Financial Service Assignment 2 Essay Example | Topics and Well Written Essays - 3000 words

Financial Service Assignment 2 - Essay Example vital contributor towards the steadiness with regard to the financial structure along with being a significant element in the course of operations associated with the existent economy (Department of Mathematics, 2008). The structure of derivatives market in the present times has been learnt to lure increased concentration next to the present environment related to fraud cases, financial crisis along with the collapse of few of the market participants. It was an evident fact that the recent financial catastrophe principally occurred because of the planned credit-linked securities which were not actually derivatives. This made the regulators and the policy developers think regarding intensification of the guidelines for boosting the lucidity and security for both the wide array of financial instruments as well as derivatives (Department of Mathematics, 2008). Derivatives are referred as financial contracts the worth of which is considered as a resultant of certain definite underlying assets. The underlying assets are believed to entail equity indices as well as equities, loans, exchange rates, commercial along with residential mortgages, bonds, interest rates, commodities and natural calamities like the hurricanes and the earthquakes. The derivative contracts appear or are available in numerous forms however, the most widespread forms entail forwards or futures, swaps and options (Acharya & et. al., 2009). A forward contract is referred to a certain contract in which the involved two parties comply to trade the definite â€Å"underlying asset† in the upcoming days at a specific point of time which has been ascertained earlier and at a preset price. Thus, the buyer complies today to purchase a definite form of asset in the upcoming days and the other party i.e. the seller complies to give delivery of that definite asset at the agreed and predetermined time. Futures are regarded as standardised form of forwards that are capable of being dealt in on the exchange

Current methods for Cancer Stem Cell characterisation and isolation Essay

Current methods for Cancer Stem Cell characterisation and isolation - Essay Example Apart from achieving a 40-98% enrichment, this technique also produced spheres with enhanced tumorigenicity in immune-compromised mice [Ponti et.al. 2005]. Such a methodology has also been adopted for the enrichment of CSCs from brain [Singh et. al. 2003], bone sarcomas [Gibbs et.al. 2005], pancreas [Gou et. al. 2007], melanomas [Fang et. al. 2005] and colon [Ricci-Vitiani et. al. 2007]. The spheres produced in all these instances had a high level of surface markers that belong to the respective tumor initiators, namely CSCs. The exploitation of the sphere forming properties of CSCs for their enrichment in culture is considerably more preferable than using surface markers or SPs. In spite of its utility, the process of isolation of CSCs based on sphere formation has significant limitations, the biggest one of which is that they are a heterogeneous population, wherein, only a few cells undergo self-renewal [Ponti et. al. 2005]. Furthermore, upon immunofluorescence analysis of spheres obtained in prostrate cell lines, it has been found that these are heterogenous for CSC surface markers [Patrawala et. al. 2006]. Moreover, variation in sphere size, culture medium and the differences in employed techniques for enrichment also limit the success of the process, as shown in neurosphere cultures [Jensen & Parmar 2006]. The ALDH enzyme plays an important role in the conversion of aldehydes into weak acids. This reaction is vital for the generation of biologically active substances. The ALDEFLUOR assay is based on an enzymatic reaction that measures aldhehyde dehydrogenase 1 (ALDH 1) activity. The detoxifying enzyme, ALDH 1, is responsible for the formation retinoic acid, a biologically active substance, from the oxidation of retinol. The enzyme ALDH1 is abundant in primitive hematopoietic cells and is expressed in the early

The short story the lottery and conformity Essay

The short story the lottery and conformity - Essay Example Conformity is valuable to the society because cohesion and smooth running of events and processes. A person who drives on the right side of the road is a good example of definition of conformity and illustrates its benefits through safe road usage. Deciding to act against the norm by driving on the wrong side of the road will however risk the life of the actor as well as the life of other road users. In the short story, the society is deeply rooted to its Lottery tradition and even though no one compels it to commit the murder act, it chooses to stand by its tradition. Even though the specific example identifies a wrong act, murder of an innocent member of the society, the author communicates the power of conformity to tradition that can help a society to achieve its objectives. Conformity therefore promotes retention of good cultural beliefs in a society and may improve resistance from negative practices from other cultures. The city residents’ resistance to abandoning their culture and assume practices or changes in other societies demonstrates this. The author uses the black box and the lottery as symbols for illustrating this role of conformity. Even though the real box was lost and the current one is old, the villagers have chosen to stick by the two symbols and this shows the power of conformity that may facilitate a society’s theme regardless of dynamism around the society (Jackson 2- 27). Conformity is also valuable to society because it allows us to adapt to the society in a normal way and for our own good so that we might not hurt ourselves later in life. Even though The Lottery only highlights the murder ritual, there could be positive values that the tradition facilitates. The society’s reaction to the lottery also suggests that such values develop naturally and the uniformity means that an individual is less likely to be in

Philosophy Essay Example for Free

