ce 370 manual

King Fahd University of Petroleum & Minerals

Civil Engineering Department

CE 370-Water Supply and Wastewater Engineering

Laboratory Manual

August 2003

Preface

This manual is designed to serve as a laboratory textbook for CE 370-Water

Supply and Wastewater Engineering students. With the help of this manual,

students will carry out experiments in fluid mechanics related to water

distribution systems in addition to experiments related to water quality

evaluation and treatment. The last few experiments presented in this manual

are mainly designed to examine and characterize physical, chemical and

biological properties of wastewater.

To make the manual easy to understand, it has been written in a very simple

language and the experimental procedures were presented clearly.

The information presented in this manual along with field visits to water and

wastewater treatment facilities will complement the theory presented in the

course and will give the students a practical favor of the field applications in

water and wastewater engineering.

Contributions from Mr. M.H. Essa and Mr. M. Saleem to the development of

this manual are appreciated.

Dr. Mohammad S. Al-Suwaiyan

Dhahran, Saudi Arabia

August 2003

i

Table of Contents

Page

Preface......................................................................................................... i Safety Instructions........................................................................................ 1 Experiment # 1: Losses in Piping System.................................................... 3 Experiment # 2: Characteristic Curves of Centrifugal Pumps...................... 10 Experiment # 3: Determination of Chezy & Manning Coefficients............... 13 Experiment # 4: Gravimetric Analysis.......................................................... 16 Experiment # 5: Introduction to Env. Eng. Chemical Lab............................. 19 Experiment # 6. Alkalinity............................................................................. 21 Experiment # 7: Hardness........................................................................... 24 Experiment # 8. Jar Test.............................................................................. 28 Experiment # 9. Spectrophotometry-Calibration Curves.............................. 31 Experiment # 10. Activated Carbon Adsorption........................................... 33 Experiment # 11: Dissolved Oxygen (DO)................................................... 36 Experiment # 12: Biochemical Oxygen Demand (BOD).............................. 38 Experiment # 13: Chemical Oxygen Demand (COD).................................. 41

Experiment # 14. Bacteriological Analysis of Water.................................... 43 Experiment # 15. Determination of Chlorine forms in Water........................ 45 Appendices:

Bibliography.................................................................................................. 49

Instructions for Preparing Lab Reports......................................................... 50

Conversion Factors....................................................................................... 53

Basic information on common elements....................................................... 54

ii

Safety Instructions

The basic purpose of these safety instructions is to protect students,

researchers, technicians and teachers from the many hazards that might be

encountered during the use of the various materials and equipment in the

Environmental Engineering laboratories. Please read the information and

follow the instructions presented here which are given to safeguard you while

in the laboratory.

1. No running, eating, drinking or smoking in the lab.

2. Wear Safety glasses, protective shoes and aprons while conducting

experiments.

3. Know locations of first aid, eye station, safety shower, fire blanket, fire

extinguishers and gas masks.

4. Avoid cross contamination from the various microbiological cultures,

media and samples that are handled in this laboratory.

5. (a) While transferring liquids, remember 'ACID TO WATER'.

(b) Use gloves while pouring corrosive liquids.

(c) Use funnel while filing bottle/flask. Prevent air block by raising

funnel.

(d) Avoid mouth contact with any laboratory equipments including

pipettes. Use safety filler to fill pipettes.

6. (a) While handling glassware, avoid direct heating on the flame.

(b) Never try to free 'frozen' stopper or ground joint by force.

(c) Broken or chipped glassware should be discarded.

(d) Properly support glassware using stand, clamps, etc.

(e) Use proper rings to place round bottom flasks.

7. (a) Use only chemicals and reagents having proper labels.

(b) Chemicals in eye: rapid treatment is vital. Run large amount of

water over eye ball until medical help is available.

(c) Alkali materials in the eyes are most dangerous.

(d) Use sodium carbonate flowed by water for acid spills.

1

(e) For alkali spills on bench, wash with water followed by dilute acetic

acid.

8. (a) Reduce fire hazard.

(b) Use safety shower for fire victims.

(c) While fire on clothing, do not run or fan flames.

(d) Smother flames by wrapping in fire blankets.

(e) Spills of flammable solvents can be a source of fire.

2

Experiment # 1.A: Major Losses in Piping Systems Introduction: A Fluid loses part of its energy as it flows in conduits as a result of the wall

resistance or viscous effects throughout the total length of the pipe. Such loss

is called major loss. One of the most common problems in fluid mechanics is

the estimation of head or pressure loss.

Objective:

To measure the major head losses in a straight pipe line.

Expressions for Head Losses:

The head loss along a length L of a straight pipe of constant diameter D is

given by the Darcy-Weisbach equation:

hL = f L V2/ 2gD (1)

where:

f is a dimensionsless constant (i.e. friction factor) which is a function of the

Reynold's Number and the roughness of the internal surface of the pipe, V is

the mean velocity (m/s) and g is the acceleration due to gravity (9.81

m/sec2).

Experimental procedure: 1. Open full the water control on the hydraulic bench.

2. With the globe valve closed, open the gate valve fully to obtain maximum

flow through the dark blue circuit. Record the readings on the piezometer

tubes (Dark Blue Circuit). Measure the flow rate by timing the level rise

in the volumetric tank.

3. Repeat the above procedure for a total of ten different flow rates obtained

by closing the gate valve, equally spaced over the full flow range.

4. Measure the water temperature.

3

5. Close the gate valve, open the globe valve and repeat the experimental

procedure for the light blue circuit.

Note: Before switching off the pump, close both the globe valve and the gate

valve. This prevents air from gaining access to the system and so

saves time in subsequent setting up.

Report: In addition to tables showing all experimental results, the report must include

the following:

a. Obtain the relationship between the straight pipe head loss and the volume

flow rate (hL a Qn) by plotting log hL against log Q.

b. Plot friction factor versus Reynold's number for the straight pipe (L=0.914

m, D=13.7 mm). Also, obtain relationship between f and Re, by plotting log f

against log Re. Comment on your results by comparing with literature.

4

EXPERIMENTAL RESULTS FOR DARK BLUE CIRCUIT

Test # Vol. (liter) Time,

(sec)Flow Rate Piezometric Tube Readings

(mm) water

1 2

3 4

5 6

*1

2

3

4

5

6

7

8

9

10

* Valve is fully open. Water Temperature =

5

Experiment # 1.B: Minor Losses in Piping Systems Introduction: A Fluid also loses part of its energy due to localized effects like sudden

changes in flow area (expansion, contraction) or the presence of valves,

bends, and elbows among others. Such loss is called minor loss.

