Table of Contents

ABSTRACT......................................................................................................................................2

OBJECTIVES...................................................................................................................................2

INTRODUCTION............................................................................................................................2

THEORY...........................................................................................................................................3

METHODOLOGY...........................................................................................................................7

OBSERVATIONS AND RESULTS .............................................................................................8

DISCUSSION................................................................................................................................12

CONCLUSION...............................................................................................................................15

APPENDIX.....................................................................................................................................16

QUESTIONS..................................................................................................................................16

REFERENCES...............................................................................................................................19

AbstractThis laboratory report comprises of three experiments that test

predominantly chemical and physical characteristics of water to determine the quality of water from various sources, comparing it to international Water Quality Standards. These experiments are performed on a small scale to simulate the works of a water treatment plant on an even larger scale. This is all done through the comparison tabulated and plotted results. These results demonstration how important a water treatment plant is to prevent the spread of disease through contaminated water. It also demonstrates how fragile and susceptible our water supply and the eco system is to contaminated water. These experiments also show us how to determine where the water maybe coming from, whether ground, surface or saltwater.

ObjectivesThe objectives of the laboratory experiments are:

To attain a better understanding of the water treatment processes that are used by the water treatment plants.

To determine the bacteriological quality of water for various samples. To obtain the optimum alum dosage that can be used to treat and

remove turbidity from the provided river water. To determine the sources, of three different water sample provided

using various experiments. To interpret laboratory results and be able to analyze the water

samples to determine if it conforms to the water quality standards.

Introduction

Water can be said to be one of the most important substances on earth. All plants and animals must have water to survive. If there were no presence of water on earth there would be no life. It is most important that the water which people drink and use for other purposes is clean water. This means that the water must be free of germs and chemicals and be clear (not cloudy). Water that is safe for drinking is called potable water. Disease-causing germs and chemicals can find their way into water supplies. When this happens the water becomes polluted or contaminated and when people drink it or come in contact with it in other ways they can become very sick. A

series of test are performed in order to prevent any disease carry water from reaching the taps with-in the public housing sector.

An essential experiment carried out is the bacteriological analysis using membrane filter (MF) technique. This involves using various sources of water to examine the amount of bacteria present within the water body. This analysis uses indicators to evaluate the water quality based on the concept of microbial organisms, which are always present within fecal material. This is because most of these waterborne disease-causing organisms originate from humans or animal bodies and are discharged as part of the body’s waste. This technique is used mainly in water and wastewater treatment to ensure that the disease carrying organisms are identified and prevented from infiltrating the public water supply. This allows a check for the water quality entering the public water supply which must meet the World Health Organisation (WHO) standards.

The next step in the analysis of water quality is the jar test. The jar test is a common laboratory procedure used to determine the optimum dose of different coagulants, on a small scale in order to predict the functioning of a large-scale treatment operating conditions for water or wastewater treatment. Raw water contains. These impurities are in suspension, which leads to turbidity, odor and taste problems. These impurities stay suspended in solution due to their small size. In order to remove these particles, they must agglomerate and grow in size in order to settle out of solution. Therefore to obtain agglomeration a chemical coagulant such as alum is used. This causes the suspended particles to agglomerate and form flocs, which are then heavy enough to settle and removed.

Source determination is a method used by water treatment companies to determine the origins of a water leak or unidentified water body. Each and every water source has varying physical and chemical characteristics. The determination of each characteristic allows for a water treatment company to determine the source. These physical and chemical characteristics include pH level, turbidity, hardness, odour, the level of alkalinity, chloride and chlorine concentrations. The values obtained from the experiments for these physical and chemical characteristics are compared to the expected values to determine the source.

