SANITARY LABORATORY MANUAL - Philadelphia University

1st

Sem

este

r

2019/2020

Philadelphia University Faculty of Engineering

Civil Engineering Department

SANITARY LABORATORY MANUAL

Prepared by Reviewed by

Eng.Isra’a Alsmadi Lab Instructor

Dr. Mohammad Younes Assistant Professor

Prepared by: Eng. Isra’a I. Al-Smadi

SYLLABUS

(Sanitary Laboratory)

Course number and name 0670444: Sanitary Laboratory

Credits and contact hours 1 Credit Hour

Instructor’s : Instructor: Eng.Isra’a Alsmadi

Text book, title, author, and year

“Sanitary Laboratory Manual”, (Prepared Eng.Isra’a Alsmadi/ Civil Engineering

Department/Philadelphia University),(2019)

Specific course information

Brief description of the content of the course (catalog description)

Determination of pH ,Preparation of Primary& Secondary Standards ,Acid –

Base Titration ,Determination of Acidity of Water, Determination of Alkalinity

of Water, Determination of Hardness Water, Determination Of Turbidity,

Determination Of Conductivity ,JAR Testing of Coagulation-Flocculation

Process, Determination of Solid and Determination of Dissolved Oxygen

Prerequisites

Prerequisite: Sanitary Engineering (0670443)

Course objectives:

The students will be able to understand and follow procedures, through lab manual.

The students will be able to work in teams, as experiments are conducted in

groups.

The students will be able to prepare a technical report, as the findings of

experiments have to be reported in well-structured format.

The students will be able to critically evaluate their results, by comparing them

with related published information.

The students will be able to understand how results of a practical are influenced by

the status of the apparatus.


Course outcomes:

Students who successfully complete this course will have demonstrated ability to:

Identify, Solutions it is types, and the characteristics of each type.

Understand basic units of measurement, convert units, and appreciate their

magnitudes.

Measure some of the important characteristics of water quality such as pH,

alkalinity, acidity …etc.

Use word and excel software in writing reports.

Compare the results of analytical models introduced in the lab to the standards of

drinking water.

List of experiment:

1) Determination of pH

2) Preparation of Primary& Secondary Standards

3) Acid – Base Titration

4) Determination of Acidity of Water

5) Determination of Alkalinity of Water

6) Determination of Hardness Water

7) Determination of Turbidity

8) Determination of Conductivity

9) JAR Testing of Coagulation-Flocculation Process

10) Determination of Solid

11) Determination of Dissolved Oxygen

Evaluation

60 % Lab work [quizzes and lab reports]

40 % final Exam

Attendance and Course Policies

Absence: - two absences are allowed with accepted excuse and the experiments must be

recovered. Any exceeding for the permitted absences will be restricted from taking the

final exam

Reports: no late submission will be accepted. Missing reports will result in a zero grade.

Cheating is not tolerated. A student guilty of cheating will receive a zero grade. Cheating is

any form of copying of another student’s work, or allowing the copying of your own work.

The late on the lab time: - the student is allowed to enter the lab after 10 minutes from

the starting the lab only.

Discipline: any student make any disturbance in the lab will be dismissed immediately

Dismissing: no student is allowed to dismiss from the lab until the lab is finished for any

excuse.

Quizzes: - it is about the previous experiment and it is given at the end of each lab after

finishing the experiment

All cellular phones must be turned off before lab begins.


List of Experiments

1) Determination of pH

2) Preparation of Primary& Secondary Standards

3) Acid – Base Titration

4) Determination of Acidity of Water

5) Determination of Alkalinity of Water

6) Determination of Hardness Water

7) Determination of Turbidity

8) Determination of Conductivity

9) JAR Testing of Coagulation-Flocculation Process

10) Determination of Solid

11) Determination of Dissolved Oxygen


HOW TO WRITE A LAB REPORT?

LAB REPORT ESSENTIALS

1. Title Page

It would be a single page that states:

a. The title of the experiment.

b. Your name and the names of any lab partners.

c. Your instructor's name.

d. The date the lab was performed or the date the report was submitted.

2. Title

The title says what experiment you did.

3. Introduction / Purpose

Usually, the Introduction is one paragraph that explains the objectives or purpose of the

lab. Sometimes an introduction may contain background information, briefly summarize

how the experiment was performed, state the findings of the experiment, and list the

conclusions of the investigation. Even if you don't write a whole introduction, you need

to state the purpose of the experiment, or why you did it. This would be where you state

your hypothesis.

4. Materials

List everything needed to complete your experiment.

5. Methods or procedure

Describe the steps you completed during your investigation. This is your procedure. Be

sufficiently detailed that anyone could read this section and duplicate your experiment. Write it

as if you were giving direction for someone else to do the lab. It may be helpful to provide a

Figure to diagram your experimental setup.

6. Data and Results

Numerical data obtained from your procedure usually is presented as a table. Data encompasses

what you recorded when you conducted the experiment. It's just the facts, not any interpretation

of what they mean.


7. Discussion or Analysis

The Analysis section contains any calculations you made based on those numbers. This is where

you interpret the data and determine whether or not a hypothesis was accepted. This is also

where you would discuss any mistakes you might have made while conducting the investigation.

You may wish to describe ways the study might have been improved.

8. Conclusions

Most of the time the conclusion is a single paragraph that sums up what happened in the

experiment, whether your hypothesis was accepted or rejected, and what this means.

9. Figures & Graphs

Graphs and figures must both be labeled with a descriptive title. Label the axes on a graph,

being sure to include units of measurement.

10. References

If your research was based on someone else's work or if you cite facts that require

documentation, then you should list these references.

WHAT IS A SCATTER PLOT?

A scatter plot is a chart with points that show the relationship between two or more sets of data.

The data is plotted on the graph as Cartesian coordinates, also known as data on an X-Y scale.


