Steam Methane Reforming free essay sample

Hydrogen is an important chemical in petroleum refining and is manufactured most commonly in the United States by steam methane reforming. | Hydrogen as an industrial chemical is used in petroleum refining and in the synthesis of ammonia and methanol. The two largest industries consuming hydrogen in the United States are petroleum refining and the synthesis of ammonia. The hydrogen needed for refinery operations is produced through either manufacturing or by-product recovery. The largest portion (77%) of industrial hydrogen produced in the United States is manufactured by steam reforming of natural gas. Hydrogen is also produced by steam reforming of naphtha, partial oxidation of oil, coal gasification, and water electrolysis, but these processes together produce a relatively small amount compared to steam reforming of methane. This is, in part, due to steam reforming having the highest thermal efficiency and lowest net production cost of the available processes for producing hydrogen. Steam reforming involves converting light hydrocarbon feeds into synthesis gas by a reaction with steam over a catalyst in a reformer furnace. We will write a custom essay sample on Steam Methane Reforming or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Before entering the steam reformer, the hydrocarbon feeds must be desulfurized by processes tailored to the amount of sulfur to be removed. The mixture of gas and process steam is then introduced into the primary reformer with a nickel–based catalyst where a reversible reaction takes place. The water gas shift reaction step then converts the resulting CO to CO2 and hydrogen. After cooling, the CO2 is scrubbed out of the process and remaining carbon oxides are converted to methane through the use of a methanation catalyst. This produces a typical product of 98. 2% hydrogen. If a higher purity hydrogen is desired, the shifted gas can be purified by pressure-swing adsorption (PSA) instead of CO2 scrubbing and methanation and will result in a purity greater than 99% pure hydrogen. There are environmental concerns related to these processes, and much attention is given to minimizing the environmental impact of hydrogen manufacturing. Attention must be also be paid to the health and safety factors of hydrogen production, and regulations followed for each. The first step in the steam methane reforming process is feed preparation. The light hydrocarbon feeds used range from natural gas to straight run naphthas, all of which contain sulfur that must be removed before they enter the steam reformer. If the hydrocarbon feed contains small amounts of sulfur, the first desulfurization step consists of converting organic sulfur compounds to H2S by passing the feed at about 300-400Â °C over a Co-Mo catalyst in the presence of 2-5% H2. The next step reduces the sulfur level to less than 0. 1 ppmwt by adsorption of H2S over ZnO catalyst. If the feed contains several hundred ppm sulfur or higher, bulk removal of H2S uses solvents such as monoethanolamine prior to the ZnO desulfurization step. The effluent from the Co-Mo reactor must be cooled for bulk removal and reheated for the ZnO purification in this case. Once the feeds have been desulfurized the resulting gas and process steam mixture moves on the reaction section of the process. The reaction of the hydrocarbon feeds and steam over a nickel-based catalyst to produce synthesis gas takes place in a primary reformer furnace. The primary reformer furnace is a direct-fired chamber containing high nickel-alloy tubes arranged in single or multiple rows. The tube alloys are selected according to operating pressure and temperature specifications. The reaction process of hydrogen production is usually operated at 800-870Â °C and 300-400psig. The catalyst is made up of 5-25% nickel as NiO and usually contains potassium to inhibit coke formation from the use of feedstocks such as LPG and naphtha. The NiO is supported on calcium aluminate, alumina, magnesium aluminate, or calcium aluminate titanate. Temperature of the outlet gas is between 800 and 870Â °C and outlet pressures are usually between 300 and 350 psig. The outlet gas composition correlates a 0Â °C to 25Â °C temperature approach to steam-reforming equilibrium. Temperatures of the flue gases exiting the convection section of the furnace reach 980-1040Â °C. Greater efficiency is achieved by reclaiming this heat and using it to heat other process such as the hydrocarbon feed before sulfur removal, the feed mixture entering the radiant section of the furnace, the combustion air for the radiant section burners, and for heating or superheating steam. The primary reformer can achieve up to a 95% conversion of CH4, and this step results in a hydrogen concentration of about 76. 