EXPERIMENT NO.

1 TEMPERATURE TEST
OBJECTIVE
TO DETERMINE THE TEMPERATURE OF WATER SAMPLES
APPARATUS REQUIRED
The apparatus for the temperature test consists of following:
 Analog/Digital Thermometer
 Beaker
 Clean cloth
SAMPLES REQUIRED
The sample should be true representative of the actual water. In taking out samples, care should
be taken that no further contamination or purification can be placed after collection and before the
analysis is completed. Well cleaned bottle should be used and it is cleaned by the same water.
THEORY
Density, viscosity, vapor pressure and surface tension of water is related to the temperature of
water. Chemical, Biochemical and biological activity also depends upon temperature. So the
temperature of water is determined for design of different units in water supply system.
Temperature of surface water is equivalent to the atmospheric temperature whereas that of ground
water may be more or less than atmospheric temperature.
In general, for public water supply it should be between 4.4°C to 10°C, greater than 25°C is
undesirable and greater than 35°C is unfit for drinking purpose.
PROCEDURE
 Water sample was taken in a clean beaker.
 Digital thermometer was used for measurement. For that, the probe was cleaned with
distilled water, was wiped with clean cloth, and the instrument was turned on, unit was
selected and the thermometer was dipped into beaker containing sample and reading was
taken when the reading became stable.
OBSERVATIONS
Sample Measured Temperature (°C)
S.No. Remarks
No. Observation 1 Observation 2 Observation 3 Average
1 A 30 29.7 29.6 29.7
2 B 31.3 31.4 31.5 31.4

RESULT
Hence, the temperature for sample A was 29.7°C and the temperature for sample B was 31.4°C.
CONCLUSION & DISCUSSION
With the help of thermometer we can determine temperature for different water samples and the
temperature of water samples can help us identify whether the water is suitable for drinking or not
according to the guidelines. In our case, both samples were undesirable for drinking purpose as
the temperature was greater than 25°C.
EXPERIMENT NO. 4: SOLID TEST

OBJECTIVE:

TO DETERMINE THE TOTAL SOLID (TS), TOTAL SUSPENDED SOLID (TSS) AND
TOTAL DISSOLVED SOLID (TDS) FOR WATER SAMPLES.

APPARATUS REQUIRED:

The apparatus required for pH test consists of following:

 Beakers
 Funnel
 Stand
 Weighing Balance
 Burner set/Oven
 Porcelain Basin
 Whatman filter paper (No. 44)

SAMPLES REQUIRED:

The sample should be true representative. In taking out samples, care should be taken that no
contamination or purification can be placed after collection and before the analysis is
completed. Well cleaned bottle should be used and it is cleaned by the same water.

THEORY:

Solid testing in the context of water supply is essential to evaluate the physical properties and
structural integrity of solid materials used in water infrastructure, such as pipes, tanks, and
fittings. This testing involves assessing the durability, strength, and resistance of materials to
various stressors, including pressure, temperature fluctuations, and chemical exposure from the
water. Solid testing helps prevent failures that could lead to leaks, contamination, and service
interruptions, thus maintaining the integrity and efficiency of the water supply network.

Water can contain various solids, such as silt, clay, algae, and fungi, which remain suspended
within it. Additionally, as water flows over rocks and soil, it can dissolve minerals and salts,
earning its title as the universal solvent. The concentration of these solids is typically measured
in parts per million (PPM) or milligrams per liter (mg/l). To measure total suspended solids
(TSS), the residue left on a filter paper after the filtered water sample is evaporated is weighed.
High levels of TSS can result in poor taste, increased hardness, and alkalinity in water. Total
dissolved solids (TDS) are determined by weighing the residue after evaporating the filtered
water sample. In drinking water, TSS is generally lower than TDS. The total solids (TS) in
water are the sum of TSS and TDS and can also be measured by weighing the residue left after
the complete evaporation of the water sample.