Objective:

To measure the minor head losses in a piping system.

Expressions for Head Losses:

The expressions that give minor head loss for several cases are presented

below.

1) Due to sudden expansion - The head loss at a sudden expansion is given

by the expression:

hL = (V1 - V2)2 / 2g (1)

Where V1 and V2 are the average velocity before and after the change in flow

area.

2) Due to sudden contraction - The head loss at a sudden contraction is given

by the expression:

hL = K V22 / 2g (2)

where K is a dimensionless coefficient which depends upon the area ratio as

shown in Table 1.

6

Table 1: Loss Coefficient for Sudden Contraction

A2/A1 0.0 0.1 0.2 0.3 0.4 0.6 0.8 1.0K 0.50 0.46 0.41 0.36 0.30 0.18 0.06 0.0

3) Due to valves - The head loss due to a valve is given by the expression:

hL = K V2 / 2g (3)

where the value of K depends upon the type of valve and degrees of opening.

Table 2 gives typical values of loss coefficients for gates and globe valves:

Table 2 : Loss Coefficient for Sudden Contractions

Valve Type KGlobe valve, fully open 10.0Gate valve, fully open 0.2Gate valve, half open 5.6

Experimental procedure:

1. Open full the water control on the hydraulic bench.

2. With the globe valve closed, open the gate valve fully to obtain maximum

flow through the dark blue circuit. Record the readings on the piezometer

tubes and the U-tube(Light Blue Circuit). Measure the flow rate by timing

the level rise in the volumetric tank.

3. Repeat the above procedure for a total of ten different flow rates obtained

by closing the gate valve, equally spaced over the full flow range.

4. Measure the water temperature.

5. Close the gate valve, open the globe valve and repeat the experimental

procedure for the light blue circuit.

Note: Before switching off the pump, close both the globe valve and the gate

valve. This prevents air from gaining access to the system and so

saves time in subsequent setting up.

7

Report:

In addition to tables showing all experimental results, the report must include

the following:

a. Compare the measured head loss across a sudden expansion with the loss

calculated on the assumption that of head loss is given by the expression:

hL=0.396V12 / 2g for all the ten readings. Plot measured head loss against

calculated head loss.

b. Compare the measured fall in head across a sudden contraction with the

fall calculated on the assumption of head loss is given by the expression: hL =

1.303 V22/2g. Plot measured head loss against calculated head loss.

c. Obtain the value of K for the globe valve when it is fully opened and

compare with literature (Table 2).

8

EXPERIMENTAL RESULTS FOR LIGHT BLUE CIRCUIT

Test #

Vol. (liter)

Time, (sec)

Flow Rate

Piezometric Tube Readings(mm) water

U-tube(mm) Hg

7 8 9 10 11 12 13 14 15 16 Globe Valve

*1

2

3

4

5

6

7

8

9

10

* Valve is fully open. Water Temperature =

9

Experiment # 2: Characteristic Curves of Centrifugal Pumps

Introduction:

Centrifugal pumps are used for producing the flow or increasing the flow rate

in water and wastewater systems. The head that is developed by a pump is a

decreasing function of the discharge. The head developed by a particular

pump for various flow rates at a constant impeller speed is usually provided

by the pump manufacturer as the characteristic curve for the pump. Such

curves are established through pump tests conducted by the manufacturer.

Objective:

To develop the characteristic curves of a centrifugal pump. These include:

head versus discharge, efficiency versus discharge and discharge versus

power.


The experiment will be conducted on Gilkes tutor pump GH62. Since the

motor which derives the pump is of variable speed, a set of characteristic

curves for various speeds can be drawn.

1) Start the pump. Make sure that the valve is fully closed. See that the

regulator is at the zero position, while starting.

2) Turn the regulator to some suitable position to give a constant speed.

3) Open the valve, and for this valve opening read the following:

i. Head from the gauge

ii. Discharge from the V-notch

iii. Force from the force gauge attached to the motor

10

iv. Speed of the motor with the hand tachometer

4) Change the valve opening and repeat the reading from step 3. Repeat

this step 8-10 times.

5) Change the motor speed, step 2, and repeat steps 3 and 4.

Report:

In addition to tables showing all experimental data and results, the report

should include the following, for a given impeller speed:

1) The pump characteristic curve showing head (Hp) versus flow rate (Q)

2) Flow rate (Q) versus output break horse power (BHP)out

where (BHP)out = γ Q Hp / 550

3) Flow rate (Q) vs. efficiency, (h)

where h = BHPout/BHPin

and (BHP)in = 2 π F R N / (60 x 550)

F force in (lbs) from force gage

R length (ft) of torque

arm = 6.3125 inches

N RPM

Discuss the resulting curves indicating the best efficiency point (bep) and

compare the obtained characteristic curves at various speeds with the

theoretical curves which can be obtained from the characteristic curve for the

first motor speed.

11

EXPERIMENTAL DATA SHEET

Serial #Speed, RPM

Head, ft

Discharge, cfm

Force, lbPower

input, hpPower

output, hpEfficiency, %

12

Experiment # 3: Determination of Chezy and Manning Coefficients for Steady Uniform Flow

Introduction:

Open channel flow through sewer lines is the main way of wastewater

transportation to wastewater treatment plants. It is customary to assume

uniform steady flow for the design of sewers which allows the use of

traditional Chezy and Manning's equations.

Objective:

To get familiar with the traditional equations used to analyze steady, uniform

open channel flow.

Chezy and Manning's equations:

A French engineer called Chezy developed the following equation to describe

the steady uniform flow in an open channel:

V = C R1/2 S1/2

Where:

V = Velocity in the channel (cm/sec)

R = Hydraulic radius (cm).

S = Bed slope (dimensionless).

C = Chezy coefficient.

The values of C depend on the type channel surface and varies with

Reynold's number. Manning later suggested replacing Chezy coefficient by

the following expression:

C = R1/6 / n

13

Where n is called Manning coefficient which depends on the channel surface.

Which when substituted for gives the famous Manning equation:

V = (1/n) R2/3 S1/2


1. Give suitable slope to the channel.

2. Start the pump and adjust the valve.

3. Measure depths at various locations after the flow have become steady

and uniform.

4. Measure the discharge and the Reynold's numbers using mean values

obtained.

5. By keeping the slope constant, measure another discharge and repeat

about six times.

