Lecture 18Lecture 18Water PollutionWater Pollution

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Clean Water

Water TerminologyWater Terminology

Surface waterSurface water: Fresh water found on Earth surface in stream and : Fresh water found on Earth surface in stream and rivers, lakes, ponds, reservoirs, and wetlandsrivers, lakes, ponds, reservoirs, and wetlands

GroundwaterGroundwater refers to the water below the water table where refers to the water below the water table where saturated conditions existsaturated conditions exist

This water originates as surface water seeps into the soil and This water originates as surface water seeps into the soil and finds its way to the groundwater aquiferfinds its way to the groundwater aquifer

AquiferAquifer is an underground zone or body of Earth material from is an underground zone or body of Earth material from which groundwater can be obtainedwhich groundwater can be obtained

Water BudgetWater Budget is a model that balances the inputs, outputs, and is a model that balances the inputs, outputs, and storage of water in a systemstorage of water in a system

The various processes of the hydrologic cycle are input & output The various processes of the hydrologic cycle are input & output terms of the water balanceterms of the water balance

The The global water budget isglobal water budget is balancedbalanced by the circulationby the circulation systemssystems on on land, in the atmosphere, and in the oceans that move water from land, in the atmosphere, and in the oceans that move water from areas of excess to area of deficitareas of excess to area of deficit

Water UseWater Use

Water use can be classified into four broad categories: Water use can be classified into four broad categories: (1)(1) domestic usedomestic use; ; (2)(2) agricultural useagricultural use; ; (3)(3) industrial useindustrial use; and ; and (4)(4) in-stream usein-stream use

It is important to remember that some uses of water are It is important to remember that some uses of water are consumptiveconsumptive, while others are , while others are nonconsumptivenonconsumptive

Domestic use accounts for about Domestic use accounts for about 10%10% of the total water of the total water withdrawalswithdrawals

However, in regions experiencing rapid population growth However, in regions experiencing rapid population growth domestic use is expected to increase sharplydomestic use is expected to increase sharply

Water UseWater Use

Water use can be classified into four broad categories: Water use can be classified into four broad categories: (1)(1) domestic usedomestic use; ; (2)(2) agricultural useagricultural use; ; (3)(3) industrial useindustrial use; and ; and (4)(4) in-stream usein-stream use

It is important to remember that some uses of water are It is important to remember that some uses of water are consumptiveconsumptive, while others are , while others are nonconsumptivenonconsumptive

Domestic use accounts for about Domestic use accounts for about 10%10% of the total water of the total water withdrawalswithdrawals

However, in regions experiencing rapid population growth However, in regions experiencing rapid population growth domestic use is expected to increase sharplydomestic use is expected to increase sharply

Water UseWater Use

Agricultural UseAgricultural Use Irrigation is the major Irrigation is the major

consumptive use of water consumptive use of water in most parts of the world in most parts of the world and it accounts for about and it accounts for about 68%68% of the total water of the total water withdrawalswithdrawals

Improved agricultural Improved agricultural irrigationirrigation could reduce could reduce withdrawals by between withdrawals by between 20 and 30%20 and 30%

Industrial water use Industrial water use accountsaccounts for about for about 22%22% worldwideworldwide. Since most . Since most industrial processes industrial processes involve heat exchanges, involve heat exchanges, 90% of the water used by 90% of the water used by industry is for cooling and industry is for cooling and is returned to the source, is returned to the source, so only a small amount is so only a small amount is actually consumed actually consumed

Water UseWater Use

In-stream UseIn-stream Use includes the use of includes the use of rivers for navigation, rivers for navigation, hydroelectric power hydroelectric power generation, fish and generation, fish and wildlife habitats, and wildlife habitats, and recreationrecreation

Consumptive UseConsumptive Use is an is an off-stream off-stream use in which water does not return to use in which water does not return to the stream or groundwater resource the stream or groundwater resource immediately after useimmediately after use

