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Title: LIVING WITH THE EARTH


1
LIVING WITH THE EARTH
CHAPTER 9 WATER AND WASTEWATER
2
Objectives for this Chapter
  • A student reading this chapter will be able to
  • 1. List and describe the different stages of the
    hydrological cycle and the relative amounts of
    freshwater on the planet.
  • 2. List the three main consumers of water, noting
    each consumers major use of water.

3
Objectives for this Chapter
  • A student reading this chapter will be able to
  • 3.Discuss water scarcity, pointing out the areas
    of the world at risk of water shortage and
    potential associated conflict. Describe some
    methods of water management.
  • 4. List and describe several sources of
    freshwater, and describe the types of wells used
    to pump groundwater.

4
Objectives for this Chapter
  • A student reading this chapter will be able to
  • 5. Describe groundwater formation, including a
    discussion of contamination, recharge, water
    mining, fossil water and some problems associated
    with overuse.
  • 6.List the various sources and types of pollution
    threatening water supplies, noting the difference
    between point and nonpoint sources.

5
Objectives for this Chapter
  • A student reading this chapter will be able to
  • 7. Briefly outline the Clean Water Act and the
    Safe Drinking Water Act, explaining the purpose
    of each.
  • 8.Describe the process and purpose of wastewater
    treatment. List the components of a septic
    system, and the components of a typical
    wastewater treatment plant. Define and describe
    BOD and sag curve.

6
WATER and WASTEWATER
  • Introduction
  • Water is cheap, accessible, plentiful, and
    relatively safe to drink.
  • Differences in beliefs about the importance of
    water quality, water scarcity, and water use can
    cause conflict and hinder a joint effort to
    protect the worlds water supplies.

7
The Properties of Water
  • Water is a unique compound (Fig. 9-1)
  • Water exerts a major influence on the earths
    environments.
  • Water carries partial negative charge and partial
    positive charge, and easily dissolves most polar
    molecules. It is critical to life.
  • Water exists as a solid, a liquid, and a vapor.
    Water is essential in maintaining temperature of
    planet.

8
Fig. 9-1
9
Hydrological Cycle
  • The hydrological cycle is a process involving the
    sun, the atmosphere, the earth and water (Fig.
    9-2).
  • This cycle consists of evaporation, condensation,
    transportation, transpiration, precipitation, and
    runoff.

10
Fig. 9-2
11
Water Resources
  • Water covers 71 of the earths surface. The
    approximate amount of water on the earth is 1.3
    billion cubic kilometers.
  • Humans and animals require freshwater for
    consumption, which makes up only 3 of the total
    amount of water.

12
Water and Health
  • Access to clean water is critical to human
    well-being and survival.
  • Over 1.7 billion people in the world lack access
    to clean drinking water.

13
Water Shortage and Scarcity
  • A 1995 World Bank report indicated that 40 of
    the worlds population live in countries facing
    water shortages.
  • Globally, the demand for water has been
    increasing at about 2.3 annually, with a
    doubling of demand occurring every 21 years.

14
Water Shortage and Scarcity
  • One out of every five people on this planet lacks
    a clean water supply.
  • At some point in the future, worldwide water use
    will be limited by physical, economic and
    environmental limitations.

15
Water Rights and Conflicts
  • Many major water sources cross national
    boundaries, ensuring disputes between countries
    staking their claim to this valuable resource.
  • Bangladesh, India, Pakistan
  • NYC

16
Water Consumption and Management
  • Many factors impact the amount and the way a
    country uses water, including the economy,
    available technology, level of industry, and
    agriculture, culture, and climate.

17
Water Consumption and Management
  • Effective water management would improve water
    efficiency, decrease consumption, and help
    preserve remaining resources.
  • Sustainable water use implies that current needs
    are met without diminishing the resource for
    future generations use and at no expense to
    environmental need.

18
Water Use
  • Overview
  • The three major water consumers in the world are
    agriculture, industry, and households or
    individual use.
  • In the United States, the average daily per
    capita water use from public supplies is
    approximately 180 gallons per day.

19
Water Use
  • Agriculture
  • Agriculture consumes the largest portion of the
    freshwater supply, with over two-thirds of the
    worlds water demand used for irrigation.
  • Sixty percent of this water is lost to
    evaporation or runoff.

20
Water Use
  • Industry
  • The industrial sector also uses large quantities
    of water for numerous purposes, including
    manufacturing, cooling and condensation by power
    plants, and waste disposal.
  • Approximate industrial water use in the United
    States is over 200 billion gallons per day.

21
Water Use
  • Domestic
  • Per capita domestic use in the United States
    ranges between 75-135 gallons per capita per day
    (gpcd) (Fig. 9-3).
  • The bulk of domestic water use serves for
    flushing toilets, showering, and watering lawns.