6. Repeat the procedure using another channel slope.

Report:

a. Record the readings and perform the calculations in the tabular forms

provided and submit results complete with sample calculations.

b. Determine from experimental data the Chezy and Manning's coefficient of

the Perspex flume.

c. Determine the value of C from the above formula using n = 0.01 for six

values of R and compare the experimental values of C and those obtained

from the equation using n = 0.01.

d. Examine the variation of C & n with Reynold's number.

14

A. Slope __________

Trial

Depth (1)(cm

)

Depth (2)(cm

)

Avg.

Depth

Q(l/s)

A(cm

2)

V(cm/

s)

P(cm)

R(cm)

Reynold#

Cfrom

Experiment

nfrom

Experiment

1

2

3

4

5

6

B. Slope __________

Trial

Depth (1)(cm

)

Depth (2)(cm

)

Avg.

Depth

Q(l/s)

A(cm

2)

V(cm/

s)

P(cm)

R(cm)

Reynold#

Cfrom

Experiment

nfrom

Experiment

1

2

3

4

5

6

15

Experiment # 4: Gravimetric Analysis

Introduction:

The concentrations of the various solids that exist in water and wastewater

are important indicators of their quality. Solids present in water and

wastewater can be broken into two categories, suspended and dissolved

solids (non-filterable and filterable, respectively). Each of the aforementioned

categories is also divided into organic (volatile) and inorganic (non-volatile)

constituents. The processes that are used to separate the different solid

categories are filtration and combustion.

Total Solids is the term applied to the material residue left in the vessel after

evaporation of a sample and its subsequent drying in an oven at a defined

temperature (103-1050C). Total suspended solids refer to the non-filterable

residue retained by a standard filter disk and dried at 103-1050C. Total

dissolved solids refer to the filterable residue that pass through a standard

filter disk and remain after evaporation and drying to constant weight at 103-

1050C.

Objective:

To use the principles of gravimetric analysis to characterize the quality, in

terms of solids concentrations, of three types of water, namely: tap water,

drinking water, and secondary effluent.

Materials:

Porcelain dish (100 ml), steam bath, drying oven, muffle furnace, desiccator,

Gooch crucible, analytical balance, glass fiber filter disk, filtration apparatus,

pipettes, measuring cylinders.

16


a) Total Solids

1. Ignite a clean evaporating dish at 5500C in a muffle furnace for 1 hr.

2. Cool the dish, weigh and keep it in a desiccator.

3. Transfer carefully 50 ml of sample into the dish and evaporate to

dryness on a steam bath.

4. Place the evaporated sample in an oven adjusted at 1030C and dry it

for 1 hr.

5. Repeat drying at 1030C till constant weight is obtained.

6. Determine the total solids with the following formula:

mg/l total solids = ((A-B) * 106 ) / ml sample

where

A = weight of residue + dish

B = weight of dish

b) Total suspended solids:

1. Place a filter disk on the bottom of a clean Gooch crucible.

2. Pour 20 ml distilled water and apply vacuum. Repeat the process two

more times.

3. Remove crucible to an oven and dry it for 1 hr at 1030C.

4. After drying, the crucible is kept in a desiccator.

5. Weigh the crucible and place it on a suction unit.

6. Pour 25 ml of sample. Wash pipette with distilled water and pour the

washing also into the crucible.

7. After filtration, dry the crucible at 1030C for 1 hr

8. Weigh till constant weight is obtained.

9. Determine the total suspended solids with the following formula:

Mg/l total suspended solids = (( A-B) * 106) / ml sample

where:

A = weight of residue and crucible

B = weight of crucible

17

c) Total Dissolved Solids:

Mg/l total dissolved solids = total solids – total suspended solids

Report:

In addition to tables showing all experimental results, consider the following

points while preparing your report:

a. Compare the TS, TSS and TDS for the three samples.

b. Describe the results using a mass balance approach.

c. What sources of errors that could affect the accuracy of your results?

18

Experiment # 5: Introduction to Environmental Engineering Chemical Laboratory

Introduction:

In the next several experiments, chemical characterization of water and

wastewater will be done. Different tools, materials and equipment will be used

in order to perform such task. Various chemicals such as buffer solutions and

colorimetric indicators as well as basic techniques like preparing primary and

secondary standard solutions, titration and pH measurements are essential

for any person that will use this facility. In any analytical laboratory it is

essential to maintain stocks of solutions of various reagents: some of these

will be of accurately known concentration (standard solutions) and correct

storage of such solutions is imperative. Primary standards are usually salts or

acid salts of high purity that can be dried at some convenient temperature

without decomposing and that can be weighed both at high degree of

accuracy. Secondary standards are solutions that have been standardized

against primary standards.

Objectives:

1) To become familiar with the terminology, various materials and chemicals

used in the environmental engineering laboratory.

2) To prepare primary and secondary standards and to understand the

principles involved in their preparation.

Materials :

Analytical balance, 250-ml Erlynmer flask, pH meter, sodium carbonate,

methyl orange indicator, standard buffers, sulfuric acid, magnetic stirrer,

volumetric flasks, funnel, burette (50 ml), and beakers.

19

Experimental Procedure:

1. Prepare one liter of standard 0.02N Na2CO3 by dissolving 1.06g anhydrous

reagent grade Na2CO3, (dried at1030C for 4 hrs), in distilled water.

2. Mount a 50 ml burette and fill it to the mark with the pre-prepared acid

solution.

3. Take 50 ml of Na2CO3 solution in a flask, add 5 drops of methyl orange

indicator and place on a magnetic stirrer.

4. Add acid slowly while stirring till orange color turns to pink

5. Check the pH of the solution after titration is completed which should be

approximately 4.3

6. Record the volume of acid used.

7. Repeat titration two more times and calculate average volume of acid used.

Calculations:

Calculate the normality of the sulfuric acid (H2SO4).

20

Experiment # 6: Alkalinity

Introduction :

Alkalinity of water is a measure of its capacity to neutralize acids or the

amount of acid required to lower the pH to about 4.3. Alkalinity is significant in

many processes involving water and wastewater treatment. For example, if no

sufficient alkalinity is present during the addition of alum to water for

coagulation the pH may be greatly reduced. An other example is that of the

softening reactions using lime. If there is no sufficient bicarbonate alkalinity,

then carbonate ions must be added to the water so that calcium will

precipitate out of the water in the form of calcium carbonate.

The main species that contribute to alkalinity are bicarbonate, carbonate and

hydroxyl. However, since most natural waters have a pH value between 6 and

8, it is usually assumed that alkalinity is equal to the bicarbonate

concentration.

