Water Pollution

Water Pollution Comes from Point and Nonpoint Sources

• Point sources
• Located at specific places
• Easy to identify, monitor, and regulate
• Examples

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• Nonpoint sources
• Broad, diffuse areas
• Difficult to identify and control
• Expensive to clean up
• Examples

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Water Pollution Comes from Point and Nonpoint Sources

• Agriculture activities: leading cause of water pollution
• Sediment eroded from the lands
• Fertilizers and pesticides
• Bacteria from livestock and food processing wastes
• Industrial facilities
• Mining

• Other sources of water pollution
• Parking lots
• Human-made materials
• E.g., plastics
• Climate change due to global warming

�Point Source of Polluted Water in Gargas, France

Nonpoint Sediment from Unprotected Farmland Flows into Streams

• Physical Parameters

Total Suspended Solids

Turbidity

Colour

Taste

Odour

Temperature

• Turbidity is a measure of the degree to which the water loses its transparency due to the presence of suspended particulates. The more total suspended solids in the water, the murkier it seems and the higher the turbidity. Turbidity is considered as a good measure of the quality of water.

• Chemical Parameters

Total Dissolved Solids

Alkalinity

Hardness

Fluorides

Metals- Normal metals, Toxic metals

Organics- Biodegradable/Non biodegradable

Nutrients

• Alka
• Alkalinity or A_T measures the ability of a solution to neutralize acids measures the ability of a solution to neutralize acids to the equivalence point of carbonate or bicarbonate. Alkalinity is the presence of

• Biological Parameters

Pathogenic Organisms

Bacteria

Virus

Protozoa

Helminths

Common Diseases Transmitted to Humans through Contaminated Drinking Water

TYPES OF WATER POLLUTANTS

• Infectious agents
• Oxygen demanding wastes
• Plant nutrients
• Organic chemicals
• Inorganic chemicals
• Sediments
• Heavy metals
• Thermal
• Suspended particulate matter

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Major Water Pollutants and Their Sources

Pollutants Found in Runoff�

Sediment

Soil particles transported from their source

Biochemical Oxygen Demand (BOD)

● Oxygen depleting material

• Leaves
• Organic material

Toxics

● Pesticides

• Herbicides
• Fungicides
• Insecticides

● Metals (naturally occurring in soil, automotive emissions/ tires)

• Lead
• Zinc
• Mercury

● Petroleum Hydrocarbons (automotive exhaust and fuel/oil)

Debris

Litter and illegal dumping

Nutrients

● Various types of materials that become dissolved and suspended in water (commonly found in fertilizer and plant material):

• Nitrogen (N)
• Phosphorus (P)

Bacteria/ Pathogens

Originating from:

● Pets

● Waterfowl

● Failing septic systems

Thermal Stress

Heated runoff, removal of streamside vegetation

Science Focus: Testing Water for Pollutants (1)

• Variety of tests to determine water quality:

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• Coliform bacteria: Escherichia coli, significant levels

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• Level of dissolved oxygen (DO)

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• Chemical analysis

Science Focus: Testing Water for Pollutants (2)

• Indicator species
• Examples

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• Bacteria and yeast glow in the presence of a particular toxic chemical

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• Color and turbidity of the water

Fig. 20-A, p. 535

Good

8–9

Water Quality

DO (ppm) at 20°C

Slightly polluted

6.7–8

Moderately polluted

4.5–6.7

Heavily polluted

4–4.5

Gravely polluted

Below 4

Fig. 20-5, p. 536

Point source

Pollution-tolerant fishes (carp, gar)

Types of organisms

Normal clean water organisms (Trout, perch, bass,

mayfly, stonefly)

Fish absent, fungi, sludge worms,

bacteria (anaerobic)

Pollution-tolerant fishes (carp, gar)

8 ppm

Normal clean water organisms (Trout, perch, bass,

mayfly, stonefly)

Dissolved oxygen (ppm)

8 ppm

Biochemical oxygen demand

Clean Zone

Recovery Zone

Septic Zone

Decomposition Zone

Clean Zone

Cultural Eutrophication

• Eutrophication

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• Oligotrophic lake
• Low nutrients, clear water

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• Cultural eutrophication

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Fig. 20-13, p. 545

SOLUTIONS

Groundwater Pollution

Prevention

Cleanup

Find substitutes for toxic chemicals

Pump to surface, clean, and return to aquifer (very expensive)