Theory

Experiment 1 – Bacteriological Analysis using Membrane Filter (MF) Technique

Most modern laboratories use a refinement of total plate count in which serial dilutions of the sample are vacuum filtered through purpose made membrane filters and these filters are themselves laid on nutrient medium within sealed plates. The methodology is otherwise similar to conventional total plate counts. Membranes have a printed millimetre grid printed on and can be reliably used to count the number of colonies under a binocular microscope. A typical membrane filtration method for water analysis is performed by passing a known volume of water through a sterile membrane filter with a pore size small enough to retain bacterial cells. The filter is then transferred aseptically to the surface of an agar plate, or an absorbent pad saturated with a suitable selective medium, and incubated. Colonies are allowed to develop on the surface of the filter and can be counted and examined directly. MF methods are quick and easy to perform, require little incubator space and can handle very large volumes of water if required.

Some common indicator organisms used to indicate the presence of harmful microorganisms include total coliform bacteria and fecal coliform bacteria. Most of the coliform type of bacteria are non-pathogenic and are found in the digestive tract and feces of warm-blooded animals. They exist in large numbers in water and wastewater and are therefore easily detected.

Experiment 2 – Jar Test

Raw water or wastewater must be treated to remove turbidity, color and bacteria. Colloidal particles are in the size range between dissolved substance and suspended particles. The particles are too small to be removed by sedimentation or by normal filtration processes. Colloidal particles an effect, when light passes through liquid containing colloidal particles, the light is reflected by the particles. The degree to which colloidal suspension reflects light at 90º angle to the entrance beam is measured by turbidity. The unit of measure is a Turbidity Unit (TU) or Nephlometric Turbidity Unit (NTU). Turbidities in excess are easily detectable in a glass of water and are usually unpleasant for aesthetic reasons. The higher the turbidity of water means the higher the concentration of colloidal particles.

Finely dispersed solid (colloids) suspended in wastewater are stabilized by negative electric charges on their surfaces, causing them to repel each other. Since this prevents these charged particles from colliding to form larger masses, called flocs, they do not settle. To assists in the removal of colloidal particles form suspension, chemical coagulations and flocculation

are required. These processes are usually done in sequence and, are a combination of physical and chemical procedures. Chemicals are mixed with wastewater to cause the aggregation of the suspended solids into particles large enough to settle or be removed. Coagulation is the destabilization of colloids by neutralizing the forces that keep them apart. Cationic coagulants provide positive electric charges to reduce the negative charge of the colloids. As a result, the particles collide to form larger particles (floc). Rapid mixing is required to disperse the coagulant throughout the liquid. A coagulant is the chemical that is added to the water to achieve coagulation. The colloids most commonly found in natural waters are negatively charged; hence a cation is required to neutralize the charge. The coagulant that is added must precipitate out of solution so that high concentrations of the ion are not left in the water. Such precipitation greatly assists the colloid removal process. The two most commonly used coagulants are aluminum (Al3+) and ferric iron(Fe3+).

The type of source water will have a large impact on how often jar tests are performed. Plants which treat groundwater may have very little turbidity to remove are unlikely to be affected by weather-related changes in water conditions. As a result, groundwater plants may perform jar tests seldom, if at all, although they can have problems with removing the more difficult small-suspended particles typically found in groundwater. Surface water plants, in contrast, tend to treat water with a high turbidity, which is susceptible to sudden changes in water quality. Operators at these plants will perform jar tests frequently, especially after rains, to adjust the coagulant dosage and deal with the changing source water turbidity.

To put it briefly, these organisms are good indicators of the potential contamination of a water source. Coliform bacteria have been used to evaluate the general quality of water. Testing for coliform bacteria is faster and cheaper than testing for specific organisms and pathogens.

Experiment 3– Source Determination

pH Test- the pH value is an important determining factor in a majority of chemical processes and the pH meter has, consequently, become the most widely used analytical laboratory instrument. Measurement of pH by means of electronic instrumentation and electrodes holds a key position in the modern laboratory. The pH of a solution is a measure of the molar concentration of hydrogen ions in the solution and as such is a measure of the acidity or basicity of a solution. The letters pH stands for “power of

hydrogen” and the numerical value is defined as the negative base 10 logarithm of the molar concentration of hydrogen ions.

pH = -log10[H+]

Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline. Pure water has a pH very close to 7.

