Water Analysis Laboratory

Environmental Engineering I - CVNG 3007

Student Name Kevin Blache

Student ID No. 813117777

Date Performed Wednesday 30th September, 2015

Date Submitted Wednesday 14th October, 2015

Item No.

Report SectionsPage No.

Marks Allocated Marks Received

1 Title Page 1 2

2 Abstract 2 2

3 Objectives 3 2

4 Introduction 3 3

5 Theory 4 3

6 Procedures 5 3

7 Results 5-7 10

8 Discussion 8-12 10

9 Conclusion 12 3

10 Appendix 13-15 0

11 Questions 15-17 10

12 References 18 2

TOTAL 50

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Abstract:

This report deals with various aspects of water analysis. Its basis is related to the need for potable

and palatable water for human use and consumption, given that water that is readily available

may not be to a standard that is acceptable based on International Stipulations. Adequate

knowledge of the methodologies associated with ascertaining the different characteristics of

water is included within and delved into so as to perform the requisite tasks in order to ascertain

said characteristics. The results of said analyses is presented and discussed at length so as to

achieve the objectives presented. These objectives include but are not limited to, determining the

bacteriological status of three (3) water samples (raw river water, river water treated with bleach

and tap water), determining the best coagulant dosage for turbidity removal and the source of

origin for three (3) water samples (from a river, a saltwater aquifer and seawater). The

conclusions drawn are correlated to documented standards (as shown in appendices and

reference section) and subsequently several questions are answered, which reinforce the concepts

throughout the course of the laboratory experiments.

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Objectives:

The aim of this experiment is to carry out an analysis of various aspects of water, in order to

ultimately gain a better understanding of the water treatment process. This is done via the

following objectives:

1. To demonstrate standard procedures/ methods, tools, apparatus and equipment used in an

environmental laboratory;

2. To classify water based on source;

3. To provide experience in analyzing laboratory test results;

4. To illustrate the shortcomings of some laboratory tests.

Introduction:

Water covers roughly 70% of the Earth’s surface and coincidentally it also makes up

approximately 70% of the human body, and is thus essential for survival. It is safe to say that in

no way can we as humans get away from water.

Water is used in many ways by humans, including but not limited to, drinking, bathing and other

hygienic purposes. The water we use must thus possess certain characteristics, for example, be

both potable and palatable.

The hydrologic cycle is nature’s way of purifying and redistributing water over the Earth’s

surface, but this water is subsequently contaminated through natural means and due to the action

of humans. It is because of this contamination that several agencies across the World, such as the

World Health Organization (WHO) set standards as to what the aforementioned characteristics

should be. On a smaller scale, that is, from country to country, local agencies have adopted and

adapted some of the criteria. These modifications were to suit various intrinsic factors.

The water which is readily (sometimes not so readily) available come from a plethora of sources,

such as rivers, lakes and streams (surface), aquifers and wells (groundwater) and the oceans

(seawater). Given the vagary of sources and their interaction with the Earth’s surface, soil and

human activities, physical, biological and chemical changes occur.

These changes therefore have to be reversed in order to return to levels that are safe for

consumption and use as stipulated.

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Theory:

During the course of the analyses carried out, several terms and concepts are introduced and used

throughout. In this regard it is of utmost importance that these terms are defined and additional

pertinent information be stated, in order to properly assess the various aspects of the water

analysis process.

The following definitions were found in the Penguin Dictionary of Civil Engineering:

(A) Bacteriological Analysis

1. Bacteriological analysis : is a laboratory test performed to determine the type and

concentration of microscopic disease causing organisms (pathogens) present in a water

sample.

(B) Jar Test

1. Jar test : is a laboratory test to estimate the ideal or minimum dose of coagulant required

to achieve particular water-quality objectives.

2. Turbidity : is a measure of the light scattering properties of water caused by suspended

matter.

(C) Source Determination

1. pH : is a logarithmic measure (negative logarithmic value of H+ ion concentration) of the

hydrogen concentration of a solution; each unit represents a tenfold change in acidity or

alkalinity.