Keep toxic chemicals out of the environment

Install monitoring wells near landfills and underground tanks

Inject microorganisms to clean up contamination (less expensive but still costly)

Require 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 nanoparticles of inorganic compounds to remove pollutants (still being developed)

Sewage Treatment Reduces �Water Pollution (1)

• Septic tank system

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• Wastewater or sewage treatment plants
• Primary sewage treatment
• Physical process
• Secondary sewage treatment
• Biological process
• Tertiary or advance sewage treatment
• Bleaching, chlorination

STEPS IN PRIMARY TREATMENT

• Screening
• Comminuting
• Grit removal
• Sedimentation
• Floatation
• pH Neutralization

PRIMARY TREATMENT

• Removal of large objects from

influent sewage.

Ex. by physical separation of grit and large objects (material to landfill for disposal)

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UV light radiation

• Damage the genetic structure of bacteria, viruses and other pathogens.
• Advantages: no chemicals are used
• water taste more natural
• Disadvantages: high maintenance of the UV-lamp

Ozonation

• Oxidized most pathogenic microorganisms
• Advantages: safer than chlorination

fewer disinfection by-product

• Disadvantage: high cost

SUMMARY

Solutions: Primary and Secondary Sewage Treatment

SEDIMENTATION TANK

FLOATATION TANK

Secondary treatment

• Utilizes biological treatment processes
• removes dissolved colloidal and organic matter from waste water.
• microorganisms convert nonsettleable solids to settleable solids.

Ex….

Bacteria and protozoa

:Three approaches are there to accomplish this

ACTIVATED SLUDGE PROCESS

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Trickling filter

TRICKLING FILTERS

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• Organic material present in the wastewater is metabolised by the biomass.

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• Biological slime grows in thickness as the organic matter abstracted from the flowing wastewater is synthesized into new cellular material.

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• The liquid then washes the slime off the medium and a new slime layer starts to grow------sloughing.

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• The collected liquid is passed to a settling tank used for solid- liquid separation.

Tertiary treatment

(Disinfection)

PURPOSE: Destruction of harmful (pathogenic) microorganisms,i.e.disease causing germs.

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Done through:

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1. Chlorination
2. Ozone:more powerful but unstable to store.
3. Ultraviolet light
4. Hydrogen peroxide:similar to ozone but activators such as formic acid is required to improve its working.

Chlorination

• Most common
• Advantages: low cost & effective
• Disadvantages: chlorine residue could be harmful to environment

Types of Marine Pollution

• Sedimentation

• Agricultural runoff (herbicides, pesticides and

nutrients)

• Energy (thermal and light)

• Sewage (Faecal Coliform and nutrients)

• Solid Waste

• Chemicals, Metals and Radioactive Substances

• Oil

• Biological

Fig. 20-15, p. 548

Industry Nitrogen oxides from autos and smokestacks, toxic chemicals, and heavy metals in effluents flow into bays and estuaries.

Cities Toxic metals and oil from streets and parking lots pollute waters; sewage adds nitrogen and phosphorus.

Urban sprawl

Bacteria and viruses from sewers and septic tanks contaminate shellfish beds and close beaches; runoff of fertilizer from lawns adds nitrogen and phosphorus.

Construction sites

Sediments are washed into waterways, choking fish and plants, clouding waters, and blocking sunlight.

Farms

Runoff of pesticides, manure, and fertilizers adds toxins and excess nitrogen and phosphorus.

Red tides

Excess nitrogen causes explosive growth of toxic microscopic algae, poisoning fish and marine mammals.

Toxic sediments

Chemicals and toxic metals contaminate shellfish beds, kill spawning fish, and accumulate in the tissues of bottom feeders.

Oxygen-depleted zone Sedimentation and algae overgrowth reduce sunlight, kill beneficial sea grasses, use up oxygen, and degrade habitat.

Healthy zone

Clear, oxygen-rich waters promote growth of plankton and sea grasses, and support fish.

Closed shellfish beds

Closed beach

Oxygen-depleted zone

Factories:

- discharge the hot water loaded with toxic chemicals and metals into sea

- pollute the soils on land which are then dumped into sea

- oil spillage from ships occasionally contaminates the sea

Transport:

Some major types of pollutants:

• garbage
• sewage
• chemicals
• radioactive waste
• eutrophication
• heavy metals
• oil

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3. Many beaches are polluted with solid wastes which means a loss of recreational resource.

