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Example research essay topic: Al 2000 P Oxygen Molecules - 2,956 words

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Membrane Processes Human exposure to pollutants in the air, water, soil and food-whether in the form of short-term, high-level, or long-term, low-level exposure-is a main cause of increased morbidity and death. However, the disease burden attributable to these exposures is not known with any degree of certainty because levels of general environmental pollution fluctuate greatly, methods for analyzing the relationships are incompletely developed, and the quality of available data is generally poor. Precise measures of the association between pollution levels and health outcomes are therefore rare. Exposure to environmental pollution is also usually involuntary. People may be unaware of this and / or its possible effects; as a result they may exert little control over their risk of exposure. Biological and chemical agents in the environment are nevertheless responsible for the premature death or disablement of millions of people worldwide every year (WHO cited in Wainwright & Thornes, 2004, p. 17).

It has recently been estimated that almost one quarter of the global burden of disease is attributable to environmental factors (WHO cited ibid. ). This estimate, which is based on published data, was made by attributing an environmental causal fraction to each disease category with a known environmental link. The ability to link health and environmental data, and thereby to determine the relationship between levels of exposure and health effects, is clearly vital to control exposure and protect health. Standards and guidelines against which to assess levels of environmental pollution are now widely available. For example, the World Health Organization (WHO) has developed environmental quality guidelines for various pollutants in the air, drinking-water, food and workplace (Tibbetts, 2004, p. 472). These guidelines are based on epidemiological and toxicological studies and indicate the maximum environmental levels, or the maximum levels of human exposure, considered acceptable in order to protect human health.

Nevertheless, individual susceptibility to pollution varies, to the extent that it is possible that some individuals may experience adverse effects at levels below the maximum recommended levels. Moreover, in many areas of the world these levels are frequently exceeded, in some places by as much as several times the recommended levels, and reduction of human exposure may be difficult or very costly (Rupp, 2001, p. 22). Adverse effects on human health are therefore likely to continue to be observed in these areas. In such situations, analysis of data on human health and the environment provides a valuable tool for obtaining estimates of the health impact of pollution, which can be used to set priorities for action. Many epidemiological studies have been undertaken to analyze the relationship between specific forms of environmental pollution and health effects. Most of these studies have been conducted in developed countries, and the methods used may not be applicable to other settings, especially if high quality data are unavailable or too expensive to collect.

Major problems often exist in obtaining data on health and particularly on environmental exposure at the individual level. As a consequence, it is normally necessary to rely on so-called ecological methods, in which the statistical unit of observation is a population rather than an individual (Harry et al. , 2000, p. 19). A serious limitation in conducting epidemiological studies concerns the measurement of exposure in individuals. Routinely collected environmental data are widely available in most countries and, where relevant, can be used as a proxy for exposure data. For example, monitoring networks provide data on pollution levels at specific sites, which can be used to characterize average exposures for geographical regions. Environmental data are also often compared with guideline values or maximum recommended levels in order to determine levels of compliance with prevailing policies.

The data are, however, rarely used to quantify the potential health effects. Equally, although many countries routinely collect data on health outcomes in the form of morbidity and mortality statistics, attempts are rarely made to link the data to environmental or other factors in order to attribute outcomes to their cause (Linsky, 2001, p. 29). Linking environmental and health data offers considerable benefits, but also poses many dangers if not carefully carried out. In linking such data it is all too easy to overlook the statistical problems and inconsistencies of the different data sets, or to misinterpret their apparent relationships. Valid linkage thus relies on the use of both valid data and appropriate linkage methods.

Numerous methods for data linkage have been developed in many different areas of application. Their suitability for linking environmental and health data, however, is often limited and always needs to be assessed carefully. Two important criteria must be considered in this context. First, the methods must be politically acceptable.