This water is consumed by plants and This water is consumed by plants and animals or in industrial processes and animals or in industrial processes and enters human tissue or products or enters human tissue or products or evaporates during use but is not evaporates during use but is not returned to its sourcereturned to its source

Water PollutionWater Pollution Water Pollution Water Pollution refers to degradation of water qualityrefers to degradation of water quality Any physical, chemical, or biological change in water quality Any physical, chemical, or biological change in water quality

that adversely affects living organisms or makes water that adversely affects living organisms or makes water unsuitable for desired use can be considered pollutionunsuitable for desired use can be considered pollution

Water pollutantsWater pollutants include excessive amounts of heavy metals, include excessive amounts of heavy metals, certain radioactive isotopes, fecal coliform bacteria, certain radioactive isotopes, fecal coliform bacteria, phosphorus, nitrogen, sodium, and other useful elements, phosphorus, nitrogen, sodium, and other useful elements, acids, suspended solids and sediment, organic chemicals, acids, suspended solids and sediment, organic chemicals, oxygen demanding wastes and effluents, as well as certain oxygen demanding wastes and effluents, as well as certain pathogenic bacteria and virusespathogenic bacteria and viruses

The signs of water pollutionThe signs of water pollution: bad taste, offensive odors from : bad taste, offensive odors from lakes, rivers, and sea beaches; unchecked growth of aquatic lakes, rivers, and sea beaches; unchecked growth of aquatic weeds in water bodies; decrease in number of aquatic animals in weeds in water bodies; decrease in number of aquatic animals in surface water bodies; oil and grease floating on water surfaces; surface water bodies; oil and grease floating on water surfaces; coloration of water, etc. Outbreak of a waterborne disease is a coloration of water, etc. Outbreak of a waterborne disease is a particularly visible type of water pollution particularly visible type of water pollution

Water Pollution SourcesWater Pollution Sources

Natural sourcesNatural sources include poison springs, oil seeps, include poison springs, oil seeps, sedimentation from erosionsedimentation from erosion

With exploding human population pollution by agricultural, With exploding human population pollution by agricultural, municipal and industrial sources has become a major concern municipal and industrial sources has become a major concern for the welfare of mankindfor the welfare of mankind

All segments of our societyAll segments of our society (urban, rural, industrial, agricultural, (urban, rural, industrial, agricultural, military) may contribute to the problem of water pollutionmilitary) may contribute to the problem of water pollution

MostMost of the sources result from of the sources result from runoffrunoff and and leaksleaks or or seepageseepage of of pollutantspollutants

Pollutants are also transported by air and deposited in water Pollutants are also transported by air and deposited in water bodiesbodies

Water Pollution SourcesWater Pollution Sources

Point sourcesPoint sources include include factories, power plants, factories, power plants, sewage treatment plants, sewage treatment plants, underground coal mines, underground coal mines, oil wells, etcoil wells, etc

Nonpoint sourcesNonpoint sources such such as runoff are diffused and as runoff are diffused and intermittent and influenced intermittent and influenced by many factors such as by many factors such as land use, climate, land use, climate, topography, hydrology, topography, hydrology, vegetation etcvegetation etc

Difficult to monitor and Difficult to monitor and controlcontrol

Urban nonpoint sourcesUrban nonpoint sources include urban runoff from include urban runoff from streets or fieldsstreets or fields

Such runoff contains all Such runoff contains all sorts of pollutants, from sorts of pollutants, from heavy metals to chemicals heavy metals to chemicals and sediment and sediment

Rural sources of Rural sources of nonpointnonpoint pollution are pollution are associated with associated with agriculture, mining, or agriculture, mining, or forestryforestry

Point source

Muddy River polluted by SedimentMuddy River polluted by Sediment//// Nonpoint Nonpoint sourcesource

Nonpoint sourceNonpoint source

Dust storm, Texas

Eutrophication

Water PollutionWater Pollution

Arsenic Contamination of Groundwater Arsenic Contamination of Groundwater has been reported in has been reported in 20 countries20 countries of the of the world encompassing all the continents but world encompassing all the continents but the extent of groundwater contamination in the extent of groundwater contamination in BangladeshBangladesh is by far the most severe as it is by far the most severe as it covers almost covers almost 80% of the country80% of the country