7%. After exiting the primary reformer, the gases enter the shift conversion section for the gas shift reaction step which will convert the CO into CO2 and hydrogen. The reaction begins in the high temperature shift (HTS) reactor at about 370Â ° at the inlet on a chromium-promoted iron oxide catalyst. The gasses are converted and exit the HTS to be cooled to 200-215Â °C before being sent to the low temperature shift (LTS) converter to complete the water gas shift reaction over a copper-zinc oxide catalyst supported on alumina. This step is completed at as low a temperature as possible in order to operate at the most favorable equilibrium constants. The gas is then cooled and the heat recovered for other use. The gas shift reaction step produces gas with a H2 concentration of about 77%. The last steps for low purity hydrogen include the CO2 scrubber and methanation. The CO2 is scrubbed out by hot potassium carbonate or one of several other processes. The gases are then reheated to 315Â °C and passed over a methanation catalyst of nickel on silica to convert the remaining carbon dioxides to methane. CO and CO2 are hydrogenated to CH4 on this catalyst before the outlet gasses are cooled and any entrained water is separated. The result is a hydrogen product with a concentration of about 98. 2% H2. When high purity hydrogen is needed the shifted gas can be purified by pressure-swing adsorption (PSA) instead of the CO2 scrubbing and methanation. Pressure-swing adsorption purification separates the hydrogen gas from the other, larger, molecules by selective adsorption through the use of a molecular sieve. Because hydrogen has a very weak affinity for adsorption, the PSA process produces very pure hydrogen and, with increased adsorption stages, at recoveries up to 90%. This process operates at room temperature in a pressurization-depressurization cycle. The desorption process is endothermic and the adsorption process is exothermic. The adsorption bed is then depressurized and purged with pure hydrogen to accomplish regeneration. The PSA system concentrates to 99% H2 and offers safer, more reliable hydrogen production with efficient heat recovery and reduced production costs in exchange for increased feed requirements and a larger reformer furnace. Large scale production of hydrogen does have environmental impacts. The generation of synthesis gas is the primary area requiring environmental controls. Different processes require different controls, with the methane steam reforming process being the most environmentally friendly. Environmental concerns regarding hydrogen manufacturing can be minimized by using natural gas reforming and recovering hydrogen as a by-product. Concerns for coal feedstocks stem from potential particulate emissions and require careful handling of condensate streams, ash, and slag. Concerns over partial oxidation of heavy liquid hydrocarbons are eased by scrubbing the soot from the raw synthesis gas for recycling or recovery. The potential pollutants produced are less than with coal gasification although the sulfur and condensate treatments are generally similar. The cleanest of the synthesis gas generations is reforming of natural gas or naphtha. The low levels of sulfur in most natural gasses can be removed in a fixed-bed adsorption system. Higher levels of sulfur are treated in solvent adsorption-stripping systems for acid gas removal. Naphtha’s organic sulfur compounds are usually hydro treated and stripped as hydrogen sulfide before residual sulfur is removed in a fixed-bed system similar to use for natural gas before reforming. Process condensate is treated by steam stripping, a process that has become more environmentally conscious in recent years. Hydrogen gas also has health and safety factors that must be considered. While hydrogen gas itself is not toxic, it can cause suffocation by the exclusion of air. Its extreme flammability in oxygen or air presents the largest danger when working with liquid and gaseous hydrogen. Hydrogen is difficult to detect if released, partly due to it being odorless, colorless, and burning with a nearly invisible flame. Hydrogen can be explosive in mixtures with fluorine and has much wider detonation and flammability limits when mixed with air than either gasoline or methane. There are mandatory regulations governing the safe distribution, handling, and use of both liquid and gaseous hydrogen. The steam methane reforming process for producing chemical hydrogen is the most common manufacturing process for hydrogen and is vital to the petroleum refining industry. Steam methane reforming desulfurizes light hydrocarbon feeds and converts them into synthesis gas which is then purified by CO2 scrubbing and methanation or through pressure-swing adsorption purification depending on the level of purity desired. Natural gas or naphtha reform is the most environmentally friendly and cost effective of the processes available to produce hydrogen. The health and safety concerns for hydrogen are mostly due to its flammability in oxygen or air combined with difficulties detecting a hydrogen spill. Large scale hydrogen production can have environmental impacts, but when federal and local regulations are followed the environmental effects are minimized.