4. Due to the polluted beaches, we have fewer places to carry out recreational activities.

4. Drinking water containing pollutants pose hazards to health. Pathogens in water would cause illnesses in human.

5. Consumption of seafood accumulated with pollutants,

would also affect our health.

What Are the Major Water Pollution Problems Affecting Oceans?

• The great majority of ocean pollution originates on land and includes oil and other toxic chemicals and solid wastes, which threaten aquatic species and other wildlife and disrupt marine ecosystems.

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• The key to protecting the oceans is to reduce the flow of pollutants from land and air and from streams emptying into these waters.

Marine Garbage

• Garbage includes junked out fishing nets, plastics, general household garbage
• In one case an island 300 miles from the nearest inhabited island) had 950 pieces of garbage ranging from plastics to tin cans.
• Garbage in the oceans is a serious issue as fish entangle themselves in fishing nets and animals sometimes eat trash products and die.
• There are numerous examples each year of dolphins, sharks and whales entangling themselves in fishing nets and dying from oxygen starvation.

Oceanic Sewage Disposal

• Typically the problem with sewage is that it causes massive nutrient loading in the ocean ecosystem.
• When nutrient loading occurs there will often be algae blooms in the water leading to the loss of dissolved oxygen.
• After the depletion of oxygen levels from sewage, many organisms in the ocean die from being unable to breathe properly.

Oceanic Sewage Disposal Cont’d

• Other problems associated with sewage include parasites/bacteria that require the closing of coastal beaches and poisoned shellfish fisheries.
• For the most part cities in the developed world have sewage treatment facilities but many of the cities in poorer areas have little to no sewage treatment.

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Oceanic Sewage Disposal Cont’d

• Other problems associated with sewage include parasites/bacteria that require the closing of coastal beaches and poisoned shellfish fisheries.
• For the most part cities in the developed world have sewage treatment facilities but many of the cities in poorer areas have little to no sewage treatment.

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Chemicals

• These are toxic substances that are released by the industrialized nations and make their way into ocean systems.
• Toxic chemicals often enter ocean systems through food chains and affect organisms at different times and places from where they were released.

Example: DDT

• (Dichlorodiphenyltrichloroethane)
• DDT was used for years as a pesticide on farms.
• Later it was found that it does not breakdown, This compound is relatively insoluble in water and bonds strongly to particles.
• Although DDT is not used in the marine environment it enters marine food webs through land runoff, precipitation and dumping.
• DDT is absorbed by plankton but cannot be metabolized.
• Since, it is not metabolized it accumulates in the food chain until it reaches the top carnivore, where more drastic effects are seen.
• For example, in marine birds, DDT interferes with calcium deposition in the eggshells. The eggs shells are extremely thin and therefore easily broken.

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Radioactive waste

• Radioactive waste enters the ocean from nuclear weapon testing, the releasing or dumping of wastes from nuclear fuel cycle systems, and nuclear accidents.
• Dumping of high-level radioactive waste is no longer permitted in the ocean, but dumping of low-level wastes is still permitted. Low-level waste contains less radioactivity per gram than high-level waste. High-level wastes usually have longer half-lives.
• For example, one common high-level waste that is produced by spent nuclear fuel has a half-life of 24,100 years!
• It has been suggested that contained nuclear waste should be disposed in the deep sea. So little is known about the deep sea environment or the consequences of containment leakage and failure, that the effects could be devastating.

Ocean Pollution Is a Growing and Poorly Understood Problem

• 2006: State of the Marine Environment
• 80% of marine pollution originates on land
• Sewage
• Coastal areas most affected

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• Deeper ocean waters
• Dilution
• Dispersion
• Degradation

Oil Spills

• Biological characteristics of the organisms affected will determine the severity of impact.
• These characteristics include the type of species, life stage (larval, juvenile or adult) and size.

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Cleaning-up oil spills:

• 1. Dispersants: Oil can be broken down more quickly by spraying dispersants (chemicals) on the oil slick from boats or planes. This method only works on fresh, small oil spills.
• 2. Booms: A boom has a floating skirt suspended down in the water and a sail holding it above the water line. The floating skirt stops the oil from passing. These are used to prevent oil from entering delicate and protected areas.
• 3. Slick-lickers: This method uses a belt of oil absorbing material that sucks up the oil from the ocean water. The oil is then squeezed out of the absorbing material into a collecting bin.