Chlorine Residual- Residual Chlorine is the amount of available chlorine present in wastewater after treating the water with chlorine. The presence of chlorine residual in drinking water indicates that:

A sufficient amount of chlorine was added initially to the water to inactivate the bacteria and some viruses that cause diarrheal disease; and,

The water is protected from recontamination during storage. The presence of free residual chlorine in drinking water is correlated with the absence of disease-causing organisms, and thus is a measure of the portability of water.

When chlorine is added to water, some of the chlorine reacts first with organic materials and metals in the water and is not available for disinfection. The remaining chlorine concentration after the chlorine demand is accounted for is called total chlorine. Total chlorine is further divided into: 1) the amount of chlorine that has reacted with nitrates and is unavailable for disinfection which is called combined chlorine and, 2) the free chlorine, which is the chlorine available to inactivate disease-causing organisms, and thus a measure to determine the portability of water. For example, if using completing clean water the chlorine demand will be zero, and there will be no nitrates present, so no combined chlorine will be present. Thus, the free chlorine concentration will be equal to the concentration of chlorine initially added. In natural waters, especially surface water supplies such as rivers, organic material will exert a chlorine demand, and nitrates will form combined chlorine. Thus, the free chlorine concentration will be less than the concentration of chlorine initially added. The WHO guideline value for free residual chlorine in drinking water is 0.5mg/L to 5 mg/L.

Hardness- Hardness in water is that characteristic, which “prevents the lathering of soap”. This is due to presence in water of certain salts of calcium, magnesium and other heavy metals dissolved in it. A sample of hard water, when treated with soap does not produce lather, but on other hand forms a white scum or precipitate. This precipitate is formed, due to the formation of insoluble soaps of calcium and magnesium. Thus, water that does not produce lather with soap solution readily, but forms a white curd, is

called hard water. On the other hand, water which lathers easily on shaking with soap solution, is called soft water. Such water consequently does not contain dissolved calcium and magnesium salts in it. The degree of hardness of drinking water has been classified in terms of the equivalent CaCO3 concentration as follows:

Figure 1. Water HardnessAlkalinity- Alkalinity is a property of the water sample, which measures the acid-neutralizing capacity of a water sample.  It can be interpreted in terms specific substances only when a complete chemical composition of the sample is also performed. The alkalinity of surface water is due to the carbonate, bicarbonate and hydroxide content and is often interpreted in terms of the concentrations of these constituents. Higher the alkalinity, greater is the capacity of water to neutralize acids. Conversely, the lower the alkalinity, the lesser will be the neutralizing capacity. To detect the different types of alkalinity, the water is tested for phenolphthalein and total alkalinity, using Equations:

Once P and T are determined, then three types of alkalinities, i.e, hydroxides, carbonates and bicarbonates can be easily calculated from Alkalinity Forms table. (Refer to Table 2 in Appendix)

Chloride- Chloride ions, or ionized chloride atoms, are derived mostly from salt deposits that leech into water. Some common chlorides include sodium chloride (NaCl) and magnesium chloride (MgCl2). Fresh water has almost no chlorine ions whatsoever, whilst saltwater from the ocean has the highest quantity of chloride ions. Many wells and water reservoirs can also build up chlorine ions from underground salt deposits, or deep aquifers that originate from ancient marine basins. Industrial processes combined with poor maintenance of filters and controls can also lead to a high Chloride concentration. Chlorides can corrode metals and pipes. It can affect the taste of food products, cause nausea and vomiting. Therefore, water that is used in industry or processed for any use has a maximum Chloride level. Chlorides can also contaminate fresh water streams and lakes, leading to death of aquatic life.

Methodology

Experiment 1 – Bacteriological Analysis using Membrane Filter (MF) Technique

The procedure completed, adhered to the procedure provided in the lab script.

Experiment 2 – Jar Test

The procedure completed, adhered to the procedure provided in the lab script with exception of:

The appropriate volumes of stock solution with a concentration of 10,000 mg/L were calculated to give the required dosages of 0, 10, 30, 50, 70 and 90mg/L.