61 out of 64 districts61 out of 64 districts, the Southern, South-, the Southern, South-Western, and North-eastern regions of the Western, and North-eastern regions of the country are worst affected, threatening lives country are worst affected, threatening lives of almost of almost 75 million people75 million people

Levels of arsenic in underground drinking Levels of arsenic in underground drinking water is so high so that water is so high so that WHO describesWHO describes arsenic contamination of Bangladesh’s arsenic contamination of Bangladesh’s water supply as water supply as “ the largest poisoning of “ the largest poisoning of population in history”population in history”

Waterborne Diseases and Health Effects of Water PollutionWaterborne Diseases and Health Effects of Water Pollution Each year Each year several billionseveral billion people particularly in poor countries are people particularly in poor countries are

exposedexposed to waterborne diseases whose effects vary in severity from to waterborne diseases whose effects vary in severity from upset stomach to deathupset stomach to death

Historically, outbreaks of serious waterborne diseases such as Historically, outbreaks of serious waterborne diseases such as diarrhoea, cholera, and typhoid feverdiarrhoea, cholera, and typhoid fever have caused tremendous have caused tremendous hardships on society and hardships on society and killed thousandskilled thousands of people of people

As much as 80% of all disease and some 25 million deaths each year As much as 80% of all disease and some 25 million deaths each year may be attributable to water contaminationmay be attributable to water contamination

Escherichia coliEscherichia coli, a type of fecal coliform bacteria responsible for , a type of fecal coliform bacteria responsible for causing humancausing human illness and deathillness and death

Outbreaks result from eating Outbreaks result from eating contaminated meatcontaminated meat and drinking and drinking contaminated contaminated juices or waterjuices or water

Water with any fecal coliform bacteria unsuitable for drinkingWater with any fecal coliform bacteria unsuitable for drinking

Human and animal wastes usually create the most serious health-Human and animal wastes usually create the most serious health-related water pollution problemsrelated water pollution problems

More than 500 typesMore than 500 types of disease-causing bacteria, viruses, and of disease-causing bacteria, viruses, and parasites can travel parasites can travel from human and animal excrementfrom human and animal excrement through water through water

Pollution ControlPollution Control

Two approachesTwo approaches to deal with water pollution problems are: to deal with water pollution problems are:1.1. Reduce the sourcesReduce the sources

2.2. Treat the water to remove or convert the pollutants to Treat the water to remove or convert the pollutants to harmless formsharmless forms

Reduction at the source is the most environmentally preferable Reduction at the source is the most environmentally preferable way of dealing with pollutantsway of dealing with pollutants

The second method is used for a variety of pollution problemsThe second method is used for a variety of pollution problems—include chlorination and filtering of water to remove —include chlorination and filtering of water to remove contaminants and chemical treatment with material such as contaminants and chemical treatment with material such as ozone which oxidizes certain pollutantsozone which oxidizes certain pollutants

Soil conservation methods help protect water qualitySoil conservation methods help protect water quality Applying precisely determined amounts of fertilizers, irrigation Applying precisely determined amounts of fertilizers, irrigation

water, and pesticideswater, and pesticides Preserving wetlandsPreserving wetlands

Wastewater Treatment Plant

Water Conservation & Sustainable UseWater Conservation & Sustainable Use

Water ConservationWater Conservation is the careful use and protection of water is the careful use and protection of water resources and involves both the quantity of water used and its resources and involves both the quantity of water used and its quality quality

Conservation is an essential component of Conservation is an essential component of sustainable water sustainable water useuse

Sustainable Water UseSustainable Water Use may be defined as the use of water may be defined as the use of water resources by people that allows our society to develop and resources by people that allows our society to develop and flourish into an indefinite future without degrading the various flourish into an indefinite future without degrading the various components of the hydrologic cycle or the ecological systems components of the hydrologic cycle or the ecological systems that depend on itthat depend on it

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