Philosophy Essay 1. Settings: I scheduled my AA meeting for Tuesday September the 18th at 10 p.m. at the Sobe Room in Miami Beach (1718 Bay Rd. Miami Beach, Fl. 33139). When I arrived I noticed that the parking was far away from the actual meeting point. The meeting point was a church type structure with no sing or any other identification. The door was open so I just went in; I waited about 5 minutes for the meeting to start. The meeting took place in a large room, and the chairs were organized in a semicircle and at the front there was a kind of podium. In the Sobe Room all meetings are open, so I didn’t have to set an appointment. In the meeting were about 50 people, I guess because it was in south beach the majority were young people under 40. There were mostly white males, followed by white females some Latin and some African Americans. There were about 15 people who were there for the first time. I didn’t have to say why I was there but I did have to say my name when everyone else did. 2. Philosophy Alcoholics Anonymous (AA) was founded in 1935 by Bill Wilson and Dr. Bob Smith. The primary purpose of AA is to stay sober and help other alcoholics achieve sobriety. Although AA was founded on Christian principles and by white men, the organization has evolved to be multicultural. AA doesn’t keep a list of members names, but estimates that it has 2 million members who come from all backgrounds. The philosophy behind Alcoholics Anonymous is that alcoholism is a disease. Even if someone stops drinking, they are not cured. The individual is a recovering alcoholic. The organization follows a 12-step structure designed to help the recovering alcoholic have a healthy mind and spirit. By following the 12 steps in sequence, the recovering alcoholic can improve their thought processes and work on healing their emotions. 3. Therapeutic content Even though AA is an independent organization and is not based on psychological or therapeutic research or interventions, they have adopted some techniques of different theoretical models to help the group members deal with their illness. AA uses techniques from diverse psychological theoretical models such as existentialism, gestalt, and narrative therapy. The existentialism theory invites clients to explore their being and ask themselves philosophical questions such as what is the meaning of live, how do actions define individuals and to continually revise their set of values. AA uses this approach in its program when they talk about the greater power, the purpose of their lives, etc. Gestalt theory sees each client as a unique individual and states that any change made by the client has to be his or her own decision, gestalt therapy is also very confrontational, and in both characteristics are included in the AA program. AA states that the client will get better if and only they really want it and commit to it. Also AA uses an approach similar to the narrative therapy by treating the addiction as an illness and as a problem independent of the client, it externalizes it to try to confront it. 4. Impressions and significance: When I arrived to the meeting the first thing that called my attention was the fact that we had to park really far away from the actual site (about two blocks) I later found out that it was purposely made this way so the members wouldn’t feel self conscious about having their cars outside of something that could be affiliated with alcoholism. I entered the location, it wasn’t an actual church, but it had a church like structure. The doors were opened and most people seemed to know each other, before the meeting started some people said hi to me but no one asked any questions. The meeting began with a shot prayer called the serenity prayer, which had me thinking about some contradictions found in the AA philosophy since they claim not to have any religious affiliation but it certainly felt a little inclined towards the Christian side. After the prayer everyone introduced themselves (most people said their names and I’m an alcoholic, but some didn’t) I said my name but gave no further information. Then someone proceed to talk a little about the AA program and the 12-step structure. After the greeting process a guy (27) stood up and went to the podium. He started by repeating his name and saying he was an alcoholic. He said that since this time he saw a lot of new faces he wanted to share his story again. The man shared a very powerful story about his involvement with alcohol, he stated he started drinking around the age of 14, he said that at the moment he thought he was just having fun and doing the same that everyone else did, but that now that he thinks about it he realizes he was using alcohol as a coping mechanism to deal with the confusion he was facing about his sexuality. He stated that he came out of the closet at the age of 16, that it was a very difficult time and that he was dating older men who encouraged him to drink. He continued talking about what coming out had done to the relationship with his family members; he described the time as very painful and he cried while telling the story (some of the people in the meeting cried as well). He said that his mother was very supportive since the beginning, that his younger brother had a hard time understanding; he said that he was a jog in school, so no one expected him to come out since he wasn’t â€Å"the gay type†. But that the real issue was with his father, as soon as he gave him the news the father became very angry and he kicked him out of the house. He said that he sort of expected the reaction but thought that he would eventually get over it, but that that hadn’t happened yet, and that it’s been 10 years and 7 months since the last time he spoke with his father. He said that he joined AA when he was 23, he decide to attend a meeting because he and his partner were having terrible fights while he was under the influence of alcohol and he even tried to hit him once. At that point the partner threatened with leaving him if he didn’t get treatment. He stated that it was the best decision he made in his live. He has now been sober for 3 years and 4 months. Before going to the meeting I had many opinions about what I would find there, I was sure that most people would be people of low socioeconomic status probably many homeless and very angry people. I was afraid of being forced to speak and that they wouldn’t understand the reason that I was participating in the meeting. I expected to see a lot of people praying, singing, and hugging at the end. But the truth is that the reality was very different to what I had in my imagination, I think my perception was heavily influenced by movies I’ve see about it. One thing that caught my attention was the first to realize that most people in the group were people with jobs and life situations fairly normal. But mostly I was surprised that people were a bit cold and distant. I was hoping that dodos were united and friendly to each other but not the case. For me the story of gay guy was very powerful and I felt good to see people around me responding positively and nodding. One thing I did not like was the strong Christian influence of the program; I feel that excludes many people who do not feel identified with this dogma. I think AA is a very powerful tool and can help many clients, but I also think is not for everyone. I would recommend it to clients with maladaptive behaviors that do not have the skills to deal with day-to-day problems. I think that a person has to be religious to some point to really identify with the program. I would not recommend this program to teenagers because I think that there are other programs more suitable for this population.