The speed was reduced to 20 rpm and continued mixing for 7 minutes (without stopping the process).

The mixing was stopped and the contents of the beaker were allowed to settle for 7 minutes

Experiment 3– Source Determination

The procedure completed, adhered to the procedure provided in the lab script with exception of:

pH

1) A small amount of the sample was poured into a beaker.2) The electrode was emerged into the sample.3) The magnetic mixer was used to stir the sample.4) The pH meter was allowed to stabilize, and then the reading was

recorded.5) These steps were repeated for all the samples.

Chlorine Residual

Two bottles were filled up to the indicated 10ml mark with the sample.

Observations and Results

Table 1. Total and Fecal Coliform for each sample

TNTC- To Numerous To CountTD- Too Diluted

Table 2. Source Determination Results

Table 3. Jar Test Results

0 20 40 60 80 100 1200

20406080

100120140160

TURBIDITY VS. ALUM DOSAGE

ALUM DOSE (mg/L)

Turb

idty

(NTU

)

Figure 2. Graph of Turbidity vs. Alum Dose

Table 4. Adjusted Jar Test Results

0 20 40 60 80 100 1200

50

100

150

TURBIDITY VS. ALUM DOSAGE

ALUM DOSE (mg/L )

Turb

idty

(NTU

)

Figure 3. Adjusted Graph of Turbidity vs. Alum Dose

Calculations:

Experiment 1 – Bacteriological Analysis using Membrane Filter (MF) Technique

For filtered volume of 0.001

TotalColiformcolonies for100ml of sample= ¿of coloniescountedvolume of sample filtered

∗100

TotalColiformcolonies for100ml of sample= 30.001

∗100=300000

FecalColiformcolonies for 100ml of sample= 10.001

∗100=100000

Experiment 2 – Jar Test

Calculating the volume of stock for the 30mg/l dosage.

Volumeof stock Alum=Concentrationof Jar∗Volume of waterAlumConcentration

¿( 30∗100010000 )=3mL

Experiment 3– Source Determination

Sample calculations for sample Y:

Hardness= Titre value∗1,000vol. of sample tested

=0.4∗1,00025

=16mgCaCO3/L

Chloride= Titre value∗500vol . of sample tested

=38∗50025

=760mgCl /L

Initial burette reading (ml) = 15.5

Final Burette reading (ml) = 17.8

Volume of titrant used (ml) = 2.3

A lkalinity=T itre value∗0.02∗50000vol. of sample tested

=2.30∗0.02∗5000100mL

=23mgCaCO3/L

Discussion The water that enters our water distribution system and out of our

faucets has three, primary sources. These primary sources are categorised as Sea Water, Ground Water (e.g. Aquifers) and Surface Water (e.g. rivers and lakes). It so happens that the raw water from these sources must not and should not be consumed directly, without first being treated and purified to the consumable water quality standard enforce by the World Health Organisation (WHO).

Desalination is the name given to the method of transforming seawater into consumable (potable) water. These processes involve the separation of salt- free fresh water from the seawater. The desalination processes can be based on thermal or membrane separation methods. The thermal separation techniques include two main categories; the first is evaporation followed by condensation of the formed water vapour and the second involves freezing followed by melting of the formed ice crystals. The main membrane desalination process is reverse osmosis, where fresh water permeates under high pressure through semi-permeable membranes leaving behind highly concentrated salt water call brine solution. The other membrane process is electrodialysis. In this process the electrically charged salt ions are separated through selective ion exchange membranes leaving behind low salinity water. Highly concentrated brine is formed on the other side of the membrane. Proper and effective pre-treatment of the seawater is required to

increase the efficiency and life of the reverse osmosis system. Ferric chloride is used as a coagulant and a cationic polymer is used as a coagulant aid. These chemicals, via the coagulation, flocculation and sedimentation processes remove the solids from the seawater. In addition to the solids, the seawater also contains micro-organisms. Shock chlorination sequences, using sodium hypochlorite, are used to minimize/prevent bio-fouling of the reverse osmosis membranes from the biological activity in the seawater. Sulphuric acid is utilized as an anti-scalant to eliminate carbonate and sulphate scaling. The water enter the supply is treated with Sodium hypochlorite to provide residual chlorine which ensures that the drinking water is clear of any biological activity (bacteria) and lime (calcium carbonate) is added to maintain a pH of 7 – 8.5.