Analytical Essay Topics For College Students

Analytical Essay Topics For College StudentsAnalytical essays can be created to reflect a deeper understanding of a specific subject. Many people choose to develop their own topic based on an interest that they have. The following are just a few topic options available to undergraduate students who desire to have an analytical essay.This is a very interesting topic because it allows you to give insight into one of the main institutions of this world. If you are a student of a specific area then this is a great topic to pursue. These types of analytical essays allow you to explore a topic in depth. This can lead to insight into something that might not otherwise be explored.Most students have a common perspective about the work place. That is the perspective that you want to explore here. From here you can discuss your job and why you love what you do. Some of the topics you can discuss include motivation, what it means to be part of a team, and how people feel when they are working t ogether.One reason why many college students give a lot of homework is because of the subject matter. The analytical essay topics for college students can also include writing papers or essays for class assignments. The focus of these types of essays is important to consider. You may be asked to think about a particular topic or you may be given a choice. The first option allows you to write from your personal point of view but does not usually permit you to talk about why you love the subject.These analytical essay topics for college students are generally categorized as research related. The focus here is on the topic being investigated. For example, if you were studying to become a dentist you could work on your essay and mention how a particular tooth cavity affected you in such a way. Perhaps you will discuss how people view dentists and why you would like to join the profession. This is often the more personal of the analytical essay topics for college students.If you were a h igh school science teacher then this type of essay would be perfect for you. It is a little more detailed and focuses on the areas of study you would like to specialize in. Although this is more focused than many other topics, this can help you hone in on a subject that you enjoy. The topics may include trends in the field, which can be useful in the future.These are just a few of the topics available to you if you are interested in creating analytical essay topics for college students. It is important to decide which one you would prefer. There are also many methods available to help you decide which topics are most helpful to you.

Why You Should Avoid Checkbook Journalism

Why You Should Avoid Checkbook Journalism Checkbook journalism is when reporters or news organizations pay sources for information, and for a variety of reasons most news outlets frown on such practices or ban them outright. The Society of Professional Journalists, a group that promotes ethical standards in journalism, says checkbook journalism is wrong and shouldnt be used- ever. Andy Schotz, chairman of the SPJs ethics committee, says paying a source for information or an interview immediately puts the credibility of the information they provide in doubt. Exchanging money when youre looking for information from a source changes the nature of the relationship between the reporter and the source, Schotz says. It calls into question whether theyre talking to you because its the right thing to do or because theyre getting money. Schotz says reporters thinking about paying sources for information should ask themselves: Will a paid source tell you the truth, or tell you what you want to hear? Paying sources creates other problems. By paying a source you now have a business relationship with someone youre trying to cover objectively, Schotz says. Youve created a conflict of interest in the process. Schotz says most news organizations have policies against checkbook journalism. But lately there seems to be a trend to try to make a distinction between paying for an interview and paying for something else. This seems to be especially true for TV news divisions, a number of which have paid for exclusive interviews or photographs (see below). Full Disclosure is Important Schotz says if a news outlet does pay a source, they should disclose that to their readers or viewers. If theres a conflict of interest, then what should come next is explaining it in detail, letting viewers know you had a separate relationship other than just that of a journalist and a source, Schotz says. Schotz admits that news organizations not wanting to be scooped on a story might resort to checkbook journalism, but he adds: Competition doesnt give you license to cross ethical boundaries. Schotz advice for aspiring journalists? Dont pay for interviews. Dont give sources gifts of any kind. Dont try to exchange something of value in return for getting a sources comments or information or access to them. Journalists and sources shouldnt have any other relationship other than the one involved in gathering news. Here are some examples of checkbook journalism, according to the SPJ: ABC News paid $200,000 to Casey Anthony, the Florida woman accused of killing her 2-year-old daughter, Caylee, for exclusive rights to videos and pictures that ran on the network and its website. Earlier ABC had paid for Caylee Anthonys grandparents to stay three nights at a hotel as part of the networks plan to interview them.CBS News reportedly agreed to pay Caylee Anthonys grandparents $20,000 as a licensing fee to participate in the networks news coverage.ABC paid for Pennsylvania resident Anthony Rakoczy to pick up his daughter in Florida after a fake kidnapping attempt and for return plane tickets for Rakoczy and his daughter. ABC covered the trip and disclosed the free air travel.NBC News provided a chartered jet for New Jersey resident David Goldman and his son to fly home from Brazil after a custody battle. NBC got an exclusive interview with Goldman and video footage during that private jet ride.CNN paid $10,000 for the rights to an image taken by Jasper Schuringa, the Dutc h citizen who overpowered an alleged Christmas Day bomber on a flight from Amsterdam to Detroit. CNN also got an exclusive interview with Schuringa.