Laboratory Safety Requirements

صحیةاللعامة في مختبر السلامة اءات ارجا

:اتلمختبرامشرفي ولطلبة التالیة من قبل العامة السلامة دئ التقید بمباایجب

.لملابسوالیدین والسلامة للجسم العمل لتأمبن اء ارواب اتدرلطلبة باام الزورة اضر )1(

.لمختبراخل دالنقالة اتف الھوام استخدایمنع )2(

سمير عمل لمختبر لمن لیس لھاخل داجد التوایمنع )3(

ايلمختبر للعمل في ازیة ھجان ضمات وضیارلادوات والاوالمختبر اعلى نظافة ظ لحفاایجب )4(

.قتو

.هلانتبام اعد عن ناتجةادث یة حوع المختبر منعا لوقواخل دالركض اح او المزایمنع )5(

.ضلمراو التعب العمل في حالة ایمنع )6(

.لعملاي في حالة ة وھلاجھزایمنع تنظیف )7(

.لعملت الاواة وطلاجھزت واضیارلاالمحافظة على نظافة ایجب )8(

.ةلاجھزالك لتامین سلامة رب وذلتجاا من ءلانتھاابعد ة لاجھزء افااطلتاكد من ا )9(

:ما یلية عاالمختبر مرس امھندف او لمشرا علىو

.لمختبردرة اقبل مغاالاحھزة لكھربائي عن ر التیاالتاكد من فصل ا )1(

.درةلمغااقبل ء لماء والكھرباء افااطلتاكد من ا )2(

.مسبقاة لاجھزالتاكد من صلاحیة واا اؤھجري المنورب التجاة والمسبق للاجھزالتحضیر ایجب )3(

.لمختبرالي في ولاف اللاسعاوق یجب توفر صند )4(

للمختبر لرئیسيا بلباا من قریب نمكا في ضعھاوو لمختبرا في مناسبة حریق فایةط توفر یجب )5( .زلغات انااسطووالطاقة ارة والحردر اا عن مصادھبعاوا .لیھال الوصوالتسھیل


Page | 8

Experiment 1

DETERMINATION OF pH

OBJECTIVES:

To measure the pH for different samples.

APPARATUS:

pH meter Standard flasks

Wash Bottle Magnetic Stirrer

Tissue Paper Funnel

REAGENTS:

Buffers Solutions of pH 4.01, 7.0 and 9.2

Potassium Chloride

Distilled Water

THEORY:

The term pH refers to the measure of hydrogen ion concentration in a solution and

defined as “the negative log of H+ ions concentration in water and wastewater”. The

values of pH 0 to a little less than 7 are termed as acidic and the values of pH a little

above 7 to 14 are termed as basic. When the concentration of H+ and OH– ions are

equal then it is termed as neutral pH.

The pH electrode used in the pH measurement is a combined glass electrode. It

consists of sensing half cell and reference half cell, together form an electrode system.

The sensing half cell is a thin pH sensitive semi permeable membrane, separating two

solutions, viz., the outer solution, the sample to be analyzed and the internal solution

enclosed inside the glass membrane and has a known pH value. An electrical potential

is developed inside and another electrical potential is developed outside, the difference

in the potential is measured and is given as the pH of the sample.


Page | 9

Drinking water with a pH between 6.5 and 8.5 is generally considered satisfactory.

Acidic waters tend to be corrosive to plumbing and faucets, particularly if the pH is

below 6. Alkaline waters are less corrosive. Waters with a pH above 8.5 may tend to

have a bitter taste.

PROCEDURE:

CALIBRATING THE INSTRUMENT

Using the buffer solutions calibrate the instrument.

Step 1

In a 100 mL beaker take pH 9.2 buffer solution and place it in a magnetic stirrer,

and stir well.

Now place the electrode in the beaker containing the stirred buffer and check for

the reading in the pH meter.

If the instrument is not showing pH value of 9.2, using the calibration knob adjust

the reading to 9.2.

Take the electrode from the buffer, wash it with distilled water and then wipe

gently with soft tissue.

Step 2


and stir well.




the reading to 7.0.



Step 3


and stir well.




the reading to 4.0.


Page | 10



Now the instrument is calibrated.

TESTING OF SAMPLE

In a clean dry 100 mL beaker take the water sample and place it in a magnetic

stirrer and stir well.

Now place the electrode in the beaker containing the water sample and check for

the reading in the pH meter. Wait until you get a stable reading. Repeat this step

for different water samples and record each sample pH value.

Take the electrode from the water sample, wash it with distilled water and then

wipe gently with soft tissue.

TABLE OF OBSERVATIONS AND CALCULATIONS:

measure the value of pH of the given water sample, by using the pH meter at

different temperatures ,then fill the readings obtained into the following table :

Sample No

Temperature of Sample (ºC)

pH

1.

2.

3.

4.

5.


Page | 11

CONCLUSION AND RECOMMENDATIONS:

What are alternative methods for determining the pH of aqueous samples?

What are typical pH values of drinking water in Jordan? How do your data

compare with these values?

Discuss the relationship between (a) pH and hydrogen ion concentration (b) pH

and hydroxide ion concentration?

What are the potential health and environmental effects if any of extreme pH

values? (for humans)

Classify these samples for acidic ,basic or neutral

Arrange them according the pH values.


Page | 12

Experiment 2

PREPARATION OF PRIMARY& SECONDARY STANDARDS

OBJECTIVES:

Define standard, explain its uses, classify standard with proper example and explain

various properties of standards

Prepare a primary and secondary solution.

Exchange between concentration expressions.

APPARATUS:

Burette 25 ml Beaker 500 ml

pH meter Magnetic stirrer

Volumetric flask 100 ml Erlenmeyer flask 250 ml

Analytical balance

REAGENTS:

Sodium carbonate Na2CO3 Standard buffers

Sulfuric acid solution H2SO4 Methyl orange indicator

THEORY:

Standards are materials containing a precisely known concentration of a substance for

use in quantitative analysis.

Standards can be divided into two types:

Primary standard

Secondary standard

The Primary standard is a reagent that is extremely pure, stable, has no waters of

hydration, and has a high molecular weight .


Page | 13

Some primary standards for titration of acids:

sodium carbonate: Na2CO3, mol wt. = 105.99 g/mol

Tris-(hydroxymethyl) aminomethane (TRIS or THAM): (CH2OH)3CNH2, mol wt.

= 121.14 g/mol

Some primary standards for titration of bases:

potassium hydrogen phthalate (KHP): KHC8H4O4, mol wt. = 204.23 g/mol

potassium hydrogen iodate: KH(IO3)2, mol wt. = 389.92 g/mol

Some primary standards for redox titrations:

potassium dichromate: K2Cr2O7, mol wt. = 294.19 g/mol

The Secondary Standards is a standard that is prepared in the laboratory for a specific

analysis. It is usually standardized against a primary standard.

Normality is a measure of concentration equal to the gram equivalent weight per liter of

solution. Gram equivalent weight is the measure of the reactive capacity of a molecule.