In general, TDS should not be greater than 500 mg/, 500 - 1500 mg/l is tolerated and more than
1500 mg/l is not accepted for water for human consumption. As per 'National Water Quality
Guidelines 2062' of Nepal, TDS must be below 1000 mg/l for drinking water.
PROCEDURE:

1. Determination of Total Dissolved Solids (TDS):

Whatman filter paper no. 44 was used to filter 100 ml of water into a crucible. The water was
then evaporated to dryness in an oven set at 105°C.The weight of the dry residue left in the
crucible was measured, and the following formula was used.
wt.of dry residue left in crucible in mg
TDS = Volume of water sample taken in crucible in litre (mg⁄liter or ppm)

2. Determination of Total Suspended Solids (TSS):

The weight of the dry residue left on the filter paper from step 1 was measured. This residue
was then evaporated to dryness in an oven set at 105°C. The weight of the dry residue left in
the crucible was measured, and the following formula was used.

wt. of dry resideu left in filter paper in mg

TSS = (mg⁄liter or ppm)
Volume of water sample filtered in litre

3. Determination of Total Solids (TS):

A sample of 100 ml of water was placed in a crucible and evaporated to dryness in an oven at
105°C. The weight of the dry residue left in the crucible was measured.

wt. of dry residue left in crucible in mg

TS = (mg⁄liter or ppm)
Volume of water sample taken in crucible in liter

Alternatively, TS=TSS+TDS

OBSERVATIONS:

1. For TS

Vol. of sample taken (vs1) = 10 ml

Wt. of dry crucible (w1) = 53 mg

Wt. of dry crucible with oven dry residue (w2) = 54.5 mg

𝑤2 − 𝑤1
TS = ∗ 1000 = 150 (mg⁄liter or ppm)
𝑣𝑠1
2. For TSS

Vol. of sample taken (vs2) = 10 ml

Wt. of dry filter paper (w3) = 2.54 mg

Wt. of dry filter paper with oven dry residue (w4) = 3.46 mg

𝑤4 − 𝑤3
TSS = ∗ 1000 = 92 (mg⁄liter or ppm)
𝑣𝑠2

3. For TDS

Vol. of sample taken (vs2) = 10 ml

Wt. of dry crucible (w5) = 77.54 mg

Wt. of dry crucible with oven dry residue (w6) = 78.22 mg

𝑤6 − 𝑤5
TDS = ∗ 1000 = 68 (mg⁄liter or ppm)
𝑣𝑠2

Check: TSth = TSS+TDS = 160 mg/liter or ppm

% error = [TS – TSth]/TS * 100% = 6.67 %

RESULT:

The TDS was found to be 68 mg/L. The concentration of suspended solids was 92 mg/L, and
the Total Solid was found out to be 150 mg/L experimentally.

CONCLUSION:

The results obtained suggest that the TDS was lesser than the value provided by the guidelines,
also the suspended particles were high in comparison to dissolved solids which can later be
treated with sedimentation and other techniques.
EXPERIMENT NO. 5: OPTIMUM DOSE OF COGULANTS
OBJECTIVE:
TO DETERMINE THE OPTIMUM DOSE OF COAGULANT (ALUM) FOR A WATER
SAMPLE.

APPARATUS REQUIRED:
The apparatus for the optimum dose of coagulant (Alum) test consists of following:
 Jar Test Apparatus: An electrically operated jar test apparatus consists of SIX stirring
paddles noncorrosive metal which can be rotated at any desired speed by gear and
spindle system
 Six test beakers: Beakers of 1 to 2 liters capacity to keep water sample
 Electronic balance: For accurate weighing of coagulants.
 Measuring cylinder: To measure water sample.

SAMPLE AND CHEMICAL REQUIRED:

• Water sample: It should be free from oil grease, etc and taken after plain sedimentation
so that large amount of suspended materials are removed from plain sedimentation.
• Alum or aluminum sulphate [Al2(SO4)3.18H2O]

THEORY:
After physical, chemical and biological examination of water, the degree of treatment required
and hence treatment process required is known. Different impurities can be removed by
different process as shown in table below.

S.N. Impurities Process of Treatment

1 Large suspended and floating matters like leaves, fish, living Screening
organism, dead bodies tree branches bushes etc.
Suspended matters, few colloidal and dissolved impurities Plain Sedimentation
2
(silt, sand, clay, etc.)
3 Sedimentation with
Very fine suspended and colloidal impurities
Coagulation.
4 Microorganisms, very fine suspended and colloidal impurities. Filtration
5 Taste and odour, dissolved gases etc. Aeration
6 Pathogenic organisms by killing them Disinfection
7 Hardness Softening
8 Excessive chlorine De-chlorination
9 Iron, Manganese and other harmful constituents Miscellaneous