5 Differences Between Italian and English Capitalization

5 Differences Between Italian and English Capitalization While there aren’t a ton of differences between Italian and English when it comes to areas like punctuation or writing style, there are a handful you should know about in the realm of capitalization. Many words that are capitalized in English are not capitalized in Italian, and while knowing this won’t increase your spoken conversational ability, it will make your written communication, like emails and text messages, feel more natural. Differences in Capitalization Between Italian and English Italian and English capitalization differs in these areas: Days of the weekMonths of the yearProper adjectivesTitles of books, movies, plays, etc.Personal titles such as Mr., Mrs., and Miss. Days of the Week Here are some examples with the days of the week.   Arriva domenica. - He is arriving on Sunday.Ci vediamo lunedà ¬! - We’ll see each other on Monday! / See you Monday!Sei libero giovedà ¬? Ti va di prendere un aperitivo? - Are you free on Thursday? Do you want to get an aperitivo with me?A mercoledà ¬! - To Wednesday! (This is a common way to tell someone that you’ll be seeing them for the plans you made. In this case, the plans are on Wednesday.) Months of the year Il mio compleanno à ¨ il diciotto aprile. - My birthday is April 18.Vado in Italia a gennaio. Sicuramente si geler! - I’m going to Italy in January. It’s going to be really cold!A marzo, ho appena finito un corso intensivo di italiano. - I just finished an intensive Italian course in March. TIP: Notice how the preposition â€Å"a† goes before the month. Proper adjectives Proper adjectives are the descriptive form of the noun. For example, she’s from Canada (proper noun), which makes her Canadian (proper adjective). Lei à ¨ russa. - She’s Russian.Penso che siano canadesi. - I think they’re Canadian.Riesco a capire dal suo accento che lui à ¨ italiano. - I can tell from his accent that he’s Italian. Titles of Books, Movies, Plays, Etc. If you’re writing about a recent book or movie that you just read, you won’t capitalize the beginning of each letter in the title (excluding articles and conjunctions). Abbiamo appena visto â€Å"La ragazza del fuoco† L’hai visto anche tu? - We just saw Catching Fire. Did you also see it?Hai letto â€Å"L’amica geniale† di Elena Ferrante? Ti à ¨ piaciuto? - You read My Brilliant Friend by Elena Ferrante? DId you like it? Personal titles such as Mr., Mrs., and Miss. Il signor Neri à ¨ italiano. - Mr. Neri is Italian.Il mio nuovo capo si chiama signora Mazzocca. - My new boss’s name is Mrs. Mazzocca. TIP: You can use both forms with personal titles. In a formal context, like an email or a reference letter, you’ll want to capitalize all of the titles, like Prof. Arch. Dott. or Avv. minuscole a b c d e f g h i l m n o p q r s t u v z maiuscole A B C D E F G H I L M N O P Q R S T U V Z

Sustainability and Waste Management in uk catering industry Dissertation

Sustainability and Waste Management in uk catering industry - Dissertation Example .. 3.0 Methodology†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. 4.0 Result and Findings†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦... 5.0 Discussion†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. 6.0 Conclusion and Recommendation†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. 7.0 References†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. 8.0 Figures and Tables Figure 1: UK Catering Services Providers’ Perception of Environmental Pollution†¦ Figure 2: Common Hindrances to the Implementation of Sustainability Policies†¦Ã¢â‚¬ ¦. Table 1: Factors Influencing Effective Waste Management†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. 1.0 Abstract/Introduction This paper investigates the factors affecting sustainability and waste development in UK catering industry. Efforts are made to explain the current level of awareness of the environmental pollution. Some dramatic ways to manage the waste are appropriately highlighted. This is done with a great emphasis on the governmental challenges in confronting the menace of environmental pollution and waste management. ... Elaborate literature review is conducted to buttress the fact that the threat of waste and environmental pollution is real. The methodology employed for this study is an integration of qualitative and quantitative. Questionnaires were handed out to randomly select catering services providers. And the corresponding results and findings from this study are clearly presented and utilized in discussing the continuous danger environmental pollution poses on UK catering services. Appropriate conclusion and recommendations are provided at the end of this paper. 2.0 Literature Review Sustainable development has recently become a hot topic for discussion in most businesses. According to the World Commission on Environment and Development Report (1987, P. 43), sustainable development is defined as â€Å"meeting the needs of the present without compromising the ability of future generations to meet their own needs.† We can use the resources from the ecological system based on the availab le capacity of the resource base, and making sure that the wastes we create do not threaten the capacity of that particular ecosystem (Jennings and Zandbergen, 1995, P. 1019). Although some companies want to reduce environmental problems, two different perspectives are just holding back the progress (Hoffman, 2000, P. 9): The traditional aspect is concentrated on the debate about the observation of environmental legislation and the firms’ social responsibility. Second, the managers must accept that the firm’s overall strategy and environmental concerns inevitably must go hand in hand. Then, they need to find a way that satisfies the objectives of economic competitiveness and environmental protection at the same time. The environmental policy is guided by