22
Fig. 9-3
23
Sources of Drinking Water
  • Surface Water
  • The United States has vast amounts of surface
    water, with 3.5 million miles of rivers and
    streams and 41 million acres of lakes.
  • Due to its exposed state, surface water is prone
    to contamination from a number of sources,
    including diffuse pollution such as agricultural
    runoff.

24
Surface Water
  • Surface water sources and water sheds require
    protection and management to limit or prevent
    contamination.
  • Watershed fencing, limited recreational access,
    and public education can help protect surface
    waters against pollution.

25
Ground Water
  • Groundwater volume worldwide is estimated to be
    8.5 million km3 or 0.62 of the total water
    volume.
  • Groundwater sources supply drinking water to 50
    of the people living in the United States and to
    90 of people living in U.S. rural areas.

26
Ground Water
  • When rain falls on the earth, some of the water
    percolates downward through the spaces in the
    soil, pulled by gravity.
  • At a certain point, the water reaches an
    impermeable layer of rock. At this layer, the
    water stops moving (Fig. 9-4).

27
Fig 9-4
28
Wells
  • Several types of wells exist, ranging from the
    crude to the sophisticated. Some wells are dug
    (Fig. 9-5) or bored others are driven or
    drilled (Fig. 9-6).

29
Fig. 9-5dug well
30
Fig. 9-6drilled well
31
Groundwater Contamination
  • Potential pollution sources in the United States
    include
  • (1) over 23 million septic systems
  • (2) between five and six million underground
    storage tanks
  • (3) millions of tons of pesticides and
    fertilizers and
  • (4) municipal landfills, and abandoned hazardous
    waste sites.

32
Groundwater Contamination
  • Point Source
  • Refers to pollutants entering the environment
    from a specific point such as a pipe or a
    specific source such as a factory or treatment
    plant.
  • Non-point source
  • Refers to pollutants entering the environment
    from a broad area and may include scattered
    sources (Table 9-1).

33
Table 9-1
34
Recharge and Water Mining
  • Recharge is the replacement of groundwater by
    natural processes.
  • Water stress is an actual term defined as the
    ratio of water withdrawal to water availability.

35
Recharge and Water Mining
  • Water systems such as the Ogallala aquifer are
    stressed from the large quantities of water being
    pumped out of these underground sources (Fig.
    9-7).

36
Fig. 9-7
37
Recharge and Water Mining
  • Certain sources of groundwater are considered
    nonrenewable resources, like coal or oil.
  • The overuse of these fossil waters is called
    water mining, because the resource is being
    permanently depleted.

38
Subsidence and Salination
  • Subsidence
  • Involves a settling of the soil as the water is
    pumped out.
  • Salination
  • As water is pumped out of the aquifer, the zone
    of saturation decreases at both the upper and
    lower levels. Saltwater can seep into the aquifer
    at the lower level, polluting the freshwater.

39
The Following Laws Protect the Waters of the U.S.
  • RCRA
  • CERCLA
  • SDWA
  • FIFRA
  • TSCA

40
Water Pollution
  • Much of the pollution that threatens our water
    supply today is anthropogenic in that it is
    generated by humans, and not part of a natural
    process.
  • Industry, agriculture, and overpopulation have
    all contributed to pollution of the worlds water
    supply.

41
Water Pollution
  • Some strategies to protect water supplies include
    protection of areas near sources of drinking
    water, limitations on pollutant discharges into
    our waterways, and the processes of chlorination
    and filtration.

42
Water Pollution
  • Federal Water Pollution Control Act of 1972
  • Clean Water Act of 1977
  • The EPA estimates that public and private costs
    for water pollution treatment is 64 million/year.

43
Water Quality
  • Water quality encompasses various characteristics
    of water, from taste, and color to temperature
    and purity.
  • Water quality can vary, depending on its intended
    use high quality is needed for drinking water
    lower quality is sometimes acceptable for
    irrigation purposes, as in wastewater reuse.

44
Water Quality
  • Different types of pollutants may contaminate a
    water supply, these can be categorized as
  • physical,
  • chemical,
  • biological and
  • radioactive contaminants.

45
Types of Pollution
  • Inorganic compounds
  • Of particular concern are lead, cadmium, mercury,
    arsenic, and copper.
  • These substances can cause serious acute and
    chronic health problems.

46
Types of Pollution
  • Synthetic Organic Chemicals
  • Synthetic organic compounds can be classified as
    volatile organic compounds (VOCs) or synthetic
    organic chemicals (SOCs).
  • Sources of synthetic organic compounds include
    industry, agriculture, even households.

47
Synthetic Organic Chemicals
  • VOCs present a threat to groundwater, where they
    are less able to vaporize and can accumulate.
  • SOCs threaten surface waters, through both
    accidental and purposeful discharges into water
    ways.

48
Types of Pollution
  • Radiation
  • The most common radioactive substances in water
    are radium, uranium, radon and certain man-made
    radionuclides.
  • While naturally occurring radionuclides appear
    mainly in groundwater, surface waters are more
    likely to contain artificial radionuclides from
    atmospheric fallout.

