My Water Analysis

Table of Contents Abstract...........................................................................2 Objective..........................................................................2 Introduction...................................................................... 2 Theory.............................................................................. 3 Procedure......................................................................... 4 Observation and Results....................................................5 Discussion........................................................................7 Conclusion........................................................................9 Questions.......................................................................10 References......................................................................13

Abstract This report is gives an idea of the importance of the chemical and physical analyses associated with the assessment of portable water quality in accordance with the water quality standards.

Objective The Objectives for the lab are: -

introduce students to the common parameters and tests used to classify water. Provide students with experience in analyzing results obtained from laboratory tests. Illustrate the shortcoming of these tests

Introduction Two thirds of the earth's surface covered by water and the human body consisting of 75 percent of it, it is evidently clear that water is one of the prime elements responsible for life on earth” [citied from http://www.laleva.cc/environment/water.html ]. However this abundance is not acceptable for regular domestic or drinking consumption as there are minerals and solids in the water that can affect our health. The three (3) main sources of water are the ocean, groundwater and surface water. All contain some measure of impurities that are not healthy to ingest or use in households therefore it is necessary to treat the water in order to reduce or eliminate any possible transmission of waterborne diseases by pathogens (An agent that causes disease, especially a living microorganism such as a bacterium or fungus) prior to distribution. As it pertains to the water sources, ocean water has the highest supply. However, the ocean has a high concentration of salts and minerals and would have to go through desalination. Surface water, the most commonly used source in Trinidad, refers to rivers, reservoirs and dams and goes through a typical treatment process. Groundwater is the cleanest source, however, it is usually high in mineral content found in the ground and will have to be treated for

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that. It is not used as extensively as surface water however due to its relatively low yield. Treatment of water is important as it primarily serves the purpose of avoiding many waterborne diseases such as cholera and typhoid. Whenever there is contamination of drinking water sources and water logging after rain there is an outbreak of infection (cited from http://ratnaveera.hubpages.com/hub/Importance-of-WaterTreatment).

Theory The tests that are carried out in this lab to check the water quality are the bacteriological analysis, the jar test, and source determination. Bacteriological analysis examines the amount of bacteria present in the water. Water quality is affected by the concentration of pathogens it contains as these are disease causing organisms. Most diseases are caused in particular from faecal contamination; bacteria originating in the guts of humans and animals. Due to the concentrations of faecal contamination being frequently small and the variety of pathogens being large, it is not practical to test for the actual pathogens in the water. This is why coliforms are used for analysis. As coliforms come from the same sources as pathogenic organisms and are relatively easy to identify, the testing for coliform bacteria can be a reasonable indication of whether other pathogenic bacteria are present. An indicator is always present when the bacteria is present hence giving an idea of how polluted/unhealthy the raw water source is (cited from http://www.health.ny.gov/environmental/water/drinking/coliform_bac teria.htm). The Jar test is intended to simulate the coagulation/flocculation process in a water treatment plant. The results that it produces are used to help optimize the performance

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of the plant (cited from http://www.rpi.edu/dept/chem-eng/BiotechEnviron/Environmental/WATER/jar.html). Coagulation alters the charges on suspended solids such that they will attract, clump together and form floc (amassed solid particles). As the water is slowly mixed, this floc grows in size until it can settle under gravitational forces (sedimentation). Alum is the chemical that is most popularly used in Trinidad for coagulation due to its economic efficiency when being compared to the more effective polymer. This test serves the purpose of determining the optimum alum dose to apply to the raw water. The more alum you add, the more floc you will gain. However, the disadvantage to adding more alum is the fact that it is acidic and will corrode the insides of distribution pipes that feed the homes being served. It also causes for increased costs due to the procuring of lime in order to adjust the pH. Therefore a delicate balance has to be struck. Source determination consists of different titrations that are used to determine the source of the water. The determination tests that are carried out in this lab are for residual chlorine, hardness, chlorides and alkalinity in the samples. Residual chlorine is a trait commonly found in treated water. When disinfecting the water, extra chlorine is added. This is done so as to provide further treatment during the distribution of the water should it become necessary. Hardness of the water refers to its mineral content. These minerals can cause for undesirable reaction products in industry water usage. The presence of minerals in the water is usually characteristic of a groundwater source. Minerals tend to be present in this particular water source as the water accumulates minerals found in the soil. Chloride pertains to the presence of CL- ions present in the water which would come from the. As aforementioned, there are different sources of raw water. A titration can be used to determine

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which source the raw water originated from or if water has already undergone treatment.