The Brain Essay Example | Topics and Well Written Essays - 500 words

The Brain - Essay Example Thus, young people should not consume alcohol as it may severely damage their learning and memory processes. The research on rats suggests that adolescent brains may be particularly vulnerable to alcohol-induced memory impairments and learning difficulties. The study conducted with young adults confirms this thesis; when tested under alcohol, people in their early 20s performed worse on a task which involved immediate and delayed recall than people in their late 20s. This data clearly shows the vulnerability of younger subjects to alcohol-induced memory impairments. Young people often experience blackouts-episodes of anterogate amnesia, during which they are likely to engage in risky behaviours, such as vandalism, unprotected intercourse, or violence. Later they have no recollection of their actions. It is suggested that alcohol affects memory formation as it disrupts brain plasticity and interferes with the changes in circuitry which are essential for the learning process. Alcohol use damages hippocampus, the brain region which is crucial for memory formation. Moreover, repeated exposure to alcohol in adolescence may result in long-lasting changes in brain function later in life (White, 2003). The study conducted with adolescent alcohol abusers reveals that despite their relatively short periods of drinking, young people experienced severe cognitive impairments weeks after they stopped drinking. These changes are due to sensitivity of adolescent hippocampus to the neurotoxic effects of long-lasting use of alcohol. The data suggests that the subjects who abuse alcohol in their early adolescence are more vulnerable to hippocampal damage in the future. Use of alcohol in adolescence severely affects the establishment of new memories as well as memorization skills and learning capacities. Due to common blackouts, adolescent drinkers are likely to engage in risky behaviours. Moreover, extensive alcohol

Social Constructions Of Tuberculosis Sociology Essay

Social Constructions Of Tuberculosis Sociology Essay Even in the twenty-first century tuberculosis is a major public health concern, with an estimated 8.9 million new cases and 1.7 million deaths in 2004 Dye, 2006. TB is an infectious disease caused by a bacterium called Mycobacterium tuberculosis and it primary affects the lungs however it can also affect organs in the circulatory system, nervous system and lymphatic system as well as others. Commonly in the majority of cases an individual contracts the TB bacterium which then multiplies in the lungs often causing pneumonia along with chest pain, coughing up blood and a prolonged cough. As the bacterium spreads to other parts of the body, it is often interrupted by the bodys immune system. The immune system forms scar tissue or fibrosis around the TB bacteria and this helps fight the infection and prevents the disease from spreading throughout the body and to other people. If the bodys immune system is unable to fight TB or if the bacteria breaks through the scar tissue, the disease r eturns to an active state with pneumonia and damage to kidneys, bones, and the meninges that line the spinal cord and brain (Crosta, 2012). Thus, TB is generally classified as either latent or active; latent TB is the state when bacteria are present in the body however presents no systems therefore is inactive and not contagious. Whereas, active TB is contagious and can consists of numerous aforementioned symptoms. This essay will attempt to illustrate the ways in which social constructions of TB reflect wider socio-cultural values within contemporary global society. In the first part I will examine the historical context of TB and its link with poverty which continues on in present time. Secondly, I will explore the stigmatism and isolation with TB and finally I will relate the social construction of TB with the work of Emile Durkheim. It is important to recognise the geographical disparities in the prevalence of TB. For example, countries such as Australia have a relatively low incidence of the disease with new cases primarily being identified in migrant populations a decade after their settlement. In some European nations with substantial public healthcare facilities, TB continues to be a problem particularly within large thriving cities such as London. This disproportionate increase in disease incidence compared with other community groups and national rates can be found in those who are socially disadvantaged including homeless, drug and alcohol addicted, people with HIV, prisoner populations as well as refugees and migrantsà ¢Ã¢â€š ¬Ã‚ ¦ (Smith, 2009: 1). This demonstrates the negative connotations society denotes to TB infected individuals as well as suggesting that in order to better understand the social construction of TB, the history of the bacterium needs to be explored. In 1882 Koch isolated the Mycoba cterium tuberculosis and it was acknowledged that the