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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