HSC 252 - Water Quality and Treatment



Spring

2002

HSC 252 Water Quality and Treatment

Laboratory Manual

ILLINOIS STATE UNIVERSITY

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Contents

Page 3…………………. Introduction and Lab Safety

Pages 4-5………………. Exercise #1: Calculations Related to Water Treatment

Pages 6-10…………….. Exercise #2: Surface and Soil-Groundwater System Models

Page 11………………… Exercise #3: Groundwater Sources, Testing and Filling/Sealing of Wells

Pages 12-14……………. Exercise #4: Surveying Techniques and Elements of a Sanitary Survey

Pages 15-20……………. Exercise #5: Chemical Analysis of Drinking Water

Pages 21-23……………. Exercise #6: Microbiological Analysis of Drinking Water

Pages 24-26…………… Exercise #7: Site Visit to Normal Drinking Water Treatment Facility

Pages 27-28…………… Exercise #8: Site Visit to Bloomington Drinking Water Treatment Facility

Pages 29-31…………… Exercise #9: Jar Tests for Coagulation, Flocculation, and Sedimentation

Pages 32-36…………… Exercise #10: Chlorine Analysis of Drinking Water

Pages 37-38…………… Exercise #11: Site Visit to Horton Pool

Introduction and Laboratory Safety

Introduction:

This lab component of this course is designed to give you practical experience through learning and application of specific skills used to determine water quality (e.g., chemical and microbiological analyses of water), analysis of movement of water and access to water through soil-groundwater and surface water systems, and site visits to drinking water treatment facilities.

After completing these laboratory exercises, you should be able to describe, discuss, justify, and perform chemical and biological tests used to determine water quality and the techniques used in a variety of treatment facilities to produce quality water for drinking purposes. You should also be able to describe the movement of surface and groundwater through runoff and leaching of water, and the associated water contamination risks.

The exercises and questions are designed to provide practice for the types of questions you will be asked on the laboratory exams. Make sure that you complete the entire exercise, answer the questions, and complete any other required associated activities in order to make sure you are prepared for the lab exams.

Laboratory safety:

Although we do not use highly dangerous chemicals or equipment in this lab, we do use chemicals and equipment that have the possibility of causing injury if used improperly. Examples include:

Acids and bases: Avoid contact with skin. If contact occurs, wash off with copious amounts of water, or use eyewash apparatus over sink. Avoid touching your mouth, nose, or eyes before you wash your hands.

Bunsen burners: Open flames are dangerous. Avoid contact of loose fitting clothing, loose hair, and other flammable materials with open flames. Use safety shower or drop and roll if on fire.

Flammable liquids: Ethyl alcohol (ethanol) is flammable. Use small amounts to sterilize forceps for microbiological analysis of water. Avoid contact with open flames when sterilizing forceps.

Dyes: Dyes (indicators) may be toxic if ingested, and can also cause stains on clothing or skin.

Lab safety equipment available includes eyewash (above main sink) and emergency shower. Please use emergency shower only when it is necessary (it will release about 30 gallons of water with no shut-off).

Laboratory safety is primarily a matter of common sense. Ask your instructor if you have any questions. Notify your instructor immediately if you have an accident, especially if it requires medical attention.

HSC 252 - Water Quality and Treatment

Laboratory Exercise #1: Calculations relating to water treatment

Objective:

The purpose of this exercise is to review basic calculations including those related to water

quality management. Upon completion of this exercise, you should be able to perform basic

mathematical calculations and apply these calculation techniques to solving problems related to water

quality.

Materials and supplies required:

Calculator (preferably with memory function)

Pencil and paper

Basic units and conversion factors (see below)

Set of problems

Procedure:

Students should work individually or in groups during the lab period and other times if

necessary to complete the calculations required to solve the problem set. Make sure that you show all

your calculations step-by-step in a sequential fashion. Round all decimals off to two places. Problem

sets are due at the beginning of the next lab period.

Basic units and some frequently used conversion factors:

1. 1 part per million (ppm) = 1 gallon per million gallons (or 1 mg/l, etc.)

