Civil Engineering PhD

1. 58
CHAPTER - 3
EXPERIMENTAL INVESTIGATION
3.1 Introduction
In order to build and validate Time series analysis models using
various physico-chemical parameters to forecast the water quality of
Vellar estuary for the pre monsoon period, extensive experimental
investigations were carried out during July 1996 to September 2000.
The primary objective of the study was to assess water quality
characteristics at almost no flow from the river to the estuary under
conditions of limited land use. Also in the hot season, with no river
flow the estuary becomes homogeneous though temperature may
become important in producing density differences by surface heating.
Five stations from the river mouth (down stream) to the upstream
covering a stretch of 5 km were identified and water sampled. The
analysis was carried out for different parameters.
3.2 Vellar Estuary
Dyer and Ramamoorthy (1969) described the Vellar estuary in
detail and stated the location as 11029'N Latitude and 79046'E
Longitude. The river Vellar originates in Servarayan Hills of Salem
District of Tamil Nadu. After passing about 480 km through areas of
red sand leached and laterised black soil and loamy red soil, it opens
into the Bay of Bengal at Parangipettai. The Vellar estuary is
connected by backwater with the nearby Coleroon estuary to form
Vellar- Coleroon estuarine complex. About 51 inlets of mangrove
vegetation on the Coloroon side dominate the Southern part of the
complex. Floodwaters of monsoon is the main freshwater source. The
Vellar river widens its mouth and at other times, the freshwater flow is
limited resulting in a formation of sand bar, which narrows down the
river mouth.

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In general, the mean tidal level in the estuary is 75 cm and
maximum level is about 105 cm. The width of the estuary is 80 m
close to the mouth and the maximum is about 565 m at a place called
Lading Centre. The average depth is 2.5 m with a maximum depth
being 4 m. The estuary shows semidiurnal tides and the tidal effect is
felt up to 12 km upstream from the river mouth. The estuary also
receives discharges from a number of irrigational channels such as
Log channel, Dog channel, Buckingham channel and railway bridge
channel.
Both sides of the river Vellar are bordered with vast stretches of
agricultural lands. These are mainly wetland areas of about 4000
hectares. There are three channels on the southern bank of the
estuary and drainage from the adjoining agricultural lands, where
application of improved techniques in agricultural management is
followed to achieve higher production. The mine drains of the Neyveli
Lignite Corporation Ltd. (50 km west of Parangipettai) are also
indirectly drained into the river course, during the monsoon period
due to surface land runoff. Parangipettai is mainly influenced by
North East monsoon. Brief information on Vellar river basin is given in
Table 3.1.
Table 3.1. Brief information on Vellar river basin
Total Catchment
Area (km2
)
Population Water use Land use
AmbientTemperature
(degrees Centigrade)
Industries
(1) (2) (3) (4) (5) (6)
7472 18,00,000
Irrigation,Water
supply,Fish
cultivation,
Industrial
processing.
Paddy
Cultivation
Animal
husbandry
Industry
Average:
high 41.1
low 21.0
Cement
Ceramic
Fertilizer
Sago
Sugar
A map showing the Vellar estuary and the location of five
sampling stations is given in Fig 3.1.

3. 60

4. 61
3.3 Sampling stations Details.
For carrying out the experimental investigation, five sampling
locations were selected from the river mouth to the upstream at
convenient locations. The details of these sampling stations were
presented in Table 3.2
Table 3.2. Location and Details of Sampling Stations
Sampling
Station No.
Name Location
1 Auction Centre
It is 0.5 km from the mouth of the
river.
2
Marine Biology
Centre
It is 3 km from the mouth of the river.
3 Thonithurai
It is 4 km from the mouth of the river.
Residential area is on the left bank of
the River. There is always movement
of people from L.B to R.B through
boats.
4
Buckingham
Canal
It is 5 km from the mouth of the river.
Drainage water of the Parangipetti
town drain at this point.
5 Railway Bridge
It is across the Vellar estuary. It is
the narrower portion in the estuary,
This is at 6 km from the river mouth
on the Villupuram – Mayiladuthurai
Railway line.
3.4 Sample Collection details
In this study, water samples from Vellar estuary at the chosen
sampling stations were collected for five years from 1996 to 2000.
Every year, samples were collected during July to September, the
premonsoon period, on weekly basis (total of 60 weeks). The collecting
time was during low tide period. A total of 300 samples were collected,
adopting the standard sampling procedure.