Good quality groundwater is an important natural resource. Unfortunately groundwater can become contaminated through a number of ways including improper handling of process chemicals or disposal of wastes. The treatment of ground water begins with aeration to remove excess and objectionable gases while adding oxygen to the water. Coagulation is then used to remove dirt and other particles suspended in the water. Alum and other chemicals are added to water to form particles called “floc” which attract the dirt particles. The combined weight of the dirt and the alum (floc) become heavy enough to sink to the bottom during sedimentation. The next step is Re-carbonation, which readjust the water pH and alkalinity. It also converts the excess lime to CaCO3 solids, which is removed by settling. Filtration is the next step in the process and is used to remove any residual solids from the settling process. The final stage is the disinfecting of the filtered water mainly by the use of chlorine.

The treatment of surface water is similar to that of ground water. Surface water typically contains, a high suspended solids content, bacteria, algae, organic matter, creating bad taste and odour. The treatment begins with screening to remove any debris from the water. The next step is the coagulation process, which uses chemicals such as Alum to form particles called “floc” which attract the dirt particles does process. The combined weight of the dirt and the alum (floc) become heavy enough to sink to the bottom during sedimentation. Filtration then removes particles and floc that are too small or light to settle by gravity through a porous medium. Disinfection is the final process used to kill any bacteria or pathogens that remain.

For the first experiment we are given three samples in which to determine the quality of the water. This experiment tested whether or not the water contained bacteria by using the membrane filter technique. The samples we were given comprised of; sample A being water from the tap,

sample B being river water treated with chlorine and sample C being river water. The number of fecal coliform and total coliforms determined in the experiment are use as indicators of the presence of water borne disease carrying bacteria or pathogens.

Using the membrane-filtration method an estimation of the numbers of bacteria present in the water could be calculated. It gives you a direct colony count for a volume of sample taken from a water body. This is shown Table 1.

Observing the results for samples A and B, it can be said that these samples do not contain any pathogens and is safe to drink. These were expected results since tap water has already completed the treatment process because is being distributed from the water treatment plant and should be of World Health Organisation (WHO) standards. Also the use of chlorine in the river water removes the water-borne bacteria from the water. Sample B’s experiment shows that chlorine is capable of removing the bacteria and why it is a main part in the water treatment process.

In the case of sample C the results were also expected. In these results sample C was contaminated with pathogens and unfit for human consumption. This was due to the fact that there was absolutely no treatment of the river water. In order to acquire sample C’s results the technique of serial dilution was used, this is where consecutive volumes of samples are diluted even more to obtain readable results. For sample C the number of fecal coliform colonies per 100mL of river water was 100,000 and for the total coliform colonies per 100mL was 300,000. These numbers indicate that the water is highly contaminated with disease carrying bacteria. The acceptable coliform standards (refer to Figure 1 in Appendix) expressed in colonies/100 ml of water sample varies depending on the use of the water. For drinking purposes, however, the number of total coliforms must not be greater than 1 TC.

The next experiment perform was the jar test using river water. This test is performed to simulate the coagulation, flocculation and sedimentation processes of a water treatment plant. This test is done on a small scale in order to predict the function of a large-scale treatment plant

For this experiment the volume of alum required for the respective alum dosages of 0 to 100 for intervals 10 were calculated. One group did odd while the other group did even volume of alum. The calculated alum was added to the jars and the solution was mixed at a speed of 100 rpm for 1 minute. This high speed mixing was to disperse and mix the coagulant evenly throughout the jar. After 1 minute the speed was reduced to 20 rpm for 7 minutes to allow for the flocculation process to take place. In observing the jars at the point the particles were colliding together and forming heavier

particles called floc. The higher the dose of alum in the jar, the clearer the samples became and the more floc was seen. After the 7 minutes the mixing was stopped and the sedimentation of the floc was allowed to take place for another 7 minutes. The optimum dosage of coagulant is determined by the dosage for which the turbidity was most improved.