Objective :

To measure the concentration of the various species that contribute to

alkalinity in different types of water.

Materials :

Burette (25 ml), Porcelain dish, Magnetic stirrer and rod, Beaker (150 ml),

Pipette, Measuring cylinder (100 ml), pH meter, 0.02N Sulphuric acid, Methyl

Orange indicator, Phenolphthalein indicator.

Experimental procedure :

For different water samples, the following procedures should be carried out to

determine the total alkalinity and the contributing species.

21

Indicator Method:

1. Pipette exactly 50 ml of sample into a glass beaker or porcelain dish

and drop in a magnetic rod.

2. Mount a 50 ml burette and fill it to the mark with 0.02N sulphuric acid

solution.

3. Add 5 drops of Phenolphthalein indicator to the sample. If the

solution turns pink, add acid slowly till pink color disappears. Record

the volume of acid in milliliters as P.

4. Add 5 drops of Methyl Orange indicator to the same sample at the

end of the first titration and add 0.02N sulphuric acid slowly till orange

color turns to pinkish yellow. Record this volume as M. Then, T =

P+M.

Potentiometric Method (pH meter):

1. Pipette exactly 100 ml of sample into a 150 ml beaker and drop in a

magnetic rod.

2. Fill the burette with 0.02N sulfuric acid solution.

3. If the pH of the sample is above 8.3 add 0.02N sulphuric acid slowly

till pH 8.3. Record the volume of acid as P.

4. Continue addition of acid till the pH of the sample reaches 4.5.

Record volume of the acid as M. Then, T = P+M.

.

Determination of alkalinity species:

Determine the various species of alkalinity present in the samples using the

relationships shown below.

Condition OH- CO3= HCO3

-

1. P = T T 0 0

2. P = 1/2T 0 2P 0

3. P > 1/2T (2P-T) 2(T-P) 0

4. P < 1/2T 0 2P (T-2P)

5. P = 0 0 0 T

22

Record the titration data in the following table:

Sample P

(ml)T

(ml)P & T Condition

Sample A

Sample B

Sample C Using the above data, calculate the concentrations of the various species of

alkalinity using the formula given below for each sample and list in the

following table.

Alkalinity, mg/l as CaCO3 = A x N x 50,000/ml sample

A = ml, sulphuric acid solution used

N = normality of acid solution.

Sample OH- CO3= HCO3

-

ml mg/l as CaCO3

ml mg/l as CaCO3

ml mg/l as CaCO3

Sample A

Sample B

Sample C

Report: In addition to tables showing all experimental results, consider the following


a. Compare the concentration of the various species contributing to alkalinity

for the different types of water.

b. What sources of errors that could affect the accuracy of your results?

23

Experiment # 7: Hardness

Introduction:

Hardness in water is caused mainly by the ions of calcium and magnesium.

Such ions exist as a result of the interaction between recharge water and

certain geological formations (i.e. limestone) that contain these ions. Public

acceptance of hardness varies from community to community, consumer

sensitivity being related to the degree to which the person is accustomed.

Hardness of more than 300-500 mg/l as CaCO3 is considered excessive and

results in high soap consumption as well as objectionable scale in heating

vessels and pipes.

Ethylenediaminetetraacetic acid and its sodium salts (abbreviated EDTA)

form a chelated soluble complex when added to a solution of certain metal

cations. If a small amount of dye such as Eriochrome Black T is added to an

aqueous solution containing calcium and magnesium ions, the solution

becomes wine red. If EDTA is added as a titrant, the calcium and magnesium

will be complexed, and when all of the magnesium and calcium has been

complexed the solution turns from wine red to blue, marking the end point of

the titration. Analysis for hardness is performed in two stages by estimating

total and calcium hardness separately calculating the magnesium hardness

from the difference between the two.

Objective:

To determine the total hardness as well as calcium and magnesium of raw

water and treated water samples using EDTA titrimetric method.

Materials:

Burette (50 ml), porcelain dish, magnetic stirrer and rod, pipette, measuring

cylinder (100 ml), ammonia buffer solution, sodium hydroxide solution,

24

Eriochrome black T indicator, Murexide ( ammonium purpurite), EDTA, raw

water sample, treated water sample


For different water samples, the following procedure should be carried out to

determine the total, calcium and magnesium hardness.

1. Pipette exactly 25 ml of raw water sample into a porcelain dish and drop

in a magnetic rod.

2. Mount a 50 ml burette and fill it to the mark with 0.01M EDTA solution.

3. Add 1-2 ml of ammonia buffer, 0.2g Eriochrome Black T indicator.

4. Start adding slowly 0.01M EDTA solution till the color of the solution

changes from wine red to blue. Record the volume of EDTA solution and

calculate total hardness using the following formula:

Hardness as mg/l CaCO3 = ( A * B * 1000) / ml sample

Where:

A= ml EDTA used

B = mg CaCO3 equivalent to 1 ml EDTA titrant (1 mg CaCO3)

5. Add 1-2 ml sodium hydroxide buffer and 0.2 g murexide indicator into 25

ml of raw water sample.

6. Start adding 0.01M EDTA solution slowly till the color of the solution

changes from purple to violet. Record the volume of EDTA used and

calculate calcium hardness using the previous formula.

7. Calculate magnesium hardness (= total hardness - calcium hardness)

8. Repeat titration for the other water samples and calculate the hardness.

25

Report:



a. Compare the hardness obtained for the various types of water.

b. Would you expect groundwater to be softer or harder than surface water?

Why?

b. What sources of errors that could affect the accuracy of your results?

26

Sample Buffer Indicator Initial

ColorFinal Color

Vol. of EDTA

Hardness mg/l

as CaCO3

A TH=

CaH=

MgH = TH - CaH MgH=

B TH=

CaH=

MgH = TH - Ca H MgH=

C TH=

CaH=

MgH = TH - Ca H MgH=

27

Experiment # 8: Jar Test

Introduction:

Water as well as wastewater may contain some solids that remain in

suspension even if left for along time to settle by gravity. Such particles are

called colloids which are characterized by their light weight and the surface

charge that will prevent them from agglomeration. One of the objectives of

water treatment is to promote the settling of suspended matter. The

coagulation process utilizes what is known as a chemical coagulant

(aluminum or iron salts) to neutralize the surface charge and therefore

promote particle agglomeration. Chemical coagulants are added to the raw

water and for a brief period rapid mixing is carried to produce what is called a

microfloc. The next process is to subject the microfloc solution to controlled

turbulence in order to bring the microflocs together to form a floc of adequate

size that will settle under gravity. This process is called flocculation. Removal

of turbidity by coagulation depends on the type of colloids in suspension, the

temperature, pH, and chemical composition of the water, the type and dosage

of coagulants, and the degree and time of mixing provided for chemical

dispersion and floc formation.