This means that they must be simple, inexpensive to implement, and operable with the available data, thus allowing rapid assessment. If the methods are overly complex, requiring extensive resources and collection of large amounts of additional data, few developing countries will be able to apply them, and even in developed countries their use may be costly and result in delays in action. Second, if the results are to be accepted as a basis for action, the methods must be scientifically credible and statistically valid. This means that they should be accurate, sensitive to variations in the data of interest and unbiased. Simple, crude methods should produce results that agree with those obtained from more detailed studies, for which the statistical precision can be quantified (Frazer, 2002, p. 37).

In practice, these requirements are rarely met in full. If they were, there would hardly be a need for individual-level studies. Nevertheless, simple methods may still have considerable value. Results from ecological studies, for example, are useful if the potential biases can be identified, evaluated and shown to be small. At the very least, the results should help to identify areas or issues requiring more detailed investigation.

Countries where detailed, individual-level studies have not been performed also urgently need access to methods which can help to shed light on the extent and health effects of specific forms of environmental pollution. Priority should be given to the development of research capabilities in developing countries for this purpose (Environmental Research, 1993 cited in Craun, 2002, p. 17). Where detailed information on the exposure-response relationship of specific pollutants is available, Quantitative Risk Assessment (QRA) techniques, based on epidemiological data, can be used to estimate the impact of exposure on different populations without the need for new substantive research (for further information, see Macalady, 1998, p. 49; Schillinger & Knorr, 2004, p. 25). This implies knowledge about exposure, the population at risk and the health effects associated with exposure in the form of a dose-response function derived from epidemiological studies (i. e. pooled study results) (Avakian et al. , 2002, p. 1115; Ramakrishnan et al. , 2005, p. 57).

Because of limitations in available research data, QRA can often be applied only by extrapolating study results from one country (usually developed) to other countries (usually less developed). The fact that the range of exposure levels and the distribution of other conditions likely to affect health outcomes may differ substantially between populations inevitably limits the validity of this approach. In addition, assessments can only be carried out reliably for pollutants for which well researched exposure-response relationships have been established (Veltri, 2000, p. 17). Even then, uncertainty regarding the assumed association between environmental pollution levels and the actual exposures in individuals is a major constraint.

QRA remains the only tool available for estimating the health outcomes of environmental pollution in areas where health monitoring is not undertaken, or where the quality of the data collected is poor (Smith, 1998, p. 214). It is also the only feasible approach for obtaining crude estimates of health impacts in very large population groups. The development and application of well tested methods of risk assessment is therefore an important priority. By imitating natural processes, we can meet the water and air needs of current and future generations. All too often, we read bold headlines claiming that the world is running out of water and air. Like so much of the information found in the media, such statements tend to exaggerate.

So far, our planet is the only truly water-rich planet known in the universe. In retrospect, we might more accurately call the planet Water or Air, not Earth. Gas Separation. The Harvard School of Public Health and the U. S. Environmental Protection Agency (EPA) claimed that about 64, 000 Americans die untimely every year because of illnesses cased by air pollutants (Walsh et al. , 2000, p. 770).

Though currently some improvements in air quality are made (principally in the sphere of automobile emissions, about 66 % Americans live in the regions that do not answer the National Ambient Air Quality Standards. Among the pollutants are particulate matter, ozone, nitrogen dioxide, and carbon monoxide. And the majority of them are generated by electrical power generating plants. The way out is Clean Energy Systems (CES) power plant. Key to its functioning is production of pure oxygen required for its advanced combustion system. It is necessary not simply pumping in the outside air, but parting oxygen from less-desirable components of the atmosphere.

Among modern approaches is membrane separation (a kind of physical process grounded on particular characteristics of every molecule). Thus, hollow tubes with a great number of thin membrane fibers are subjected to the stream of air under pressure (ibid. ). It's necessary to mention that ion transport membranes are solid materials generating oxygen by passing of the oxygen ions through some ceramic materials involving picked inorganic oxide materials. While working at high temperatures (more than 4800 C), the membranes transform oxygen molecules into oxygen ions at the surface (Frazer, 2002, p. 37). By an applied voltage or pressure differential these ions are shifted through the membrane, and convert to oxygen molecules membrane surface. By the way researchers consider ion transport membranes have the ability to provide pure oxygen at lower costs (reducing the costs from at a half) (Smith, 1998, p. 217; Wainwright & Thornes, 2004, p. 110).