49
Sources of Pollution
  • Point Source
  • Underground Injection Wells
  • Industrial Discharges
  • National Pollution Discharge Elimination System
    (NPDES)

50
Sources of Pollution
  • Nonpoint Source
  • Agriculture
  • Pesticides
  • Fertilizer
  • Eutrophication

51
Sources of Pollution
  • Nonpoint Source
  • Stormwater
  • Acid Mine Discharge
  • Waterborne Disease
  • Over 900 deaths annually in the U.S.

52
Water Treatment
  • Municipal Water Treatment
  • In the United States, most of the drinking water
    comes from 200,000 community water supply
    systems.
  • These systems include approximately 140,000 small
    scale suppliers and 60,000 municipal supply
    systems, and supply water to 241 million
    Americans.

53
Water Treatment
  • The main steps of treatment are
  • Sedimentation
  • coagulation-flocculation,
  • filtration, and
  • disinfection.

54
Disinfection
  • The most critical step in water treatment,
    disinfection, should destroy all organisms in the
    water supply.
  • Chlorine is the major disinfectant used in United
    States water systems today.
  • Trihalomethanes

55
Regulations
  • Safe Water Drinking Act
  • Allows the United States EPA to set Maximum
    Contaminant Levels (MCLs) for water pollutants to
    protect the public health.
  • Enforcement of the SDWA is left to the individual
    states, with oversight provided by the Office of
    Groundwater and Drinking Water, a division of the
    USEPA.

56
Water Disposal and Treatment
  • Sewage
  • In many developing countries around the world,
    human waste pollutes the land and the water.
  • This organic material can serve as food for
    organisms living in the water.

57
Biological Oxygen Demand (BOD)
  • As microorganisms decompose organic material in
    surface water, they use oxygen dissolved in the
    water.
  • If a waterway is overloaded with biodegradable
    organic pollutants, this decomposition process
    can deplete the supply of dissolved oxygen.

58
Biological Oxygen Demand (BOD)
  • The deoxygenation and reaeration of water can be
    presented graphically as a Sag Curve.
  • A Sag Curve demonstrates the level of dissolved
    oxygen over time, showing the critical level
    where aquatic life dies (Fig. 9-8).

59
Fig. 9-8
60
Types of Disposal
  • Pit privies (Fig. 9-9)
  • Septic Systems (9-10, 9-11)
  • Municipal Sewage Treatment

61
Fig. 9-9
62
Fig. 9-10
63
Fig 9-11 Failed septic system
64
Fig 9-12a
65
Fig 9-12b
66
Municipal Sewage Treatment
  • Sewage treatment speeds up waters natural
    process of purification, through biooxidation,
    filtration and settling.
  • Several stages of treatment include primary
    secondary and tertiary treatments and sludge
    disposal ( Fig. 9-13).

67
Fig. 9-13a
68
Fig. 9-13b
69
Municipal Sewage Treatment
  • Primary Treatment
  • Primary treatment is largely a mechanical
    process, concerned with the removal of solids.
  • Sewage first passes through a bar screen, then a
    grinder or Comminuter (Figs. 9-14a 9-14b)
  • Clarification or solids separation (Fig. 9-15a
    9-15b))

70
Fig. 9-14a
71
Fig 9-14b
72
Fig. 9-15a
73
Fig 9-15b
74
Municipal Sewage Treatment
  • Secondary Treatment
  • Trickling filters and activated sludge treatment
    employ bacteria to breakdown and digest organic
    material in the sewage (Figs. 9-16a 9-16b)
  • Sludge form primary or secondary treatment is
    dried (Fig 9-17a) and then disposed of in
    landfill or composted (Fig 9-17b)

75
Fig. 9-16a
76
Fig 9-16b
77
Fig. 9-17a
78
Fig. 9-17b
79
Municipal Sewage Treatment
  • Tertiary Treatment
  • A number of tertiary treatments or advanced
    wastewater treatment methods, including air
    stripping by ammonia and rapid granular
    filtration, reduce the BOD even more.

80
Municipal Sewage Treatment
  • Sludge Treatment and Disposal
  • Sludge refers to the solids and liquids separated
    out of wastewater during sewage treatment.
  • Sludge disinfection is a crucial step, as it
    destroys pathogens in the sludge to prevent the
    spread of disease. Digested sludge may be air
    dried.

81
Water Pollution and Health
  • Increased risks of cancer and uncertainty about
    the future are just two issues the consumers of
    polluted water are faced with.
  • Consumers armed with information about their
    water sources can protect themselves from
    exposure to polluted water.

82
Future Outlook
  • On a planet covered with water, yet plagued by
    waterborne disease, drought, and water
    mismanagement, we must promote conservation,
    efficiency, and frugality.
  • Every drop counts.
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