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Chemistry Essay代寫范文-水處理過程

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案例簡介

  • 作者:致遠教育
  • 導讀:本文是一篇介紹水處理過程的ChemistryEssay代寫范文,主要介紹了水處理過程的背景,生物原理、化學原理,水處理的基本要求、常用方法,優勢劣勢等等。
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  • 預計閱讀時間:11分鐘

案例詳情

本文是一篇介紹水處理過程的Chemistry Essay代寫范文,主要介紹了水處理過程的背景,生物原理、化學原理,水處理的基本要求、常用方法,優勢劣勢等等。對于英文化學Essay代寫作業而言,化學公式的正確引用、寫作格式、譜圖書寫格式、圖表格式、字體段落、頁面格式、研究方法等都很重要,希望大家在進行Chemistry Essay寫作中一定注意這些細節。

Essay代寫范文

titleWater treatment Processes

題目:水處理過程

Question問題

Limit of detection

Stating the water supply (Water Quality) Regulations 2001, "limit of detection is calculated as three times the relative within batch standard deviation of a natural sample containing a low concentration of the parameter. Also, its means five times the relative within batch standard deviation of a blank sample".

根據2001年供水(水質)條例,“檢測限按含有低濃度參數的天然樣品的相對批內標準偏差的三倍計算。同時,其平均值是空白樣品批內相對標準偏差的五倍”。

DA Armbruster et al (1994) stated that "the limit of detection may be determined statistically based on measuring replicate blank negative samples or empirically by measuring progressively more dilute concentrations of analyte".

DA Armbruster等人(1994年)指出,“檢測限可基于測量重復空白陰性樣品或通過逐步測量更稀釋的分析物濃度來經驗確定”。

Limit of detection (In analysis)

"Limit of detection is expressed as the concentration, cl, or the quantity, ql, is derived from the smallest measure, xl, that can be detected with reasonable certainty for a given analytical procedure. The value of xl, is then given by the equation:

“檢測限表示為濃度,cl或量,ql,由最小的測量值xl導出,對于給定的分析程序,可以合理確定地檢測到。xl的值,然后由公式給出:

xL = xbi + ksbi

Where xbi = Mean of the blank measures

Sbi = Standard deviation of the blank measures

K = The numerical factor chosen according to the confidence level desired". (IUPAC Compendium of Chemical Terminology 2 (2007)).

Trueness

Stating the water supply (Water Quality) Regulations 2001, "trueness also referred to as the systematic error is the calculated difference between the true value and the main value of the large number of repeated measurements".

《2001年供水(水質)規例》:“真實性也稱為系統誤差,是指大量重復測量的真實值與主要值之間的計算差。”。

Andrzej Bobrowski et al (2004) stated that "trueness indicates the closeness between an accepted reference value and the average value of the considered laboratory test".

 Andrzej Bobrowski等人(2004年)指出,“真實性是指可接受的參考值與所考慮的實驗室試驗平均值之間的接近程度”。

Practically, it is defined as "the closeness of agreement between the mean of the result of a measurements of a measurand obtained specifically between day precision conditions and the true or conventional true value of the measurement" Dr. Xavier Fuentes-Arderiu (2009).

 實際上,它被定義為“測量結果的平均值與在日精度條件下獲得的測量值的真值或傳統真值之間的一致性的接近性”,Xavier Fuentes Arderiu博士(2009)。

Precision

By stating the water supply (Water Quality) Regulations 2001, "precision also referred to as the random error is being calculated as twice the standard deviation (within a batch and between batches) of the spread of result about the mean".

通過說明2001年《供水(水質)規例》,“精度(也稱為隨機誤差)的計算方法是平均值結果傳播標準差(一批內和批間)的兩倍”。

According to Andrzej Bobrowski et al (2004), "precision indicates the closeness of agreement between independent test results obtained under stipulated conditions and thus, should be obtained by using the standard fortified samples (blanks) at different circumstances across working range. The most common way to express precision is in form of standard deviation. However, it is also expressed as a variance or a coefficient of variation".

根據Andrzej Bobrowski等人(2004年)的說法,“精密度是指在規定條件下獲得的獨立測試結果之間的一致性,因此,應通過在工作范圍內的不同情況下使用標準強化樣品(空白)來獲得。最常用的表示精度的方法是標準差的形式。然而,它也被表示為方差或變異系數”。

Question 2

Part 1 Directive requirements

Chemical Parameter

According to the Water Supply (Water Quality) Regulations 2001, Benzene is indentified as a chemical parameter under part 1 directive requirements with maximum concentration value of 1.0 and it is measured in ?μg/1. Its point of compliance is in the consumer's taps.