2. Chlorine Residual : is the amount of chlorine that remains in water after a certain period

or contact time.

(i) Free - composed of dissolved hypochlorite ions, hypochlorous acid and chlorine gas.

(ii) Combined - composed of chloramines that kill bacteria and oxidize organic matter.

(iii) Total - the sum of free and combined residual chlorine.

3. Chloride : a compound of chlorine with another element or group, especially a salt of the

anion Cl-.

4. Hardness : is the total concentration of calcium and magnesium ions in water, expressed

as a calcium carbonate equivalent.

5. Alkalinity : is the capacity of water to neutralize acids though content of carbonate,

bicarbonate and/or hydroxide.

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Procedure:

The procedures for all experiments were performed in accordance with stipulations of the

laboratory manual, except for the following:

(A) Bacteriological Analysis

- No Changes

(B) Jar Test

- pH determined using an electrometric - pH meter.

- Alum concentrations of 0, 20, 40, 60, 80 and 100 mg/L

(C) Source Determination

- pH determined using an electrometric - pH meter.

Results:

The following results were obtained from the various laboratory tests:

(A) Bacteriological Analysis

Table 1. Showing the Results of the Bacteriological Analysis.

Sample Volume Total Coliform Fecal Coliform Total Coliform Fecal ColiformA 100 0 0 0 0B 50 0 0 0 0  25 0 0 0 0

C1 0.1 115 16 115000 16000  0.01 8 6 80000 60000

C2 0.001 5 0 500000 0  0.0001 0 0 0 0

C3 0.00001 0 0 0 0

The following sample calculations was done using the sample C1:

Coliform Colonies for 100 ml of Sample=No . of ColoniesCounted ×100Volumeof SampleTested

=115× 1000.1

=115000colonies

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Results (Continued):

(B) Jar Test

Table 2. Showing the Results of the Jar Test.

Sample Concentration (mg/L)

Turbidity pH

0 5.1 7.8

2 6.1 7.59

4 6.8 7.36

6 6.2 7.2

8 4.1 7.02

10 2.6 6.86

(C) Source Determination

Table 3. Showing the Results of the Source Determination Tests.

Source X Y Z

pH 7.33 7.56 7.17

Hardness

Initial 0.5 6.5 7.4

Final 6.5 7.4 9.9

Titration 6 0.9 2.5

CaCO3 240 36 100

Alkalinity

Initial 8.2 0 2

Final 23.2 2 8.2

Titration 15 2 6.2

P 0 0 0

T 150 20 62

Chloride

Initial 12.4 10.4 16.2

Final 16.2 12.4 18.1

Titration 3.8 2 1.9

Cl- 76 40 38

Chlorine ResidualFree 3.8 0.7 2.1

Total 4.4 0.8 2.9

Sample Calculations:

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The following sample calculations were done using the sample from Source X:

Hardness= TitreValue ×100Volumeof SampleTested

=6 ×10025

=240mgL

of CaCO3

Alkalinity (T )=Titre Value× 0.02× 50000Volume of SampleTested

=15× 0.02× 50000100

=150mgL

of CaCO3

Chloride= Titre Value× 500Volume of SampleTested

=3.8 ×50025

=76mgL

of Cl−¿¿

0 2 4 6 8 10 120

1

2

3

4

5

6

7

8

Graph 3. Showing Turbidity (NTU) vs. Alum Dose (mg/L)

Alum Dose

Turbidity

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Discussion:

(A) Bacteriological Analysis

The water samples used originated from three (3) sources:

Sample A - from the laboratory tap

Sample B - river water treated with household bleach

Sample C - untreated river water

According to the Microbiological and Biological Quality Standards [see Appendix (A)], as set

forth by the World Health Organization (WHO), for piped water supplies there should be no

number of fecal or total coliforms present and for unpiped water supplies a total of 10 coliform

organisms should be present.