Microfiltartion, ultrafiltration, reverse osmosis. From the early 1800 s until midway through the 20 th century, the federal government encouraged the westward movement of the population by promoting agriculture and ensuring reliable water supplies. During that period, the federal government and private entrepreneurs built dams and crafted water-diversion schemes at an unprecedented pace. Though the heyday of such innovation and investment in infrastructure is over, these technologies continue to provide utility customers with the highest quality of water in the world. Unfortunately, technology can't reduce the demand for water, so water providers will need to turn again to human ingenuity to usher in a Throughout the world, water-supply projects have applied different technologies to filter agricultural irrigation waters, municipal wastewater, brackish coastal and ocean waters, and salt-laden ground and surface waters. Consider the 22 countries that make up the Middle East and North Africa.

This region contains the world's largest thermal desalination operations, which account for 50 percent of the world's annual desalinated water production, or over 4 billion gallons a year of drinking-quality water (Bender, 1995, p. 407). Several processes are used to create potable water by extracting salts from sea water. The most common method of desalination is membrane processes. Among the kinds of membrane technologies are: reverse osmosis and electrodialysis. Both processes mimic nature and work by separating salts and water molecules as the water passes through microphones within the structures of thin membranes that prevent the salts from passing through (Davson 1973, p. 222). Membrane processes are also increasingly popular for removal of suspended matter from source water.

Microfiltrantion, for instance, used in the beverage industry and in computer-chip manufacturing. It is also used to sterilize medicine that cannot be heated. For micro filtration and ultrafiltration, membranes of synthetic polymers have been in use for some years. Ceramic membranes for micro filtration are a relatively new development, and they have promise in the drinking-water field. They are generally much more resilient than polymeric membranes, so they should be able to withstand the wear and tear of filtration, back-pulsing, and cross-flow washing, thus showing longer lifetimes (Harry et al. 2000, p. 20). Microfiltration will be followed by reverse osmosis filtration, which acts like a strainer to allow only water molecules to pass through while filtering out all the minerals and contaminants, including salts, bacteria, viruses, and pesticides.

Reverse osmosis systems operate in a closed environment under pressure that literally pushes water molecules through the membrane and leaves the salts behind as reject material. This technology is applied today to desalt seawater, wastewater, and agricultural irrigation waters very efficiently. New plants currently in the works in Israel will provide substantial supplies for Israelis, Palestinians, and Jordanians. Finding solutions to the water problems in the Middle East is the key for reducing, if not eliminating, the tensions within the region (Schillinger & Knorr 2004, p. 27). The energy costs of reverse osmosis are much lower than for distillation, and the amount of potable water derived from the "feed water" is usually higher. Costs of reverse osmosis have fallen significantly in recent years.

Desalinating an acre-foot of seawater cost $ 2, 000 in 1990, but this has been cut to $ 900 today, according to the U. S. Desalination Coalition. This Washington, D. C. -based organization comprises 13 water agencies and utilities from California to Florida and is seeking an increased federal role in advancing desalination (Craun et al. 2002, p. 18). There are disadvantages to reverse osmosis, however.

The membranes tend to clog, and they require cleaning, according to a March 2004 report by the California Coastal Commission, Seawater Desalination and the California Coastal Act. The feed water also must be broadly pretreated, usually by using biocides, coagulants, and other compounds. The procedure of reverse osmosis and its use of cleaning agents generates wastes that can involve toxic chemicals, metals, and other materials that are discharged back into the sea. Desalination plants also release a highly concentrated salt substance called brine that can affect marine life when it's discharged back into the ocean. (Tibbetts 2004, p. 472). California by now has approximately a dozen existing desalination facilities along its coastline, despite the fact that they are comparatively small. In total, they produce about 3, 300 acre-feet per year.