Microbiological Parameter

Under the part 1 directive requirements of the Water Supply (Water Quality) Regulations 2001, Escherichia coli is a microbiological parameter with maximum concentration value of 0, unit of measurement in Number/100ml and point of compliance in the consumer's taps.

Part II National Requirements

Chemical Parameter

According to the Water Supply (Water Quality) Regulations 2001, Manganese is a part II national chemical parameter with maximum concentration value of 50, unit of measurement as ?μg/Mn/1 and its point of compliance is in the consumer's taps.

Microbiological Parameter

Coliform bacteria is a part II national microbiological parameter Water Supply (Water Quality) Regulations 2001 with maximum concentration at 0, unit of measurement as Number/100ml and its point of compliance is at the service reservoir and water treatment works.

Question 3

Part I Directive requirements

Exposure to benzene causes depression of the central nervous system (CNS), drowsiness, and nausea, loss of co-coordination, confusion and unconsciousness. "At 25 ppm, it has no effects, but between 50 to 150 ppm, it produces headaches and tiredness" (Canadian centre for occupational health and safety (2007)).

Long term exposure or inhalation of benzene causes blood disorders in the human. Specifically, benzene affects the bone marrow and causes damages to the immune system. Also, chronic exposure to benzene in women leads to reproductive effects such as decrease in the size of the ovaries, menstrual disorders etc.

It causes severe bloody diarrhoea and abdominal cramps. In children below age 5 and the elderly, it causes an infection called "haemolytic uremic syndrome", which destroys the red blood cells and leads to kidney failure (US Environmental protection Agency (2006)).

Chemistry Essay代寫范文

 Part II National requirements

In the book by Levy J.S and Nasetta W.J (2003) "Chronic inhalation of manganese into the human body may cause damage to the nervous system and the respiratory tract".

Excessive exposure to manganese causes an irreversible brain disease with a prominent psychological and neurological disturbance which looks like "Parkinson diseases" also known as "Manganism" (Bureau of Environmental health (2009)).

"Basically, coliform bacteria do not cause sickness in human but their presence in a water gives rise to public health concerns due to the potential of other pathogenic or disease causing organism like bacteria, protozoa and viruses also being present in the water. The waterborne diseases from these organisms involves flu-like systems such as fever, diarrhoea vomiting and nausea" (Michigan Department of Environmental Quality (1998)).

Question 4

Rational for the use of the indicator Parameter:

The rational for the use of conductivity as an indicator is detecting water pollution. Water has a comparatively invariable range of conductivity and once the conductivity is established, it is being used as the bases for assessment with regular conductivity measurements. Conductivity determines a number of applications relating to the water quality. These applications are stated below;

Quick notification of difference or variance in wastewaters and natural water.

Conductivity is used in the determination of the amount of treatment chemicals to be added in a water sample.

It is used in determining mineralization: this is referred to as total dissolved solids and the total dissolved solids results is used to determining the overall ionic effect in water source

Lastly, it is used in the estimation of the size of samples to be for other chemical analyses.

Question 5

Quality of the abstracted water

The Abstracted water in Peidiwch Yfed y Dwr is comprised of chemical parameters with values that does not correspond with the value stated by the Water Supply (Water Quality) Regulations 2001. According to the regulations, the limit for iron in water is 200?μg/l which is below 2mg/l, the concentration level of iron in the abstracted water. Binnie et al (2002) stated that "iron may be derived from raw water or from corrosion of iron water mains and they are common in ground waters" (p9). High concentration of iron makes water corrosive with reddish or brownish yellow stains. (See figure 1 below). "It will also have operational effects on the plumbing equipments due to corrosion which might result in blocking up the water distribution system" Binnie et al, (2002).

The water regulation allows maximum concentration value of 50?μg/l for manganese which is below the concentration of manganese in the abstracted water. "Manganese is derived from raw water" Binnie et al, (2002) and since the level of manganese in the water is 1mg/l, the water will be toxic which causes "Toxicity to the nervous system something similar to Parkinson's disease" (Connecticut department of public health(2010)).

The abstracted water having a pH of 6.3 makes it acidic. The required pH for water under the regulations is 6.5. Due to its acidic nature, it would contain metal ions which causes a "blue green" staining of the sinks and damage to metal piping due to corrosion and health risk associated with the toxic metals.

