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.

7.

(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.

(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 α 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

*1 2 3 4 5 6 7 8 9 10

* Valve is fully open.

Water Temperature =

5

4 5

6

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 K

0.0 0.50

0.1 0.46

0.2 0.41

0.3 0.36

0.4 0.30

0.6 0.18

0.8 0.06

1.0 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 Globe valve, fully open Gate valve, fully open Gate valve, half open

K 10.0 0.2 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 7

8

9

10

11 12

13 14

U-tube (mm) Hg 15 16

*1 2 3 4 5 6 7 8 9 10

* Valve is fully open.

Water Temperature =

9

Globe Valve

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.

Experimental procedure: 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, (η) where η = 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, lb

12

Power input, hp

Power output, hp

Efficiency, %

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

Experimental procedure: 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 __________

T rial

D ept h (1) ( cm)

D ept h (2) ( cm)

A vg. D ept h

Q ( l/s )

A (c m2)

V (cm/ s)

P (c m)

R (c m)

Reyn old #

C from Experi ment

n from Experim ent

Q ( l/s )

A (c m2)

V (cm/ s)

P (c m)

R (c m)

Reyn old #

C from Experi ment

n from Experim ent

1 2 3 4 5 6

B. Slope __________

T rial

D ept h (1) ( cm)

D ept h (2) ( cm)

A vg. D ept h

1 2 3 4 5 6

15

16

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 1031050C.

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.

17

Experimental procedure: 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 18

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?

19

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.

20

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).

21

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.

22

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

23

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.

OH−

Sample ml

mg/l as CaCO3

HCO3−

CO3= 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 points while preparing your report: 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?

24

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,

25

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

Experimental procedure: 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.

26

Report: In addition to tables showing all experimental results, consider the following points while preparing your 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?

27

Sample

Buffer

Indicator

Initial Color

A

Final Color

Vol. of EDTA

Hardness mg/l as CaCO3 TH= CaH=

MgH =

TH - CaH

B

MgH= TH= CaH=

MgH = TH - Ca H C

MgH= TH= CaH=

MgH = TH - Ca H

28

MgH=

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.

29

Experimental Procedure: 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.

30

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

31

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

32

Experimental Procedure: 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.

33

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.

Experimental Procedure: 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. 34

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.

35

Time (min) 0.0

Absorbanc e

Concentration (mg/l)

5.0 10 15 30 45 60

36

C/Co

Mg of MB transferred/gm of Carbon

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.

37

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.

38

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.

39

Materials: BOD bottles, pipette, burette (25 ml), 250 ml flasks, measuring cylinders, DO meter, incubator, Phosphate buffer, magnesium sulphate, calcium chloride, ferric chloride.

Experimental Procedure: 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: In addition to the standard report, please consider the following points in your 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.

40

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.

% Wastewater

Range of BOD mg/l

0.10 0.20 0.50 1.00 2.00 5.00 10.00 20.00 50.00

2000 to 7000 1000 to 3500 400 to 1400 200 to 700 100 to 350 40 to 140 20 to 70 10 to 35 4 to 14

41

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). 42

Experimental Procedure: 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 bluegreen 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: In addition to the standard report, please consider the following points in your 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.

43

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. 44

Experimental Procedure: 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?

45

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

46

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

Experimental procedure: 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: In addition to tables showing all experimental results, consider the following points while preparing your report:

47

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?

48

Appendices

49

Bibliography Davis, M. and Cornwell. Introduction to Environmental Engineering, 3rd ed., McGraw-Hill, 1998. Hammer and Hammer. Water and Wastewater Technology, 4th 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, 4th ed., McGraw-hill International Editions, 1994. Snoeyink and Jenkins. Water Chemistry, John Wiley & Sons, 1980. Standard Methods for the Examination of Water and Wastewater, 20th. 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.

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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).

51

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.

52

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 wellorganized, concise and brief report. Two or three pages, with graphs, should be all that is required.

53

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

54

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

55