1、PART 1 INTRODUCTION TO ENVIRONMENTAL ENGINEERINGThe book includes:Description of what is meant by environment and by environmental systemsInformation on the basis causes of environmental disturbancesBasis scientific knowledge necessary to understand the nature of environmental problems and to be abl
2、e to quantify themCurrent state of the technology environmental control in its application to water, air and pollution problemsConsiderable gaps in our current scientific knowledge of understanding and controlling many of the complex interactions between human activities and natureMany environmental
3、 problems which could be eliminated or reduced by the application of current technology, but which are not dealt with because of societys lack of will to do so, or in many instances because of a lack of resources to do so.Some Important DefinitionsWhere they are first used in this book, definitions
4、are introduced in block form, as shown here, or printed in bold type.Environment is the physical and biotic habitat which surrounds us; that which we can see. hear, touch, smell, and taste.System, according to Webster s dictionary , is defined as “a set or arrangement of things so related or connect
5、ed as to form a unit or organic whole; as, a solar system, irrigation system, supply system, the world or universe”.Pollution can be defined as an undesirable change in the physical, chemical, or biological characteristics of the air, water, or land that can harmfully affect the health, survival, or
6、 activities of humans or other living organisms.When the goal of improving environmental quality is taken to be improving human well being. The word “environment” broadens to include all kinds of social, economic, and cultural aspects. Such broadness is unworkable in many real situations and impract
7、ical in a textbook designed for a one-semester course. Our examination of environmental problems is therefore limited by our definition of “environment”.Interaction of SystemsA number of different environmental problems are associated with water, air, or land systems. Many of these problems will app
8、ly only within one of these systems, justifying the breakdown into these categories. Such a classification is also useful for easier comprehension of related problems within one system. Moreover, it is sensible because, for managerial and administrative reasons, such subfields as air pollution, wate
9、r supply, wastewater disposal, and solid waste disposal are often dealt with separately by governmental agencies.Unfortunately, many important environmental problems are not confined to an air, water, or land system, but involve interactions between systems. A current example is the acid rain proble
10、m stemming from the emission of sulfur dioxide and nitrogen oxide gases into the atmosphere from the stacks of generating stations, smelters, and automobile exhausts. These gases are then transported by air currents over wide regions, Rainfall “washes them out”, creating acid rain which is harmful t
11、o aquatic life, forests, and agricultural crops. Two examples of interaction between systems that cause major environmental disturbances are presented-the buildup of atmospheric carbon dioxide, a global problem, and the acid rain problem, normally of regional nature.Environmental DisturbancesMany ma
12、jor improvements to our standard of living can be attributed to the application of science and technology. A few examples are noted here. Can you think of others? The production of more and better quality food The creation of housing as protection from extremes from climates and as living apace The
13、building of fast and reliable means of transportation The invention of various systems of communication The invention of machines to replace human or animal power The supply of safe water and the disposal of wastes The elimination of many infectious diseases The elimination of most water-borne disea
14、ses in the developed world through improved water technology The availability of leisure time through greater productivity, providing the opportunity for cultural and recreational activities The protection from the worst effects of natural disasters such as floods, droughts, earthquakes, and volcani
15、c eruptions.With these improvements, however, have come disturbing side effects, such as lost arable land, disappearing forests, environmental pollution, and new organisms resistant to controls. Many effects originally considered to be just nuisances are now recognized as potential threats to nature
16、 and to humans. In an agrarian society, people lived essentially in harmony with nature, raising food, gathering firewood, and making clothing and tools from the land. The wastes from animals and humans were returned to the soil as fertilizer. Few, if any, problems of water, land, or air pollution o
17、ccurred.The cities of ancient times, particularly those of the Roman Empire had systems to supply water and to dispose of wastes. The aqueducts supplying the ancient city of Rome (population about 1 million) with safe water from the Cloaca Maxims, the best known and one of the earliest sewers to be
18、built, are examples of such systems. The municipal technology of ancient cities seems to have been forgotten for many centuries by those who built cities throughout Europe. Water supply and waste disposal were neglected, resulting in many outbreaks of dysentery, cholera, typhoid. and other waterborn
19、e diseases. Until the middle of the nineteenth century, it was not realized that improper wastes disposal polluted water supplies with disease-carrying organisms. The industrial revolution in nineteenth- century Britain, Europe, and North America aggravated the environmental problems since it brough
20、t increased urbanization with the industrialization. Both phenomena, urbanization and industrialization, were and are fundamental causes of water and air pollution which the cities of that time were unable to handle.Rapid advances in technology for the treatment of water and the partial treatment of
21、 wastewater took place in the developed countries over the next few decades. This led to a dramatic decrease in the incidence of waterborne diseases. Note that all wastes discharge into the environment, and thus pollute our water, air, and land systems.Unit 1: Introduction of environmental engineeri
22、ng and scienceThe scope of environmental engineering and science continues to expand both in terms of the number of cities and countries of the world where water and air quality problems are in urgent 3need of attention, and in terms of the pollutants themselves, which now so often seen to have inte
23、rnational and global impacts Due to diligent efforts of environmental engineers and scientists, great progress has been made in our understanding of the fate and transport of substances that contaminate our air, surface water, soil, and subsurface water systems. That progress has led to better techn
24、ologies for controlling emissions and for cleaning up contaminated sites. With increased understanding and better technologies, it has been possible to craft more sophisticated legislation to address these problems. And, with a better sense of the enormous cost of cleaning up problems after they are
25、 created, we are beginning to focus on pollution prevention. In some parts of the developed world, the result has been air that is getting cleaner, greater areas of surface waters that allow beneficial uses such as fishing and swimming, some improvement in subsurface water quality, and, very importa