If water contents suspended impurities, it can be removed by plain sedimentation but very fine
suspended particle such as silt < 0.06 mm requires maximum detention time in the
sedimentation tank, which is impracticable. Also, water containing electrically charged
colloidal impurities in motion and never settle down due to gravitational forces.
Hence, to remove such very fine suspended particles not removed by plain sedimentation and
the electrically charged particles, a method is used which is called sedimentation with
coagulation. When certain chemicals such as alum (aluminum sulphate), chlorinated copperas.
ferrous sulphate & lime, Magnesium carbonate etc are added in to water it produces gelatinous
(sticky) precipitates called floc which absorbs the fine suspended and colloidal impurities then
sedimentation can be done. This process also removes colour, odour and test in water. The
chemical added are called coagulants.
It is generally done after plain sedimentation. In this process, the coagulants (chemicals like
etc) are added in water by feeding devices then thoroughly mixed with mixing devices and send
to flocculators (a slow stirring mechanism which helps to produce floc) to produce precipitate
or floc then send to the sedimentation basin so that the floc may settle down due to force of
gravity and it is then removed without disturbance. In fact, the sedimentation with coagulation
requires the following processes.

Coagulants feeding Mixing Flocculation Sedimentation

(In raw water) (In mixtures) (In flocculatiors) (Sedimentation tanks)

Coagulation: A chemical process that involves the formation of chemical flocs, which adsorb,
entrap & bring together the suspended matters.
Flocculation: The process of forming flocs. Sedimentation: The process to allow the particles
settles down.
Aluminum hydroxide or alum [Al2(SO4)3.18H2O] is insoluble precipitate. Alum is found to be
most effective between pH ranges of 6.5 to 8.5. Its dose depends upon various factors such as
turbidity, color, pH, temperature etc. The common test, which is performed to determine
optimum quantity of coagulant, is known as jar test and it is the trial and error method.

PROCEDURE:
• Six beakers were taken with 1 liter of water sample.
• Chemical coagulant (alum) was added in each beaker in increasing quantity (for 1 mg, 2
mg, 3 mg, 4 mg, 5 mg and 6 mg) for the first trial.
• The beakers were arranged in the apparatus containing stirrer in order.
• Then the chemicals were mixed at the speed of high speed (about 100 rpm) for 2 minutes
and reduced the speed 20 rpm for 10 to 15 minutes and stop the rotation.
• Allowed the floc to settle down for 10-30 minutes.
• The floc formed in each jar was visualized and the beaker with minimum turbidity was
chosen which gave the best floc the clear water. The clarity was measured with turbidity
test as in experiment no 6. The dose of coagulant on that beaker gave the optimum dose
of coagulant.
• If clear water was not seen or turbidity was beyond the acceptable range of turbidity,
another set of dose was tried.
OBSERVATION:
Source of water: Tap water
Optimum dose of coagulant alum: 0.6-0.8g
RESULT:
We found that the optimum dose of coagulant was found to be in between 0.6-0.8g.

