1. CHAPTER 1: Water Pollution
Prepared by: Shaheen Sardar
COURSE TITLE: Environmental issues of textile
industry
2. INTRODUCTION
• It was estimated in year 2000; 2.2 billion
people in developing countries will lack access
to safe drinking water services, 2.7 billion
people will lack to sanitation. (Glerk, 1993)
5. • Most urban centers in Africa and Asia have no
sewage system at all including many cities
with populations over one million people.
Result is tragic rate of morbidity and mortality
in less developed parts of the world.
• Water born diseases such as Cholera and
Typhoid cause more than 1.5 billion episodes
of diarrhea each year, resulting in 4 million
deaths annually (UNEP, 1993).
INTRODUCTION
6. UNUSUAL PROPERTIES OF WATER
• 2 Hydrogen to Oxygen chemical bonds form a
105° angle with each other, resulting in a
molecule that has a slightly positive charge at
one end and a slightly negative charge at the
other.
7. UNUSUAL PROPERTIES OF WATER
• This dipolar character means water molecules
are attracted to each other.
• This dipolar property shows, Water boils at
high temperature and need an unusual
amount of energy to cause it to vaporize.
• This also shows, water has high surface
tension to allow heavy objects such as insects
to keep on surface, adheres to other surfaces
easily.
8. UNUSUAL PROPERTIES OF WATER
• Combination of surface tension and adhesion
lets water crawl up the sides of objects- it
causes to Sap to rise in trees, Water to raise in
soil, and food to move through organisms.
• The dipolar property also makes water a very
effective solvent since water molecules tend
to surround charged ions and effectively
neutralize them.
9. UNUSUAL PROPERTIES OF WATER
• Density: Water expands when it freezes.
Maximum density at 4°C, below 4°C becomes
lighter, hence ice floats on surface. Above 4°C
becomes lighter, hence warm water floats on
top of cold water in lakes.
10. UNUSUAL PROPERTIES OF WATER
• Melting and Boiling Point: High boiling and
freezing (0°C) temperatures, High difference in
temperature between Melting point (0°C) and
Boiling point (100°C), thus remaining a liquid
over most of the globe.
11. UNUSUAL PROPERTIES OF WATER
• Specific Heat: Higher heat capacity (4184J/ kg
°C) than any liquid except ammonia, 5 times
higher than specific heat of most common
heavy solids, such as rock and concrete. As a
result it takes longer to heat up and to cool
down water than almost anything else. This
high heat capacity helps make the oceans the
major moderating factors in maintaining the
temperature of the surface of earth.
12. UNUSUAL PROPERTIES OF WATER
• Heat Of Vaporization: The heat required to
vaporize water (2258 KJ/ kg) is one of the
highest of all liquids. It means water vapor
stores large amount of energy, energy that is
released when the water vapor condenses.
This property distributes heat from one place
on the globe to another and is major factor
affecting the earth’s climate.
13. UNUSUAL PROPERTIES OF WATER
• Water as Solvent: It dissolves more
substances than any other common solvent.
• Greenhouse Effect: H2O Vapor is in fact the
most important green house gas in our
atmosphere. H2O Vapor in atmosphere
absorbs solar energy. H2O molecules absorb
infrared radiation leaving the earth surface.
14. THE HYDROLOGIC CYCLE:
• 97% of water in oceans.
• High concentration of salts makes it unusable.
• Evapotranspiration removes an amount of
water equivalent to a layer about 1 meter
thick around the globe each year.
• 88% evaporation is from the oceans, 12%
Evapotranspiration from land
15. THE HYDROLOGIC CYCLE:
• Removing water from wet surfaces by
evaporation, removing water from leaves from
leaves of plants by transpiration. Combination
of processes is called Evapotranspiration.
• The resulting water vapor is transported by
moving air masses and eventually condenses
and returns to earth.
• Over the ocean, there is more evaporation
than precipitation.
16. THE HYDROLOGIC CYCLE:
• Over the land, there is more precipitation than
Evapotranspiration.
• Precipitation – Evapotranspiration = Runoff
(The difference between Precipitation and
Evapotranspiration on land is water that is
returned to the oceans both by flow and
ground water flow, as runoff.
• 60% of precipitation falling on earth’s land
masses is returned to atmosphere.
17. THE HYDROLOGIC CYCLE:
• 40% of collects on surface, flowing into
streams and rivers and emptying into oceans,
while some seeps into soil to become
underground water that slowly moves toward
the seas.
• This runoff water 47,000 km3/year is a
renewable supply of fresh water that can
potentially be used year after year without
ever depleting the fresh water resources of
the world.
18.
