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2- Chemical Engineering Lab Report - Material

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1 Abstract There are many sources of water in nature, such as rain water, sea water, rivers etc. However, water undergoes a series of processes before being used as drinking water, irrigation water or even as industrial water. One of the adequate methods for handling this process is “Reverse Osmosis”. Moving on through this report, the whole mechanisms of R.O in which water undergoes are thoroughly explained. Numerous advantages of the R.O method will come out clear as it is compared to the feebly ecological and economical other solutions of water treatment, such as thermal disinfection, where gigantic amounts of energy are wasted.
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Page 1: 2- Chemical Engineering Lab Report - Material

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Abstract

There are many sources of water in nature, such as rain water, sea water, rivers etc. However, water undergoes a series of processes before being used as drinking water, irrigation water or even as industrial water.

One of the adequate methods for handling this process is “Reverse Osmosis”. Moving on through this report, the whole mechanisms of R.O in which water undergoes are thoroughly explained. Numerous advantages of the R.O method will come out clear as it is compared to the feebly ecological and economical other solutions of water treatment, such as thermal disinfection, where gigantic amounts of energy are wasted.

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Table of Contents

INTRODUCTION 3

OSMOSIS & REVERSE OSMOSIS 4

WATER TREATMENT PROCESS 5

CONCLUSIONS 10

REFERENCES 11

APPENDICES 12

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Introduction

Water is one of the most vital sources of life on Earth, hence the need for a clean, safe and adequatefrom a variety of natural resources, depending on the georegion. In the U.A.E; however, sea water is the only attainable resource of water.

Of course, sea water is not almost no real usage. And thus comes the need foread in Wikipedia, water treatment is the process of making water more acceptable for a desired endprocesses, irrigation, medical usage and many other uses. perfect for a certain purpose, could be actually dangerous if used for another! In this lab report; however, emphasis is put on water treatment with the aim of producing healthy drinking water.

Drinking Water or potable waterstated in Wikipedia, is water fit for human consumption or utilization without any risk of short-term or long2006, waterborne diseasescause 1.8 million deaths eachhighlighting the profound lack of healthy water in undeveloped countries

The TDS, or Total Dissolved Solids, of drinkable water should notwords, every kg of the drinking water should have no more than 200 mg of solids.

Water is one of the most vital sources of life on Earth, hence the need and adequate supply of water. Water could be obtained

natural resources, depending on the georegion. In the U.A.E; however, sea water is the only attainable resource of

Of course, sea water is not drinkable. In fact, untreated sea water has almost no real usage. And thus comes the need for Water Treatment

, water treatment is the process of making water more acceptable for a desired end-use. These include: drinking water, industrial processes, irrigation, medical usage and many other uses.

a certain purpose, could be actually dangerous if used for another! In this lab report; however, emphasis is put on water treatment

producing healthy drinking water.

or potable water, as is water fit for human

consumption or utilization without any risk of term or long-term harm. In waterborne diseases were estimated to

cause 1.8 million deaths each year, highlighting the profound lack of healthy water in undeveloped countries Figure 1.

The TDS, or Total Dissolved Solids, of drinkable water should not exceed 200 PPM (Particle Per Million)

the drinking water should have no more than 200 mg of

Water is one of the most vital sources of life on Earth, hence the need Water could be obtained

natural resources, depending on the geography of the region. In the U.A.E; however, sea water is the only attainable resource of

. In fact, untreated sea water has Water Treatment. As

, water treatment is the process of making water more use. These include: drinking water, industrial

processes, irrigation, medical usage and many other uses. Water considered a certain purpose, could be actually dangerous if used for

another! In this lab report; however, emphasis is put on water treatment

200 PPM (Particle Per Million). In other the drinking water should have no more than 200 mg of

Figure 1

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Figure 2

Osmosis & Reverse Osmosis

Osmosis, as stated in Gondar Design Biology, is the passage of water from a region of high water concentration through a semi-permeable membrane to a region of low water concentration. Osmosis is of extreme importance in living organics.

A Semi-permeable Membrane allows certain substances to pass through it and prevents other substances from doing so, depending on the diameter of the substance and the diameter of the membrane’s holes. The pressure exerted by the flow of water is called the Osmotic Pressure Figure 2.

A formal definition of Reverse Osmosis from Wikipedia states that reverse osmosis is the process of forcing a solvent from a region of high solute concentration through a membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure.

Apparently, Osmosis is a natural process. Meaning that, unlike reverse osmosis, it doesn’t require an external source of pressure. Reverse osmosis; however, requires an external source of pressure, which is usuallygenerated via an H.P.P, or a High Pressure Pump Figure 3.

Figure 3

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Water Treatment Process

Water treatment could be executed through several methods. One of which is evaporation, which requires immense amounts of energy. Reverse osmosis; however, is an economical and efficient way of water treatment. Thus, it’s the most commonly used method.

When water is treated in order to produce drinking water, we are actually removing substances that include bacteria, algae, viruses, fungi,minerals such as iron and sulfur, and man-made chemical pollutants. So, the process of water treatment using reverse osmosis is rather more sophisticated than expected.