Evaluating The Waste Water Treatment Processes Environmental Sciences Essay

Evaluating The Waste Water Treatment Processes Environmental Sciences Essay Domestic wastewater treatment or sewage treatment, is the process of removing contaminants from wastewater and household sewage, both runoff (effluents) and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants. Its objective is to produce an environmentally-safe fluid waste stream (or treated effluent) and a solid waste (or treated sludge) suitable for disposal or reuse (usually as farm fertilizer). Using advanced technology it is now possible to re-use sewage effluent for drinking water, although Singapore is the only country to implement such technology on a production scale in its production of NEWater. 1.2 ORIGIN OF WASTE WATER Sewage is created by residential, institutional, and commercial and industrial establishments and includes household waste liquid from toilets, baths, showers, kitchens, sinks and so forth that is disposed of via sewers. In many areas, sewage also includes liquid waste from industry and commerce. The separation and draining of household waste into greywater and blackwater is becoming more common in the developed world, with greywater being permitted to be used for watering plants or recycled for flushing toilets. Sewage may include stormwater runoff. Sewerage systems capable of handling stormwater are known as combined systems. Combined sewer systems are usually avoided now because precipitation causes widely varying flows reducing sewage treatment plant efficiency. Combined sewers require much larger, more expensive, treatment facilities than sanitary sewers. Heavy storm runoff may overwhelm the sewage treatment system, causing a spill or overflow. Sanitary sewers are typically much smaller than combined sewers, and they are not designed to transport stormwater. Backups of raw sewage can occur if excessive Infiltration/Inflow is allowed into a sanitary sewer system. Modern sewered developments tend to be provided with separate storm drain systems for rainwater. As rainfall travels over roofs and the ground, it may pick up various contaminants including soil particles and other sediment, heavy metals, organic compounds, animal waste, and oil and grease. (See urban runoff.) Some jurisdictions require stormwater to receive some level of treatment before being discharged directly into waterways. Examples of treatment processes used for stormwater include retention basins, wetlands, buried vaults with various kinds of media filters, and vortex separators (to remove coarse solids). CHAPTER TWO 2.1 OVERVIEW OF WASTE WATER TREATMENT PROCESSES Sewage can be treated close to where it is created, a decentralised system, (in septic tanks, biofilters or aerobic treatment systems), or be collected and transported via a network of pipes and pump stations to a municipal treatment plant, a centralised system, (see sewerage and pipes and infrastructure). Sewage collection and treatment is typically subject to local, state and federal regulations and standards. Industrial sources of wastewater often require specialized treatment processes as shown in the diagram below: Process Flow Diagram for a typical treatment plant via Subsurface Flow Constructed Wetlands (SFCW) Sewage treatment generally involves three stages, called primary, secondary and tertiary treatment. Primary treatment consists of temporarily holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil, grease and lighter solids float to the surface. The settled and floating materials are removed and the remaining liquid may be discharged or subjected to secondary treatment. Secondary treatment removes dissolved and suspended biological matter. Secondary treatment is typically performed by indigenous, water-borne micro-organisms in a managed habitat. Secondary treatment may require a separation process to remove the micro-organisms from the treated water prior to discharge or tertiary treatment. Tertiary treatment is sometimes defined as anything more than primary and secondary treatment in order to allow rejection into a highly sensitive or fragile ecosystem (estuaries, low-flow rivers, coral reefs etc.). Treated water is sometimes disinfected chemically or physically (for example, by lagoons and microfiltration) prior to discharge into a stream, river, bay, lagoon or wetland, or it can be used for the irrigation of a golf course, green way or park. If it is sufficiently clean, it can also be used for groundwater recharge or agricultural purposes. 2.2 PRE-TREATMENT Pre-treatment removes materials that can be easily collected from the raw waste water before they damage or clog the pumps and skimmers of primary treatment clarifiers (trash, tree limbs, leaves, etc.). SCREENING The influent sewage water is screened to remove all large objects like cans, rags, sticks, plastic packets etc. carried in the sewage stream. This is most commonly done with an automated mechanically raked bar screen in modern plants serving large populations, whilst in smaller or less modern plants a manually cleaned screen may be used. The raking action of a mechanical bar screen is typically paced according to the accumulation on the bar screens and/or flow rate. The solids are collected and later disposed in a landfill or incinerated. Bar screens or mesh screens of varying sizes may be used to optimize solids removal. If gross solids are not removed they become entrained in pipes and moving parts of the treatment plant and can cause substantial damage and inefficiency in the process. GRIT REMOVAL Pre-treatment may include a sand or grit channel or chamber where the velocity of the incoming wastewater is adjusted to allow the settlement of sand, grit, stones, and broken glass. These particles are removed because they may damage pumps and other equipment. For small sanitary sewer systems, the grit chambers may not be necessary, but grit removal is desirable at larger plants. FAT AND GREASE REMOVAL In some larger plants, fat and grease is removed by passing the sewage through a small tank where skimmers collect the fat floating on the surface. Air blowers in the base of the tank may also be used to help recover the fat as a froth. In most plants however, fat and grease removal takes place in the primary settlement tank using mechanical surface skimmers. 