chapter 21 water pollution. core case study: using nature to purify sewage ecological wastewater...

Chapter 21Chapter 21

Water PollutionWater Pollution

Core Case Study: Using Nature to Core Case Study: Using Nature to Purify SewagePurify 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).

Figure 21-1Figure 21-1

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

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 : cannot be traced to a single site of discharge (atmospheric single site of discharge (atmospheric deposition, agricultural / industrial / deposition, agricultural / industrial / residential runoff) residential runoff)

Water Quality FactorsWater Quality Factors DODO BODBOD Fecal coliform - Fecal coliform -

0/100 ml for drinking 0/100 ml for drinking water, 200 water, 200 colonies/100 ml for colonies/100 ml for swimmingswimming

Chemical analysisChemical analysis Indicator speciesIndicator species Visual analysisVisual analysis


Water Pollution Problems in StreamsWater Pollution Problems in Streams

Oxygen sag curve (5 zones)Oxygen sag curve (5 zones) Factors affecting it: volume, temp, flow rate, pHFactors affecting it: volume, temp, flow rate, pH


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.

POLLUTION OF POLLUTION OF FRESHWATER LAKESFRESHWATER LAKES

Dilution of pollutants in lakes is less effective Dilution of pollutants in lakes is less effective

- - Lakes and reservoirs are often Lakes and reservoirs are often stratified and undergo little mixing.stratified and undergo little mixing.- Low flow makes them susceptible Low flow makes them susceptible

to runoffto runoff- Cultural eutrophicationCultural eutrophication

POLLUTION OF GROUNDWATERPOLLUTION OF GROUNDWATER

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. Groundwater has low flow rates, few bacteria, & Groundwater has low flow rates, few bacteria, &

cold temps - all slow down recovery timecold temps - all slow down recovery time Avg. recycling time for groundwater = 1400 yearsAvg. recycling time for groundwater = 1400 years

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

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.

Fig. 21-9, p. 504

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

Red tidesRed tides Dead zones (usually about 61/year)Dead zones (usually about 61/year)


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

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 algae blooms.algae blooms.

Figure 21-AFigure 21-A

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

Largest US estuaryLargest US estuary ShallowShallow Slow flushing (1%)Slow flushing (1%) High phosphates, High phosphates,

nitrates, mercury, nitrates, mercury, leadlead


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 POLLUTION OCEAN POLLUTION CONTRIBUTORSCONTRIBUTORS

Tanker accidentsTanker accidents BlowoutsBlowouts PipelinesPipelines Offshore wellsOffshore wells RunoffRunoff Dredge spoilsDredge spoils SludgeSludge


Fig. 21-14, p. 509

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

Prevent runoff Prevent runoff Buffer zone vegetationBuffer zone vegetation Reduce erosionReduce erosion Clean Water Act - increases Clean Water Act - increases

fishable/swimmable lakes, cuts erosion, fishable/swimmable lakes, cuts erosion, increases sewage treatment, decreases increases sewage treatment, decreases wetland losswetland loss

Water Quality Act - drinking water suppliesWater Quality Act - drinking water supplies

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.



Primary sewage treatmentPrimary sewage treatment: a : a physicalphysical process that uses screens and a grit tank to process that uses screens and a grit tank to remove large floating objects and allows remove large floating objects and allows settling - removes 60% of solidssettling - removes 60% of solids

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 much as 90% of dissolved and biodegradable, oxygen demanding organic biodegradable, oxygen demanding organic wastes.wastes.


Primary and Secondary sewage treatment.Primary and Secondary sewage treatment.Figure 21-16Figure 21-16


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).

Some areas use natural wetlands.Some areas use natural wetlands.

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.

Water LawsWater Laws

SDWA ‘74 - EPA establishes national SDWA ‘74 - EPA establishes national drinking water standards - not on wellsdrinking water standards - not on wells

Water Quality Act ‘65 - established water Water Quality Act ‘65 - established water quality standards for streamsquality standards for streams

Ocean Dumping Act ‘72 - must have permit to Ocean Dumping Act ‘72 - must have permit to dispose of materialsdispose of materials

Clean Water Act - federal assistance for Clean Water Act - federal assistance for sewage treatment, permit to discharge, EPA sewage treatment, permit to discharge, EPA sets pollution standardssets pollution standards

chapter 21 water pollution. core case study: using nature to purify sewage ecological wastewater...

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