5. 62
3.5 Analysis of water samples
The 300 samples collected were analysed as per ‘Standard
Methods for examination of water and wastewater – APHA’ for the
parameters, Alkalinity, Calcium, Chloride, Electrical Conductivity,
Fluoride, Hardness, Iron as Fe, Nitrate, pH value, Sulphate, Total
Dissolved Solids and Turbidity. The analysis procedure of each
parameter is given elaborately in the following sections.
3.5.1 ALKALINITY
A.Procedure
i) 50 mL of sample was taken in an Erlenmeyer flask. If the pH
is 8.3 or above, 2drops of meta cresol purple indicator was
added. It was titrated with N/50 H2SO4. At the end point the
colour changes from pink to yellow. Titrate volume V2 was
noted. V1 is the initial reading of the burette.
ii) Titration was continued after adding 2 drops of Brom Cresol
green indicator. At the end point (Blue to Yellow), titrate
volume V3 is noted.
iii) If the pH was less than 8.3 immediately after addition of
meta cresol purple, end point was reached. Therefore V1 was
equal to V2. Immediately afterwards Brom Cresol green
indicator was added and titration was continued.
B.Calculation
(V2-V1) x 1000
Alkalinity, at 8.3 as CaCO3 mg/L = -----------------------
mL sample
(V3-V1) x 1000
Alkalinity, at 4.5 (Total) as CaCO3 mg/L = -----------------------
mL sample

6. 63
C.Reagents
S.No. Reagents Preparation
1. 0.02 N H2SO4 Diluted 10 mL 1 N H2SO4 TO 500 mL
d.H2O
2. 1 N H2SO4 100 mL d.H2O in a 250 mL std flask
was taken and added slowly 7 mL
con. H2SO4 make upto 250 mL.
3. Metacresol
purple
indicator.
Dissolved 100 mg metacresol purple
in 100 mL d.H2O
4. Brom cresol
green
indicator
Dissolved 100 mg. Brom Cresol green
+ 20 mg methyl red in 100 mL
isopropylalcohol
Note : PD – Polythene dropping bottle.
3.5.2 CALCIUM
A.Procedure
50 mL or a portion of sample was taken and diluted to 50 mL.
1 mL 1 N HCl was then added. It was heated and boiled for 1 minute
and cooled. 2-3 mL 1 N Na OH mix was then added. Also 0.21 g
Eriochrome Blue Black – R Indicator was added. It was titrated
against standard EDTA. The end point was noted when the colour
changed from red to blue.
B. Calcium
mL EDTA x 1000 x 0.4 x C.F
Ca mg/L = ----------------------------------------
mL sample
Where C.F = correction factor.

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C. Reagents
S.No Reagent Preparation
1. Na OH 1 N 10 g Na OH was dissolved in 250 mL of
H2O.
2. Std EDTA 0.01 M 3.723 g EDTA was dissolved in d.H2O
and make up to 1000 mL.
3. HCL 1 N 22 mL conc. HCl was diluted to 250 mL
with dH2O.
4. Erichrome Blue
Black – R Indicator
(calcon)
Grinded 200 mg powder dye + 100 g
NaCl
3.5.3 CHLORIDE
A. Procedure
S.No Nature of
sample
Sample treatment Titration and end
Point
1. Colourless and
clear
100 mL was taken or a
suitable portion
diluted to 100 mL.
1 mL of K2Cr O4
indicator was added
and titrated with
standard Ag NO3, and
end point was noticed
as pinkish yellow.
2. Coloured and
turned.
100 mL was taken or a
suitable portion
diluted to 100 mL. 3
mL Al (OH)3
suspension was added
and then filtered.
1 mL of K2Cr O4
indicator was added
and titrated with
standard Ag NO3, and
end point was noticed
as pinkish yellow.
3. n presence of
sulphide,
sulphite or
thiosulphate.
100 mL or a portion
diluted to 100 ml. 1
mL H2O2 (30%) was
added and stirred for 1
minute.
1 mL of K2Cr O4
indicator was added
and titrated with
standard Ag NO3, and
end point was noticed
as pinkish yellow.