disease was spread through overcrowded conditions, insufficient nutrition and a penurious lifestyle. It can be argued that TB has been constructed in two main ways: socially and biologically. Biologically through science as an organism and socially by the community as a slow wasting death that was often associated with pale individuals being removed from the community (Smith, 2009: 1). Throughout history TB has been ambiguously represented. Much of the Western nineteenth century fictional literature highly romanticized the disease and reinforced the prevailing practices and beliefs. Often referred to as consumption; people were described as being consumed and exhausted by the disease as symptoms were assumed to be individuals looking delicate, pale and drained of energy. Treatment during this period in history mirrored these romanticised notions. Medical care was commonly described as a combination of fresh air, companionship and rest. In contrast, many non-European countries negatively popularised TB as part of vampire myths as people tried to make sense of the disease symptoms (Smith, 2010). As a result, diseased bodies were exhumed and ritually burnt to remove vampires existence (Smith, 2009: 1). This demonstrates the contrasting representations of TB within differing societies, suggesting that the hegemonic socio-cultural values of a disease in this case TB pla ys a crucial role in the social representations of a disease. As well as illustrating the importance of considering the impact of spatial and temporal differences. Following the identification of the disease the discovery of streptomycin and other anti-tuberculosis medications quickly emerged. This gave the impression that TB was no longer a major health problem but instead incurable and controllable. Despite being important for treating TN, streptomycin, isoniazid and other anti-tuberculosis drugs contained limits for treatment. Resistance quickly developed and resistant strains of the bacterium quickly emerged limiting the use of many drugs. Consequently, to stop resistance several of the anti- TB drugs are required in combination and need to be taken for a period between 6 months and two years during therapy (Gandy and Zumla, 2002). However, recent outbreaks of multi-drug (MDR) TB have once again brought the disease to the forefront of global health problems. MDR TB is said to have emerged due to inadequate treatment of TB, commonly due to over- prescribing or improper prescribing of anti-TB drugs. Problems with treatment generally occur in immunocompromised patients, such as malnourished patients and Immune Deficiency Syndrome (AIDS) patients (Craig et al., 2007). In addition, it can be observed that the increase in TB closely reflects the rise cases of human immunodeficiency virus (HIV) and AIDS globally. Frequently, individuals with immune disorders are not only more likely to contract and develop TB, they are also more likely to be in contact with other TB patients due to often being placed in special wards and clinics, where the disease is easily spread to others (Gray, 1996: 25). In 2009, 12% of over 9 million new TB cases worldwide were HIV-positive, equalling approximately 1.1 million people (WHO, 2010). One of the most significantly affected countries is South Africa, where 73% of all TB cases are HIV-positive (Padarath and Fonn, 2010). Furthermore, in the early twentieth century improved medical knowledge and technology allowed for better diagnosis. During this period words such as contagion and plagues were popularly used in negative terms in association to judge societies. TB was reported as a form of societal assessment, infecting the bad and the good being disease free. A number of reports suggest a sense of apprehension became apparent as differing tuberculosis beliefs began to emerge (Smith, 2009: 1). This highlights the importance of social representations in terms of common terms associated with a disease play in the social constructions of TB. Moreover, it could be argued that peoples perceptions of a disease are not only shaped by their direct experiences and the impressions received from others but also significantly through media representations of the disease (Castells, 1998). It is important to recognise the symbiotic relationship between media representations of a disease and the dominant public disc ourses. It should be acknowledged that the term discourse has multiple meanings, nevertheless this essay will employ Luptons (1992) assessment that discourse as a set of ideas or a patterned way of thinking which can be discerned within texts and identified within wider social structures. The discourses that are founded and circulated by the media (mainly newspapers) can be regarded as working to produce what Foucault (1980) calls particular understandings about the world that are accepted as truth (Waitt, 2005). Thus in the process of disseminating such truths, it could be argued that the media as a collective and commercial institution is implicated in governing populations. Meaning that the power of the media can (directly or indirectly) influence the conduct of its audiences (Lawrence et al., 2008: 728). This illustrates that media representations of a disease (TB) impact and are themselves influenced by dominant societal discourses thus helping to shape the social constructions of TB. Moreover, it could be argued that there is strong link between those associated with TB and stigmatism and isolation as well