Hard water relates to the level of calcium and magnesium compounds present in water. Hard water does not pose a health risk but it causes scale in water. Water hardness ranging between 60 - 120 mg/l is moderately hard (American ground water trust (2003)). Since the hardness is 70mg/l, the content is not acceptable.

The concentration of total pesticides in the water poses a great risk to human health (See figure 2 below). The maximum value allowed for total pesticides in the water is 0.50?μg/l which is below the concentration in the abstracted water. Thus, the water is not of good quality. Buzzi, (1992) states that "effects of pesticides can range from premature birth to birth defects involving the CNS and internal organs" (p100).

The concentration of polycyclic aromatic hydrocarbons allowed under the regulations is 0.10?μg/l which is above the concentration of polycyclic aromatic hydrocarbon in the abstracted water. According to N.F. Gray (1994) "World health organization has set a level for 3,4-benzopyrene of 10ng/l which is equivalent to 0.00001mg/l. Water containing more than these amounts would cause gastrointestinal and oesophageal tumours" (p 147).

Cryptosporidium outbreak in the town may occur due to faecal-contamination of the water resources directly or indirectly by sewage or animal waste. According to Gray (1994), "they are parasitic protozoa that forms oocyst which allows them to survive longer in water while waiting to be ingested by a host"(p160) (See figure below)."Low level exposure to the oocyst is capable of initiating an infection" Rose (1990) and in a study by Blewett et al (1993) "it was indicated that a single oocyst may be enough to cause infection". N.F. Gray (2004) stated that "the main symptoms of cryptosporidiosis are stomach cramps, nausea, dehydration and headaches"(p160).

Technology/Operation to make the abstracted water wholesome

To make the abstracted water wholesome, it will undergo some treatment process. Firstly, the concentration of iron and manganese in the water are at 2mg/l and 1mg/l respectively compared to 200?μg/l and 50?μg/l which is the value for the water to be wholesome. Therefore, it would be treated by coagulation or flocculation which is the addition of chemical such as ferric sulphate that forms floc and entraps the impurities in the water. The floc will then be separated from the water through sedimentation. To remove the taste and odour, the water will undergo aeration, ozonation and adsorption on actuated carbon.

The pH level will be adjusted to 6.5 by adding alkaline substances such as calcium carbonate i.e. free lime or by aeration. The water will then undergo boiling at a very high temperature so that the bicarbonate will decompose to produce calcium/magnesium carbonate which is not soluble in water. Thus, it precipitates out thereby reducing the hardness of the water. Carbon filtration will be done in other to reduce the total pesticides present to 0.50?μg/l which is the level required by the regulation.

The polycyclic aromatic hydrocarbon present in the water differs from the stipulated concentration according to the regulations which is 0.9?μg/l, therefore microfiltration will be done to adjust the level of polycyclic aromatic hydrocarbons in the water.

The water will undergo ultraviolet filtration to treat the effect of cryptosporidium which involves ultra filtration, microfiltration and nano filtration. This process will remove organic compounds from the water thereby reducing the effect of cryptosporidium in the water. Finally, the water will be disinfected with the addition of chlorine to deactivate all pathogenic microorganisms present in the water before consumption.

Advantages

The advantage of coagulant water treatment is that it is very effective in removing particles that are otherwise very difficult to remove in water.

Also, using water softeners in reducing the water hardness and adjusting the pH value prevents limescale and increases heating efficiency in water.

The advantage of using activated carbon filters in water is that it effectively removes organic contaminants from the water.

The advantage of using ultra violet water filters in treating the effect of cryptosporidium is due to the fact that it generally kill 99.9% of bacteria and viruses in water.

The advantage of chlorine disinfection is that it is cheap and readily available in gas, liquid or powder.

Disadvantages

The disadvantage of coagulants is the cost and the need for accurate dosing and frequent monitoring.

In using water softeners, the disadvantage involved is that the output water may not be suitable for drinking.

The disadvantage in the use of carbon filters is that it does not remove microbes, nitrates, sodium and hardness.

The disadvantages of using ultraviolet water filters in treating the effect of cryptosporidium is that it only kills the bacteria, it won't remove the dead cell and other contaminants in the water.

The disadvantage of chlorine disinfection is taste and odour problems.

Treatment Train

Water is usually given an appropriate treatment to ensure the water supply is of high and consistent quality. A potential treatment train flow chart to produce water meeting the requirements of the Water Supply (Water Quality) Regulation 2001 is shown below:

References

N.F. Gray. (1994) Drinking water quality: problems and solutions. John Wiley & Sons.