Given these standards it is thus safe to say that the water from laboratory tap (Sample A) is

suitable for use and even consumption on the basis of the absence of fecal and other coliform

bacteria. This shows that the efforts made by the Water and Sewage Authority (WASA) of

Trinidad and Tobago were successful in eliminating potentially harmful disease carrying

bacteria.

The river water treated with household bleach (Sample B) was also void of any fecal or other

coliform bacteria, however, due to the use of bleach for sterilization purposes, this water may not

be suitable for consumption. This gives credence to the fact that several parameters must be

satisfied in order to make water both potable and palatable. The other aspects that must thus be

analyzed are the turbidity [as seen in Experiment (B) the Jar Test] and the various water quality

parameters such as pH and Hardness [as seen in Experiment (C) the Source Determination].

The untreated river water (Sample C), unlike the first two samples, can be said to be teeming

with coliform bacteria in the more concentrated dilutions of the sample. Coliform populations in

excess of tens of thousands can be found in the samples. This may be indicative of the effects of

human beings on the surface water source, where undertreated and untreated waste may be

discharged directly into the river or some groundwater intrusion via direct contact with some

septic system may have occurred and subsequently found its way into the river. In the subsequent

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dilutions of the sample, however, the coliform populations dwindled, eventually becoming zero

(0).

Limitations/ Sources of Error:

As can be expected with any laboratory experiment which requires measurement, parallax errors,

may have been induced into the sample due to human error. This would subsequently affect the

accuracy of the readings obtained particularly when pipetting during the sample dilution.

Additional errors may be induced when handling the membrane filters, as well as, the petri

dishes. It is thus important to wear gloves and use properly sterilized tools so as to avoid

bringing contaminated objects into contact with the membrane.

(B) Jar Test

The Jar Test is essentially a simulation of the flocculation and sedimentation portion of the water

treatment process. In this aspect of the process, a coagulant is added to the water destined for

treatment and is agitated. This coagulant is used to destabilize the particles which are suspended

in the water. Next, the rate of agitation is decreased in order to facilitate the interaction between

the newly coagulated particles (floc) to allow further interaction, leading to enlargement of

smaller particles and subsequently sedimentation.

This test is important as it allows the operators of a water treatment plant to determine a safe

volume of coagulant to add to water from a particular source in order to maximize the amount of

colloidal particles that are removed from suspension. Removing these particles is important as

their presence may affect the aesthetics of the water, bringing about doubts in the mind of the

persons who would use it, given the fact that it is unclear. They may also impede the disinfection

process by shielding harmful micro-organisms from the chemical added for said process.

Any particles which have not settled after this process, can subsequently be removed via the

filtration system used in that particular water treatment plant.

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In terms of the results of the jar test performed, after the coagulant (alum) was added, flocs could

be seen forming in all samples. When the speed of the paddles was reduced, an increase in the

number of flocs present could be seen, with the sample in which 2mg/L of alum was placed

having the least and the sample in which 10mg/L of alum was placed having the most.

The effectiveness of alum as a coagulant can be observed as the samples with the greater dosage

having a smaller value of turbidity. However, in can also be seen that with a greater dosage of

alum, the pH of the samples decreased thus showing a direct relationship. Therefore, it is

important to compromise between the dosage of coagulant added so as to minimize costs,

turbidity and subsequent changes to the pH and possibly other aspects of the water quality.

It can therefore be said, that a reasonable estimate for an alum dosage would be 7mg/L. This

value was obtained using the graph (Figure) by locating the minimum point on the curve of

turbidity versus alum dosage. This value can also be assumed to have a pH value between 7.2

and 7.0 which places it well within the acceptable range for water to be distributed. Additionally,

the Turbidity value would lie below the acceptable value of 5 NTU, i.e. at 2.2 NTU. [See

Appendix (B)]

Limitations/ Sources of Error:

The sources of error of this experiment are similar to that of the previous experiment, being

associated mainly with human error through parallax when taking measurements as it relates to

the alum doses to be added to the water samples.