as poverty and dirt (Scambler, 1998). Historically, TB was romanticised and referred to as consumption, however once its infectious nature was recognised this notion quickly changed. By the early twentieth century, the prevailing social and cultural values at the time generally believed that the disease festered in environments of dirt and squalor and was known as the diseases of the poor which could then be spread to the middle and upper classes. However, by the twenty-first century this discourse shifted from the poor (although marginalised groups such as the homeless and those with AIDS were still implicated) to the role played by Third World populations in harbouring the disease which threatens to explode into the developed world (Lawrence et al., 2008: 729). This demonstrates that as societys socio-cultural values change the way in which disease is constru cted and perceived also changes. It is important to consider the ways which these socio-cultural values change as well as acknowledge the interlinked relationship between dominant discourses, media representations and prevailing socio-cultural values. The relationship between TB and poverty has been recognised (Elender, Bentham and Langford, 1998) and arguably may not only reflect medical and social characteristics of poor individuals, but also characteristics of housing and neighbourhood which foster airborne spread of TB infection, such as crowding and poor ventilation. Population groups with an increased prevalence of latent infection (such as new immigrants) are disproportionately found in poor areas- often with lower quality housing (Wanyeki et al,. 2006: 501). This illustrates that not only socio-cultural values influence the social constructions of TB but socio-economic factors such as income and housing play a key role too. Additionally, it is important to recognise the global disparities with TB. For example, Dodor et al (2008) argue that in countries where treatment for TB is not readily available, the disease has become highly stigmatised and infected individuals are exceedingly discriminated. According to Link and Phelan (2001) stigma arises when a person is identified by a label that sets the person apart and prevailing cultural beliefs link the person to undesirable stereotypes that result in loss of status and discrimination (Gerrish, Naisby and Ismail, 2012: 2655). This can be illustrates in common cases where people with TB often isolate themselves in order to avoid infecting others may try to hide their diagnosis to reduce the risk of being shunned (Baral et al,. 2007). From research in Thailand, Johansson et al. (2000) distinguish two main forms of stigma; one based on social discrimination and second on fear from self-perceived stigma. Furthermore, patients commonly experience social isolati on in family sphere where they are obligated to eat and sleep separately (Baral et al,. 2007). This is a common case in countries such as India where little factual knowledge exists about the causes and treatments of TB and access to the necessary healthcare is diminutive (Weiss and Ramakrishna, 2006). As well as many rural communities where knowledge is passed through previous generations; stigmatism and isolation related to TB is substantial- representing the social cultural beliefs of the community. It is important to recognise that the stigma and its associated discrimination have a significant impact on disease control (Macq, Solis and Martinez, 2006). Concern about being identified as someone with TB can potentially put off people who suspect they have TB to get proper diagnosis and treatment. These delays in diagnosis and treatment mean that people remain infectious longer thus are more likely to transmit the disease to others (Mohamed at al,. 2011). In a study conducted by Balasubramanian, Oommen and Samuel (2000) in Kerala, India stated that stigma and fears about being identified with TB were responsible for 28% of patients and this was a significantly greater problem for women (50%) than men (21%). This illustrates those socio- cultural values, for example the gender inequality highly present in Indian societies has a crucial impact on the social construction of TB. Also, in another study of social stigma related to TB conducted in Maharashtra, India, showed that stigma and discrimination of the disease resulted in late diagnosis and treatment. Moranker et al,. (2000) found that 38 out of 80 patients they studies (40 women and 40 men) reported to actively attempting to hide their disease from the community. Social vulnerability contributed to womens reticence to disclose TB, and such women were typically widows or married and living with joint families (Weiss, Ramakrishna and Somma, 2006: 281). This demonstrates the extent to which negative socio-cultural beliefs and values about TB can help to construct the disease- in terms of diagnosis, treatment and contagion. Emile Durkheims (1915) work can help to better understand the argument that social constructions of TB reflect wider socio-cultural values. One of Durkheims core arguments was his claim that the ideas of time, space, class, cause and personality are constructed out of social elements. This allows us to examine the human body not only as a reflection of social elements but it draws attention to changes over time. Durkheims idea that space and classification are socially constructed stems from the collective experience of the social group. According to Durkheim the