Molarity concentration unit, defined to be the number of moles of solute divided by the

number of liters of solution.

Molality of a solution is defined as the amount of substance (in mol) of solute, divided

by the mass (in kg) of the solvent .

How to prepare .02N Na2CO3?

By using the following equation:

N = weight /(equivalent weight ∗ volume)

1. We need to know the weight that makes 0.02N. From the above equation :

Weight = N ∗ equivalent weight ∗ volume

2. The equivalent weight is unknown!!! So ,

equivalent weight = molecular weight /charge

Where:

The molecular weight is known = 106 gram/mol (23*2+3*16+12)

The charge = 2, by the following relationship:

Na2CO3 2Na + + CO3-2. (The charge = 2).


Page | 14

Then; The equivalent weight = 106 / 2 = 53

3. Weight = 0.02 * 53 * 1 L

= 1.06 gram

So we need to add 1.06 grams of Na2CO3 to 1000 ml of distilled water (1 litter) to make

0.02N solution.

*Different concentration expressions :

(1) The Molarity :

From the above definitions we can use the following equations:

The Molarity = number of moles / volume of solution

Example:

Calculate the Molarity solution consists of 20 a gram of sodium hydroxide (NaOH)

dissolve in500 cm3 of water?

Solution:

The Molarity = number of moles / volume of solution

number of moles = weight / molecular weight

= 20/40

= 0.5 mole

Volume of solution (litters) = 500/1000 = 0.5 litter

The Molarity = 0.5 / 0.5 = 1 M

(2) The Molality :

From the above definitions we can use the following equations:

The Molality = number of moles of dissolved / weight of solvent (Kg)

Example:

Calculate Molality of solution consists of dissolving 40grams of sodium hydroxide

dissolved in 2 liters of water?

Solution:

number of moles of NaOH = weight / molecular weight

= 40 / 40 = 1 mole

Weight of solution = volume of solution ∗ density of water

= 2000 cm3 ∗ 1 gram/cm3 = 2000 grams = 2 Kg

The Molality = 1 /2 = 0.5 mole / Kg


Page | 15

PROCEDURE:

1) Prepare standard Na2CO3 with 0.02N (by adding 10.6 grams of Na2CO3 to 1000

ml of distilled water).

2) Dissolve concentrated sulfuric acid H2SO4 with unknown volume to make 1000

ml solution.

3) Use the burette and fill it to the mark with the acid solution.

4) Put Na2CO3 with volume of 50 ml in Erlenmeyer flask, then add 5 drops of

Methyl Orange Indicator and place the flask on the Magnetic Stirrer.

5) While stirring, add acid slowly until the orange color disappear and pink appear.

6) Record the volume of the used H2SO4.

7) Record PH of the solution after titration (~=4.3).

8) Repeat the titration more times by follow the pervious steps, and measure the

H2SO4 volume used by change Na2CO3 volume.


We want to calculate the normality of H2SO4 by using the following equation:

N1V1 = N2V2

Where,

N1 = normality of acid solution (unknown)

V1 = the volume of acid solution used.

N2 = normality of base solution.

V2 = the volume of base solution used.

Then fill the following data table:

N1 V1 V2 N2 #

1

2

3

4

5


Page | 16


Compare between the primary and the secondary standards

What is an indicator? Which indicator is used in the titration? Can the titration be

performed by using some other indicator?

Explain the term ‘end point’?

What do you mean by 1.0 M solution?


Page | 17

Experiment 3

ACID –BASE TITRATION CURVE & ACID –BASE INDICATORS

OBJECTIVES:

Learn about the interaction between acids and bases.

Finding the equivalent point of acid and base reaction

APPARATUS:

pH meter Beakers different sizes

Magnetic stirrer Graduated cylinder

Burettes Erlenmeyer flask 250 ml

REAGENTS:

Na2CO3 Phenolphthalein indicator solution

H2SO4 Methyl orange indicator solution

THEORY:

Acids are a solution have a pH below 7.0, a sour taste, releases hydroxyl ions in water,

and turn litmus paper red.

Acids are divided into two main classes

Strong acids: are very corrosive and cause severe skin burns, examples are

hydrochloric acid, nitric acid, and sulfuric acid

Also called mineral or inorganic acids.

Weak acids are mildly corrosive and normally do not affect skin, examples are

acetic acid (vinegar), citric acid (citrus fruit juice acid), and tartaric acid (used

in making mayonnaise). Also called natural or organic acids.

Bases are solutions with a pH greater than 7, Bases tend to taste bitter and feel slippery.

At home, we use bases as cleaning agents and as antacid medications. Common examples

of bases found at home include soaps, lye (found in oven cleaners, for example), milk of

magnesia, and Tums. Each has a pH value greater than 7, has the potential for accepting

free hydrogen, and can neutralize acids.


Page | 18

When a strong acid and a strong base solution are mixed, a neutralization reaction

occurs, and the products do not have characteristics of either acids or bases. Instead, a

neutral salt and water are formed. Look at the reaction below:

HCl (aq) + NaOH (aq) H2O (l) + NaCl (aq)

The anion from the acid (Cl–) reacts with the cation from the base (Na+) to give a salt,

and a salt is defined as any compound formed whose anion came from an acid and whose

cation came from a base.

When a strong acid and a weak base are mixed, the resulting salt will be acidic.

When a strong base and a weak acid are mixed, the resulting salt will be basic

ex: K2CO3 (basic salt) is formed when the base, potassium hydroxide (which is

strong), reacts with the acid, H2CO3 (which is weak).

Acid–Base titration is the determination of the concentration of an acid or base by

exactly neutralizing the acid or base with an acid or base of known concentration. This

allows for quantitative analysis of the concentration of an unknown acid or base solution.

It makes use of the neutralization reaction that occurs between acids and bases.

Titration involves the slow addition of one solution where the concentration is known to

a known volume of another solution where the concentration is unknown until the

reaction reaches a desired level. For acid/base titrations, a color change from a pH

indicator is reached or a direct reading using a pH meter. This information can be used to

calculate the concentration of the unknown solution.

If the pH of an acid solution is plotted against the amount of base added during a titration,

the shape of the graph is called a titration curve. All acid titration curves follow the

same basic shapes.

At the beginning, the solution has a low pH and climbs as the strong base is added. As the

solution nears the point where all of the H+ is neutralized, the pH rises sharply and then

levels out again as the solution becomes more basic as more OH- ions are added.