19. STOCKS OF WATER ON EARTH
Location Amount 106Km3 Percent of Water Supply
Oceans 1338 96.5
Glaciers and permanent
snow
24.1 1.74
Ground Water 23.4 1.70
Ground ice/ Permafrost 0.30 0.022
Fresh water lakes 0.091 0.007
Saline lakes 0.085 0.006
Swamp Water 0.011 0.008
Atmosphere 0.013 0.001
Average in stream
channels
0.002 0.002
Water in living biomass 0.001 0.001
Source = Shiklomanov (1993)
20. WATER USAGE
• 10 % of world’s runoff is withdrawn for human
use each year.
• Asia with 60% World’s population has only
36% global runoff.
• South America with 5% World’s population
has 25% of runoff.
• Egypt depends on the Nile for 97% of its
surface water supply, while its neighbor
Ethiopia, controls all of the Nile’s total flow.
21. WATER USAGE
• Similar circumstances exist all around the
globe.
• Withdrawal = Consumption + Returns
• Following Scatter chart shows Per Capita
water availability for North America, Africa
and Asia due to growing population
(Shiklomanov, 1993, reprinted by permission
of Oxford University press).
23. WATER POLLUTANTS
• Withdrawal water is used for some purpose and
returned with pollutants.
• Agriculture return water contains pesticides,
fertilizers, and salts.
• Municipal return water carries human sewage.
• Power plants return water has high temperature.
• Industry return water contains chemical
pollutants and organic wastes.
24. WATER POLLUTANTS
PATHOGENS:
• Pathogens are disease-causing organisms that
grow and multiply within the host.
• The resulting growth of microorganisms in a
host is called an infection.
• Examples of pathogens associated with water
include Virus, Bacteria, Protozoan, and
Helminthes.
• Diseases include Cholera, Malaria, and
Dengue.
25. WATER POLLUTANTS
OXYGEN DEMANDING WASTES:
• Oxygen Demanding Wastes are usually
biodegradable organic substances contained
in municipal waste water or influents from
certain industries.
• These oxidize in receiving body of water. As
bacteria decompose these wastes, they utilize
oxygen dissolved in water, which reduces
remaining amount of dissolved oxygen (DO).
26. WATER POLLUTANTS
OXYGEN DEMANDING WASTES:
• Important measure of quality of water source
is the amount of dissolved oxygen.
• Saturated value of dissolved oxygen (DO) in
water is 8-15 mg of oxygen/ liter of water.
• For heavy fish population recommended
amount of dissolved oxygen (DO) is minimum
5mg/ liter.
27. WATER POLLUTANTS
• Nutrients: Nutrients are chemicals such as
Nitrogen, Phosphorus, Carbon, Sulfur,
Calcium, Potassium, Iron, Manganese, Boron,
and Cobalt, which are essential to the growth
of living things.
• They are pollutants when their concentrations
are sufficient to allow growth of aquatic
plants, particularly algae.
28. WATER POLLUTANTS
• Nutrients: There are over 21,000 known types
of algae that are grouped into 7 different
categories by microbiologists.
• When algae die and decompose, their
decomposition removes oxygen from H2O
making the water unacceptable.
31. WATER POLLUTANTS
• Nutrients: Important nutrients are Carbon,
Nitrogen, and Phosphorus.
• Carbon is available from alkalinity,
atmosphere, and decaying organic matter.
• Nitrogen is available from municipal
wastewater discharges, runoff from animal
feedlots, chemical fertilizers, and atmosphere.
32. WATER POLLUTANTS
• Nutrients:
• Nitrogen in water is found in the form of
nitrate NO3, which is not toxic. Certain
bacteria found in intestinal tract of infants
convert nitrates NO3, nitrites NO2.
• Phosphorous is available from agriculture
runoff in heavily fertilized areas and domestic
sewage from human feces and detergents.
33. WATER POLLUTANTS
• Salts: Water naturally accumulates a variety of
dissolved solids, or salts, as it passes through
soils and rocks on its way to the sea.
• These salts include cations and anions.
• Cations are Sodium, Calcium, Magnesium, and
Potassium.
• Anions are Chloride, Sulfate, and Bicarbonate.
34. WATER POLLUTANTS
• Salts: The concentration of dissolved solid is
an important indicator of the usefulness of
water for various applications.
• For drinking water, maximum 500 mg/liter of
total dissolved solids (TDS) is suitable.
• For crops up to 1500 mg/liter TDS is
acceptable with little loss of yield, But above
2100 mg/liter TDS, H2O is unsuitable for
irrigation.
35. WATER POLLUTANTS
SALTS:
• Fresh water has concentration of total
dissolved solids (TDS) less than 1500 mg/liter.
• Brackish water has less than 5000 mg/liter
TDS.
• Saline water has above 5000 mg/liter TDS.
• Sea Water contains 30,000 – 34,000 mg/liter
TDS
36. WATER POLLUTANTS
• Thermal Pollution: A large steam electric
power plant requires an enormous amount of
cooling water.