(C) Source Identification

The water treatment process is constituted of several other processes which are each important in

their own different way. A concise version of the water treatment process, after extraction of raw

water, is:

1. Coagulation

2. Sedimentation

3. Filtration

4. Disinfection

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5. Storage/ Distribution

A schematic of this can be found in the Appendix (C) of this laboratory report.

Depending on the source from which it comes or the desired usage, the water treatment process

will have variations. This simply means, that water from a fresh water source such as a river,

lake or aquifer will be processed differently to water from a saltwater source. The variation in the

process will occur in stage three (3) or the filtration process. For a freshwater source, the

filtration would be done using either sand, gravel or charcoal filters. For a saltwater source, the

process of reverse osmosis (desalination) will be employed in order to remove dissolved

molecules and ions, particularly salts. The coagulation and flocculation processes are classified

as a pretreatment processes in this case, used to remove algae, mineral particles and dissolved

organic matter. It is important to note that desalination can be used for freshwater as well but due

to its operational cost, other methods are preferred.

Given knowledge of the properties of the water samples provided, i.e. X, Y and Z, it is now

possible to make a determination as to where each may have come from. It is difficult to glean

any insight into the source of the samples from their respective pH values, as they all lie within

the normal acceptable range for treated water. It is then best to use the hardness, alkalinity,

chloride and chlorine residual values to make a determination. Alkalinity and Hardness are two

related properties and given the relationships between the former and latter values, i.e. X=150 &

240 mg/L, Y=20 & 36mg/L and Z= 62 &100mg/L respectively, it can be said that sample Y is

from a freshwater source. This leaves samples X and Z yet to be determined. In terms of chloride

content samples Y and Z have relatively close values, however, it is possible for river water to

contain dissolved salts similar to saltwater.

It can then be said that sample X is from a seawater source. In Trinidad and Tobago, any water

obtained from the desalination process is primarily used for the manufacturing and petroleum

industry. As a result of this usage the requirements for the level of hardness, alkalinity and

chlorides are set at a much higher threshold than that of water for regular consumption and

public use, which typically comes from a surface source. Therefore sample Y was obtained from

a saltwater aquifer.

Limitations/ Sources of Error:

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Similar to the previous two experiments, parallax errors were possible when carrying out

titrations. Also errors can occur when testing the pH of successive samples. Therefore due care

and attention must be paid when carrying out said titrations. Additionally, it is of particular

importance to rinse off the pH meter thoroughly in order to safe guard against said contamination

of successive samples.

Conclusion:

It can be concluded that all of the objectives set forth for these laboratory experiments were

successfully completed. For the bacteriological analysis, a full understanding of the various

pieces of apparatus necessary for the developing of cultures for the growth and quantification of

fecal and total coliform populations was achieved. Sample C was found to have the greatest fecal

and total coliform populations, while Samples A and B were suitable for consumption and use.

For the jar test, a greater appreciation for the coagulation, flocculation and sedimentation

portions of the water treatment process was gained. The importance of finding a mutual ground

between alum dosage and pH in order to reduce the turbidity of a water sample. It was

determined that an alum dose of 7 mg/L was best suited for removing turbidity. Finally, the

various properties of water from differing sources were measured and analyzed in order to make

comparisons and thus deduce their places of origin. It was then determined that sample X came

from seawater, sample Y from a surface water source (river) and sample Z from a saltwater

aquifer.

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Appendix (A):

Table (A) Microbiological Quality Standards based on WHO Recommendations.

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Source: Salvato, J.A., Nemerow, N.L. and Agardy F.J., 2003, Environmental Engineering, 5th Ed. Wiley

Appendix (B):

Table (B) Aesthetic Quality Standards based on WHO Recommendations.

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Source: Salvato, J.A., Nemerow, N.L. and Agardy F.J., 2003, Environmental Engineering, 5th Ed. Wiley

Appendix (C):

Table (C) Schematic of a Water Treatment Plant according to the US Environmental Protection Agency (US-EPA).