CONCLUSION
From this experiment, for the given sample we got to observe that the optimum dose of
coagulants was in between 0.6 -0.8g i.e. the solution with 0.6g of alum was found to be more
clear than other solutions with more sediments. Since, this is a hit and trial method, to get the
exact value of alum needed trial between 0.6g and 0.8g can be conducted.
EXPERIMENT NO: 3 COLOR TEST
OBJECTIVE
TO DETERMINE THE COLOR OF WATER SAMPLES
APPARATUS REQUIRED
The apparatus for the turbidity test consists of following:
 Digital Photo Colorimeter:
A compact instrument which digitally displays the measurement of optical density (absorbance)
of any solution. It consists of filters of wavelength 400nm to 700nm and can be controlled by a
rotating disc. The front panel consists of a slot with cap to insert test tubes with standard solution
or sample; a digital display; ‘Set Zero’ and ‘KLET Zero’ switch with ‘Set Zero’, ‘KLET Coarse’
and ‘KLET Fine’ knobs. The main principle of instrument is that in the ON condition, the light
from tungsten lamp passes through solution to the photocell and displays the optical density value.
 Standard Test Tubes or cuvettes: To test samples and standard solution.
 Beakers
CHEMICALS AND SAMPLES REQUIRED
 Standard Platinum-Cobalt solution: This solution of known value of color in mg/l of
platinum cobalt scale can be prepared from proper procedure as stated in IS 8768:2000
using Cobalt Chloride Hexahydrate, Hydrochloric Acid of specific gravity 1.19, Platinum,
Aqua Resia. We can take ready- made standard solution of known color.
 Water samples to be tested: The sample should be true representative of the actual water.
In taking out samples, care should be taken that no further contamination or purification
can be placed after collection and before the analysis is completed. Well cleaned bottle
should be used and it is cleaned by the same water.
 Distilled Water to clean test tubes
THEORY
Colour in water is due to organic matters in colloidal condition and mineral and dissolved
impurities (iron, manganese etc), decayed vegetable matter, weeds, humus, plankton and industrial
wastes. It makes water in undesirable appearance which is disliked by the people and it may spoil
clothes and affect industrial process.
Tintometer, glass colored disk and digital photo colorimeter are the instruments used for color test.
Here we are using colorimetery technique to determine color from digital photo colorimeter. It is
measured in terms of mg/l of platinum cobalt scale.1 mg/l in platinum cobalt scale = colour
obtained from the solution of 1 mg of platinum cobaltin 1 liter of distilled water. For drinking
water colour should not be greater than 5 ppm in platinum cobalt scale. Greater than 5 is tolerable
but rejected if greater than 25 ppm. As per 'National Water Quality Guidelines 2062' of Nepal, it
should be below 5 mg/l and rejected if more than 15 mg/l in platinum-cobalt scale.
Color is removed by sedimentation, filtration, aeration and use of chemicals.
PROCEDURE
 The instrument was switched on and was kept on for 5 minutes.
 Appropriate filter was selected. Here, we used 480nm filter (ie filter ‘A’) for color test in
water.
 Distilled water was filled on the clean test tube up to mark and was placed on the test tube
holder of the instrument and the ‘set zero’ knob was rotated to adjust display to zero
optical density then test tube was removed. ‘Coarse’ and ‘Fine’ KLET knobs were used to
make perfect zero.
 The standard Platinum-Cobalt solution of known value of color (Co) was filled in the clean
test tube up to mark and was placed it in the test tube holder and the reading on display
for optical density of standard solution (lo) was noted, then the test tube was removed.
 Water sample was filled in the clean test tube up to mark and was placed it on the test tube
holder and the reading on display for optical density of water sample (Is) was noted.
EXPERIMENT NO 7: DISSOLVED OXYGEN (DO) TEST

OBJECTIVE

TO DETERMINE THE DISSOLVED OXYGEN (DO) CONTENT IN THE WATER

SAMPLES

APPARATUS REQUIRED

The apparatus for the DO test consists of following:

 Digital DO Meter: Here, we are using Lutron Dissolved Oxygen Meter of Model DO-
5519 CL- 936. It consists of input socket for DO electrode and four button to operate
the DO meter. The front panel consists of a digital display.
 DO electrode: It consists of gold and silver electrode and an electrolyte tube with a ring
with DO membrane within which electrolyte can be kept. The electrode has a provision
to fit in the DO socket at DO meter.
 DO membrane with ring
 Readymade Electrolyte OXEL-03
 BOD bottles: To collect water samples and test DO
 Beakers and measuring cylinders etc.

SAMPLES AND CHEMICALS REQUIRED

 Water samples to be tested: Collect the sample in narrow BOD bottle. Special
precautions are required to avoid entrainment of atmospheric oxygen into the sample.
While sampling from tap, a rubber tube attached to the tap is extended to the bottom of
the bottle. Allow water to overflow two-three times its volume and then place the
stopper over the bottle so that no air bubbles are entrained. In sampling from surface
source of water, sink the BOD bottle inverted into the source of water and collect the
water sample at least 20cm below the surface.
 Distilled Water to clean electrode

THEORY

Dissolved oxygen is the content of oxygen in water. Surface water gets the dissolved oxygen
either from (i) Diffusion of oxygen from air, which is a physical phenomenon depends upon
solubility of oxygen and (ii) Photosynthesis activity in water, which is the biological
phenomena happened due to the activities of algae, tiny aquatic plants etc.

