LIVING WITH THE EARTH

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LIVING WITH THE EARTH
CHAPTER 9 WATER AND WASTEWATER
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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.

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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.

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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.

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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.

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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.

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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.

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Fig. 9-1
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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.

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Fig. 9-2
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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.

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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.

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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.

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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.

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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

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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.

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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.

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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.

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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.

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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.

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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.

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Fig. 9-3
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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.

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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.

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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.

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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).

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Fig 9-4
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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).

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Fig. 9-5dug well
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Fig. 9-6drilled well
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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.

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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).

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Table 9-1
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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.

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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).

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Fig. 9-7
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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.

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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.

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The Following Laws Protect the Waters of the U.S.

• RCRA
• CERCLA
• SDWA
• FIFRA
• TSCA

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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.

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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.

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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.

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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.

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Water Quality

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

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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.

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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.

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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.

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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.

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Sources of Pollution

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

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Sources of Pollution

• Nonpoint Source
• Agriculture
• Pesticides
• Fertilizer
• Eutrophication

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Sources of Pollution

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

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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.

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Water Treatment

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

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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

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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.

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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.

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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.

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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).

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Fig. 9-8
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Types of Disposal

• Pit privies (Fig. 9-9)
• Septic Systems (9-10, 9-11)
• Municipal Sewage Treatment

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Fig. 9-9
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Fig. 9-10
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Fig 9-11 Failed septic system
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Fig 9-12a
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Fig 9-12b
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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).

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Fig. 9-13a
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Fig. 9-13b
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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))

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Fig. 9-14a
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Fig 9-14b
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Fig. 9-15a
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Fig 9-15b
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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)

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Fig. 9-16a
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Fig 9-16b
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Fig. 9-17a
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Fig. 9-17b
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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.

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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.

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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.

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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.