26、nt, continued access to safe drinking water.Unfortunately, the numbers of people globally who do not enjoy these environmental benefits continues to grow, some traditional environmental problems still seem intractable, the global implications of greenhouse gases and ozonedepleting substances seem ev
27、en more threatening, and, in spite of the importance of the work to be done, our public will to face these challenges seems no longer assured. It is hoped that some of the science, technology, and policy instruments that have enabled parts of the United States to approach clean air and water goals c
28、an be applied to the enormous pollution problems that are coming to light as the former Soviet Union and other eastern bloc countries transform their economies. Similarly, the continued rapid population growth and urbanization occurring in the developing countries of the world is causing unparallele
29、d environmental health risks as people flock to cities that lack basic sanitation services and other infrastructure to control air and water contamination. Environmental engineers will play an increasingly important role as these countries attempt to improve their lot.Since last decade, there have b
30、een a number of significant studies and actions that are changing the way we think about and deal with our environmental challenges. The Clean Air Act Amendments of 1990, for example, are shifting the approach taken to emission controls from the traditional “command and control” methods, in which go
31、vernment dictates the use of technology, to a more marketbased approach that allows major sources to buy and sell emission allowances. In the area of groundwater cleanup, which has received much of the research funding and offered a significant fraction of the professional environmental engineering
32、work in the last decade, a 1994 National Research Council report concluded that the most commonly used remediation technologies have little hope of ever restoring many of our contaminated aquifers to drinking water quality, our perceptions of “how clean is clean?” are changing. The Comprehensive Env
33、ironmental Response, Compensation, and Liabilities Act that crested superfund, which deals with such sites, has been only moderately successful and has been severely criticized as providing too little risk reduction for too many dollars. Partly in response, the concept of “brownfields”, with more fl
34、exible cleanup goals and much more limited liability to owners who redevelop abandoned urban industrial sites is emerging as a way to stimulate local economies while speeding cleanup of modestly polluted sites.In the area of global atmospheric contamination, the impact of the Montreal Protocol on Su
35、bstances that Deplete the Ozone Layer is beginning to be felt as the ban on production and use of ozonedepleting substances takes effect, the atmospheric concentrations of the most important chlorofluorocarbons are no longer increasing, and models suggest that the ozone layer will begin to repair it
36、self in the early twentyfirst century. The apparent success of the Montreal Protocol is serving as a model for negotiations on the other global atmospheric problem, global warming. The 1996 assessments by the Intergovernmental Panel on Climate Change (IPCC) have concluded that the current global war
37、ming trend is not entirely natural in origin. Our understanding of the implications of continued warming, how fast it will occur, and how extensive it will be is fraught with uncertainties. How we make decisions about adaptation or mitigation for such a potentially critical environmental problem, gi
38、ven those uncertainties, is sure to be a contentious issue in the coming years. Unit 2: Text: Historical Overview of Hazardous Substance Disposal in the USAHazardous substance disposal practices in the United States have traveled full circle. Prior to 1978 there were few if any regulations regarding
39、 the disposal of these materials. Improper disposal of many of these chemicals resulted in health problems for many citizens, contaminated water supplies, and destruction of wildlife. With the enactment of the Resource Conversation and Recovery Act (RCRAY1 of 1978, manufacturing facilities now have
40、an obligation to account for all waste materials that are generated by the facility. Implementation of RCRA has been slow.From the very early industrial period in the United State, which started about 1920, until several years after the Second World War, there was little concern for the proper metho
41、ds of disposal of waste materials that were generated as by-products during manufacturing processes. Up until the 1960s it was quite common to find fresh water rivers and streams fouled with waste chemicals from manufacturing, salt water from oil production wells and waste acids from steel mill acti
42、vities. Virtually every conceivable waste oil, solvent, or resin waste could be found in the rivers. The laws of the time were either non-existent or not enforced. The literature has many examples of health problems of individuals as well as destruction of fish and wildlife habitat. Many other cases
43、 occurred that were not reported in the literature.Other waste materials were dumped haphazardly in makeshift excavations either at the factory side or throughout the country aide. Because of ignorance and lack of economic incentives to do so, the factories made no attempt to prevent contamination o
44、f underground water supplies by the chemicals that were disposed of. In fact, knowledgeable scientists of the time accepted land irrigation and percolation into the porous underground formations as methods of waste treatment. Although these treatment methods may have been intended for non-hazardous
45、materials, they were employed for hazardous materials as well. Again, there were no governmental regulations protecting the underground aquifers from these practices.The problem of disposal of hazardous chemicals did not improve with the creation of the Environmental Protection Agency (EPA) in 1966.
46、 The first task of the new agency was to clean up rivers and streams. Unfortunately, no one in power in the government at the time had insight into the problems that were to be created by the new agency.The EPA was quite successful in those early days in the enforcement of the many water pollution l
47、aws that evolved. As the practice of the dumping of hazardous materials into the rivers and streams was eliminated, those same materials created other disposal problems.Many of the chemicals saved from the sewer were either worthless or of such a low value as to render recovery uneconomical, In some
48、 cases, recovery was technically impossible. Asa result, the waste chemicals were disposed of by any convenient method. The makeshift dumps 5sites were expanded. Because there were no regulations regarding disposal, persons with no technical expertise entered into the business of waste disposal. The
49、 profits were high because these individuals did not treat the chemicals. In most cases, the waste materials were transported to impounding areas located on privately owned land.The factories that generated the waste felt secure in the belief that the waste transporter was disposing of the materials in an acceptable manner. In most cases, this was not a correct assumption.The unregulated dumps grew both in size and complexity. When the dumps were in close proximity to populated areas or public water supplies, a series of problems begin to develop. Citizens in the vicinity