Sea water has a TDS of about 35,000 PPM, which is a very high concentration. In order to transform sea water into drinking water, the TDS must be reduced to 100-200 PPM. If more than 200 PPM is present in the water, serious health issues, such as kidney failure, could be triggered.

We now briefly go through the steps of water treatment:

1- Screening: This is the first step in the water treatment process.Screening is used to remove large wastes and trashes by passing the sea water through a screen calledthe wire mesh Figure 4. The wire mesh contains small holes to let

water pass through and prevent fish and shells from doing so.

Figure 4

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2- Sedimentation: After the screening process, there will be minute particles in water. So, we move the water to a special container, called the Sedimentation TankFigure 5, and leave it for some time, so that the sand particles would settle down and

get well-separated from the water. Larger particles, of course, settle down more rapidly than small particles. These particles form a layer of sludge that must be removed and treated.

3- Softening: A rather crucial step in the water treatment process is softening. The Softening Cylinder Figure 6 is divided into three main layers (bottom to top):A) Sand Filter: The sand in the bottom of

the softening cylinder captures some of the suspended particles in the water, reducing the TSS.

B) Active Carbon (A.C): The bad odor of the water is removed by using activated calcium carbonate CaCO3.

C) Deionization Units: Used to replace the hard ions (Magnesium ion, Iron ion, etc.) with Sodium ions.

4- R.O Filter: After the softening process, the water is removed from the softening cylinder to the R.O filter Figure 7. The pressure is measured before the inlet of water in the R.O filter and after the outlet using Pressure Gauges In order to measure and compare the permeability of the water.

Figure 5

Figure 6

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In R.O, filters containing lots of holes are used to separate water from the remaining solids. Each hole’s size is equal to the size of one water molecule. This allows water to pass through while blocking other solids. Water molecules are forced to pass through these holes via the H.P.P Figure 8. In the end, solids’ molecules will accumulate on one side of the filter, while fresh water is moved to the Product Tank.

5- Sampling: The supposedly fresh water gathered in the product tank has yet to go through several quality tests. These tests include:A) BOD/COD: Used to measure the activity of aerobic microorganisms.B) TDS/TSS Tests: Used to check the concentration levels of dissolved

and suspended solids.C) pH.D) Permeability: Measured via the Flow Indicator (F.I) and the

pressure gauges.E) Conductivity.F) Turbidity.

Figure 7

Figure 8

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6- Minerals Addition: After making sure the water is clear and pure, we have to add several useful minerals to it, in order to make sure it’s healthy and suitable for human consumption, as its minerals’ concentrations are between 10-15 PPM only. These minerals include Calcium, Magnesium and Potassium. And they could be obtained from the remains in the membrane.

7- Disinfection: This is the last step in the process. In this stage, harmful microorganisms, such as bacteria and viruses, are removed. Several options are available to perform this task, which include:A) Chlorine: One of the most commonly used disinfectants for water

disinfection. Chlorine can be applied for the deactivation of most microorganisms and is relatively cheap.

B) Ultra Violet Light: Ultraviolet disinfection of water consists of a purely physical, chemical-free process. UV-C radiation in particular, with a wavelength in the 240 to 280 nanometers range, attacks the vital DNA of the bacteria directly.

C) Ozone: Ozone has been known for over 100 years, and although it has been used in water treatment for over 100 years, it has not found widespread use as a disinfectant in the water industry. Statistics are not quite reliable, but probably less than 1 percent of the water treatment plants worldwide use it. The major reason for its low use is the costs.

D) Heating.

8- Backwash: During the R.O process, solids are trapped in the membrane. To remove these solids, we need a process calledBackwash, in which the clean water is re-pumped to the R.O filter from the product tank using a pipe in order to rinse the solids from

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the membrane. It is a regeneration process to clean the membrane, and it’s very efficient as we only need very little amounts of the fresh water to clean the membrane for very short periods. And we use the H.P.P to move the clean water from the product tank to the R.O filter.

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Conclusions

1- Reverse osmosis is a very efficient and economical method of water treatment compared to other methods, such as evaporation. It requires little amounts of energy, and it’s highly practical.

2- Backwash is a very cheap and intelligent method to clean the membrane. It almost only requires a single pipe!

3- The amount of minerals to be added is significantly affected by the season. In winter, 200 PPM concentrations of minerals should be added to the water. While in summer, 100 PPM concentrations are advisable. This is due to the consumption habits of people in winter and summer.

4- Using Chlorine to disinfect water contains some health risks. Ozone and UV light are much healthier options.

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References

1- http://en.wikipedia.org/wiki/Reverse_osmosis

2- http://en.wikipedia.org/wiki/Drinking_water

3- http://www.purchon.com/biology/osmosis.htm

4- http://en.wikipedia.org/wiki/Water_treatment

5- http://www.cmhc-schl.gc.ca/en/co/maho/wawa/wawa_001.cfm

6- http://en.wikipedia.org/wiki/Osmosis

7- http://www.reverseosmosisinfo.com/how-reverse-osmosis-works.html

8- http://www.ozoneapplications.com/watertreatment/ozone%20and%20water.htm

9- http://en.wikipedia.org/wiki/UV_water_disinfection

10-http://www.lenntech.com/water-disinfection/disinfectants-chlorine.htm


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