The solubility of oxygen depends upon temperature, water movement, presence of oxygen
demanding organic matters. The organic wastes cause rapid depletion of DO from water. At
higher temperature water can hold smaller amount of DO.
Saturation DO values of distilled water

Oxygen Oxygen Oxygen Oxygen Oxygen Oxygen

°C °C °C °C °C °C
Solubility Solubility Solubility Solubility Solubility Solubility

0 14.3 9 11.3 18 9.4 27 7.9 36 6.9 45 6

1 13.9 10 11.1 19 9.2 28 7.8 37 6.8 46 5.9

2 13.6 11 10.8 20 9 29 7.6 38 6.7 47 5.8

3 13.2 12 10.6 21 8.8 30 7.5 39 6.6 48 5.7

4 12.9 13 10.4 22 8.7 31 7.4 40 6.5 49 5.6

5 12.5 14 10.1 23 8.4 32 7.3 41 6.4 50 5.5

6 12.2 15 10 24 8.3 33 7.2 42 6.3

7 11.9 16 9.8 25 8.2 34 7.1 43 6.2

8 11.6 17 9.6 26 8.1 35 7 44 6.1

The presence of oxygen in water is necessary to keep it fresh and sparkling. The quantity of
6ppm of dissolved oxygen is essential in water to be used for drinking purpose and 4ppm for
fish and aquatic life. Excess of dissolved oxygen create corrosion of pipe material due to the
oxidation.

PROCEDURE

1. Preparation of electrolyte:

 One drop of readymade Electrolyte OXEL-03 was prepared in ring with DO membrane
and was fitted it into electrode.

2. Making instrument ready:

 The electrode was connected at the socket of the DO meter. The electrode was cleaned
with distilled water and was wiped it with clean cloth.

3. Calibration of instrument:

 The instrument was powered by pushing power On/Off" button under wide and
ventilating environment. It displayed ‘O2%’ and ‘Temp.’ value. Further operations was
carried when Stable value of ‘O2%’ was displayed.
 The ‘Hold’ button was pressed and was assured to display ‘Hold’ indicator. Press
‘Record’ button was pressed to display ‘CAL’ indicator and countdowns was allowed
from 30 to 0.
  When ‘CAL’ indicator was turned to ‘End’ and upper display showed value 20.9 or
20.8 for ‘O2%’,the calibration process is finished and instrument is ready for use.
 'FUNC' button was pressed continuously for 2 seconds then it displayed ‘O2%’ in mg/l.

4. Testing the Sample:

 Electrode of the DO meter was inserted in that stirred distilled water sample to a depth
of at least 10 cm.
 The value of DO was taken when the reading on the display was stable.

OBSERVATION TABLE

Sample Measured DO value (ppm)

S. N Remarks
No.
Observation 1 Observation 2 Observation 3 Average

1 A 4.7 5.9 4.2 4.9

2 B 4.2 5.1 3.9 4.4

RESULT & CONCLUSION

Sample A: Dissolved Oxygen (DO) = 4.9 ppm

Sample B: Dissolved Oxygen (DO) = 4.4 ppm

Both the samples of water doesnot have enough presence of dissolved oxygen for it to be
drinkable, however, the water may be good for aquatic life.
EXPERIMENT NO: 2 pH TEST
OBJECTIVE
TO DETERMINE THE pH OF WATER SAMPLES
APPARATUS REQUIRED
The apparatus for the pH test consists of following:
 Digital pH Meter: We were using Digital Turbidity Meter of HANNA Model HI-8010
consisting of off, temperature (°C) and pH selector switch, a digital display and a
calibration screws at the front panel as shown in figure. It consists of a pH electrode
connected at the back side.
 Beakers: To take water sample for test.
 Buffer Bottles and pipette etc. for preparation of standard buffer solution.
CHEMICALS AND SAMPLES REQUIRED
 Buffer tablet or powder of pH 7 and 4 or 10 for calibration
 Distilled water to prepare standard buffer solutions
 Water samples to be tested:
The sample should be true representative of the actual water. In taking out samples, care
should be taken that no further contamination or purification can be placed after collection
and before the analysis is completed. Well cleaned bottle should be used and it is cleaned
by the same water.

THEORY
In water, pH is the chemical characteristic and this test comes in the chemical examination of
water. The water found in nature may be acidic or basic depending on the nature of dissolved salts
and minerals. The acidity and alkalinity is measured in terms of pH value because pH value
indicates the hydrogen ion concentration in water.
Water (H2O) is the combination of positively charge of Hydrogen ions (H) or cations and
negatively charged Hydroxyl ions (OH) or anions. In pure water the concentration of H* ions and
OH ions are equal. When some substances is dissolved in pure water, the solution formed ionized
(i.e. splits up into H and OH ions) and the balance between the concentration of the same are
disturbed. If concentration of H+ ion is greater than the water is acidic and alkaline if that of OH
ion is greater. For example, if HCI is added, the water becomes acidic and if NaOH is added it
becomes alkaline.
Acidic if: Alkaline if:
H2O ↔ H+ + OH- H2O ↔ H+ + OH-
HCL ↔ H+ + Cl- NaOH ↔ Na+ + OH-
Applying the Law of Mass Action in Physical Chemistry, in a pure water solution, the the hydrogen
ion concentration is found to be 10-7 moles/liter. [moles = molecular wt in gram].
Also, the pH is defined as the logarithm of the reciprocal of hydrogen ion concentration.
Mathematically,
1
pH= log10 H = log10 [H+]-1 = - log10 [H+] = log10 [10-7] = 7