• A typical nuclear plant warms about 150,000
m3 / hour of cooling water.
• If that heat is released into a local river or
lock, the resulting rise in temperature can
affect the aquatic life
37. WATER POLLUTANTS
• Heavy metals:
• From a physical perspective, metals are
characterized by high thermal and electrical
conductivity, high reflectivity, and metallic
luster, strength and ductility.
• From a chemical perspective, metal is an
element that will give up one or more
electrons to form a cation in an aqueous
solution. About 80 elements can be called
metals.
38. WATER POLLUTANTS
• Heavy metals:
• In terms of their environmental impacts, the
most important heavy metals are mercury
(Hg), Lead (Pb), Cadmium (Cd), and arsenic
(As).
• Toxic metals are Aluminium, Beryllium,
Bismuth, Cadmium, Chromium, Cobalt,
Copper iron, Lead, Manganese, Mercury,
Nickel, Selenium, Strontium, Thallium, Tin,
Titanium, and Zinc.
39. WATER POLLUTANTS
• Heavy metals:
• Metals are non-degradable.
• Chromium and iron are essential nutrients,
but high doses have bad impacts on the body
including nervous system and kidney damage,
creation of mutations, and induction of
tumors.
• Metals may be inhaled, and they may be
ingested like Lead and Mercury.
40. WATER POLLUTANTS
• Heavy metals:
• Liquid Hg is less toxic, but Mercury vapor is
highly toxic. Hg vapor enters the lungs and
diffuses into blood stream. When this blood
reaches the brain, causes serious damage to
the central nervous system.
• Lead vapor is less toxic, but most dangerous
when it is dissolved into its ionic form Pb++.
41. WATER POLLUTANTS
• Heavy metals:
• Lead dissolved in blood is transferred to vital
organs including kidneys and brain, and causes
damage.
• Metals are eliminated through kidneys.
Chemicals that are toxic to the kidneys are
called nephrotoxic. Cd, Pb, and Hg are
examples of nephrotoxic metals.
42. WATER POLLUTANTS
PESTICIDES:
• Pesticides are the chemicals that kill
undesirable organisms.
• Some water related pesticides are
Insecticides, herbicides, rodenticides, and
fungicides.
• Pesticides have adverse effect on the life of
human, birds, and animals.
43. WATER POLLUTANTS
• Volatile organic compounds (VOC): These are
commonly found contaminant in groundwater. They
are used as solvent in industrial process. Following
are five toxic Volatile organic compounds. Most toxic
of five is vinyl Chloride (Chloroethylene).
(1) Vinyl Chloride,
(2)Tetrachloroethylene,
(3)Trichloroethylene,
(4)1,2-dichloroethane,
(5)Carbon Tetrachloride
44. STATUS OF SURFACE WATER QUALITY
• Body of water is said to be impaired when at
least one of the designated beneficial uses,
such as fish consumption, is not supported b
the quality of water.
• These beneficial uses of surface water are
given on the next slide. (Source: U.S. EPA,
1994)
45. BENEFICIAL
USE
DESCRIPTOR
Aquatic life
support
The water body provides suitable habitat for survival and
reproduction of desirable fish, shellfish, and other aquatic
organisms.
Fish Consumption The water body supports a population of fish free from
contamination that could pose a human health risk to consumer.
Shellfish
Harvesting
The water body supports a population of shellfish free from
toxicants and pathogens that could pose a human health risk to
consumer.
Drinking Water
Supply
The water body can supply safe drinking water with conventional
treatment.
Primary Contact
recreation
People can swim in the water body without risk of adverse human
health effects.
Secondary
Contact recreation
People can perform activities (like Kayaking) on the water body
without risk of adverse human health effects from occasional
contact with water.
Agriculture The water quality is suitable for irrigating livestock.
46. STATUS OF SURFACE WATER QUALITY
Percent of assessed lake acres impaired by pollution (a) by pollutants (b) by
sources of pollution (U.S. EPA, 1994):
(a) BY POLLUTANT
0 10 20 30 40 50
Metals
Nutrients
Organic Enrichment/ DO
Siltation
Priority organic chemicals
Percent
47. STATUS OF SURFACE WATER QUALITY
Percent of assessed lake acres impaired by pollution (a) by pollutants (b) by
sources of pollution (U.S. EPA, 1994):
(b) BY SOURCE
Percent
0 10 20 30 40 50 60
Agriculture
Urbon runoff/ storm Sewers
Hydrologic/ habitat modification
Municipal Point Sourse
Onsite wastewater disposed
48. STATUS OF SURFACE WATER QUALITY
Percent of assessed river miles impaired by pollution (a) by pollutants (b) by
sources of pollution (U.S. EPA, 1994):
(a) BY POLLUTANT
Percent
0 10 20 30 40 50
Siltation
Nutrients
Pathogen indicators
Peticides
Organic Enrichment/ DO
49. STATUS OF SURFACE WATER QUALITY
Percent of assessed river miles impaired by pollution (a) by pollutants (b) by
sources of pollution (U.S. EPA, 1994):
(b) BY SOURCE
Percent
0 10 20 30 40 50 60 70 80
Agriculture
Municipal Point Sourse
Urbon runoff/ storm Sewers
Resourse extraction
Industrial point sourse
Silviculture
Hydrologic/ habitat modification
50. WATER TREATMENT SYSTEMS
• Purpose is to bring raw water up to drinking
water quality.