About two dozen more desalination Facilities are proposed, and some would be the largest in the country. The total output of all proposed facilities would produce about 260, 000 acre-feet per year, an 80 -fold increase over current production (Veltri, 2000, p. 17). After the centuries of extraction, people now face the problem of finding sufficient sources of water from diminishing natural resources. The difficulty is not a lack of proper technology, but of diminishing resources. People are fast becoming the plentiful resource, while natural resources are rather becoming limited. Water is an asset that gives services of actual worth.

To guarantee the maintenance of these important services for future generations, we must invest in the asset. The hydrologic cycle is the planet's life insurance policy. That's why water reuse, recycling, or reclamation are absolute necessities if generations to come are to enjoy an economically and environmentally secure future. References Avakian, M. D. , Dellinger, B. , Fiedler, H. , Gullet, B. , Kosh land, C. , Marklun, S. , et al. (2002). The Origin, Fate, and Health Effects of Combustion By-Products: A Research Framework.

Environmental Health Perspectives, 110 (11), 1155. Bender, A. E. , & Bender, D. A. (1995).

A Dictionary of Food and Nutrition. Oxford: Oxford University Press. Craun, G. F. , Nwachuku, N. , Calderon, R.

L. , & Craun, M. F. (2002). Outbreaks in Drinking-Water Systems, 1991 - 1998. Journal of Environmental Health, 65 (1), 16. Davson, H. , Daniel, J.

F. , & Harvey, E. N. (1973). The Permeability of Natural Membranes. Cambridge: The University Press. Frazer, L. (2002). The Gas Is Greener.

Environmental Health Perspectives, 110 (1), 36. Harry, T. M. , Clancy, J. I. , Bukhari, Z. , & Marshall, M. M. (2000). Shedding UV Light on the Cryptosporidium Threat.

Journal of Environmental Health, 63 (1), 19. Linsky, R. B. (2001). Mother Nature's Machine. Forum for Applied Research and Public Policy, 16 (1), 29. Macalady, D.

L. (Ed. ). (1998). Perspectives in Environmental Chemistry. New York: Oxford University Press. Ramakrishnan, V. , Oral, A. V. , & Lindner, A. S. (2005).

Impacts of Co-solvent Flushing on Microbial Populations Capable of Degrading Trichloroethylene. Environmental Health Perspectives, 113 (1), 55. Rupp, G. L. (2001). The Challenges of Installing Innovative Treatment in Small Water Systems. Journal of Environmental Health, 64 (1), 22.

Schillinger, J. , & Knorr, S. D. (2004). Drinking-Water Quality and Issues Associated with Water Vending Machines in the City of Los Angeles. Journal of Environmental Health, 66 (6), 25. Smith, R. S. (1998).

Profit Centers in Industrial Ecology: The Business Executive's Approach to the Environment. Westport, CT: Quorum Books. Tayabali, A. F. , & Seligy, V. L. (2000). Human Cell Exposure Assays of Bacillus Thuringiensis Commercial Insecticides: Production of Bacillus Cereus-Like Cytolytic Effects from Outgrowth of Spores.

Environmental Health Perspectives, 108 (10), 919. Tibbetts, J. (2004). The State of the Oceans, Part 2: Delving Deeper into the Sea's Bounty. Environmental Health Perspectives, 112 (8), 472. Veltri, A. , De genova, J. , O'Hara, P. , & Art, G. L. (2000).

Recycling Spent Ultrapure Rinse Water-A Case Study in the Use of a Financial Analysis Tool. Journal of Environmental Health, 63 (4), 17. Wainwright, J. , & Thornes, J. B. (2004). Environmental Issues in the Mediterranean: Processes and Perspectives from the Past and Present.

London: Routledge. Walsh, L. P. , Mccormick, C. , Martin, C. , & Stock, D. M. (2000).

Roundup Inhibits Steroidogenesis by Disrupting Steroidogenic Acute Regulatory (StAR) Protein Expression. Environmental Health Perspectives, 108 (8), 769.


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