2.3 PRIMARY TREATMENT In the primary sedimentation stage, sewage flows through large tanks, commonly called primary clarifiers or primary sedimentation tanks. The tanks are used to settle sludge while grease and oils rise to the surface and are skimmed off. Primary settling tanks are usually equipped with mechanically driven scrapers that continually drive the collected sludge towards a hopper in the base of the tank where it is pumped to sludge treatment facilities. Grease and oil from the floating material can sometimes be recovered for saponification. The dimensions of the tank should be designed to effect removal of a high percentage of the floatables and sludge. A typical sedimentation tank may remove from 60 to 65 percent of suspended solids, and from 30 to 35 percent of biochemical oxygen demand (BOD) from the sewage. 2.4 SECONDARY TREATMENT Secondary treatment is designed to substantially degrade the biological content of the sewage which are derived from human waste, food waste, soaps and detergent. The majority of municipal plants treat the settled sewage liquor using aerobic biological processes. To be effective, the biota require both oxygen and food to live. The bacteria and protozoa consume biodegradable soluble organic contaminants (e.g. sugars, fats, organic short-chain carbon molecules, etc.) and bind much of the less soluble fractions into floc. Secondary treatment systems are classified as fixed-film or suspended-growth systems. Fixed-film or attached growth systems include trickling filters and rotating biological contactors, where the biomass grows on media and the sewage passes over its surface. Suspended-growth systems include activated sludge, where the biomass is mixed with the sewage and can be operated in a smaller space than fixed-film systems that treat the same amount of water. However, fixed-film systems are more able to cope with drastic changes in the amount of biological material and can provide higher removal rates for organic material and suspended solids than suspended growth systems.[6]:11-13 Roughing filters are intended to treat particularly strong or variable organic loads, typically industrial, to allow them to then be treated by conventional secondary treatment processes. Characteristics include filters filled with media to which wastewater is applied. They are designed to allow high hydraulic loading and a high level of aeration. On larger installations, air is forced through the media using blowers. The resultant wastewater is usually within the normal range for conventional treatment processes. A generalized, schematic diagram of an activated sludge process. A filter removes a small percentage of the suspended organic matter, while the majority of the organic matter undergoes a change of character, only due to the biological oxidation and nitrification taking place in the filter. With this aerobic oxidation and nitrification, the organic solids are converted into coagulated suspended mass, which is heavier and bulkier, and can settle to the bottom of a tank. The effluent of the filter is therefore passed through a sedimentation tank, called a secondary clarifier, secondary settling tank or humus tank. ACTIVATED SLUDGE In general, activated sludge plants encompass a variety of mechanisms and processes that use dissolved oxygen to promote the growth of biological floc that substantially removes organic material. The process traps particulate material and can, under ideal conditions, convert ammonia to nitrite and nitrate and ultimately to nitrogen gas. SURFACE-AERATED BASINS (LAGOONS) Many small municipal sewage systems in the United States (1 million gal./day or less) use aerated lagoons. Most biological oxidation processes for treating industrial wastewaters have in common the use of oxygen (or air) and microbial action. Surface-aerated basins achieve 80 to 90 percent removal of BOD with retention times of 1 to 10 days. The basins may range in depth from 1.5 to 5.0 metres and use motor-driven aerators floating on the surface of the wastewater. In an aerated basin system, the aerators provide two functions: they transfer air into the basins required by the biological oxidation reactions, and they provide the mixing required for dispersing the air and for contacting the reactants (that is, oxygen, wastewater and microbes). Typically, the floating surface aerators are rated to deliver the amount of air equivalent to 1.8 to 2.7  kg O2/kW ·h. However, they do not provide as good mixing as is normally achieved in activated sludge systems and therefore aerated basins do not achieve the same performance level as activated sludge units. Biological oxidation processes are sensitive to temperature and, between 0  °C and 40  °C, the rate of biological reactions increase with temperature. Most surface aerated vessels operate at between 4  °C and 32  °C. CONSTRUCTED WETLANDS Constructed wetlands (can either be surface flow or subsurface flow, horizontal or vertical flow), include engineered reedbeds and belong to the family of phytorestoration and ecotechnologies; they provide a high degree of biological improvement and depending on design, act as a primary, secondary and sometimes tertiary treatment, also see phytoremediation. One example is a small reedbed used to clean the drainage from the elephants enclosure at Chester Zoo in England; numerous CWs are used to recycle the water of the city of Honfleur in France and numerous other towns in Europe, the US, Asia and Australia. They are known to be highly productive systems as they copy natural wetlands, called the Kidneys of the earth for their fundamental recycling capacity of the hydrological cycle in the biosphere. Robust and reliable, their treatment capacities improve as time go by, at the opposite of conventional treatment plants whose machinery age with time. They are being increasingly used, alt hough adequate and experienced design are more fundamental than for other systems