water waste

yiyi1996

Chap-9.ppt

Home >Biology homework help >Ecology homework help >water waste

WATER and WASTEWATER - Moore

LIVING WITH THE EARTH

WATER and WASTEWATER - Moore

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 consumer’s major use of water.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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 world’s water supplies.

WATER and WASTEWATER - Moore

The Properties of Water

Water is a unique compound (Fig. 9-1)
Water exerts a major influence on the earth’s 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.

WATER and WASTEWATER - Moore

Fig. 9-1

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

Fig. 9-2

WATER and WASTEWATER - Moore

The hydrological cycle. Condensation leads to precipitation which leads to transpiration and evaporation. Deep ground water contains 0.307%, shallow groundwater contains 0.307% as well. Soil moisture, .005%, oceans, 97.22%. Atmosphere, 0.001%, icecaps and glaciers 2.147%, Freshwater lakes 0.009%, freshwater streams/rivers 0.0001%.

WATER and WASTEWATER - Moore

Water Resources

Water covers 71% of the earth’s 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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

Water Shortage and Scarcity

A 1995 World Bank report indicated that 40% of the world’s 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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

Water Use

Agriculture
Agriculture consumes the largest portion of the freshwater supply, with over two-thirds of the world’s water demand used for irrigation.
Sixty percent of this water is lost to evaporation or runoff.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

Fig. 9-3

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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).

WATER and WASTEWATER - Moore

Fig 9-4

WATER and WASTEWATER - Moore

Raincloud with water flowing between two areas if impervious bedrock into a recharge area, which leads to an aquifer running into an artesian well. A zone of saturation (aquifer) is on the other side of the impervious bedrock, along with surface water and a shallow well. A cone of depression is associated with drawdown from the well. A gas pump is also on the other side of the bedrock, with oil flowing down and a plume of pollution entering shallow well and surface water.

WATER and WASTEWATER - Moore

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).

WATER and WASTEWATER - Moore

Fig. 9-5
dug well

WATER and WASTEWATER - Moore

Fig. 9-6
drilled
well

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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).

WATER and WASTEWATER - Moore

Table
9-1

WATER and WASTEWATER - Moore

Planned activities on the surface that lead to pollutants on the surface include waste disposal such as surface impoundments, non-point source landfills and open dumps, and point sources of waste tailings and land application of sewage sludge. Also on the surface, storage and transport of point source material stockpiles. In agriculture , non-point source pesticides, fertilizers, and irrigation practices and point source animal feeding. Other planned activity surface pollution includes road de-icing. Planned activities in the subsurface include waste disposal point sources of injection wells, septic tanks, cesspools, and other wells and non-point source sewage pipelines. Subsurface storage or transport includes point source underground storage tanks and non-point source pipelines. Unplanned activities affecting the surface are non-point source urban runoff, acid deposition, and natural leachates and point source accidental spills. Unplanned activities in the subsurface include non-point source saltwater intrusion and groundwater/surface water interaction.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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).

WATER and WASTEWATER - Moore

Fig. 9-7

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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

RCRA
CERCLA
SDWA
FIFRA
TSCA

WATER and WASTEWATER - Moore

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 world’s water supply.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

Water Quality

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

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

Sources of Pollution

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

WATER and WASTEWATER - Moore

Sources of Pollution

Nonpoint Source
Agriculture
Pesticides
Fertilizer
Eutrophication

WATER and WASTEWATER - Moore

Sources of Pollution

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

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

Water Treatment

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

WATER and WASTEWATER - Moore

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

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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).

WATER and WASTEWATER - Moore

Fig. 9-8

WATER and WASTEWATER - Moore

SAG curve: The DO conditions in a stream under a one-time waste load. Time in days on x axis, dissolved oxygen (mg/L) ranging from 0 to 10 on y axis. At O, DO is at 10, then as time goes on there is a u shaped curve. The maximum oxygen deficit happens at 5.0 DO, which it the critical point. Levels slowly rise to rearation recovery.

WATER and WASTEWATER - Moore

Types of Disposal

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

WATER and WASTEWATER - Moore

Fig. 9-9

WATER and WASTEWATER - Moore

Fig. 9-10

WATER and WASTEWATER - Moore

Fig 9-11 Failed septic system

WATER and WASTEWATER - Moore

Fig 9-12a

WATER and WASTEWATER - Moore

Fig 9-12b

WATER and WASTEWATER - Moore

Municipal Sewage Treatment

Sewage treatment speeds up water’s 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).

WATER and WASTEWATER - Moore

Fig.
9-13a

WATER and WASTEWATER - Moore

Raw sewage goes through various stages of treatment. First a bar screen prevents large objects such as branches from entering system. A comminuter grinds up large materials from storm drains and sewer. Grit chamber separates out rocks, gravel and dense objects by rapid sedimentation. Primary clarifier allows sewage to settle and separate into sludge on bottom, scum on top, and intervening liquid layer. Activated sludge- a widely used biological oxidation process that mixes oxygen and microbes (activated) to rapidly break down organic matter, thereby further reducing BOD. Secondary clarifier- liquid portion of material from activated sludge tank is allowed to settle. Most BOD and bacteria are removed in this process.

WATER and WASTEWATER - Moore

Fig.
9-13b

WATER and WASTEWATER - Moore

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))

WATER and WASTEWATER - Moore

Fig. 9-14a

WATER and WASTEWATER - Moore

Fig 9-14b

WATER and WASTEWATER - Moore

Fig. 9-15a

WATER and WASTEWATER - Moore

Fig 9-15b

WATER and WASTEWATER - Moore

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)

WATER and WASTEWATER - Moore

Fig. 9-16a

WATER and WASTEWATER - Moore

Fig 9-16b

WATER and WASTEWATER - Moore

Fig. 9-17a

WATER and WASTEWATER - Moore

Fig. 9-17b

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore

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.

WATER and WASTEWATER - Moore