Page | 19

The first curve shows a strong acid being titrated by a strong base. There is the initial

slow rise in pH until the reaction nears the point where just enough bases are added to

neutralize all the initial acid. This point is called the equivalence point. For a strong

acid/base reaction, this occurs at pH = 7. As the solution passes the equivalence point, the

pH slows its increase where the solution approaches the pH of the titration solute.

Figure 1: Acid base titration curves


Page | 20

PROCEDURE:

1. Prepare acid solution (H2SO4 0.05 N). 2. Prepare base solution (Na2CO3 0.02 N). 3. Put Na2CO3 with volume of 50 ml in Erlenmeyer flask, and then add Phenolphthalein

indicator to have a pink color. 4. Then measure the pH value before titration starting. (Needed titration solution

volume. =0). 5. then start titrate by putting the acid in the burette .the base color will change from the

pink to the colorless 6. Here, you will measure the pH value, which should be around 8.3, and measure the

needed titration solution volume. (equivalent point 1 ) 7. Next, Add the Methyl orange indicator, which give the yellow color to the solution. 8. Then start titrate by add the H2SO4 from the burette .the solution color will change

from the yellow to the red. 9. Now, you will measure the pH value, which should be around 4.5, and measure the

needed titration solution volume. (equivalent point 1 ) Note: we prepare the Phenolphthalein indicator solution by weighting 1 gram Phenolphthalein indicator and dissolve it in 100 ml alcohol (ethanol C2H2OH).


Page | 21


Show me how can you prepare the acid and base solution needed?

From the experiment results, complete the following data table:

pH

Titration volume

solution(ml)

#

0 1

5 2

10 3

15 4

20 5

25 6

30 7

35 8

40 9

45 10

50 11

GRAPHICAL RELATIONSHIP:

(1) Draw the titration curve by using the data in the table above.

(2) Specify the two equivalent points from the table : (where the color changed )

(3) From the curve determine the type of the acid and the base which you used.

Equivalent points 1: …………… titration volume 1: ………….

Equivalent points 2: …………….titration volume 2: ………….


Page | 22


After that, Compare between your experimentally point titration volume and pH

with the actual ones, where:

Equivalent points 1(actual) at pH = 8.3

Equivalent points 2(actual) at pH = 4.5

And calculate the errors %.

What is the difference between an end point and an equivalence point?


Page | 23

Experiment 4

DETERMINATION OF ACIDITY OF WATER

OBJECTIVES:

To determine the acidity of given water sample

APPARATUS:

Pipette Beakers different sizes



REAGENTS:

NaOH Phenolphthalein indicator solution

Distilled water Methyl orange indicator solution

THEORY:

Acidity is a measure of the capacity of water to neutralize bases.

Acidity is the sum of all titrable acid present in the water sample. Strong mineral acids,

weak acids such as carbonic acid, acetic acid present in the water sample contributes to

acidity of the water. Usually dissolved carbon dioxide (CO2) is the major acidic

component present in the unpolluted surface waters.

The volume of standard alkali required to titrate a specific volume of the sample to pH

8.3 is called phenolphthalein acidity (Total Acidity).

The volume of standard alkali required to titrate a specific volume of the water sample

(wastewater and highly polluted water) to pH 3.7 is called methyl orange acidity

(Mineral Acidity).To determine the acidity( as CaCO3 equivalent mg/l) for given water

sample , we will use the following equation :

�� = �� ∗ � �� ∗ �� ∗ ��

��

�� = �� ∗ � �� ∗ �� ∗ ��

��

Where: N is the Normality of NaOH.


Page | 24

PROCEDURE: 1. Rinse the burette with 0.02N sodium hydroxide (NaOH) and then discard the

solution.

2. Fill the burette with 0.02N sodium hydroxide and adjust the burette.

3. Fix the burette to the stand.

4. A sample size is chosen as the titre value does not exceed 20mL of the titrant. For

highly concentrated samples, dilute the sample. Usually, take 100 mL of a given

sample in a conical flask using pipette.

5. Add few drops of methyl orange indicator in the conical flask.

6. The color changes to orange. Now titrate the sample against the 0.02N sodium

hydroxide solution until the orange color faints.

7. Record the volume (V1) consumed for titration. This volume is used for

calculating the mineral acidity.

8. To the same solution in the conical flask add few drops of phenolphthalein

indicator.

9. Continue the titration, until the color changes to faint pink color.

10. Record the total volume (V2) consumed for titration. This volume is used for

calculating the total acidity.

11. Repeat the titration for concordant values.


Page | 25


Normality of NaOH =____________

#

sample

V1

ml

V2

ml Mineral Acidity Total Acidity


How does pH play a role in affecting acidity of given water sample?

What are typical water acidity values in drinking water in Jordan? How do your

data compare with these values?

How can acidity be removed for domestic and industrial purposes?

What are the potential human health and environmental effects of excess acidity

in potable water?


Page | 26

Experiment 5

DETERMINATION OF ALKALINITY OF WATER

OBJECTIVES:

To determine the alkalinity of given water sample

APPARATUS:




REAGENTS:

H2SO4 Phenolphthalein indicator solution

Distilled water Methyl orange indicator solution

THEORY:

Alkalinity of water is a measurement of its capacity to neutralize the acid .Alkalinity is

important for fish and aquatic life because it protects or buffers against rapid pH changes.

Higher alkalinity levels in surface waters will buffer acid rain and other acid wastes and

prevent pH changes that are harmful to aquatic life. But Large amount of alkalinity

imparts bitter taste in water.

The alkalinity of water can be determined by titrating the water sample with Sulphuric

acid of known values of pH, volume and concentrations. Based on stoichiometry of the

reaction and number of moles of Sulphuric acid needed to reach the end point, the

concentration of alkalinity in water is calculatedusing the following formula as CaCO3

equivalent mg/l

�� = �� H2SO� ∗ � H2SO� ∗ �� ∗ ��

��

Where: N is the Normality ofH�SO4.


Page | 27

3

3

PROCEDURE: 1. Rinse the burette with 0.02N Sulphuric acid H2SO4 and discard the solution.

2. Fill the burette with 0.02N sulphuric acid and adjust it to zero.

3. Fix the burette in the stand.

4. Using a measuring cylinder exactly measure 100 mL of sample and pour it into a

250 mL of conical flask.

5. Add few drops of phenolphthalein indicator to the contents of conical flask. The

color of the solution will turn to pink. This color change is due to alkalinity of

hydroxyl ions in the water sample.