and space limitation may impede their use. FILTER BEDS (OXIDIZING BEDS) In older plants and those receiving variable loadings, trickling filter beds are used where the settled sewage liquor is spread onto the surface of a bed made up of coke (carbonized coal), limestone chips or specially fabricated plastic media. Such media must have large surface areas to support the biofilms that form. The liquor is typically distributed through perforated spray arms. The distributed liquor trickles through the bed and is collected in drains at the base. These drains also provide a source of air which percolates up through the bed, keeping it aerobic. Biological films of bacteria, protozoa and fungi form on the medias surfaces and eat or otherwise reduce the organic content. This biofilm is often grazed by insect larvae, snails, and worms which help maintain an optimal thickness. Overloading of beds increases the thickness of the film leading to clogging of the filter media and ponding on the surface. SOIL BIO-TECHNOLOGY A new process called Soil Bio-Technology (SBT) developed at IIT Bombay has shown tremendous improvements in process efficiency enabling total water reuse, due to extremely low operating power requirements of less than 50 joules per kg of treated water. Typically SBT systems can achieve chemical oxygen demand (COD) levels less than 10  mg/L from sewage input of COD 400  mg/L. SBT plants exhibit high reductions in COD values and bacterial counts as a result of the very high microbial densities available in the media. Unlike conventional treatment plants, SBT plants produce insignificant amounts of sludge, precluding the need for sludge disposal areas that are required by other technologies. BIOLOGICAL AERATED FILTERS Biological Aerated (or Anoxic) Filter (BAF) or Biofilters combine filtration with biological carbon reduction, nitrification or denitrification. BAF usually includes a reactor filled with a filter media. The media is either in suspension or supported by a gravel layer at the foot of the filter. The dual purpose of this media is to support highly active biomass that is attached to it and to filter suspended solids. Carbon reduction and ammonia conversion occurs in aerobic mode and sometime achieved in a single reactor while nitrate conversion occurs in anoxic mode. BAF is operated either in upflow or downflow configuration depending on design specified by manufacturer. Schematic diagram of a typical rotating biological contactor (RBC). The treated effluent clarifier/settler is not included in the diagram. ROTATING BIOLOGICAL CONTACTORS Rotating biological contactors (RBCs) are mechanical secondary treatment systems, which are robust and capable of withstanding surges in organic load. RBCs were first installed in Germany in 1960 and have since been developed and refined into a reliable operating unit. The rotating disks support the growth of bacteria and micro-organisms present in the sewage, which break down and stabilise organic pollutants. To be successful, micro-organisms need both oxygen to live and food to grow. Oxygen is obtained from the atmosphere as the disks rotate. As the micro-organisms grow, they build up on the media until they are sloughed off due to shear forces provided by the rotating discs in the sewage. Effluent from the RBC is then passed through final clarifiers where the micro-organisms in suspension settle as a sludge. The sludge is withdrawn from the clarifier for further treatment. A functionally similar biological filtering system has become popular as part of home aquarium filtration and purification. The aquarium water is drawn up out of the tank and then cascaded over a freely spinning corrugated fiber-mesh wheel before passing through a media filter and back into the aquarium. The spinning mesh wheel develops a biofilm coating of microorganisms that feed on the suspended wastes in the aquarium water and are also exposed to the atmosphere as the wheel rotates. This is especially good at removing waste . MEMBRANE BIOREACTORS Membrane bioreactors (MBR) combine activated sludge treatment with a membrane liquid-solid separation process. The membrane component uses low pressure microfiltration or ultra filtration membranes and eliminates the need for clarification and tertiary filtration. The membranes are typically immersed in the aeration tank; however, some applications utilize a separate membrane tank. One of the key benefits of an MBR system is that it effectively overcomes the limitations associated with poor settling of sludge in conventional activated sludge (CAS) processes. The technology permits bioreactor operation with considerably higher mixed liquor suspended solids (MLSS) concentration than CAS systems, which are limited by sludge settling. The process is typically operated at MLSS in the range of 8,000-12,000  mg/L, while CAS are operated in the range of 2,000-3,000  mg/L. The elevated biomass concentration in the MBR process allows for very effective removal of both soluble and particula te biodegradable materials at higher loading rates. Thus increased sludge retention times, usually exceeding 15 days, ensure complete nitrification even in extremely cold weather. SECONDARY SEDIMENTATION The final step in the secondary treatment stage is to settle out the biological floc or filter material through a secondary clarifier and to produce sewage water containing low levels of organic material and suspended matter. TERTIARY TREATMENT The purpose of tertiary treatment is to provide a final treatment stage to raise the effluent quality before it is discharged to the receiving environment (sea, river, lake, ground, etc.). More than one tertiary treatment process may be used at any treatment plant. If disinfection is practiced, it is always the final process. It is also called effluent polishing. FILTRATION Sand filtration removes much of the residual suspended matter. Filtration over activated carbon, also called carbon adsorption, removes residual toxins. LAGOONING Lagooning provides settlement and further biological improvement through storage in large man-made ponds or lagoons. These lagoons are highly aerobic