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B.Calculation
(A-B) x 1000
Chloride mg/L = ------------------- x C.F
2 x V
Where A = mL. Litre volume for the sample.
B = mL. Litre volume for the blank.
V = Volume of the sample
C.F = Correction Factor
C. Reagent
S.No Reagent Preparation
1. Standard Silver Nitrate
(1 mL = 0.5 mgcl)
2.395 g Ag NO3 was dissolved in
d.H2O and make upto 1000 mL.
2. Aluminium Hydroxide
Suspension.
Dissolved 12.5 g Al K (SO4)2, 12 H2O
in 100 mL,d.H2O heated to 600C
concentrated NH4OH, 5.8 mL was
added slowly and stirred. After one
hour precipitate was washed by
through mixing and decanting with
d. H2O. The suspension was then
stored.
3. Potassium Chromate 12.5 g K2 CrO4 was dissolved in a
little d.H2O. Ag NO3 solution was
thenadded until a definite red
precipitate was formed. It was kept
for 12 hours and then filtered and
diluted to 250 mL with d.H2O.
4. Hydrogen Peroxide
H2O2.
30%
5. Std. Sodium chloride
(1 mL=0.5 mgCl)
824 mg NaCl (dried at 1400C) was
dissolved in d.H2O and make upto
1000 mL.

9. 66
Standardisation
10 mL std. NaCl was taken in a cesserol. 90 mL . d H2O was
added. 1mL K2 CrO4 was also added then titrated with std. Ag NO3.
End point was noticed as pinkish yellow colour (A) Similarly a reagent
blank titration (B) was conducted.
Correction factor = 10/A-B.
3.5.4 ELECTRICAL CONDUCTIVITY
A. Procedure
i) Standardision of meter : Distilled H2O was taken in two 50
mL beakers (marked as D1 and D2). Standard KCl (1413) is
taken in two 50 mL beakers (marked as 1413 A and 1413 B).
Conductivity cell was dipped in D1, D2, 1413A and 1413B in
that order. When the cell was dipped in 1413B the meter was
adjusted to read 1413 E.C.
ii) Conductivity measurements for sample : Each sample is
taken in two 50 mL beakers (the beakers are marked as nA
and nB where ‘n’ is the sample number). First the
conductivity cell was dipped in nA and then in nB. When the
cell was dipped in nB conductivity value of the sample was
observed.
iii) Measuring conductivity of other standards : When any of the
sample conductivity was higher than 2000 E.C, other
standards each in 50 mL beakers was taken (marked as SA
and SB where S is the value of standard). Conductivity cell is
first dipped in SA and then in SB. When it is dipped in SB
conductivity value was observed for that standard. (Each time
before measuring the conductivity of the sample/ standard
the conductivity cell was dipped in D1 and D2 in that order).

10. 67
B.Calculation
Observed Conductivity Theoretical Conduct.
Sample Value for sample X Value for standard KCl
Conductivity= --------------------------------------------------------------------
mic. S/cm Observed Conductivity value for same standard. KCI.
C. Reagent
S.No
Conductivity
Value for std
KCl. MicS/cm
Conc in
M
Weight of the KCl dissolved
and diluted to1 litre mg
1. 14.9 0.0001 7.456
2. 73.9 0.0005 37.28
3. 146.9 0.001 74.56
4. 717.5 0.005 372.8
5. 1412 0.01 745.6
6. 2765 0.02 1491.2
7. 6667 0.05 3728.0
8. 12890 0.1 7456.0
9. 24800 0.2 14912.0
10. 58670 0.5 37280.0
11. 111900 1.0
3.5.5 FLUORIDE
(ION SELECTIVE ELECTRODE METHOD)
A.Procedure
10 mL was taken and calibrated the meter with 1 mg/L and 10
mg/L standards (for calibration 10 mL std and 10 mL buffer) of
sample and 10 ml buffer in a small beaker. Electrode was immersed
and potential developed was measured while stirring.
B. Calculation
Fluoride mg/L = Measured reading x Dilution factor