6. Titrate it against 0.02N sulphuric acid till the pink color disappears. This

indicates that all the hydroxyl ions are removed from the water sample. Record

the titter value (V1).This value is used in calculating the phenolphthalein

alkalinity.

7. To the same solution in the conical flask add few drops of methyl orange

indicator. The color of the solution turns to orange.

8. Continue the titration from the point where stopped for the phenolphthalein

alkalinity. Titrate till the solution becomes pink. The entire volume (V2) of

sulphuric acid is noted down and it is accountable in calculating the total

alkalinity.

9. The value of titration is 8.3mL.

10. Repeat the titration for concordant values.


Page | 28


Normality of H2SO4 =____________

#

sample

V1

H2SO4

V2

H2SO4

Phenolphthalein

Alkalinity Total alkalinity


Which is the major form of alkalinity? How is it formed?

What are typical phenolphthalein and total alkalinity values for rivers, streams

and drinking water in Jordan or the world? How do your data compare with

these values?

Why does the pH change on aerating the water?

Why do we should use CO2 free distilled water for analysis?

Are there other methods that can determine the alkalinity in water samples?


Page | 29

Experiment 6

DETERMINATION OF TOTAL HARDNESS

OBJECTIVES:

To determine the hardness of given sample of water.

APPARATUS:




REAGENTS:

Buffer solutions Standard EDTA solution

Distilled water EBT (Erichrome Black T )

THEORY:

Hardness is the ability of water to neutralize soap and it is a natural characteristic of

water so as hardness increases, more soap is needed to achieve the same level of cleaning

due to the interactions of the hardness ions with the soap.

Chemically, hardness is often defined as the capacity of cations in water (Ca+2, Mg+2,

Sr+2, Mn+2 and Fe+2) to replace the Sodium (Na) or Potassium (K) ions in soap and form

insoluble products.

Classification of hardness:

There are three methods to classify the hardness:

1. According to the removing method:

Temporary hardness : can be removed simply by boiling the water

Permanent hardness: cannot be removed by boiling but can often be

removed by chemical treatment

Total hardness equals the sum Temporary hardness and Permanent hardness.

2. According to the cause(cations):

Calcium hardness (Ca+2)


Page | 30

Magnesium hardness(Mg+2)

Total hardness equals the sum Calcium hardness and Magnesium

hardness

3. According to the type of anions:

Carbonate hardness: Carbonate hardness is usually due to the presence of

bicarbonate [Ca (HCO3)2 and Mg (HCO3)2] and carbonate (CaCO3 and

MgCO3) salts.

Noncarbonate hardness: Noncarbonate hardness is contributed by salts such

as calcium chloride (CaCl2), magnesium sulfate (MgSO4), and magnesium

chloride (MgCl2).

Total hardness equals the sum of carbonate and noncarbonate

hardness.

Hardness is usually reported as equivalents of mg/L calcium carbonate (CaCO3) and is

generally classified as soft, moderately hard, hard, and very hard. The classification

scheme used by the U.S. Environmental Protection Agency (EPA) is shown in Table 1.

Table (1): Water hardness classifications (reported as CaCO3 equivalents) by the

U.S. EPA (EPA 1986).

Classification CaCO3 equivalent (mg/L)

Soft <75

Moderately hard 75–150

Hard 150–300

Very hard >300

The measurement of water hardness is important in water quality monitoring and is

usually performed by means of an Ethylenediaminetetraacetic acid (EDTA) complexation

titration. By convention, the total hardness of water is quoted in terms of the parts per

million of calcium carbonate, ignoring the contribution of magnesium salts. In this

method a sample of tap water will be analyzed.


Page | 31

Calcium and magnesium ions form 1:1 complexes with EDTA according to the

equations:

The indicators used are Erichrome Black T which changes from red to blue in the

presence of excess EDTA.

And hydroxynaphthol blue which changes from

The separate calcium and magnesium concentrations can then be found by a separate

titration at higher pH. By adding NaOH, the magnesium precipitate as Mg (OH) 2 and the

calcium can be determined separately. Simple subtraction from the total concentration of

magnesium + calcium, the magnesium concentration can also be found.

Generally hardness is calculated using the following equation:

Total Hardness (as CaCO� equivalent mg/l) = V�� ∗ N ∗ 50.000

V��

Where,

V EDTA: volume of EDTA needed to titration.

N: EDTA normality = 0.02 N

50: equivalent weight of CaCO3.

1000 = (Convert the volume from ml to litter)

V sample: the volume of the measured sample.


Page | 32

PROCEDURE:

The total hardness in Tap water :

1) Fill 100 ml of tap water.

2) To rise the PH reading (9.5 – 10 ) , we need to put amount of ammonia

3) Add EBT indicator which will give you pink (wine red).

4) Add EDTA titrant until the color changes to blue & record volume of EDTA that

use.

Calcium hardness in Tap water :

1) Fill 100 ml tap water.

2) To rise PH reading ( 12 – 13 ) ,use amount of NaOH with [ 1 N ] buffer

3) Add murxide indicator which will give you pink color.

4) Add EDTA titrant until the color changes to purple & record volume of EDTA

that use.


Hardness type Total hardness EDTA volume

ml Sample

volume ml Sample

20 1

50 2

100 3

150 4


Page | 33


What is degree of hardness? How will you classify water in terms of degree of

hardness?

What are typical water hardness values in rivers, streams, lakes and drinking

water in Jordan/World?

Explain the significance of determination of hardness of water in environmental

engineering.

How can you remove permanent hardness from water?

What are the principal cations causing hardness in water and the major anions

associated with them?

Define softening. Why it is necessary? What are the advantages of soft water?


Page | 34

Experiment 7

DETERMINATION OF TURBIDITY

OBJECTIVES:

To determine the turbidity of the given water sample

APPARATUS:

Turbidity meter Tissue Papers

Sample cell Thermometer

REAGENTS:

Distilled water

Different water sample

THEORY:

Turbidity is the term referring to the cloudiness of a solution and it is a qualitative

characteristic which is imparted by solid particles obstructing the transmittance of light

through a water sample. Turbidity often indicates the presence of dispersed and

suspended solids like clay, organic matter, silt, algae and other microorganisms.

Turbidity has some environmental impacts such as:

The colloidal material which exerts turbidity provides adsorption sites for

chemicals and for biological organism that may not be harmful.

They may be harmful or cause undesirable tastes and odors.