• Surface water tends to have more contamination,
so filtration is a necessity.
• Ground water is uncontaminated, has relatively
little suspended solids, so filtration is less
important.
• Ground water may have objectionable dissolved
gases and hardness (ions of calcium and
magnesium).
51. WATER TREATMENT SYSTEMS
WATER TREATMENT:
A treatment plant for surface water includes the
following sequence of steps.
(1) Screening: To remove large floating and
suspended debris.
(2) Mixing the water with chemicals: Chemicals
encourage suspended solids to coagulate into
large particles, which will settle more easily.
(3) Flocculation: Process of gently mixing the
water and coagulant, allowing the formation of
large particles of floc.
52. WATER TREATMENT SYSTEMS
WATER TREATMENT:
(4) Sedimentation and filtration: In the
Sedimentation, flow is slowed enough so that
gravity will cause the floc to settle. In the
filtration, effluent is cleaned.
(5) Sludge processing: The mixture of solids and
liquids collected from the settling tank is
dewatered and disposed of.
(6) Disinfection and fluoridation: To ensure that
the water is free of harmful pathogens, and to
control dental caries.
(7) Hardness Removal or Softening: It may be
added as an additional step for ground water.
53. WATER TREATMENT SYSTEMS
WATER TREATMENT:
Mixing
Tank
Flocculation
Basin
Settling
Tank
Sand
Filter
Disinfection
Fluoridation
Sludge
processing
Source
Screening
Addition of
coagulant
54. HAZARDOUS WASTES
• Hazardous substances or materials have some
commercial value.
• There are more than 1000 Hazardous
chemicals.
• Hazardous waste is a material that has been
used, spilled, or is no longer needed.
55. HAZARDOUS WASTES
• Hazardous waste is defined as “Anything which
(because of its quantity, concentration, or physical,
chemical, or infectious characteristics) may cause or
significantly contribute to an increase in mortality; or
cause an increase in serious (irreversible, or
incapacitating reversible) illness; or pose a
substantial present or potential hazard to human
health and the environment when improperly
treated, stored, transported, or disposed of or
otherwise managed.”
56. HAZARDOUS WASTES
• Hazardous substances have following four
characteristic attributes:
• (1) Reactivity: Reactive substances are
instable under control conditions. They can
cause explosions and/ or liberate toxic fumes,
gases, and vapors when mixed with water.
• (2) Ignitability: Ignitable substances are easily
ignited and burn vigorously and persistently.
57. HAZARDOUS WASTES
• Hazardous substances have following four
characteristic attributes:
• (3) Corrosivity: Corrosive substances include
liquids with PH less than 2 or greater than
12.5. They are capable of corroding metal
containers.
• (4) Toxicity: Toxic substances are harmful or
fatal when ingested or absorbed.
58. HAZARDOUS WASTES
• Hazardous wastes are organized into following
three categories:
• (1) Source specific wastes: These include
Sludges and wastes waters from treatment and
production processes in specific industries.
• (2) Generic wastes: These include wastes from
common manufacturing and industrial
processes.
• (3) Commercial chemical products: These
include benzene, creosote, mercury and various
pesticides.
59. HAZARDOUS WASTE TREATMENT
TECHNOLOGIES:
• In the past, there was little treatment, and disposal
was often on land.
• Treatment technologies have following categories:
• (1) Chemical treatment: It transforms waste into less
hazardous substances using such techniques as PH
neutralization, oxidation or reduction, and
precipitation.
• (2) Biological treatment: It uses microorganisms to
degrade organic compounds in the waste stream.
60. HAZARDOUS WASTE TREATMENT
TECHNOLOGIES:
• (3) Physical treatment: It includes gravity separation,
phase change systems such as air and steam
stripping of volatiles from liquid wastes, various
filtering operations including carbon adsorption.
• (4) Thermal Destruction Process: These include
incineration, and pyrolysis (chemical decomposition
of waste brought about by heating the material in
the absence of oxygen).
61. HAZARDOUS WASTE TREATMENT
TECHNOLOGIES:
• (5) Fixation/ Stabilization techniques: These involve
removal of excess water from a waste and solidifying
the remainder either by mixing it with a stabilizing
agent, such as Portland cement, or vitrifying it to
create a glassy substance.