11. 68
C. Reagents
S.No Reagent Preparation
1. Fluoride buffer To 500 mL d.H2O in a 1 lit. beaker 57 mL
of glacial acetic acid was added. 58 g
NaCl, and 4 g.EDTA were also added. It
was placed in a cool water bath and
slowly 6 N NaOH was added (about 125
mL) with stirring until pH was between
5.3 and 5.5. It was then transferred to a 1
litre flask and diluted to 1 litre.
2. Stock Fluoride
1000 mg/L
(1 mL= 1 mg F)
221 mg anhydrous NaF was dissolved in a
d.H2O and make upto 100 mL.
3. Std. Fluoride I
10 mg/L
(1mL=0.01 mg F)
Diluted 10 mL stock to 1000 mL
4. Std. Fluoride II
1 mg/L
(1mL=0.01 mgF).
Diluted 100 mL standard Fluoride 1 to
1000 mL
5. NaOH 6N Dissolved 60 g. NaOH in 250 mL d.H2O.
3.5.6 HARDNESS
A.Procedure
25 mL of sample or lesser volume of sample was taken and
diluted to 50 mL. 1 mL of buffer 1 mL of Na2S inhibitor and 1 mL
calmagite indicator were added. It is then titrated against standard
EDTA. The end point was noted when the change of colour from
pinkish red to blue.
B. Calculation
` mL EDTA x 1000
Total hardness as CaCO3 mg/L = - ------------------------- x C.F
mL sample
Where C.F = Correction Factor

12. 69
C. Reagent
S.No Buffer Reagent preparation
1. Buffer 11 mL conc.HCl with 80 mL d.H2O was
mixed slowly with stirring 60 mL 2- amino
ethanol was added. Then 1 g Mg salt of
EDTA was added and diluted to 200 mL.
2. Inhibitor Dissolved 5 g Na2 S9H2O or 3.7 g Na2 S.
5H2O in 100 mL d.H2O
3. Calmagite
indicator
Dissolved 0.25 calmagite indicated in 250
mL.d.H2O.
4. Std.EDTA.
0.01 M
Dissolved 3.723 g sodium salt of EDTA in
d.H2O and make upto 1000 mL.
5. Std. Calcium
(1 mL = 1 mg
CaCO3)
250 mg anhydrous CaCO3 was taken in a
beaker. Then 1+1 HCl added to dissolve
CaCO3
50 mL of d.H2O was added and boiled for
few minutes. After cooling 2 drops of methyl
red indicator was added. Using 3N NH4 OH
or 1+1 HCl adjusted to an intermediate
orange colour and make upto 250 mL.
6. Methyl Red
indicator
0.1 g methyl red is dissolved in 100 mL
isopropyl alcohol.
Correction factor : To 10 mL of calcium standard 1 mL buffer
1 mL inhibitor and 1 mL indicator were added. This was titrated
against standard EDTA. End point was pinkish red to blue colour.
Titrate value was then noted.
10
Correction Factor = -----------------------------------
mL Titrate volume of EDTA.
3.5.7. IRON as Fe
PROCEDURE
Ferrous Iron : In the field 50 mL of sample was collected in a
bottle containing 1 mL. Conc.HCl. 20 mL of Phenanthroline solution
and 10 mL. Am. Acetate solution was added. Stirring was carried out

13. 70
vigorously and diluted to 100 ml. O.D was measured at 510 nm
within 5 to 10 minutes.
Calculation
O.D x slope x 100
Ferrous Iron = ---------------------------
mL sample
Calibration : 0,1,2,3,4,5 mL standard Iron was taken and make
upto 50 ml with d.H2O 2ml conc.HCl and 1 ml NH2OH, HCl solution
was added. The solution was heated and boiled and reduced to 20 ml.
After cooling 10 mL Am. Acetate buffer and 4 mL phenanthroline
solution were added and make upto 50 mL, O.D at 510 nm was
measured and recorded the O.DS in the tabulation.
C.Reagents
S.No. Reagents Preparation
1. Conc. HCl -
2. NH2OH.HCl solution Dissolved 25 g
NH2OH.HCl in 250 mL water.
3. Ammonium Acetate buffer Dissolved 250 g NH4C2H3O2 in
150 mL d.H2O. 700 mL glacial
acetic acid was then added.
4. Phenanthroline Solution Dissolved 500 mg 1,10
phenanthroline mono hydrate in
500 mL. dH2O. 10 drops of
Conc.HCl was added.
5. Stock Iron
(1ml = 0.2 mg.Fe)
To 5 mL
Conc.H2SO4,12.5mL.d.H2O
Was added and dissolved 0.351
g.Fe.Am.Sulphate. 0.1N KMnO4
added dropwise until a faint pink
colour persists. Diluted to 250
mL.
6. Std.Iron
(1mL=0.01 mg.Fe)
5mL stock Iron was diluted to
100 mL.
7. 0.1 N KMNO4 Dissolved 316 mg.KMNO4 in 100
mL.d.H2O.