Disinfection of turbid water is difficult because of the adsorptive characteristics of

some colloids and because the solids may partially shield organisms from

disinfectant.

In natural water bodies, turbidity may impart a brown or other color to water and

may interfere with light penetration and photosynthetic reaction in streams and

lakes.

Turbidity increases the load on slow sand filters.


Page | 35

Turbidity measurements are used to determine the effectiveness of treatment produced

with different chemicals and the dosages needed. Turbidity measurements help to gauge

the amount of chemicals needed from day-to-day operation of water treatment works.

Turbidity is based on the comparison of the intensity of light scattered by the sample

under defined conditions with the intensity of the light scattered by a standard reference

suspension under the same conditions. The turbidity of the sample is thus measured from

the amount of light scattered by the sample taking a reference with standard turbidity

suspension. The higher the intensity of scattered light the higher is the turbidity.

Formazin polymer is used as the primary standard reference suspension.

PROCEDURE:

1) To the sample cells, add turbidity free distilled water up to the horizontal mark,

wipe gently with soft tissue.

2) Place it in the turbidity meter such that the vertical mark in the sample cell should

coincide with the mark in the turbidity meter and cover the sample cell.

3) Now using the set zero knob, adjust the reading to zero.

4) To the sample cells, add sample water up to the horizontal mark, wipe gently with

soft tissue and place it in the turbidity meter such that the vertical mark in the

sample cell should coincide with the mark in the turbidity meter and cover the

sample cell.

5) Check for the reading in the turbidity meter. Wait until you get a stable reading.


Page | 36


Concentration-Turbidity relationship:

Temperature-Turbidity relationship:


Draw a curve show the relationship between the concentration and the turbidity.

Draw a curve show the relationship between the temperature and the turbidity.

((The concentration is constant for all samples))

Sample # Concentration mg/l

Turbidity FNU

1

2

3

4

5

Sample # Temperature oC Turbidity FNU

1

2

3

4

5


Page | 37


What are the alternative methods for determining the turbidity of aqueous

samples? How do they compare to this method?

Discuss the significance of determination of turbidity in sanitary engineering.

What are typical turbidity and TSS values of water in Jordan? How do your

data compare with these values? (Drinking, surface and ground water)

Discuss the nature of materials causing turbidity in:

River water during flash flood

Polluted river water

Domestic wastewater

What is the standard unit of turbidity?

What are NTU and FNU?

Comment on the relations between turbidity and temperature and concentration.

And why?


Page | 38

Experiment 8

DETERMINATION OF CONDUCTIVITY

OBJECTIVES:

Measurer the electrical conductivity of water using conductivity meter and find the

relation between EC and TDS.

APPARATUS: Conductivity meter beakers

graduated cylinder Thermometer

REAGENTS:

Distilled water

Sodium chloride (NaCl)

THEORY:

Conductivity is an expression the ability of water to conduct electric current. This ability

affected by many conditions such as temperature, Concentrations of ions in the solution

and charge of dissolved solids.

Since the electrical conductivity of the water depends on the water temperature: the

higher the temperature, the higher the electrical conductivity would be. The electrical

conductivity of water increases by 2-3% for an increase of 1 degree Celsius of water

temperature. Many EC meters nowadays automatically standardize the readings to 25oC.

The commonly used units for measuring electrical conductivity of water are:

μS/cm (micro Siemens/cm) or dS/m (deci Siemens/m); Where: 1000 μS/cm = 1

dS/m

The electrical conductivity of water provides an estimate of the total amount of solids

dissolved in water TDS, Since the electrical conductivity is a measure to the capacity of

water to conduct electrical current, it is directly related to the concentration of salts

dissolved in water, and therefore to the Total Dissolved Solids (TDS). Salts dissolve into

positively charged ions and negatively charged ions, which conduct electricity.


Page | 39

So when it is difficult to measure TDS in the field, the electrical conductivity of the

water is used as a measure the electrical conductivity of the water can be determined in a

quick and inexpensive way, using portable meters. And it could be calculated using the

following formula:

TDS (mg/L) = 0.67 X EC (μS/cm) = 670 X EC (dS/m)

Distilled water does not contain dissolved salts and, as a result, it does not conduct

electricity and has an electrical conductivity of zero.

PROCEDURE:

1) Rinse the electrode thoroughly with distilled water and carefully wipe with a

tissue paper.

2) Measure 200 mL of water sample and transfer it to a beaker and place it on the

magnetic stirrer.

3) Dip the electrode into the sample solution taken in a beaker and wait for a steady

reading. Make sure that the instrument is giving stable reading

4) Record the readings for all samples on data sheet.


Sample #

Concentration NaCl mg/l

Conductivity µS/cm

TDS mg/l

1

2

3

4

5


Page | 40


Draw the concentration Vs conductivity.

Calculate the slope, which must be between ( 0.55– 0.9 )


What are the potential sources of error in this analytical determination? How

could they be overcome?

What are alternative methods for determining the TDS of aqueous samples?

What are typical conductivity and TDS values of drinking water in Jordan? How

do your data compare with these values?

What are the main sources of TDS in water and wastewater?

What are the potential health and environmental effects if any of extreme TDS

values?

What is the common conductivity reading for deionized, distilled, drinking and

waste water?


Page | 41

Experiment 9

JAR TEST FOR OPTIMUM COAGULANT DOSE

(Coagulation-Flocculation)

OBJECTIVES:

To determine the optimum dosage of given coagulant

APPARATUS: Jar test apparatus Glass beakers

Pipette Thermometer

Turbidity meter Stopwatch

REAGENTS:

Distilled water Aluminum Sulphate (alum)

THEORY:

Coagulation/flocculation is the process of binding small particles in the water together

into larger, heavier clumps which settle out relatively quickly. The larger particles are

known as floc. Properly formed floc will settle out of water quickly in the sedimentation

basin, removing the majority of the water's turbidity. In colloid chemistry, flocculation

refers to the process by which fine particulates are caused to clump together into a floc.

The floc may then: float to the top of the liquid (creaming), settle to the bottom of the

liquid (sedimentation), or be readily filtered from the liquid.

Coagulants are used in water treatment plants

to remove natural suspended and colloidal matter,

to remove material which do not settle in plain sedimentation, and

To assist in filtration.

Alum [Al2 (SO4)3. 18H2O] is the most widely used coagulant. When alum solution is

added to water, the molecules dissociate to yield SO2–4 and Al+3 .The positive species

combine with negatively charged colloidal to neutralize part of the charge on the

colloidal particle. Thus, agglomeration takes place. Coagulation is a quite complex

phenomenon and the coagulant should be distributed uniformly throughout the solution.