and colonization by native macrophytes, especially reeds, is often encouraged. Small filter feeding invertebrates such as Daphnia and species of Rotifera greatly assist in treatment by removing fine particulates. NUTRIENT REMOVAL Wastewater may contain high levels of the nutrients nitrogen and phosphorus. Excessive release to the environment can lead to a build up of nutrients, called eutrophication, which can in turn encourage the overgrowth of weeds, algae, and cyanobacteria (blue-green algae). This may cause an algal bloom, a rapid growth in the population of algae. The algae numbers are unsustainable and eventually most of them die. The decomposition of the algae by bacteria uses up so much of oxygen in the water that most or all of the animals die, which creates more organic matter for the bacteria to decompose. In addition to causing deoxygenation, some algal species produce toxins that contaminate drinking water supplies. Different treatment processes are required to remove nitrogen and phosphorus. NITROGEN REMOVAL The removal of nitrogen is effected through the biological oxidation of nitrogen from ammonia to nitrate (nitrification), followed by denitrification, the reduction of nitrate to nitrogen gas. Nitrogen gas is released to the atmosphere and thus removed from the water. Nitrification itself is a two-step aerobic process, each step facilitated by a different type of bacteria. The oxidation of ammonia (NH3) to nitrite (NO2à ¢Ã‹â€ Ã¢â‚¬â„¢) is most often facilitated by Nitrosomonas spp. (nitroso referring to the formation of a nitroso functional group). Nitrite oxidation to nitrate (NO3à ¢Ã‹â€ Ã¢â‚¬â„¢), though traditionally believed to be facilitated by Nitrobacter spp. (nitro referring the formation of a nitro functional group), is now known to be facilitated in the environment almost exclusively by Nitrospira spp. Denitrification requires anoxic conditions to encourage the appropriate biological communities to form. It is facilitated by a wide diversity of bacteria. Sand filters, lagooning and reed beds can all be used to reduce nitrogen, but the activated sludge process (if designed well) can do the job the most easily. Since denitrification is the reduction of nitrate to dinitrogen gas, an electron donor is needed. This can be, depending on the wastewater, organic matter (from faeces), sulfide, or an added donor like methanol. PHOSPHORUS REMOVAL Phosphorus removal is important as it is a limiting nutrient for algae growth in many fresh water systems. (For a description of the negative effects of algae, see Nutrient removal). It is also particularly important for water reuse systems where high phosphorus concentrations may lead to fouling of downstream equipment such as reverse osmosis. Phosphorus can be removed biologically in a process called enhanced biological phosphorus removal. In this process, specific bacteria, called polyphosphate accumulating organisms (PAOs), are selectively enriched and accumulate large quantities of phosphorus within their cells (up to 20 percent of their mass). When the biomass enriched in these bacteria is separated from the treated water, these biosolids have a high fertilizer value. Phosphorus removal can also be achieved by chemical precipitation, usually with salts of iron (e.g. ferric chloride), aluminum (e.g. alum), or lime. This may lead to excessive sludge production as hydroxides precipitates and the added chemicals can be expensive. Chemical phosphorus removal requires significantly smaller equipment footprint than biological removal, is easier to operate and is often more reliable than biological phosphorus removal  . Another method for phosphorus removal is to use granular laterite. Once removed, phosphorus, in the form of a phosphate-rich sludge, may be stored in a land fill or resold for use in fertilizer. DISINFECTION The purpose of disinfection in the treatment of waste water is to substantially reduce the number of microorganisms in the water to be discharged back into the environment. The effectiveness of disinfection depends on the quality of the water being treated (e.g., cloudiness, pH, etc.), the type of disinfection being used, the disinfectant dosage (concentration and time), and other environmental variables. Cloudy water will be treated less successfully, since solid matter can shield organisms, especially from ultraviolet light or if contact times are low. Generally, short contact times, low doses and high flows all militate against effective disinfection. Common methods of disinfection include ozone, chlorine, ultraviolet light, or sodium hypochlorite. Chloramine, which is used for drinking water, is not used in waste water treatment because of its persistence. Chlorination remains the most common form of waste water disinfection in North America due to its low cost and long-term history of effectiveness. One disadvantage is that chlorination of residual organic material can generate chlorinated-organic compounds that may be carcinogenic or harmful to the environment. Residual chlorine or chloramines may also be capable of chlorinating organic material in the natural aquatic environment. Further, because residual chlorine is toxic to aquatic species, the treated effluent must also be chemically dechlorinated, adding to the complexity and cost of treatment. Ultraviolet (UV) light can be used instead of chlorine, iodine, or other chemicals. Because no chemicals are used, the treated water has no adverse effect on organisms that later consume it, as may be the case with other methods. UV radiation causes damage to the genetic structure of bacteria, viruses, and other pathogens, making them incapable of reproduction. The key disadvantages of UV disinfection are the need for frequent lamp maintenance and replacement and the need for a highly treated effluent to ensure that the target microorganisms are not shielded from the UV radiation (i.e., any solids present in the treated effluent may protect microorganisms from the UV light). In the United Kingdom, UV light is becoming the most common means of disinfection because of the concerns about the impacts of chlorine in chlorinating residual