Procedure Jar Test-

1. Put 1000mL of river water sample provided, in each of six (6) 1L beakers. 2. Calculate the appropriate volumes of stock (5000 mg/L) solution required to give dosage of 10, 20, 40, 60, 80, 100 mg/L. 5. Reduce speed (without stoping the process) to 20 rpm and continue mixing for 7mins. 7. Stop mixing and allow the contents of the beakers to settle for 7 mins.

Source DeterminationHardness-Add 1mL buffer solution, 4drops of the indicator and swirl flask.

Observation and Results Bacteriological Analysis Source A B B C(bottle3) C(bottle2) C(bottle2) C(bottle1) C(bottle1) Coliform Colonies Dosage (mg/L) 10 20 40 60 80 100 Source

FC

TC 0 0 0

TNTC

0 0 0 TNTC

mL of sample 100 25 50 0.1 0.01 0.001 0.0001 0.00001

95 17 10 2 0 0 0 0 1.00E+09 1.70E+08 Jar Test Vol. of stock Turbidity alum (mg) (NTU) pH 2 6 7.5 4 7 7.29 8 7 7.04 12 4 6.86 16 2 6.66 20 1 6.46 X Y Z

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Hardness as mg CaCO3/L Alkalinity(mg CaCo3/L) Cloride (mg/L) Free Total

120

40

260

47 28

14 54

152 74

Chlorine 0.61 0.74

0.37 0.42

1.47 0.61

Table1: Water Analysis results

River Water 8

7

6

5

Residual Turbidity (NTU)

4

3

2

1

0

Coagulation Dosage (mg/L) Graph 2: Residual turbidity readings and corresponding alum dosage

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Determining Coliform Colonies for 100mL of sample: of colonies counted ∗100 ( ( vol ¿filtered∗sample dilution ) )

CFU =

Sample C, Bottle 2 (0.01/100 dilution): 17 ( 0.01 )∗100=1.7 x 10 per 100 mL of sample 10 =( ∗100=1 x 10 per 100 mL of sample 0.001 ) 8

CFU TC = CFU FC

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* There was an air bubble in sample in bottle 2 of 0.01 mL which cause the # of coliforms to be affected and the other samples were too dilute to count therefore not included in calculation *There were no colour changes to pink hence all titrations were purely total alkalinity (no phenolphthalein alkalinity). Doing sample calculations for sample X: Hardness Hardness=

Titre value∗1,000 3∗1,000 = =120 mgCa CO3 / L vol . of sample tested 25

Chloride −¿ /L Titre value∗500 1.4∗500 Chloride= = =28 mg CL ¿ vol . of sample tested 25 Alkalinity As mentioned, P-alkalinity was zero, therefore, the only type of alkalinity present in the water samples would be bicarbonate (HCO3-) which is equal to the total alkalinity. T −alkalinity =

titre value∗1,000 4.7∗1,000 = =47 mgCaCO 3 / L vol. of sample tested 100 mL

Discussion After undergoing bacteriological analysis, it has been determined that the untreated river water is the only one unsafe for drinking. The tap water is the safest due to the fact that it has been through the whole water treatment process and the residual chlorine taking

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care of any bacteria that may have attempted growth along the distribution mains of the network. As it pertains to the river water samples, the addition of chlorine via household bleach to one sample made it relatively safe to drink as it eliminated a satisfactory amount of coliforms (and by extension pathogens). This result therefore validates the advice given to the public to apply bleach to untreated water so as to make it potable. The untreated river water is by far the most polluted of the 3 samples, with a maximum total coliform count of 1.7 x 105 CFU per 100mL of sample. The vital coliform group that determines the potency of the water to cause diseases, the faecal coliforms, had a maximum value of 1 x 106 CFU per 100mL. This value would classify the river as being effluent ( 105 ¿ . As said in the Introduction, the jar test serves the purpose of simulating the operations that occur in a water treatment plant. The coagulant (alum) alters the charge of the suspended particles so as to induce inter-particle attractions. As alum is acidic, its addition will in turn make the solution acidic (a pH of greater than 7). This is of concern as an acidic solution will corrode the insides of the pipes which would contaminate the portable water. After the coagulation process, flocculation takes place to form larger particles and then settle (sedimentation). In this experiment it was observed that doing coagulation the sample with the least alum had the most particles settled out of suspension but when the flocculation began the sample with the most alum had the biggest floc sizes and therefore a greater settling From the graph 1 it can be seen that the sample with 100 mg/L alum is the optimum alum dosage for this treatment operation although it has the most acidity but the lowest turbidity. The 3 water sources tested for Source Determination were surface, ground, and sea water. Each require different water treatment processes so as to make them potable.