A flash mix accomplishes this.


Page | 42

Jar test is simple device used to determine this optimum coagulant dose required. The jar

test, device consists of a number of stirrers (4 to 6) provided with paddles. The paddles

can be rotated with varying speed with the help of a motor and regulator. Samples will be

taken in jars or beakers and varying dose of coagulant will be added simultaneously to all

the jars. The paddles will be rotated at 100 rpm for 1 minute and at 40 rpm for 20 to 30

minutes, corresponding to the flash mixing and slow mixing in the flocculator of the

treatment plant. After 30 minutes settling, supernatant will be taken carefully from all the

jars to measure turbidity. The dose, which gives the least turbidity, is taken as the

optimum coagulant dose.

PROCEDURE:

1) Prepare 4 of water sample.

2) Record the initial temperature pH , and turbidity

3) Add alum dosage respectively, ex (1, 2, 3 and4 ml).

4) Start the stirrer for rapid mixing for 1 minute @ 100 rpm.

5) Then slow mixing for 20 minutes @20-40 rpm.

6) After settling for 30 minutes take a sample from the center of each beaker and

measure the turbidity.

7) Measure the pH, temperature and note the difference.

8) Compare the turbidity of each beaker after the coagulation and flocculation

process.

9) Determine the turbidity reduction for each dosage.


Page | 43


After settling takes a sample from the center of each beaker and measure the turbidity:

Compare the turbidity of each beaker after the coagulation and flocculation process:

Turbidity reduction = turbidity initial – turbidity �inal

Ef�iciency of removal % = turbidity reduction / turbidity initial ∗ 100 %


Draw a curve show the relationship between the turbidity and the alum dosage.

Then find the optimum alum dosage


Why is alum preferred to other coagulants?

What is the difference between coagulation and flocculation?

What are coagulant aids?

Write the significance of pH in coagulation using alum.

Discuss the importance of finding the optimum dosage.

Baker #

Alum dosage

ml

Turbidity

NTU

(final)

1

2

3

4

Baker # Turbidity

NTU (initial)

Turbidity

NTU

(final)

turbidity

reduction

Efficiency of

removal %

1

2

3

4


Page | 44

Experiment 10

DETERMINATION OF SOLIDS

OBJECTIVES:

The aim of the experiments is to determine the following types of solids in the given

sample(s):

Total solids

Total (inorganic) fixed solids

Total volatile (organic) solids

Total dissolved solids

Dissolved fixed (inorganic) solids

Dissolved volatile (organic) solids

Total suspended solids

Suspended fixed (inorganic) solids

Suspended volatile (organic) solids

Settleable solids

APPARATUS:

REAGENTS:

Water samples

Porcelain evaporating dishes of

150–200 mL capacity

Filter paper (preferably of glass

fiber)

Drying oven Electric muffle furnace

Analytical balance Imhoff cone


Page | 45

THEORY:

Total solid is the term applied to the material left in the vessel after evaporation of a sample of

water/waste water and its subsequent drying in an oven at a definite temperature. Total solids

include “total suspended solids” the portion of total solids retained by a filter and “total

dissolved solids” the portion that passes through the filter. Fixed solids are the residue remaining

after ignition for 1 hour at 550°C. The solid portion that is volatilized during ignition is called

volatile solids. It will be mostly organic matter.

Water that is low in organic matter and total mineral content and are intended for

human consumption may be examined under 103–105°C or 179–181°C. But water

containing considerable organic matter or those with pH over 9.0 should be dried at

179–181°C. In any case, the report should indicate the drying temperature.

The sample is filtered and the filtrate evaporate in a weighed dish on a steam bath, the

residue left after evaporation is dried to constant weight in an oven at either 103–105°C

or 179–181°C. The increase in weight over that of the empty dish represents total

dissolved solids and includes all materials, liquid or solid, in solution or otherwise,

which passes through the filter and not volatilized during the drying process.

The difference between the total solids and the total dissolved solids will give the total

suspended solids. The dishes with the residue retained after completion of the tests for

total solids and total dissolved solids are subjected to heat for 1 hour in a muffle furnace

held at 550°C. The increase in weight over that of the ignited empty vessel represents

fixed solids in each instance.

The difference between the total dissolved/total suspended solids and the corresponding

fixed solids will give volatile solids in each instance. All the quantities should be

expressed in mg/L. Settleable matter in surface and saline waters as well as domestic

and industrial wastes may be determined and reported on a volume basis as milliliter per

litter.


Page | 46

PROCEDURE:

Total solids

1) Ignite the clean evaporating dishes in the muffle furnace for 30 minutes at 550°C and cool in a desiccator.

2) Note down the empty weight of the dish (W1).

3) Pour a measured portion (50 to 100 mL) of the well-mixed sample into the dish and evaporate the contents by placing the dish on a steam bath.

4) Transfer the dish to an oven maintained at either 103–105°C or 179–181°C and dry it for 1 hour.

5) Allow the dish to cool briefly in air before placing it, while still warm in a desiccator to complete cooling in a dry atmosphere.

6) Weigh the dish as soon as it has completely cooled (W2).

7) Weight of residue = (W2 – W1) mg. W2

and W1 should be

expressed in mg. Total fixed solids

1) Keep the same dish used for determining total residue in a muffle furnace for 1 hour at 550°C.

2) Allow the dish to partially cool in air until most of the heat has dissipated, then transfer to a desiccator for final cooling in a dry atmosphere.

3) Weigh the dish as soon as it has cooled (W3).

4) Weight of total fixed residue = (W3 – W1) mg.

W3 and W1 should be

expressed in mg

Total dissolved solids

1) Filter a measured portion of the mixed sample (50 or 100 mL) through a filter paper and collect the filtrate in a previously prepared and weighed evaporating dish.

2) Repeat the steps 3 to 6 outlined in total solids procedure.

3) Weight of dissolved solids = (W5 – W4) mg. W4 = Weight

of empty evaporating dish in mg. W5 = Weight of empty evaporating dish in mg + Residue left after evaporating the

filtrate in mg.


Page | 47

Total suspended solids = Total solids – Total dissolved solids.

Total volatile solids = Total solids – Total fixed solids.

Fixed dissolved solids

1) Keep the same evaporating dish used in determining total dissolved solids in a muffle furnace for 1 hour at 550°C.