organics in the wastewater and in chlorinating organics in the receiving water. Some sewage treatment systems in Canada and the US also use UV light for their effluent water disinfection. Ozone (O3) is generated by passing oxygen (O2) through a high voltage potential resulting in a third oxygen atom becoming attached and forming O3. Ozone is very unstable and reactive and oxidizes most organic material it comes in contact with, thereby destroying many pathogenic microorganisms. Ozone is considered to be safer than chlorine because, unlike chlorine which has to be stored on site (highly poisonous in the event of an accidental release), ozone is generated onsite as needed. Ozonation also produces fewer disinfection by-products than chlorination. A disadvantage of ozone disinfection is the high cost of the ozone generation equipment and the requirements for special operators. ODOUR CONTROL Odours emitted by sewage treatment are typically an indication of an anaerobic or septic condition. Early stages of processing will tend to produce smelly gases, with hydrogen sulfide being most common in generating complaints. Large process plants in urban areas will often treat the odours with carbon reactors, a contact media with bio-slimes, small doses of chlorine, or circulating fluids to biologically capture and metabolize the obnoxious gases. Other methods of odour control exist, including addition of iron salts, hydrogen peroxide, calcium nitrate, etc. to manage hydrogen sulfide levels. PACKAGE PLANTS AND BATCH REACTORS To use less space, treat difficult waste and intermittent flows, a number of designs of hybrid treatment plants have been produced. Such plants often combine at least two stages of the three main treatment stages into one combined stage. In the UK, where a large number of wastewater treatment plants serve small populations, package plants are a viable alternative to building a large structure for each process stage. In the US, package plants are typically used in rural areas, highway rest stops and trailer parks. One type of system that combines secondary treatment and settlement is the sequencing batch reactor (SBR). Typically, activated sludge is mixed with raw incoming sewage, and then mixed and aerated. The settled sludge is run off and re-aerated before a proportion is returned to the headworks. SBR plants are now being deployed in many parts of the world. The disadvantage of the SBR process is that it requires a precise control of timing, mixing and aeration. This precision is typically achieved with computer controls linked to sensors. Such a complex, fragile system is unsuited to places where controls may be unreliable, poorly maintained, or where the power supply may be intermittent. Extended aeration package plants use separate basins for aeration and settling, and are somewhat larger than SBR plants with reduced timing sensitivity. Package plants may be referred to as high charged or low charged. This refers to the way the biological load is processed. In high charged systems, the biological stage is presented with a high organic load and the combined floc and organic material is then oxygenated for a few hours before being charged again with a new load. In the low charged system the biological stage contains a low organic load and is combined with flocculate for longer times. SLUDGE TREATMENT AND DISPOSAL The sludges accumulated in a wastewater treatment process must be treated and disposed of in a safe and effective manner. The purpose of digestion is to reduce the amount of organic matter and the number of disease-causing microorganisms present in the solids. The most common treatment options include anaerobic digestion, aerobic digestion, and composting. Incineration is also used albeit to a much lesser degree. Sludge treatment depends on the amount of solids generated and other site-specific conditions. Composting is most often applied to small-scale plants with aerobic digestion for mid sized operations, and anaerobic digestion for the larger-scale operations. ANAEROBIC DIGESTION Anaerobic digestion is a bacterial process that is carried out in the absence of oxygen. The process can either be thermophilic digestion, in which sludge is fermented in tanks at a temperature of 55 °C, or mesophilic, at a temperature of around 36 °C. Though allowing shorter retention time (and thus smaller tanks), thermophilic digestion is more expensive in terms of energy consumption for heating the sludge. Anaerobic digestion is the most common (mesophilic) treatment of domestic sewage in septic tanks, which normally retain the sewage from one day to two days, reducing the BOD by about 35 to 40 percent. This reduction can be increased with a combination of anaerobic and aerobic treatment by installing Aerobic Treatment Units (ATUs) in the septic tank. One major feature of anaerobic digestion is the production of biogas (with the most useful component being methane), which can be used in generators for electricity production and/or in boilers for heating purposes. AEROBIC DIGESTION Aerobic digestion is a bacterial process occurring in the presence of oxygen. Under aerobic conditions, bacteria rapidly consume organic matter and convert it into carbon dioxide. The operating costs used to be characteristically much greater for aerobic digestion because of the energy used by the blowers, pumps and motors needed to add oxygen to the process. Aerobic digestion can also be achieved by using diffuser systems or jet aerators to oxidize the sludge. COMPOSTING Composting is also an aerobic process that involves mixing the sludge with sources of carbon such as sawdust, straw or wood chips. In the presence of oxygen, bacteria digest both the wastewater solids and the added carbon source and, in doing so, produce a large amount of heat. INCINERATION Incineration of sludge is less common because of air emissions concerns and the supplemental fuel (typically natural gases or fuel oil) required to burn the low calorific value sludge and vaporize residual water. Stepped multiple hearth incinerators with high residence time and fluidized bed incinerators are the most common systems used to combust wastewater sludge. Co-firing in municipal waste-to-energy plants is occasionally done, this option being less expensive assuming the facilities already exist for solid waste and there is no need for auxiliary fuel. CHAPTER THREE TERTIARY TREATMENT 3.1 SLUDGE DISPOSAL When a liquid sludge is produced, further treatment may be required to make it suitable for final disposal. Typically, sludges are thickened (dewatered) to reduce the volumes transported off-site for disposal. There is no process which completely eliminates the need to dispose of biosolids. There is, however, an additional step some cities are taking to superheat sludge and convert it into small pelletized granules that are high in nitrogen and other organic materials. In N