fundamental social division is dualistic in that one is between the social group and the other not the social group; which he applied to religion resulted in the sacred and the profane. This central framework can then be used to various ways of viewing the world. Simply put as one geographic space could be labelled as A and another as not A. Social anthropologist Mary Douglas (1966) extended this Durkheimian vision and disce rned that: far from a chasm separating the sacred and profane, as Durkheim had argued, there was a potential space which existed outside the classification system: this unclassified space polluted the purity of classification and was therefore seen as potentially dangerousà ¢Ã¢â€š ¬Ã‚ ¦Douglass analysis of purity and danger can equally be applied to the rules underpinning public health which are concerned with maintaining hygiene. The basic rule of hygiene is that some things are clean and others are dirty and therefore dangerous. Danger arises primarily from objects existing outside the classification system and therefore by determining what is dangerous and where it comes from it is possible to reconstruct the contemporary classification system (Armstrong, 2012: 16-17). This illustrates the essays central argument that social constructions of TB reflect wider socio- cultural values- meaning that till present day in many parts of the world TB is still perceived as an unknown variable and thus outside of societys normal classification system therefore is commonly professed synonymously with connotations of danger and dirt. These results in significant stigmatism, isolation and discrimination associated with individuals with TB (Heijnders and Van Der Meij, 2006). Furthermore, this highlights the fluid nature of social constructions of TB- meaning that since societies change over time so do their values and beliefs resulting in changes in the ways in which disease are socially constructed. Therefore, in order to fully understand how social constructions of TB reflect wider socio-cultural values, the historical context in which these factors are based and the dominant discourses must be considered. For example, in the mid nineteenth century public health, mainly relied on quarantine as a preventative method, slowly began to classify new sources of danger in objects and processes such as faeces, urine, contaminated food, smelly air, masturbation, dental sepsis, etc. The prevailing public health strategy at the time of Sanitary Science; which monitored objects entering the body (air, food, water) or leaving it (faeces, urine, etc.). Whereas, in the twentieth century new sources of danger emerged including venereal disease and TB .Thus, a new public health regime of Interpersonal Hygiene developed. Interpersonal Hygiene identified the new dangers not as emerging from nature and threatening body boundaries but as arising from other human bodies. TB, which had been a disease of insanitary conditions in the nineteenth century, became a disease of human contact, of coughing and sneezing (Armstrong, 2012: 18). This further demonstrates the changing and interlinking relationship between socio-cultural values and social constructions of TB. In conclusion, this essay has attempted to explore the various ways in which social constructions of TB reflects wider socio-cultural values in contemporary global society, by briefly examining the history of the disease and its prevalence in present time. As well as exploring the relationship between TB and poverty- statistically it can be observed that individuals with TB often belong to marginalised social groups and economically impoverished groups. Also, global disparities of TB prevalence was noted demonstrating that since each society is different and has varying socio-cultural beliefs and in lieu of the social constructionist theory this essay has adopted it could be argued that each society has its own particular social construction of TB influenced by its unique socio-cultural beliefs. This may be problematic given that if social constructions of TB are diverse but TB is perceived as a global health problem thus requiring global action then the nuances between the diverse s ocial constructions of TB will be overlooked thereby arguably hindering the possibility of improving TB diagnosis and treatment. This also points to the need for not only considering the medical sphere of TB but also if we argue that TB is socially constructed then it is important to recognise the need for including the social aspects to health policies. Furthermore, this essay examined the link between TB and stigmatism, isolation and discrimination through time and present day. Establishing that there are two main types of stigma associated with people with TB; self-stigmatism and societal stigmatism. Both are results of the negative connotations TB has held throughout time. Also, I briefly examined the role media representations play on the social construction of TB- particularly newspapers where the reader is viewed as an active agent. Finally, I utilised Emile Durkheims work to better understand and link the arguments presented in the essay. Durkheim states that ideas of time, space, class, personality are all produced with social elements. This highlights the argument that not only does the social construction of TB reflect wider socio-cultural values but that these values change over time thus the social construction of TB also correspondingly changes. Word Count: 2997