess nitrogen causes explosivegrowth of toxic microscopic algae,poisoning fish and marine mammals.

Healthy zoneClear, oxygen-rich waterspromote growth of planktonand sea grasses, and support fish.

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

Toxic sedimentsChemicals and toxic metalscontaminate shellfish beds,kill spawning fish, andaccumulate in the tissuesof bottom feeders.

Closed shellfish bedsClosed

beach Oxygen-depletedzone

Fig. 19.11, p. 489

Ocean Pollution

Red Tides: Pollution caused by an overpopulation one of the

following four causes which MAY cause the water to turn red, green, orange or brown and MAY toxify the

waterCauses: 1) diatoms 2) photosynthetic dinoflagellates

3) cyanobacterium 4) massive blooms of phytoplankton

Case Study: Chesapeake Bay

Largest US estuary

Relatively shallow

Slow “flushing” action to Atlantic

Major problems with dissolved O2

Drainagebasin

No oxygen Low concentrationsof oxygen

PENNSYLVANIA

NEW YORK

WESTVIRGINIA

MARYLAND

DELAWARE

NEWJERSEY

ATLANTICOCEAN

VIRGINIA

Cooperstown

Harrisburg

Baltimore

Washington

Richmond

Norfolk Chesapeake Bay

Fig. 19.13, p. 490

The EPA raised its estimate of the nitrogen that flowed to the bay in 2008 from 258 million pounds to 283 million pounds.

Oil Spills Sources: offshore wells, tankers, pipelines and

storage tanks

Effects: death of organisms, loss of animal insulation and buoyancy, smothering

Significant economic impacts

OOOPSIES

Mechanical cleanup methods: skimmers and blotters

Chemical cleanup methods: coagulants and dispersing agents

More than two million gallons of dispersants have been put into the Gulf waters surrounding the BP oil spill a VIMS scientist told a

senate caucus July 29, 2011

Solutions: Preventing and Reducing Surface Water Pollution

Nonpoint Sources Point Sources

Reduce runoff

Buffer zone vegetation

Reduce soil erosion

Clean Water Act

Water Quality Act

Technological Approach: Sewage TreatmentMechanical and biological treatment

Raw sewagefrom sewers

Bar screenGritchamber Settling tank Aeration tank Settling tank

Chlorinedisinfection tank

Sludge

Sludge digester

Activated sludgeAir pump

(kills bacteria)

To river, lake,or ocean

Sludge drying bedDisposed of in landfill orocean or applied to cropland,pasture, or rangeland

Primary Secondary

Fig. 19.15, p. 494

Technological Approach: Septic SystemsRequire suitable soils and maintenance

HouseholdwastewaterPerforatedpipe

Distributionbox

(optional)

Septic tank

Manhole (forcleanout)

Drainfield

Vent pipe

Nonperforatedpipe

Gravel orcrushedstone

Fig. 19.14, p. 494

Technological Approach: Advanced Sewage Treatment

Removes specific pollutantsEffluent fromSecondarytreatment

Alumflocculation

plus sedimentsActivated

carbon

Desalination(electrodialysis

or reverse osmosis)Nitrate

removal

Specializedcompound

removal(DDT, etc.)

98% ofsuspended solids

90% ofphosphates

98% ofdissolvedorganics

Most ofdissolved salts

Recycled to landfor irrigation

and fertilization

To rivers, lakes,streams, oceans,

reservoirs, or industries

Fig. 19.16, p. 495

Technological Approach: Using Wetlands to Treat Sewage

(1) Raw sewage drains by gravity into the first pool and flows through a long perforated PVC pipe into a bed of limestone gravel.

(3) Wastewater flows through another perforated pipe into a second pool, where the same process is repeated.

(2) Microbes in the limestone gravel break down the sewage into chemicals, that can be absorbed by the plant roots, and the gravel absorbs phosphorus.

(4) Treated water flowing from the second pool is nearly free of bacteria and plant nutrients. Treated water can be recycled for irrigation and flushing toilets.

45 centimeterlayer of limestonegravel coated with

decomposing bacteriaFirst concrete pool Second concrete pool

Sewage

Wetland typeplants

Wetland typeplants

Treatedwater

Fig. 19.17, p. 497

Constructed wetland in Argentina

Drinking Water Quality

Safe Drinking Water Act

Maximum contaminant levels

Bottled water

10 to 20 percentGreater than 20 percentNot tested

Contaminated Probability

Fig. 19.10, p. 488

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