2) Repeat the steps 2 and 3 outlined in total fixed solids procedure.

3) Weight of fixed dissolved solids = (W6 – W4) mg. W6 = Weight of empty evaporating dish + Fixed solids left after ignition at 550°C.

Volatile dissolved solids = Total dissolved solids – Fixed dissolved solids.

Fixed suspended solids = Total fixed solids – Fixed dissolved solids.

Volatile suspended solids = Total volatile solids – Volatile dissolved solids.

Settleable solids by volume

1) Fill an Imhoff cone to the litter mark with a thoroughly mixed sample.

2) Settle for 45 minutes.

3) Gently stir the sides of the cone with a rod or by spinning.

4) Settle 15 minutes longer.

5) Record the volume of settleable matter in the cone as mL/L.


Page | 48


Item Sample

I

Sample

II

Sample

III

Volume of sample taken

Wt. of empty evaporating dish = W1 mg (For

total dissolved solids)

Wt. of dish + total solids = W2 mg

Total solids = (W2 – W1) mg

Wt. of dish + fixed solids = W3 in mg

Fixed solids in mg = (W3 – W1)

Wt. of empty evaporating dish = W4 mg (For

total dissolved solids)

Wt. of dish + total dissolved solids = W5 mg

Total dissolved solids = (W5 – W4) mg

Wt. of dish + fixed dissolved solids = W6 mg

Fixed dissolved solids = (W6 – W4) mg

Total solids in mg/L

Total fixed solids in mg/L

Total dissolved solids in mg/L

Total suspended solids in mg/L

Total volatile solids in mg/L

Fixed dissolved solids in mg/L

Volatile dissolved solids in mg/L

Fixed suspended solids in mg/L

Volatile suspended solids in mg/L

Settleable solids in mg/L


Page | 49

MATHEMATICAL RELATIONSHIP:

mg/L total solids = mg total solids × 1000

ml of sample

mg/L total �ixed solids = mg total �ixed solids × 1000

ml of sample

mg/L total dissolved solid = mg of total dissolved solids × 1000

ml of sample

mg/L total suspended solids = mg/L of total solids – mg/L of total dissolved solids

mg/L total volatile solids = mg/L of total solids – mg/L of total �ixed solids

mg/L �ixed dissolved solids = mg �ixed dissolved solids × 1000

ml of sample

mg/L volatile dissolved solids

= mg/L total dissolved solids – mg/L of �ixed dissolved solids

mg/L �ixed suspended solids

= mg/L total �ixed solids – mg/L �ixed dissolved solids

mg/L volatile suspended solids

= mg/L total volatile solids – mg/L volatile dissolved solids


What is the application of determination of settleable solids?

Explain the significance of determination of total solids in sanitary engineering.

How will the volatile solids affect the strength of sewage? Why?

Why do you determine the fixed solids by igniting at 550°C? How will the result

be affected, if it has magnesium carbonate content?

What significant information is furnished by the determination of volatile solids?

What is sludge volume index?


Page | 50

Experiment 11

DETERMINATION OF DISSOLVED OXYGEN

OBJECTIVES:

Determine the quantity of dissolved oxygen present in the given sample(s) by using modified

Winkler’s (Azide modification) method.

APPARATUS:

300 mL capacity bottle with stopper

Burette

Pipettes, etc

REAGENTS:

Manganous sulphate solution

(MnSO4.4H2O)

Conc. sulphuric acid (36 N)

Alkali-iodide Azide reagent Starch indicator

Standard sodium thiosulphate solution (0.025N)

Standard potassium dichromate solution (0.025N)

THEORY:

Dissolved Oxygen (D.O.) levels in natural and wastewaters are dependent on the

physical, chemical and biochemical activities prevailing in the water body. The

analysis of D.O. is a key test in water pollution control activities and waste treatment

process control.

Improved by various techniques and equipment and aided by instrumentation, the

Winkler (or iodometric) test remains the most precise and reliable titrimetric

procedure for D.O. analysis. The test is based on the addition of divalent manganese

solution, followed by strong alkali to the water sample in a glass-stoppered bottle.

D.O. present in the sample rapidly oxidizes in equivalent amount of the dispersed

divalent manganous hydroxide precipitate to hydroxides of higher valency states. In

the presence of iodide ions and upon acidification, the oxidized manganese reverts to

the divalent state, with the liberation of iodine equivalent to the original D.O. content

in the sample. The iodine is then titrated with a standard solution of thio-sulphate.


Page | 51

PROCEDURE:

1) Add 2 mL of manganous sulphate solution and 2 mL of alkali-iodide Azide reagent to the

300 mL sample taken in the bottle, well below the surface of the liquid.

(The pipette should be dipped inside the sample while adding the above two reagents.)

2) Stopper with care to exclude air bubbles and mix by inverting the bottle at least 15 times.

3) When the precipitate settles, leaving a clear supernatant above the manganese hydroxide floc, shake again.

4) After 2 minutes of settling, carefully remove the stopper, immediately add 3 mL

concentrated sulphuric acid by allowing the acid to run down the neck of the bottle.

5) Restopper and mix by gentle inversion until dissolution is complete.

6) Measure out 203 mL of the solution from the bottle to an Erlenmeyer flask. As 2 mL each

of manganese sulphate and Azide reagent have been added.

7) Titrate with 0.025 N sodium thiosulphate solutions to a pale straw color.

8) Add 1–2 mL starch solution and continue the titration to the first disappearance of

the blue color and note down the volume of sodium thiosulphate solution added (V),

which gives directly the D.O. in mg/L


After the yellow, blue, colorless color appears in Sequential way, record the needed volume of the sodium thiosulphate solution.

�� ( ��/� ) = �(�� ) ∗ � (�� ) ∗ ��

� (�� )

By using the previously relationship, fill the following table:

Sample #

Temperature ºC

V sample ml

V (sodium thiosulphate)

ml

N (sodium thiosulphate)

DO mg/l

1

2

3


Page | 52


What are alternative methods for determining the DO of aqueous samples? How do they compare to this method?

What are typical DO values of water in Jordan? How do your data compare with these values?

What are the main sources of DO in water and wastewater?

Discuss the environmental significance of dissolved oxygen.

Most of the critical conditions related to dissolve oxygen deficiency occur during summer months. Why?

The turbulence of water should be encouraged. Why?

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SANITARY LABORATORY MANUAL - Philadelphia University