Objectives:

1) To understand the process of coagulation and flocculation using alum and

ferric chloride to remove turbidity of water.

2) To determine the optimum coagulant dose for a particular water.

Materials:

Jar test, aluminum sulphate solution, ferric chloride solution, beakers,

turbidimeter, measuring cylinders, kaolin powder, sodium carbonate solution,

sampling bottles.

28


1. Arrange two sets of Jar test apparatus. Check all units of the jar test

apparatus before starting.

2. Prepare a turbid water sample by dissolving kaolin powder in distilled water

3. Determine the turbidity of the sample and record its value.

4. Prepare stock solution of alum and ferric chloride by dissolving 10 g powder

in 1 liter distilled water.

5. Prepare sodium carbonate solution by dissolving 10 g salt in 1 liter distilled

water.

6. Determine total alkalinity of the sample.

7. In the jar test units, fill each numbered beaker with sample.

8. If the measured alkalinity was low, add 6-8 ml sodium carbonate solution to

each beaker.

9. Start the stirrers at 100 rpm and add quickly the doses of alum (given in

table 1) in each beaker of set one and keep rapid mixing for exactly 1 min.

10. Reduce the speed of stirrers to 40 rpm and continue for 40 minutes.

11. Stop and raise the paddles above water level and leave the beakers for

flocs to settle for 30 minutes.

12. Siphon out clear sample from each beaker without disturbing settled

sludge.

13. Find out the turbidity of each sample.

14. Perform the same procedure with the ferric chloride (doses given in table

2) setup in parallel with alum setup.

Report:

In your report prepare a plot of the resulting turbidity values versus the

coagulant dose then use these figure to estimate the optimum dose for both

alum and ferric chloride. You should also compare and contrast between the

two types of coagulants used when you discuss the results.

29

Table 1: Alum Data

Beaker # 1 2 3 4 5 6

Coagulant, in ml 0 0.5 1.0 2.0 3.0 5.0

Coagulant, in mg 0 5 10 20 30 50

Turbidity, NTU

Table 2: Ferric Chloride Data

Beaker # 1 2 3 4 5 6

Coagulant, in ml 0 0.5 1.0 2.0 3.0 5.0

Coagulant, in mg 0 5 10 20 30 50

Turbidity, NTU

30

Experiment # 9: Spectrophotometry-Calibration Curves

Introduction:

Spectrophotometry is an optical method used for water analysis that is based

on Beer-Lambert Law, in which concentration of a light absorbing constituent

is related to the amount of light transmitted by the solution.

The Beer-Lambert Law given below, states that the absorbance, A, of light is

proportional to the concentration of the light absorbing contaminant.

Log(Io/I) = A = k C

Where:

Io = intensity of light transmitted through a blank solution

I = intensity of incident light

k = absorptivity x pathlength through which light travels

Objective:

1) To demonstrate the principles of spectrophotometry.

2) Develop a calibration curve for measuring the concentration of methylene

blue.

3) Utilize the developed curves to predict unknown concentration of

methylene blue.

Materials:

Methylene blue stock solution of 10 mg/l, volumetric flasks, assorted pipettes,

spectrophotometer

31


1. Prepare five 100 ml samples of different concentrations (0.5, 1.0, 1.5, 2.0,

3.0 mg/l) using the methylene blue stock solution.

2. Place a sample (say 1.5 mg/l) in the spectrophotometer and take

absorbance reading at different wavelengths and from that record the

wavelength that gives the peak absorbance value.

3. Using this wavelength, measure the absorbance for the different methylene

blue concentration.

4. Use the generated data to develop the calibration curve.

Report:

In addition to the standard report, please generate the following plots in your

report:

a) Absorbance spectrum obtained from step # 2

b) Calibration curve and calibration equation.

c) Calculate the unknown concentration of the provided sample.

32

Experiment # 10: Activated Carbon Adsorption

Introduction:

Adsorption is a very important process that is utilized by environmental

engineers in water and wastewater treatment. In this process the contaminant

is moved, to some degree, from the dissolved phase to the surface of another

phase. Adsorption of contaminants present in water onto activated carbon is

a common process employed in the removal of organic chemicals that

produce color, taste or odor. Activated carbon has huge specific surface due

to the presence of extremely high number of molecular sized pores. The huge

surface provides adsorption sites that will result is removal of the

contaminants from the dissolved phase. Activated carbon is prepared from

carbonaceous materials like charcoal, lignite, and nutshells. The adsorption

capacity of activated carbon is generated by controlled combustion, which

produce large adsorption surface in the grain pores of material. Activated

carbon is commercially available in powdered and granular forms.

Objective:

To utilize the adsorption phenomena to remove color from water sample using

Granular Activated Carbon (GAC).

Materials:

Granular activated carbon, Methylene blue stock solution of 10 mg/l, two liter

glass beaker, three liter baffled vessel, paddle stirrer, volumetric flask,

assorted pipettes, Spectrophotometer, drying oven, weighing balance.


1. Prepare one size activated granular carbon by sieving and drying at 105ºC.

2. Prepare two liters of a 10 mg/l solution of methylene blue.

33

3. Place the solution into a 3-liter vessel and stir vigorously with a laboratory

paddle stirrer.

4. Add 5 grams of the one size fraction of prepared granular activated carbon

and note this time as zero.

5. Keep stirring and collect sample of solution at 5, 10, 15, 30, 45, and 60

minutes.

6. Determine the absorbance of the solution in each samples and convert to

concentration units by using the given calibration curve.

7. Plot the normalized solution concentration (C/Co) versus time.

Report:

In addition to the standard report, please consider the following points in your

report:

a) Calculate the quantity of methylene blue (MB) that was transferred to the

surface of the activated carbon (mg of MB/gram of carbon) for each sample

that was collected. Plot these uptake values versus time.

b) Explain whether such figure gives an adsorption isotherm or how can they

be used to generate an isotherm.

c) What about the adsorption capacity and do you think it would be a function

of time.