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Surface water is the most commonly used source and undergoes (in chronological order) screening, primary sedimentation, coagulation and flocculation, secondary sedimentation, filtration and disinfection before distribution. These processes are done to remove the bacteria and volume of solids that are the predominant pollutants in surface water. Groundwater has to be treated for the dissolved minerals that it contains rather than the amount of particles present in it. The minerals will undergo precipitation and flocculation after the addition of select chemicals. The water would then be carried through sedimentation, filtration and disinfection before distribution. Seawater is known for containing a multitude of salts and other minerals. It therefore has to undergo desalination which is most commonly done through reverse osmosis whereby water is moved across a semi permeable membrane against the concentration gradient. All these treatment processes are case specific and are effective for their respective water sources. However, desalination uses large amounts of energy and is hence more expensive than the other two treatment processes. Desalination may be the main source of treatment in countries that receive little to no rainfall to replenish their surface and ground water sources. Surface water is what is most commonly used due the increased yield it has when compared to ground water. Due to the vital necessity of potable water for the public, this greater yield is more convenient for the industry. Hence, surface water is the predominantly used source for water treatment in countries where this resource is available. The samples where identified by their Hardness, Alkalinity and Chloride properties. Based on the hardness test, sample z had a relatively high concentration of calcium carbonates. As previously said, ground water is known to contain dissolved minerals picked up from the soil so sample is suspected to have been derived from the groundwater

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source. The hardness and alkalinity levels from a desalination plant are relatively low hence this insinuates that sample Y originates from seawater (with hardness and alkalinity values of 40 and 14mgCaCO3/L respectively). As it pertains to the residual chlorine, the surface and groundwater would be expected to have higher values as both treatments involve disinfection. The therefore renders samples Z and X was the ground and surface water sources (irrespective) with free residual chlorine values of 1.47 and 0.61 respectively. Sample Y’s low residual chlorine value of 0.37 once again insinuates that sample has been through the desalination process hence Y originates from seawater.

Conclusion A good grasp and appreciation has been taken of the processes carried out in the treatment of water. From the tests performed, the following have been concluded: 1) Bacteriological Analysis: The treated tap water and domestically treated water are relatively safe for drinking. However, the untreated river water is highly contaminated hence making it unhealthy for consumption. 2) Jar Test: The optimum alum dosage determined to obtain a balance between less corrosion of pipes and suitable turbidity removal was 100 mg/L. 3) Source Determination: From the tests performed the following samples and water sources were correlated: Sample X – Surface water Sample Y – Sea water Sample Z – Ground water

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Questions 1).Using Table 2 from the lab manual (Types of Alkalinity), the only type of alkalinity that was present in the water samples was bicarbonate due to there being no P-alkalinity (for P=0, HCO3- = Talkalinity with OH-=CO32=0). 3). Water Quality Index (WQI) is a 100 point scale that summarizes results from a total of nine measurements (Temp, pH, Dissolve Oxygen, Turbidity, Nitrates, Phosphates, Total Suspended Solids, Biochemical oxygen, Fecal coliform).The Q value for this experiment is 4). High turbidity in surface waters will prevent sunlight from reaching the aquatic organisms that would need this resource for photosynthesis and the production of dissolved oxygen. Also, the suspended particles can clog the breathing passages of aquatic animals such as fish. Lastly, due to the suspended solids absorbing heat, the water will drop in temperature hence reducing the amount of dissolved oxygen the water can hold. The process of removing turbidity from river water is by the use of a conventional water treatment plant as shown below (diagram from CVNG3007 notes):

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5). The graph from the lab corralates with the alum plot with sample (water B) with the optimum being the maximam dosage in the test. From test the optimum dosage is 100 mg/L

River Water

Residual Turbidity (NTU)

J ar Test Plots

8 7 6 5 4 3 2 1 0

Coagulation Dosage (mg/L)

A.

B.

12

B.

30

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References http://www.sciencedaily.com/articles/p/pathogen.htm http://swrp.esr.pdx.edu/publications/manual/alkalinity_introduction.p df http://www.sasta.asn.au/v2/adc/datalogging/DataSinglePagePDFs/AD CBookDatalog13-23.pdf Information Cited from    

http://www.laleva.cc/environment/water.html http://ratnaveera.hubpages.com/hub/Importance-of-Water-Treatment http://www.health.ny.gov/environmental/water/drinking/coliform_bac teria.htm http://www.rpi.edu/dept/chemeng/BiotechEnviron/Environmental/WATER/jar.html

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