Plastic Debris

• Eighty percent of marine debris is plastic - a component that has been rapidly accumulating since the end of World War II.^[46] The mass of plastic in the oceans may be as high as one hundred million metric tons.^[47]
• Discarded plastic bagsDiscarded plastic bags, six pack rings and other forms of plastic waste which finish up in the ocean present dangers to wildlife and fisheries.^[48]
• Aquatic life can be threatened through entanglement, suffocation, and ingestion.^[49][50][51]
• Fishing netsFishing nets, usually made of plastic, can be left or lost in the ocean by fishermen. Known as ghost netsFishing nets, usually made of plastic, can be left or lost in the ocean by fishermen. Known as ghost nets, these entangle fishFishing nets, usually made of plastic, can be left or lost in the ocean by fishermen. Known as ghost nets, these entangle fish, dolphinsFishing nets, usually made of plastic, can be left or lost in the ocean by fishermen. Known as ghost nets, these entangle fish, dolphins, sea turtlesFishing nets, usually made of plastic, can be left or lost in the ocean by fishermen. Known as ghost nets, these entangle fish, dolphins, sea turtles, sharksFishing nets, usually made of plastic, can be left or lost in the ocean by fishermen. Known as ghost nets, these entangle fish, dolphins, sea turtles, sharks, dugongsFishing nets, usually made of plastic, can be left or lost in the ocean by fishermen. Known as ghost nets, these entangle fish, dolphins, sea turtles, sharks, dugongs, crocodilesFishing nets, usually made of plastic, can be left or lost in the ocean by fishermen. Known as ghost nets, these entangle fish, dolphins, sea turtles, sharks, dugongs, crocodiles, seabirdsFishing nets, usually made of plastic, can be left or lost in the ocean by fishermen. Known as ghost nets, these entangle fish, dolphins, sea turtles, sharks, dugongs, crocodiles, seabirds, crabs, and other creatures, restricting movement, causing starvation, laceration and infection, and, in those that need to return to the surface to breathe, suffocation.^[52]
• Plastic debris, when bulky or tangled, is difficult to pass, and may become permanently lodged in the digestive tracts of these animals, blocking the passage of food and causing death through starvation or infection.^[54][55]

A Large Zone of Oxygen-Depleted Water in the Gulf of Mexico Due to Algal Blooms

Ocean Oil Pollution Is a Serious �Problem (1)

• Crude and refined petroleum
• Highly disruptive pollutants

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• Largest source of ocean oil pollution
• Urban and industrial runoff from land

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• 1989: Exxon Valdez, oil tanker

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• 2002: Prestige, oil tanker

Ocean Oil Pollution Is a Serious �Problem

• Volatile organic hydrocarbons
• Kill many aquatic organisms

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• Tar-like globs on the ocean’s surface
• Coat animals

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• Heavy oil components sink
• Affect the bottom dwellers

Ocean Oil Pollution Is a Serious �Problem

• Faster recovery from crude oil than refined oil

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• Cleanup procedures

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• Methods of preventing oil spills

Fig. 20-17, p. 551

SOLUTIONS

Coastal Water Pollution

Prevention

Cleanup

Reduce input of toxic pollutants

Improve oil-spill cleanup capabilities

Separate sewage and storm lines

Use nanoparticles on sewage and oil spills to dissolve the oil or sewage (still under development)

Ban dumping of wastes and sewage by ships in coastal waters

Ban ocean dumping of sludge and hazardous dredged material

Require secondary treatment of coastal sewage

Regulate coastal development, oil drilling, and oil shipping

Use wetlands, solar-aquatic, or other methods to treat sewage

Require double hulls for oil tankers

We Need to Reduce Surface Water Pollution from Nonpoint Sources

• Reduce erosion
• Keep cropland covered with vegetation

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• Reduce the amount of fertilizers

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• Plant buffer zones of vegetation

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• Use organic farming techniques

We Need to Reduce Surface Water Pollution from Nonpoint Sources

• Use pesticides prudently

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• Control runoff

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• Tougher pollution regulations for livestock operations

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• Deal better with animal waste

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Laws Can Help Reduce Water Pollution from Point Sources

• 1972: Clean Water Act

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• EPA: experimenting with a discharge trading policy

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• Could this allow pollutants to build up?

What Can You Do? Water Pollution, Ways to Help Reduce Water Pollution