34

Time(min)

Absorbance Concentration (mg/l)

C/Co Mg of MB transferred/gm of Carbon

0.0

5.0

10

15

30

45

60

35

Experiment #11: Dissolved Oxygen (DO)

Introduction:

Oxygen is slightly soluble in water and the dissolved oxygen (DO) does not

react with molecular water. As suggested by Henry's law, the saturation

solubility or maximum possible level of dissolved oxygen is directly

proportional to its partial pressure. This level is influenced by both physical

and chemical characteristics of water like temperature and salinity as well as

biochemical activities in the water body.

The analysis for DO is a key test in water pollution and waste treatment

process control. Presence of high levels of dissolved oxygen in water and

wastewater is desirable because it indicates good quality and as the level

drops it could indicate the presence of potential quality problems.

Two standard methods for DO analysis are available: Winkler (iodometric)

method and the electrometric method which uses membrane electrodes. The

iodometric method, which is more accurate and reliable, is a titrimetric

procedure based on the oxidizing property of DO.

Objective:

To determine the dissolved oxygen level in different water samples using

Winkler method.

Materials:

300 ml BOD bottles, pipette, burette (50 ml), flasks 250 ml, measuring

cylinders, alkaline-iodide-azide solution, manganous sulphate solution,

concentrated sulfuric acid, starch indicator, 0.025M sodium thiosulphate.

36

Experimental Procedure

1) Prepare aerated water sample by aerating distilled water for several hours.

Also prepare two more water samples containing chemical pollutants.

2) Fill narrow-mouth glass 300 ml BOD bottle with sample water and cap

carefully. Do not agitate the sample.

3) Add 2 ml MnSO4 solution to the bottles immersing the tip of the pipette

below the surface of water.

4) Add 2 ml alkali-iodide-azide solution to the bottles immersing the tip of the

pipette.

5) Cap the bottle tight, invert and mix thoroughly so that dissolved oxygen

present in the bottles is fixed as a brown precipitate (MnO2).

6) When the precipitate settles halfway, add 2 ml concentrated sulphuric acid

to the bottle and invert it and shake well. The color of the solution turns

orange/yellow due to the oxidation of iodide (I-) to free iodine (I20).

7) Place 203 ml of sample in a flask and place on a magnetic stirrer.

8) Fill a burette with 0.025 M sodium thiosulphate (Na2S2O3)solution and titrate

the sample till yellow tinge remains.

9) Add 1 to 2 ml starch indicator. Color will become blue then titrate till the

solution becomes colorless. Record the burette readings as mg/l DO.

10) Repeat the analysis for three given samples.

Report:

1) In your report discuss the factors that influence the saturation DO and give

the reason why would the oxygen levels in the samples given are less than

the oxygen solubility.

2) Indicate the DO levels and comment on the quality of the different samples

used in this experiment.

37

Experiment # 12: Biochemical Oxygen Demand (BOD)

Introduction:

Estimating the organic content of a wastewater is an essential information

needed for planning proper management and treatment of wastewater. The

Biochemical oxygen demand (BOD) gives an estimate of the strength of

industrial or domestic wastes in terms of the oxygen consumed by

microorganisms to decompose the organic matter present in the waste. The

higher the BOD, the more oxygen will be demanded from the waste to break

down the organics. The BOD test is most commonly used to measure waste

loading at treatment plants and in evaluating the efficiency of wastewater

treatment. The BOD test is performed by incubating a sealed wastewater

sample for the standard 5-day period, then determining the change in

dissolved oxygen content. The bottle size, incubation temperature, and

incubation period are all specified. All wastewaters contain more oxygen

demanding materials than the amount of DO available in air-saturated water.

Therefore, it is necessary to dilute the sample before incubation to bring the

oxygen demand and supply into appropriate balance. Because bacterial

growth requires nutrients such as nitrogen, phosphorous, and trace metals,

these are added to the dilution water, which is buffered to ensure that the pH

of the incubated sample remains in a range suitable for bacterial growth.

Complete stabilization of a sample may require a period of incubation too long

for practical purposes; therefore, 5-day period has been accepted as the

standard incubation period.

Objective:

The objective of the experiment is to determine the biochemical oxygen

demand of a wastewater sample.

38

Materials:

BOD bottles, pipette, burette (25 ml), 250 ml flasks, measuring cylinders, DO

meter, incubator, Phosphate buffer, magnesium sulphate, calcium chloride,

ferric chloride.


1) Prepare dilution water by aerating distilled water for several hours. Transfer

two liters into an aspirator bottle and add 2 ml each of magnesium sulphate,

phosphate buffer, calcium chloride, and ferric chloride. Fill two bottles

designated as control with the dilution water (B1 and B2).

2) If seed is required add 0.2% seed material into the dilution water (optional).

3) Add carefully an appropriate volume of the sample, using Table 1 for

guidance, to two bottles and fill them with the dilution water (D1 and D2).

4) Switch and calibrate the dissolved oxygen meter.

5) Measure the initial DO in each BOD bottle (B1 and D1) either using Winkler

method or DO meter.

6) Incubate the bottles B2 and D2 for 5 days. After 5 days measure the final

DO in each bottle by the same procedure.

Report:


report:

a) Explain why duplicate bottle were used in this test.

b) What could happen if no dilution was done?

c) Imagine that the BOD test was carried out to determine the BOD after one,

two three, four and five days, give a qualitative plot of the resulting BOD

versus time variation.

39

For calculating BOD use the following equations:

For diluted sample without seeding

BOD (mg/l) = (( D1 – D2) – ( B1 – B2))/P

For diluted sample with seeding

BOD (mg/l) = (( D1 – D2) – ( B1 – B2)*f)/P

Where:

D1: initial DO of sample before incubation

D2: Final DO of sample after incubation

B1: initial DO of control before incubation

B2: Final DO of control after incubation

P: Decimal fraction of sample, volume of BOD bottle/volume sample

used.

f: Volume of seed in diluted sample / volume of seed in seed control.

Table 1: Suggested wastewater dilution for BOD test.

% WastewaterRange of BOD mg/l

0.10 2000 to 70000.20 1000 to 35000.50 400 to 14001.00 200 to 7002.00 100 to 3505.00 40 to 140

10.00 20 to 7020.00 10 to 3550.00 4 to 14

40

Experiment # 13: Chemical Oxygen Demand (COD)

Introduction:

Similar to BOD, chemical oxygen demand COD is a test used to estimate the

organic strength of wastes. However in this test, the organics are oxidized

chemically not using microorganisms. As a result of this the COD test needs

much less time (say 2 or 3 hours) to be conducted unlike the five days for the

standard BOD test. Also since all organics are oxidized chemically, COD

values will be higher than BOD values especially if biologically resistant

organic matter is present in the waste. It is also possible, for much waste, to

generate a correlation between COD, the quick and easy test, and BOD, the

time consuming test.