Buzzi. (1992) Chemical Hazards at Water and Wastewater Treatment Plants. Lewis.

D.A Armbruster, M. D Tillman et al. (1994) Limit of detection (LQD)/limit of quantitation (LOQ): comparison of the empirical and the statistical methods exemplified with GC-MS assays of abused drugs. Clinical Chemistry, Vol 40, 1233-123.

Andrzej Bobrowski, Jan Mocak et al. (2004) Metrological Characteristics and Comparison of Analytical Methods for Determination of Chromium Traces in Water Samples. Acta Chim. Slov. 2004, 51, 77-93.

Dr. Xavier Fuentes-Arderiu. (2009) Trueness and Uncertainty - Westgard QC, Universitat de Barcelona, CATALONIA (SPAIN).

Canadian centre for occupational health and safety (2007) [online]. Available from: http://www.ccohs.ca/oshanswers/chemicals/chem_profiles/benzene/health_ben.html#_1_1 [Accessed 3rd January 2010]

US Environmental protection Agency (2006) [online]. Available from: http://www.epa.gov/safewater/contaminants/ecoli.html#four [Accessed 2nd January 2010]

Levy, J.S and Nasetta, W.J. (2003) Neurologic effects of manganese in humans: a review. International J Occup Environmental Health. 2003 Apr-Jun;9(2):153-63.

Bureau of Environmental health, health assessment section (2009) Manganese in water. Columbus, Ohio.

IUPAC Compendium of Chemical Terminology 2nd edition (2007) [online]. Available from: http://www.iupac.org/goldbook/L03540.pdf [Accessed 4th January 2010].

Chris Binnie, Martin Kimber et al. (2002) Basic water treatment. 3rd edition. Royal Society of Chemistry, Cambridge.

Connecticut department of public health(2010) [online]. Available from : www.ct.gov/dph/lib/dph/drinking_water/pdf/manganese.pdf [Accessed 5th January 2010].

Rose, J.B. (1990) Emerging issues from the microbiology of drinking water. Water Engineering and Management, July, 23.

Blewett, D.A., Wright, S.E. et al. (1993) Infective dose size studies on Cryptosporidium parvum using gnotobiotic lambs. Water Science and Technology, 27 (3-4), 61.

Health Hazard Information-From the EPA Health Effects Notebook for Hazardous Air Pollutants-Draft (2010) [online]. Available from: http://www.acute-myelogenous-leukemia.com/html/hazard.html [Accessed 5th January 2010].

U.S Environmental protection agency (2006) Drinking water contaminants [online]. Available from: http://www.epa.gov/safewater/contaminants/ecoli.html[[Accessed 4th January 2010].

Health Maxx Plus Inc (2007) What is pH? [online]. Available from: http://www.healthmaxxplus.net/#/what-is-ph/4529153688 [Accessed 5th January 2010].

Wisconsin Department of Health Services (2008) Polycyclic Aromatic Hydrocarbons (PAHs) [online]. Available from: http://dhs.wi.gov/eh/ChemFS/fs/PAH.htm [Accessed 7th January 2010].

Iron in drinking water (2003) [online]. Available from: http://www.dnr.state.wi.us/org/water/dwg/iron.htm [Accessed 5th January 2010].

Lenntech water treatment solution (2009) Iron (Fe) and water [online] Available from: http://www.lenntech.com/periodic/water/iron/iron-and-water.htm [Accessed 3rd January 2010].

APEC (2009) pH values of water explained [online]. Available from: http://www.freedrinkingwater.com/water-education/quality-water-ph.htm [Accessed 4th January 2010].

The Manganese Health Research Program (2010) Brief Background on the Health Effects of Manganese [online]. Available from: http://www.manganese-health.org/about_us/healtheffects [Accessed 7th January 2010].

Pesticides (2002) Fact Sheet Series: Pesticides in Drinking Water [online]. Available from: http://www.waterbornediseases.org/FactSheets/pesticide.htm [Accessed 6th January 2010].

Conductivity and Water Quality (2010) Environmental Impact [online]. Available from: http://www.kywater.org/ww/ramp/rmcond.htm [Accessed 8th January 2010].

Chelsea and Westminister Hospital (NHS) (2008) Water Safety & Cryptosporidium [online]. Available from: http://www.chelwest.nhs.uk/documents/hiv_factsheets/general/Water%20Safety%20%20Cryptosporidium.pdf [Accessed 4th January 2010].

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