The turbidity was expected to decrease with the increase of each alum dosage but in the case of this experiment the turbidity fluctuated (refer to Table 3.). Therefore for the determination of optimum alum dosage the values that did not decrease sequentially were removed from the results shown in table 4, this resulted in a graph that decreased when alum dosage increased (refer to figure 3.). The optimum dosage is where the largest change in turbidity occurs, which from figure 3 is 70mg/L for 66 NTU.

It was also observed the level of pH decreased as the amount of alum dosage increased. This being stated, it can be said that as the alum dosage increases the water became more acidic that it was at the start of the test.

For this experiment the three possible water sources for X, Y and Z were taken from a saltwater aquifer in El Socoro, the other was water from the Desalcott desalination treatment plant and the other was water from the Caroni River treatment plant. The chemical composition of water is based on the source from which it is extracted.

In observation and study of the results it was determine that sample X was water from the saltwater aquifer in El Socoro. This determination was firstly because of the high levels of chloride calculated [1129mg Cl/L]. Chloride ions are derived mostly from salt deposits that leech into water. Secondly the high level of hardness calcium carbonate [224 mg CaCO3/L], which is a chemical compound mainly found in rocks. Thirdly because of the high alkalinity [155 mg CaCO3/L], salt water has a higher alkalinity than that of fresh water.

It was determined that the source of sample Y was water from the Caroni River treatment plant. This was due mainly to the high levels of chloride calculated [760mg Cl/L]. The pH level is neutral [7.01] and alkalinity is low [23 mg CaCO3/L]. Its hardness is also lower than the other samples, which indicates no CaCO3 from rock deposits. These characteristics make it suitable for service water.

By elimination it can be said that sample Z was taken from the Desalcott desalination treatment plant. This determination was also made due to the fact that, it would be expected that the ground water and surface water would have the higher alkalinity since the desalination water would be treated sea water therefore removing the minerals from it.

Sources of error

Experiment 1 – Bacteriological Analysis using Membrane Filter (MF) Technique

o Sample not diluted enough, therefore obtaining results of TNTC

o Sample too dilute, therefore obtaining results of TD

o Contamination of the samples due to the mixing of the samples via the

pipettes

o Not measuring the correct volume in the pipette

o Exposing the membrane to outside contamination

Experiment 2 – Jar Test

o Finger prints could have affected the turbidity readings

o Not measuring the correct volume in the pipette

o Not allowing the contents of the beaker to settle

o Disturbing the settled floc when removing samples

o Incorrect use of the pH meter

Experiment 3– Source Determination

o Mixing up the packets of residual and total chlorine

o Finger prints could have affected the turbidity readings

o Incorrect use of the pH meter

o Not measuring the correct volume in the pipette

o Adding too much or too little indicator during titration

o Titration is based on visual assumption

Conclusion

For the bacteriological analysis using membrane filter technique, the experiment was completed successfully. It was determine that samples A – tap water and samples B- river water treated with chlorine can be used for human consumption. However for samples C- river water, it was determined to be unsafe for human consumption.

The optimum alum dosage was found to be 70mg/L for treating river water.

For the source determination, the experiment was completed successfully and the sample sources are as follows:

i) Sample X – a saltwater aquifer in El Socoro. ii) Sample Y – the Caroni River treatment plant.iii) Sample Z – the Desalcott desalination treatment plant.

Appendix

Figure 1.

Figure 2.

Figure 3.

Questions

1. Using the information provided in Table 2, determine the different

forms (T, P, HCO3, CO32

, and OH) of alkalinity in the three (3) water

samples.

In the experiment it was observed during the titration that the samples did not turn pink when phenolphthalein indicator was added. This occurrence is due to the fact that there was no presence of hydroxide or carbonate ions. This means that phenolphthalein alkalinity, P=0. However there was colour change in all samples when methyl orange indicator was added, this meant the bicarbonates are present in the sample, T = HCO3

-.