Acidity in water is caused by the presence of mineral acids, free carbon dioxide; sulphates of iron,
aluminum etc, whereas alkalinity is caused by the presence of bicarbonates of calcium and
magnesium or carbonates of hydroxide of sodium, potassium, calcium and magnesium. As per
WHO standard, a pH value of 6.5 to 8.5 should be acceptable and rejected if pH is <6.5 to >9.2 for
public water supply. Hence pH value should be as closer to 7. The lower value of pH (acidic)
causes corrosion and higher value (alkalinity) may produce sediment deposits, difficulty in
chlorination etc. As per 'National Water Quality Guidelines 2062' of Nepal, pH value should be
6.5 to 8.5 for drinking water.
The pH value of water can be measured by colorimetric method or by Electrometric method using
pH meter. Here we are using pH meter and it measures pH directly or in terms of mV (milivolts).
We are concerned here with measurement of pH directly after calibration of instrument.
The principle of pH meter is that if two solutions are separated with pH sensitive glass (i.e the bulb
of glass pH electrode, an electrical potential will be developed across the membrane. If the solution
inside the bulb contains hydrogen ion concentration, the membrane potential will change as the
hydrogen ion concentration of the other solution varies. If electrical connections are made to these
solutions inside the glass bulb by the electrode's 'internal element' and outside the glass by a
'reference electrode', the membrane potential can be measured and displayed in the display as pH
directly.
PROCEDURE
1. Preparation of Buffer Solutions:
 100 ml of distilled water was pipetted out into different clean buffer bottles.
 One packet of buffer powder or tablet of 7 and 4 or 10 pH was poured in different buffer
bottles respectively to prepare buffer solution of pH 7, 4 or 10.
2. Calibration of the instrument:
(a) Adjustment with buffer of pH 7:
 Connected pH electrode of instrument was cleaned with distilled water, and was wiped
with clean cloth and was dipped into buffer solution of pH 7.
 Temperature of buffer was measured by thermometer
 The instrument was switched on to °C mode and °C screw was adjusted to view the
measured temperature on the display.
 Instrument was changed to pH mode and was adjusted it to display 7 by rotating pH 7
screw with a screw driver.
(b) Adjustment with buffer of pH 4/10:
 The connected pH electrode of instrument was removed, cleaned with distilled water,
wiped with clean cloth and was dipped into buffer solution of pH 4 or 10.
 Temperature of buffer was measured by thermometer
 The instrument was switched on to °C mode and °C screw was adjusted to view the
measured temperature on the display.
 Instrument was changed to pH mode and was adjusted it to display 7 by rotating pH 7
screw with a screw driver.
 The instrument is calibrated and ready for about 100 test readings.
3. Measurement for pH:
 pH electrode was cleaned with distilled water, wiped it with clean cloth.
 The instrument was switched on to pH mode and was dipped into water sample taken in a
beaker.
 pH value was noted for both samples.
OBSERVATIONS
Sample Measured pH
S.No. Remarks
No. Observation 1 Observation 2 Observation 3 Average
1 A 6.30 6.24 6.25 6.26
2 B 6.43 6.37 6.34 6.38
RESULT
Hence, the pH for sample A and sample B was found to be 6.26 and 6.38 respectively.
CONCLUSION
So, with the help of pH meter we can find out the pH of any given samples, while doing so the pH
meter should be calibrated properly. These data help us determine whether the drinking water is
suitable for drinking purpose or not, by comparing these data with the “National Water Quality
Guidelines 2062”of Nepal.
EXPERIMENT NO 6: TURBIDITY TEST

OBJECTIVE

TO DETERMINE THE TURBIDITY OF WATER SAMPLES.