Arthur Miller and his Distorted Historical Accuracies :: American America History

Arthur Miller and his Distorted Historical Accuracies In 1953, Arthur Miller wrote his famous play The Crucible, in response to a fear of Communism that had developed in the United States during that decade. The "Red Scare", as it was later called by historians was led by Senator Joseph McCarthy, whose paranoia of a communist takeover spread through the nation like a wildfire. Men and women alike fell victim to McCarthy's pointed finger and as a result of this hysteria, were mostly deported from the country, their careers and lives ruined. Some argue today that McCarthy's plan had been to use the fear of the American people to throw his enemies out of office and gain power himself. Whatever McCarthy's motives may have been, Arthur Miller realized the senator's ludicracy when he attempted to accuse the President himself to be Communist. Miller and the rest of the American people drew the line and McCarthy was seen a fraud. By the time the rest of the public had came to this realization, Miller's play was written. The Crucible is a play in which Arthur Miller parallels events of the Salem witch trials of 1692 to the problems that were plaguing his own society. The statement that most readers today bring out of the play is that history has a way of repeating itself. Miller's play was an extreme hit upon release and won a Tony award. The play is so popular today that many teachers in secondary schools use it to base their lesson around when teaching their students about 1692 Salem and there are multimedia activities based on Salem through The Crucible's view. Miller is often asked to speak at events where similar "witch hunts" occur, acting as a sort of expert on the subject of Puritan Salem and acts of hysteria. The question is, why is Arthur Miller revered by so many as "the man to ask" regarding the Salem Witch trials when his play had many inaccuracies, some very obvious? Miller's play is not a historical account of the events in 1692 Salem, but rather a work of fiction. It is important to realize that what Miller wrote is not fact by revealing where his play is historically flawed. Some of the more important discrepancies are discussed below: By examining Miller's main plot relationship between characters Abigail Williams and John Proctor, we uncover many discrepancies, mainly that there was no relationship at all.

Memory :: essays research papers

Memory is defined as the faculty by which sense impressions and information are retained in the mind and subsequently recalled. A person’s capacity to remember and the total store of mentally retained impressions and knowledge also formulate memory. (Webster, 1992) â€Å"We all possess inside our heads a system for declassifying, storing and retrieving information that exceeds the best computer capacity, flexibility, and speed. Yet the same system is so limited and unreliable that it cannot consistently remember a nine-digit phone number long enough to dial it† (Baddeley, 1993). The examination of human behavior reveals that current activities are inescapably linked by memories. General â€Å"competent† (1993) behavior requires that certain past events have effect on the influences in the present. For example, touching a hot stove would cause a burn and therefore memory would convey a message to not repeat again. All of this is effected by the development of short-term memory (STM) and long-term memory (LTM). Memories can be positive, like memories of girlfriends and special events, or they can be negative, such as suppressed memories. Sexual abuse of children and Memory 3 adolescents is known to cause severe psychological and emotional damage. Adults who were sexually abused in childhood are at a higher risk for developing a variety of psychiatric disorders, anxiety disorders, personality disorders, and mood disorders. To understand the essential issues about traumatic memory, the human mind’s response to a traumatic event must first be understood. The memory is made up of many different sections with each having different consequences on one another. Can people remember what they were wearing three days ago? Most likely no, because the memory only holds on to what is actively remembered. What a person was wearing is not important so it is thrown out and forgotten. This type of unimportant information passes through the short-term memory. â€Å"Short-term memory is a system for storing information over brief intervals of time.† (Squire, 1987) It’s main characteristic is the holding and understanding of limited amounts of information. The system can grasp brief ideas which would otherwise slip into oblivion, hold them, relate them and understand them for its own purpose. (1987) Another aspect of STM was introduced by William James in 1890, under the name â€Å"primary memory† (Baddeley, 1993). Primary memory refers to the information that forms the focus of current attention and that occupies the stream of thought. â€Å"This information does not need to be brought back to mind in order to be used† (1993). Compared to short-term memory, primary memory Memory 4 places less emphasis on time and more emphasis on the parts of attention, processing, and holding. No matter what it is called, this system is used when someone hears a telephone number and remembers it long enough to write it down.