The COD test measures the oxygen required to oxidize organic matter in

water and wastewater samples by the action of strong oxidizing agent under

acidic conditions. Potassium dichromate has been found to be excellent for

this purpose. The test must be performed at an elevated temperature and in

the presence of silver sulfate as catalyst. The principal reaction using

dichromate as the oxidizing agent may be represented by following equation:

Organic matter (CaHbOc) + Cr2O7-2 + H+ ® Cr+3 + CO2 + H2O

Objective:

To determine the chemical oxygen demand (COD) of a sample using the

closed reflux, titrimetric method.

Materials:

Digestion vessels, block heater at 150 ± 20C, burette (25 ml), 250 ml flasks,

measuring cylinders, standard potassium dichromate digestion solution,

sulphuric acid reagent, ferroin indicator solution, standard ferrous ammonium

sulfate titrant (FAS).

41


1) Place 2.5 ml sample in tubes and add 1.5 ml digestion solution.

2) Add 3.5 ml sulfuric acid reagent down inside of vessel so an acid layer is

formed under the sample-digestion solution layer.

3) Tightly cap the tubes invert and shake well.

4) Place tubes in block digester preheated to 150 0C and reflux for 2 hours.

5) Cool to room temperature and place tubes in test tube rack.

6) Transfer contents to a 50ml flask and add 1 to 2 drops of ferroin indicator

and stir rapidly on magnetic stirrer.

7) Start titration against standard 0.1 M FAS until the color changes from blue-

green to reddish brown and record the volume used.

8) For blank use same volume of distilled water instead of sample volume.

9) Calculate the COD using the equation below:

COD (mg/l) = (A – B) x M x 8000/ml sample

Where:

A: ml FAS used for blank,

B: ml FAS used for sample

M: molarity of FAS, and

8000: milliequivalent weight of oxygen x 1000 ml/l

Report:


report:

a) Explain the advantages and disadvantages of the COD versus BOD tests.

b) Based on today's experiment, could you estimate the BOD for the sample

used today?

c) Would you expect larger difference between COD and BOD for domestic or

industrial wastewater? Explain.

42

Experiment # 14: Bacteriological Analysis of Water

Introduction:

Microbiological quality of water is a very important component of the

overall quality characterization and is directly related to the health and

safety of the consumers. Many of the microorganisms that cause serious

disease, such as typhoid fever, cholera, and dysentery, can be traced

directly to polluted drinking water. These disease-causing organisms,

called pathogens, are discharged along with fecal wastes and are difficult

to detect in water supplies. Fortunately, less harmful, easily isolated

bacteria called indicator organisms can be used indirectly to detect

pathogens. Among these indicators are coliform bacteria. These bacteria

live in the intestine of humans and other animals and are always present,

even in healthy persons. The presence of coliforms in water is a warning

signal that more dangerous bacteria may be present.

By definition coliform bacteria are aerobic and facultative, gram-negative,

non-spore forming, rod shaped and ferment lactose with gas formation

within 48 hours at 35°C. Those that have the same properties at a

temperature of 44°C or 44.5°C are described as fecal coliform. It is

convenient to express the result in replicate tubes and dilutions in terms of

the Most Probable Number (MPN), which is an estimate based on certain

probability formula.

Objective:

To learn enumeration technique of coliform bacteria

Materials:

Fermentation tubes with aluminum caps, Durhum tubes, lactose broth,

brilliant green bile broth, platinum loop, bunsen burner, disposable

pipettes, 10 ml, and 1ml. An incubator adjusted at 35 °C is also required.

43


MPN test is performed in three stages: Presumptive test, confirmative

test, and completed test. Presently we need only the first two.

I. Presumptive Test:

1) Prepare lactose broth and distribute 15 ml sterilized media in each

fermentation tube containing an inverted Durham tube.

2) Distribute 5 fermentation tubes in three lines and mark 10 ml, 1ml, and

0.1 ml in each line.

3) Shake well effluent and distribute specific volume 10 ml, 1 ml, and 0.1

ml in each tube under sterile conditions by sterilized pipettes.

4) Place the tubes in the incubator for 48 hours.

5) After incubation record positive tubes indicated by the presence of

trapped gas bubble inside Durham tubes.

II. Confirmative Test:

1) Transfer a loopful of sample from positive tubes to a BGB tube under

aseptic condition and mark the tubes as in the earlier test.

2) Incubate the tubes for 48 hours

3) Record positive tubes after incubation

4) Convert the reading to MPN index / 100 ml using MPN index table

presented in the Standard Methods. The table will be given and

explained during the experiment.

Report:

1) Review the microbiological quality standards for different types of water

and wastewater.

2) What are some of the water prone diseases that could be detected early

using the test conducted in this experiment?

44

Experiment # 15: Determination of Chlorine forms in Water

Introduction:

Disinfection is a very important component of water and wastewater treatment

used to reduce the disease causing microorganisms to an acceptable level.

The final level of pathogens obviously must be a function of the desired use of

the effluent. A disinfectant must be able to deal with various types of

pathogens, must work even with expected fluctuations in water treated, not be

toxic in required dose, easy to determine its concentration, reasonable cost

and safe to store and handle. It is also desired that a disinfectant stay in the

water to produce residual protection against potential contamination before

use. Such residual protection is needed to prevent and detect contamination

in water distribution networks.

The most commonly used disinfectant is chlorine, which can be added as Cl2

or as calcium or sodium hypochlorite. Chlorine can exist as free available

chlorine and or combined available chlorine depending on factors that include

pH, level of ammonia in water and applied dose. The disinfecting capacity is

much higher for free available chlorine while combined available chlorine

provides better residual disinfection because of its slower reduction, which

makes chloramines persist longer in the distribution system. With the

development of knowledge about the disinfecting powers of the various forms

of chlorine, it became important to distinguish and quantify each component.

Objective:

To determine the concentrations of the various forms of chlorine in water

samples

45

Materials:

750 ml flasks, phosphate buffer solution, standard ferrous ammonium sulfate

(FAS) titrant, potassium iodide crystals, glacial acetic acid, standard sodium

thiosulphate, DPD indicator, starch indicator


1) Prepare 500 ml of the following two chlorine solutions:

a) Approximately 2 mg/l as Cl2 in distilled water

b) Approximately 2 mg/l as Cl2 in a 2 mg NH3-N/l solution

using bleach solution (Clorox) as a source of chlorine (concentration about

50 g/l as Cl2) and distilled water.