APPARATUS REQUIRED

The apparatus for the turbidity test consists of following:

• Digital Turbidity Meter: We are using HANNA Digital Turbidity Meter of Model HI
98713. It consists of an infrared LED light source, digital LCD display, photodiode
detectors and a power supply cable. It has further a holder to keep the cuvette containing
standard solution and sample to be tested with a cover to prevent external light to enter
while sample is under test. It has a key pad for setup, edit and data input during
calibration and operation. It can measure a range of 0 to 1000 FTU (Formazin Turbidity
Unit).
• Standard cuvettes with standard solution: Four cuvette with different standard solution
of known turbidity for calibration.
• Standard blank cuvettes: Five sample cuvette for testing sample Electronic balance:
For accurate weighing of chemicals.
• Volumetric flasks: To prepare standard solution of known turbidity. Membrane filter
having holes of 0.2 mm: To filter the distilled water Measuring jars, beakers etc.

CHEMICALS AND SAMPLES REQUIRED

• Hydragine Sulphate [(NH2)2 H2So4]

• Hexamamethylenetetramine [(CH2)6 N4]
• Distilled Water
• Water samples be tested:

The sample should be true representative of the actual water. In taking out samples, care should
be taken that no further contamination or purification can be placed after collection and before
the analysis is completed. Well cleaned bottle should be used and it is cleaned by the same
water.

THEORY

Water is not important for drinking and cooking only but also used for human consumable
manufacturing processes as breweries, food processing etc. Quality of water is the degree of
goodness of characteristics (physical, chemical & biological) of water in all aspects.

Condensation of water vapor make rainfall but this water initially is pure containing two parts
of hydrogen and one part of oxygen only by volume. On the way of falling, it absorbs different
gases, dust & other impurities. Also, during surface runoff, this water carries large number of
impurities such as silt, organic, non-organic, minerals impurities, suspended matters etc. while
moving on earth surface. These substances not always be harmful but may be useful to human
life. Again, ground water contains both harmful & useful gases and minerals. Before using
water for drinking, water treatment is needed. Total purification is difficult & costly and pure
water only is not good for our health hence treatment to some extent is done. To ensure whether
the water from any selected source drinkable (wholesome) or not and to ensure the treatment
needs water should be tested.

All undesirable substance containing in water in any form is called impurities in water. Water
from any source may have following three types of impurities.

a. Suspended impurities:

Suspended impurities in water are tiny solid particles that do not dissolve and are dispersed
throughout the water. These particles can include silt, clay, organic matter, microorganisms,
and industrial waste. They cause turbidity, making the water cloudy, and can affect water
quality and health. Removing these impurities often involves filtration or sedimentation
processes.

b. Colloidal impurities:

Colloidal impurities in water are tiny particles that are dispersed throughout the water but do
not settle out due to their small size, typically between 1 nanometer and 1 micrometer. These
particles can include organic substances, such as proteins and microorganisms, as well as
inorganic materials like clay or metal oxides. They can cause water to appear turbid and may
contribute to taste, odor, and health issues. Removing colloidal impurities often requires
specialized treatment processes like coagulation, flocculation, and filtration.

c. Dissolved impurities:

Some solid, liquid and gas dissolves in the water when it moves over the rocks and soil etc.
because water is the good solvent. E.g. non-visible organic compounds, inorganic salts & gases
etc. It makes bad taste, hardness and alkalinity. Its concentration is measured in PPM (parts per
million) or mg/l and obtained by weighing the residue after evaporation of the water sample
from a filtered sample.

Due to the above stated impurities in water, water should be analyzed to classify, prescribe
treatment, control treatment and purification processes and maintains public supplies of a
standard of organic quality, clarity and palatability. Examination of water may be divided into
three as:

a. Physical Examination,

b. Chemical Examination,

c. Microbiological Examination.
Turbidity is the physical characteristic of water and this test comes in the physical examination
of water. It is caused by the suspended as well as colloidal impurities. Turbidity is the degree
of clarity of water and is the measure of the resistance to the passage of the light through it.
Turbidity is measured in terms of silica scale. One milligram of silica in one litre of distilled
water gives one PPM (parts per million) or one mg/l turbidity in silica scale. It can be measured
in terms of JTU (Jackson Turbidity Unit) or NTU (Nephelometer Turbidity Unit) or FTU
(Formazin Turbidity Unit).