14. 71
3.5.8 NITRATE (Electrode Method)
Procedure
Standard sample was prepared for potential measurement as
under
i) 10 mL d.H2O + 10 mL buffer.
ii) 10 mL 10 mg/L std.NO3 + 10 mL buffer
iii) 10 mL 100 mg/L std.NO3 + 10 mL buffer
iv) 10 mL sample (or a portion diluted to 10 mL) + 10 mL buffer.
Ion meter was standardized and the reading of the sample was
noted.
Calculation
Nitrate as NO3 mg/L = Observed value x dilution factor in mg/L.
Reagent
S.No Reagent Preparation
1. Stock Nitrate
(1 mL = 0.5 mg
NO3)
Dissolved 203.8 mg KNO3 (dried at
1050C for 24 hrs ) in 250 mL d.H2O.
2. 100 mg/L Std.NO3 50 mL stock was diluted to 250 mL
3. 10 mg/L Std.NO3 25 ml of 100 mg/l standard was
diluted to 250 mL.
4. 1 mg/L Std.NO3 25 mL of 10 mg/L standard was
diluted to 250 mL.
5. Buffer Dissolved 17.32. Al2(SO4)3 18
H2O,3.43g.Ag2SO4, 1.28g.H3BO3 and
2.52g. sulfamic acid (H2NSO3H) in
about 800 mL.d.H2O. pH was adjusted
to 3.0 by slowly adding 0.1N NaOH and
diluted to 1000 mL.
6. Reference electrode
filling solution.
0.53g (NH4)2 SO4 was dissolved in
d.H2O and make upto 100 mL.

15. 72
3.5.9. pH VALUE
A.Procedure
Distilled H2O, 7.O pH buffer and 9.2 pH buffer were taken in a
separate 50 mL beakers and they were accordingly be marked.
First the pH electrode was dipped in distilled H2O, blot dried
and then dipped in 7.00 pH . Meter knob was adjusted to read 7.00
pH. Again the electrode was dipped in distilled H2O, blot dried and
then dipped in 9.2 pH and noted whether the reading was 9.2 +/- 0.1
which indicates that the instrument was functioning alright.
Then each sample was taken in two beakers and marked them
as nA and nB where n is the sample number. The electrode is dipped
alternatively in nA and nB of successive samples. Every time the
electrode is dipped in nA for 1 minute.
The electrode is kept in the sample (nB) till the reading gets
stablised. pH value of the sample was then recorded.(Dipping in nA
was for rinsing electrode).
B.Calculation
pH. Value = Observed pH value for sample * slope.
Note: When the meter indicates the correct values of pH for buffers 7.0
and 9.2, the slope =1.
FORMULA FOR pH CALCULATION
(observed pH value–7.0)
If pH is > 7.0, pH for sample = 7.0+ ----------------------------- x 2.2
(observed pH value for
9.2 buffer – 7.0)
(7.0 - observed pH value)
If pH is < 7.0, pH for sample = 7.0- ------------------------------ x 3.0
(7.0 - observed pH value
for 4.0 buffer)

16. 73
Reagent preparation
S.No Reagent Preparation
1. pH buffer 4.0 Dissolved one pH 4.0 buffer tablet in 100
mL d.H2O
2. pH buffer 7.0 Dissolved one pH 7.0 buffer tablet in 100
mL d.H2O
3. pH buffer 9.2 Dissolved one pH 9.2 buffer tablet in 100
m d.H2O
4. pH buffer 3.557 Dissolved 5g KHC4H4O6 in 100 mL d.H2O
5. pH buffer 4.0004 Dissolved 1.012g KHC8H4O4 in 100 mL
d.H2O
6. pH buffer 6.863 Dissolved 0.3387g KH2PO4 + 0.3353g
Na2HPO4 in 100 mL d.H2O
7. pH buffer 7.415 Dissolved 0.1179g KH2PO4 + 0.43303g
Na2HPO4 in 100 mL d.H2O
8. pH buffer 9.183 Dissolved 0.38g Na2B4O7.10H20 in 100
mL d.H2O
9. pH buffer 10.014 Dissolved 0.2092g NaHCO3 and 0.2640 g
Na2CO3 in 100 mL d.H2O
10. pH buffer 12.454 Dissolved > 0.2g Ca(OH)2 in 100 mL
d.H2O
11. pH buffer 1.679 Dissolved 1.261 g KH3C4O8.2H2O in 100
mL d.H2O
Note : For preparation of buffer, freshly boiled and cooled H2O was
used.
3.5.10 SULPHATE
A. Procedure
i) Distilled H2O was used for setting of nephelometer.
ii) 100 NTU standard (used in turbidity test) was used for 100
setting of Nephelometer.
iii) 50 mL of sample was taken in a 100 mL measuring cylinder
with Penny head. 10 mL of buffer solution was added. Also
0.5 g BaCl2 was added and mixed well for 1 minute. After 5±
0.5 minutes NTU was measured.