2) Place 5 ml phosphate buffer solution and 5 ml DPD indicator solution in a

titration flask and mix.

3) Add 100 ml sample (a) in step 1 and mix.

4) Titrate rapidly with standard ferrous ammonium sulfate (FAS) until the red

color disappears and take FAS volume used as (A), which will be the

concentration of free Cl2.

5) Add a small crystal of KI to the solution from the previous step and mix.

6) Continue titrating with FAS until the red color disappears and take the total

FAS volume used as (B), which will give the concentration of free Cl2 plus

monochloramine.

7) Add about 1 g of KI crystals to the solution from the previous step and mix.

8) Allow to stand for two minutes then continue titrating with FAS until the red

color disappears and take the total FAS volume used as (C), which will give

the concentration of dichloramine.

9) Repeat step 2-8 for sample (b) in step 1.

Report:



46

a. Review the mechanisms of chlorine disinfection mechanisms.

b. Which sample would you expect to have more free chlorine even before

conducting the experiment and why?

c. How would we provide residual disinfection in water distribution network?

47

Appendices

48

Bibliography

Davis, M. and Cornwell. Introduction to Environmental Engineering, 3rd ed.,

McGraw-Hill, 1998.

Hammer and Hammer. Water and Wastewater Technology, 4 th ed., Prentice Hall,

2001.

Roberson and Crowe. Engineering Fluid Mechanics, 3rd ed., Houghton Mifflin, 1985.

Sawyer, C. McCarty, P. and Parkin, G. Chemistry for Environmental Engineering, 4 th

ed., McGraw-hill International Editions, 1994.

Snoeyink and Jenkins. Water Chemistry, John Wiley & Sons, 1980.

Standard Methods for the Examination of Water and Wastewater, 20 th. Ed., 1998,

American Public Health Association, American Water Works Association and Water

Environment Federation.

Viessman and Hammer. Water Supply and Pollution Control, 6th. Ed., Prentice Hall,

1998.

49

Instructions for Preparing Laboratory Reports

The laboratory sessions are designed to support and supplement the theories

introduced in the course and also to expose the students to some relevant

applications through laboratory experiments. It is very important, before

conducting any experiment, to make sure that you understand how the

equipment work and what measurements have to be taken. Following each

experiment, a student is required to write a report and submit it during the

next laboratory session. Final examinations on the laboratory experiments

may be held at the end of the semester.

Reporting:

Writing a technical report is very important in engineering practice. The

experience gained from writing the laboratory reports will definitely help the

student in writing any technical report in the future. Use of computer packages

to prepare both report text as well as graphs is essential.

The laboratory report should be presented in a factual, concise and complete

manner and should be free of any ambiguous or contradicting statements. All

pertinent data and sources of error should be noted. The interpretation of data

and subsequent conclusions must be supported by the experimental results.

The following is intended as a general aid in preparation of the laboratory

report. The report consists of the following:

Cover Page

The cover page should indicate the course name and number, the experiment

title the student’s name and number.

Summary

This part of the report should give the reader the sense of the report (i.e. the

objectives, method and conclusions in a condensed form).

50

Introduction, Apparatus, and Procedure

In most cases, reference need only be made to the experiment instruction

sheets. However, when certain procedures were employed or were modified

in such a way that they were not covered in the instruction sheets, it should

then be recorded.

Discussion of Results

This part represents the core of the report. All experiment findings must be

discussed here in some detail. The student should refer to all tables, charts

and graphs in his discussion. Although some numbers may be mentioned to

support the discussion, a full table of measured data or calculated results

should not be presented in this section.

Conclusions and Comments

In some cases, certain questions are asked in the instruction sheets and

these should be answered. However, in general, students are required to

make brief pertinent conclusions of their own. Give reasons for any

discrepancies which may have been noted between the obtained results and

the expected theoretical results or trends. Well thought-out conclusions in the

report are identification of the accomplishment (or not) of the objective of the

experiment. The summary together with the conclusions form an important

source of information for the busy reader.

Observed Data, Sample of Calculations and Computed Results

A composite table of observations should be prepared from the experiment

readings, with the proper units noted for each set of data. A sample of

conclusions is usually necessary to show how the results, graphs and

conclusions are derived. All calculated data that is used for graphs and

charts should be presented in a tabular form. All tables should be properly

titled and clearly identified.

51

Finally, it is important to note that the key word for writing a good report is

brevity. There is absolutely no reason for the report to be too long. Such

report is not required, and will result in no additional marks over a well-

organized, concise and brief report. Two or three pages, with graphs, should

be all that is required.

52

Conversion Factors

To convert multiply by to get

Mile, mi 1.609 kilometer, km

Yard, yd 0.9144 meter, m

Foot, ft 0.3048 meter, m

Inch, in 0.0254 meter, m

Cubic foot, cu ft 28.32 liter, l

US gallon, gal 3.785 liter, l

Ton (2000 lb) 0.9072 tonne (1000 kg), t

Pound, lb 0.4536 kilograms, kg

Pound force, lb 4.448 newton, N

Horsepower, hp 0.7457 kilowatt, kW

Horsepower, hp 550 lb-ft/s

Pounds per square inch, psi 6.895 kilopascals, kPa

Pounds per square inch, psi 0.703 meters of water

Pounds per square inch, psi 51.7151 mm of mercury

Pounds per square inch, psi 2.3067 feet of water

Pounds per square inch, psi 144 pounds per square foot

Pounds per square inch, psi 0.068046 standard atmospheres

53

Basic Information on Common Elements

Name Symbol Atomic weight Equivalent weight

Aluminum Al 27 9

Arsenic As 75 25

Calcium Cd 40 20

Carbon C 12 3

Chlorine Cl 35.5 35.5

Fluorine F 19 19

Hydrogen H 1 1

Iodine I 127 127

Iron Fe 56 28

Lead Pb 207 103.5

Magnesium Mg 24 12

Manganese Mn 55 27.5

Mercury Hg 201 100.5

Nitrogen N 14 4.7

Oxygen O 16 8

Phosphorous P 31 6

Potassium K 39 39

Silicon Si 28 6.5

Silver Ag 108 108

Sodium Na 23 23

Sulfur S 32 16

54

ce 370 manual

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