The permissible turbidity for domestic water for ideal and safe supply may be between 5 to 10
NTU and as per WHO standard, 2.5 NTU is accepted and rejected if value is greater than 25
NTU. As per 'National Water Quality Guidelines 2062' of Nepal, turbidity below 5 NTU is
accepted and rejected if value is greater than 10 NTU.

It can be tested using Turbidity Rod, Jackson Turbidimeter, Baylis Turbidimeter, Nephelometer
and Digital Turbidity Meter. Among them the recent technology is Digital Turbidity Meter.

Turbidity in the lab is determined on the principle that a light passing through a substance is
scattered by the particles in the water. In the Digital Turbidity Meter, a beam of light is sent to
the sample and the suspended matter scatter the light and this scattered light is received on the
photoelectric cell and amplified to the electronic pulse and can be seen in the digital display.

PROCEDURE

1. Preparation of Reagent:

a. Preparation of Turbidity free distilled water:

Turbidity free water is difficult to obtain but the following method was used to make turbidity
free water

• Distilled water was passed through a membrane filter having holes of 0.2 mm.
• The collecting flask was rinsed at least twice with filtered distilled water and the next
200 ml filtered distilled water was discarded. (Some commercial bottled demineralized
waters were nearly particle free.)

b. Preparation of Standard Turbidity suspension:

• Prepare Solution - I:1 g Hydragine Sulphate [(NH2)2 H2So4] was dissolved in 100 ml
of filtered distilled water in a volumetric flask.
• Prepare Solution - II: 10 g Hexamamethylenetetramine [(CH2)6 N4] was dissolve in 100
ml of filtered distilled water in a volumetric flask.
• 5 ml of Solution - I and 5 ml of Solution – II was mixed in the flask and let them stand
for 48 hrs at 25 +3°C. This suspension had turbidity of 400 NTU or 4000 FTU. Standard
Solution of 200 NTU or 2000 FTU values can be made by mixing equal amount of
distilled water to 4000 FTU solution and 1000 FTU by mixing equal amount of distilled
water to 2000 FTU solution and so on.
In our instrument of this model, the supplier provided standard solutions of turbidity <0.1 FTU,
15 FTU, 100 FTU and 750 FTU which was sufficient to calibrate the instrument. If other than
these standard solutions are to be used, we can edit these values within the instrument during
calibration.

2. Calibration of Instrument:

Calibration can be performed either in two point calibration or three point calibration or four
point calibration. It is possible to interrupt calibration procedure at any time by pressing CAL
or ON/OFF. The following steps were followed for four point calibration.

• Turned on instrument by pressing ON/OFF.

• Entered CAL which requested for "CAL P.1".
• The <0.1 FTU standard cuvette was placed into the holder and the lid was closed then
pressed READ. This requested for "CAL P.2" for 15.0 FTU standard cuvette.
• Removed first cuvette and placed the 15.0 FTU standard cuvette into the holder and
closed the lid then pressed READ. This request for "CAL P.3" for 100.0 FTU standard
cuvette.
• Removed second cuvette and placed the 100.0 FTU standard cuvette into the holder and
closed the lid then pressed READ. This requestd for "CAL P.4" for 750.0 FTU standard
cuvette.
• Removed third cuvette and placed the 750.0 FTU standard cuvette into the holder and
closed the lid then pressed READ. The four-point calibration was then completed and
the instrument automatically returned to measurement mode and was ready for testing
the sample.

(If only two point calibration is to be carried out, press CAL after step 4 and go for testing the
sample. If only three point calibration is to be carried out, press CAL after step '5' and go for
testing the sample)

3. Testing the Sample:

After calibrating instrument either by two or three or four point calibration, the following steps
were followed to measure turbidity of the water sample.

• Water samples was taken in the clean standard cuvettes.

• Placed it into the holder and closed the lid then pressed READ.
• Reading was taken on the display for turbidity of that sample.
• Similarly, readings for other samples were taken.
OBSERVATION TABLE

S. N Sample Measured Turbidity Value(FTU) Remarks

No.
Observation 1 Observation 2 Observation 3 Average

1 A 1.71 1.68 1.90 1.76

2 B 222 218 217 219

RESULT & CONCLUSION

• Turbidity of Sample A = 1.76 FTU

• Turbidity of Sample B = 219 FTU

The result suggest that the water sample B is more turbid compared to the water sample A. This
indicates that the water sample B contains a much higher concentration of suspended particles,
making it less clear and only suitable for drinking purpose with proper treatment.