2. Provide a rationale for testing water supplies for coliform bacteria and show how you would obtain 0.00001 mL of a very contaminated wastewater sample.

The rationale behind testing the water supplies for coliform bacteria is these organisms are good indicators of the potential contamination of a water source. Water systems test for indicators such as total coliforms, fecal coliforms, or E. coli to monitor water quality. If the water system has a positive test for one of these indicators, it can mean recent contamination with soil or human feces.

The following is the method of obtaining the dilution of 0.00001 mL:

I. The dilution bottles were prepared by placing 99ml of sterilize water into dilution bottle 1

II. Then 1ml of the sample was placed into bottle 1 and the sample was mixed.

III. Then 1ml of the sample was taken from bottle 1 and placed into bottle 2.

IV. And then 1ml of the sample was taken from bottle 2 and placed into bottle 3.

V. Then, 10ml of the sample was then taken from bottle 3 and this was filtered.

3. What is the Water quality Index WQI? Read the fecal coliform index value (Q fecal coliform) off the graph of Q vs. fecal coliform concentration.

A water quality index provides a single number (like a grade) that expresses overall water quality at a certain location and time based on several water quality parameters. It is a means by which water quality data is summarized for reporting to the public in a consistent manner. It is similar to the UV index or an air quality index, and it tells us, in simple terms, what the quality of drinking water is from a drinking water supply. Using the information obtained from the laboratory experiment. The highest fecal coliform value that was determined was 100,000. The Q value, which matched 100,000, is approximately 2. When comparing this value to the information on the National Sanitation Foundation Water Quality Index website, it can be stated that the water is of very bad quality and therefore should not be used for any form of water use.

4. List the negative environmental impacts of high turbidity in waters and describe the process used to remove high turbidity from river (surface) water in order to make it potable?

Some of the negative impacts are as follows:

i) It reduces the concentration of oxygen in the waterii) The water becomes warmer because of the suspended particlesiii) The turbidity must be effectively removed because no one likes

drinking water that looks dirty. This adds or increases the cost used to treat it.

iv) Turbidity can also inhibit photosynthesis by blocking sunlight. Halted or reduced photosynthesis means a decrease in plant survival and decreased dissolved oxygen output 

v) Pollutants such as dissolved metals and pathogens can attach to suspended particles and enter the water

Raw water has impurities (particles) in suspension, which can lead to turbidity, odor and taste problems. These impurities stay suspended in solution due to their small size and because they carry a negative electrostatic charge. This means that they repulse each other and thus stay in suspension. To remove these particles, they must agglomerate and grow in size in order to settle out of solution. To promote accumulation of particles, a chemical coagulant (aluminum or iron salts) is used. The chemical coagulant has positive charges, therefore, it neutralizes the negative electrostatic charges of the particles and brings them together causing them to accumulation and settle.

5. Discuss the similarities and differences of the jar test plots shown in appendix figure 2. to a similar plot for your jar test results. Determine and indicate the optimal alum dose for all three plots.

The results for the performed experiment, closely resembles that of figure 2 in the appendix (Settled Turbidity as a Function of Alum Dose at 30 rpm), in both graphs as the coagulant dosage increase the turbidity decreased.

For figure 3, in the appendix (Turbidity vs. Dose Rate for Aquapac 55), it shows that as the dosage of coagulant dosage is increased that the turbidity will start to rise as well, while in the experimental the alum dosages are not high enough to cause in increase in turbidity

The optimum alum dosage can be regarded as the amount of alum, which is required to produce the maximum turbidity removal but at the same time, it does not increase the plant’s operations.

For the Settled Turbidity as a Function of Alum Dose at 30 rpm and the Turbidity vs. Dose Rate for Aquapac 55, the optimum coagulant dosage was determine to be 2mg/L and 30mg/L respectively and for the experiment the optimum dosage was 70mg/L.

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