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Source: http://water.epa.gov/lawsregs/guidance/sdwa/upload/2009_08_28_sdwa_fs_30ann_treatment_web.pdf

Questions:

1. The samples tested contained no P Alkalinity and thus only T Alkalinity. Therefore for

the samples the following was found:

Alkalinity X Y Z

P (mg/L) 0 0 0

T (mg/L) 150 20 62

OH- (mg/L) 0 0 0

CO32 (mg/L) 0 0 0

HCO3- (mg/L) 150 20 62

2. (a) Water supplies have to be tested for coliform bacteria for the main reason that these

bacteria are diseases causing bacteria that may lead to severe illness in human beings.

These bacteria are also common in many water sources due to the interaction of ground

water with septic systems or untreated disposal of waste into surface sources. The

presence of coliform bacteria also indicates the presence of other disease causing

organisms as they live in the same conditions and environment; thus giving credence to

the quality of a water supply and requisite treatment that must be undertaken to make it

potable.

(b) To make a 0.001 mL sample, start with a 100mL volume of a sample. Next, remove

1mL from that sample and place into a subsequent 100mL volume. Then, remove 10mL

from this sample and place into another 100mL volume.

That is: 1

100=0.01=0.01 ×10

100=0.001mL

3. The following are the Water Quality Index (WQI) ratings for the fecal coliform

populations:

Sample Volume Fecal Coliform WQI

A 100 0 95

16

B 50 0 95

  25 0 95

C1 0.1 16000 8

  0.01 60000 3

C2 0.001 0 95

  0.0001 0 95

C3 0.00001 0 95

4. It is important to note turbidity levels in water courses in order to ascertain the dosage of

coagulant required to remove a sufficient amount of suspended particles. These particles

as mentioned before affect the aesthetic quality of the water and also act as a buffer for

potentially harmful bacteria. High turbidity is present in ground water due to the presence

of various minerals within the soil that may become dissolved water as it permeates

through the soil, thus leaching said minerals to the underlying aquifers. Also organic

matter which may also be water soluble is present in soils and can also be dissolved and

become part of the water. This turbidity can be removed by the process of coagulation

and flocculation which is carried out by adding a coagulant, allowing these particles to

grow/ flocculate and settle. Subsequently, more flocculated particles can be removed by

filtration.

5. (a) The similarities between Graph 1 and the Graph 3 attained for the jar test performed

in this laboratory experiment is that they both are in the same units on either axis, i.e.

turbidity on the y-axis versus alum dose (mg/L) on the x-axis. The overall shapes of the

graphs are different in that, for our experiment, there was an initial increase in turbidity

with alum dose then it decreased. However, in graph 1 there was exponential decay in

turbidity with increased alum dosage.

(b) The similarities between Graph 2 and the Graph 3 obtained from the jar test is also

that their units are the same except that on the x-axis, alum dosage was given in another

form i.e. ppm/v instead of mg/L. Another similarity was that, after the optimum alum

dosage was reached, the turbidity increased with additional alum doses. The overall shape

differed from our graph, since for low alum doses it cannot be said for sure, if turbidity

increased initially then decreased.

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(c) For Graph 1 the optimal alum dose was 8mg/L. For Graph 2 the optimum alum

dosage was 45ppm/v. For Graph 3, 7mg/L was determined to be the optimum dosage of

alum.

References:

Books:

Blockley, D., 2005. Penguin Dictionary of Civil Engineering, Penguin.

Davis, M.L. and Cornwell, D.A., 2008. Introduction to Environmental Engineering, 4th Ed.

McGraw Hill.

Masters, G.M., 1998, Introduction to Environmental Engineering and Science, Prentice Hall.

Salvato, J.A., Nemerow, N.L. and Agardy F.J., 2003, Environmental Engineering, 5th Ed. Wiley.

Websites:

http://water.epa.gov/

Notes:

Rao, S.P.V., 2005. Water Supply Engineering (For the Course of Water Supply and Sanitary

Engineering), State Institute of Vocational Education Andhra Pradesh. Hyderabad.

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