17. 74
Calculation
NTU for sample x slope x 50
Sulphate mg/L = ------------------------------------------
Volume of Sample
Reagents
S.No Reagent Preparation
1. Buffer Solution This mix consists of 30 g MgCl2 6H2O + 5
g. CH3COONa 3H2O + 1g KNO3 + 0.11 g
Na2SO4 + 20 mL CH3COOH (99%) + 500
mL. D.H2O make upto 1000 mL.
2. Barium chloride
crystal (20-30
mesh)
---
3. Stock SO4
(1 mL = 10 mg
SO4)
1.479 g anhydrous Na2SO4 was dissolved
in d.H2O and diluted to 100 mL.
4. Std.SO4
(1 mL = (0.1 mg
SO4)
1 mL stock SO4 was diluted to 100 mL.
Calibration
0, 5, 10, 15 and 20 mL standard SO4 was taken in a separate
measuring cylinders with penny head and make upto 50 mL. The
procedure (i) (ii) and (iii) cited was followed and NTU was measured
and tabulated in the form.
Volume of
std.SO4 mL
SO4 mg in
50 mL
SO4 mg/L
(y axis)
NTU
(x axis)
Slope
0 0 0
5 0.5 10
10 1.0 20
15 1.5 30
20 2.0 4.0

18. 75
3.5.11 TOTAL DISSOLVED SOLIDS
A.PROCEDURE
100 mL of sample was taken (if EC is less than 2000 micromho/
cm) or less volume (if EC is greater than 2000 micromho/cm) in a
preweighed evaporating dish. It is dried over a water bath and kept at
1800C ± 20C for one hour. Then it is cooled in a desiccator and the
final weight was taken.
B. CALCULATION
Final weight – Initial weight
Total Dissolved Solids at 1800C = --------------------------------- x 1000
Volume of sample
C. VERIFICATION OF RESULTS
Measured TDS at 1800C
i) -------------------------------- = 1.0 to 1.2
Calculated TDS
Where calculated TDS = 0.6 Alkalinity + Na + K + Ca + Mg +
Cl + SO4 +SiO3 + NO3 + F
Measured TDS at 1800C
ii) -------------------------------- = 0.55 – 0.70
E.C
3.5.12 TURBIDITY
A.PROCEDURE
The sample was thoroughly shaken for disappearances of air
bubbles.
Turbidity free d.H2O (blank) was taken, turbidity standard (100
NTU/400 NTU) and the sample (or diluted sample) were poured into
three different Turbidity meter tubes.

19. 76
Turbidity free (blank) is set for ‘0’ value Turbidity standard tube
is set for ‘100 NTU’ value. Then the turbidity value of the sample was
measured.
B. CALCULATION
1. Turbidity in NTU = Measured NTU value x Dilution factor.
(when 100 NTU is set for 100).
2. Turbidity in NTU = Measured NTU value x 4 x Dilution factor.
(when 400 NTU is set for 100).
C. Reagents
S.No Reagent Preparation
1. Turbidity
Solution I
1 gram of Hydrazine sulphate in d.H2O was
dissolved and make upto 100 mL.
2. Turbidity
Solution II
10 gram of Hexamethylene Tetramine was
dissolved and makeup upto 100 mL.
3. 400 NTU 25 mL of solution I + 25 mL of solution II in a
500 mL standard flask is taken. After 24
hours at 25 ± 30C it was diluted to 500 mL.
4. 100 NTU 25 mL was diluted. 400 NTU standard to 100
mL with d.H2O.
5. Turbidity
free d.H2O
d.H2O was passed through 0.2 micron
membrane filter. (or good quality of
commercial bottled demineralised water).
3.6 Results of Analyses
The results of analyses carried out for the twelve parameters in
the water samples collected for 60 weeks in each sampling station are
presented in Tables 3.3 to 3.27.