2. 1 part per million (ppm) = 8.34 pounds per million gallons

3. 1% = 10,000 ppm

4. Density of water = 8.34 pounds per gallon

5. 1 grain per gallon (GPG) = 17.1 mg/l

6. 1 cubic foot of water = 7.48 gallons

7. 1 cubic foot of water = 62.4 pounds

8. Area = height (H) X width (W)

9. Quantity of water flow (Q) = Area (A) ( Velocity of flow (V)

10. Specific gravity (SG) = density of a solution/density of water

11. Volume of a cylinder = ( (3.14) r (radius) 2 h (height)

12. 1 inch = 2.54 cm

13. 1 gallon = 3.785 liters

14. 1 pound = 454 grams (7000 grains)

15. 1 pound = 16 ounces

HSC 252 - Water Quality and Treatment

Problem set

1. If a flow is 600,000 gallons per day and a dose of 2 ppm is applied to the flow, how many pounds of chemical will be used in 30 days?

2. If 20 pounds of chlorine per day are used for a flow of 3 MGD (million gallons per day), what is the

average dosage rate in mg/l?

3. If 700 lbs. of Alum are used daily for a flow rate of 4 MGD, what is the average dose in grains per gallon (GPG)?

4. A rectangular tank is 30 ( 45 ( 25 feet. A pump fills the tank in 7 hours. How many gallons per minute does the pump deliver?

5. A sand filter is 35 ( 20 feet (sand area.) With the influent (input) valve shut, the water level drops 3.5 inches per minute. What is the filtration rate in MGD?

6. 30 gallons of alum solution containing 1.5 lbs/gal are added to 150 gallons of solution containing 2.5 lbs/gal. What is the concentration of alum in the new solution in pounds per gallon?

7. A rectangular flume is 12 inches wide ( 14 inches long. The water is 8 inches deep and moving at .85 ft/sec. How many gallons of water will the flume deliver in 10 hours?

8. A liquid has a specific gravity of 1.24. What is the weight in pounds of 55 gal of the liquid?

9. A cylindrical vat is 40 inches in diameter and 3 feet high. 25 pounds of soda ash are added and the vat is filled with water. A pump lowers the level of the vat 2 inches per hour. How many ounces of

soda ash are being fed per minute?

10. Stock lime is 85% calcium oxide. How many pounds per day are required to treat 4 MGD with a

dose of 6 mg/l?

11. A wash tank holds 225,000 gallons. How many pounds of HTH (calcium hypochlorite with 70% available chlorine) is needed to sterilize the tank at 50 mg/l?

HSC 252 - Water Quality and Treatment

Laboratory Exercise #2: Surface and Soil-groundwater System Model.

Objective(s):

The purpose of this exercise is to provide you with an opportunity to manipulate a model of a surface water /soil-groundwater system and determine the interaction of different components. Simulated features include shallow and deep wells, recharge zone, contamination sites, a confined aquifer and an unconfined aquifer, river, lake, and artesian well. During this lab, you should manipulate various components of the model as described below and determine the effects of these manipulations on other components within the system. Upon completion of this exercise, you should be able to describe the movement of water through surface water and soil-groundwater systems and predict the consequences of contamination of water system components to other components within the system.

Materials needed:

1. Surface water / soil-groundwater system model.

2. Pump/filtration unit to circulate and filter water.

3. Dyes to simulate contaminants to water systems.

4. Tubing, syringe, squeeze bottle to deliver dye into system.

Procedure:

Students should work in groups of two and each group should simulate at least one of the six scenarios outlined below (#1 - 8). Results for each scenario should be observed and recorded by each group.

First, observe the components of the system model and movement of water through the system model:

a. Water enters through the recharge zone (top right) and infiltrates into soil (sand).

b. Water percolates through soil into confined and unconfined aquifers.

c. Water moves slowly through aquifers and fills low topographic areas (lake, river).

d. Artesian well is formed by the water table being above the top of the well.

e. Simulated wells are drilled to various depths (shallow [surface water], into unconfined aquifer, and into confined aquifer).

Scenarios:

1. Predict what would happen if a contaminant spill occurred at the surface of the recharge zone.

a. Would the unconfined aquifer be contaminated?

b. Would the confined aquifer be contaminated?

c. Which wells could be contaminated?

e. Would surface waters be contaminated?

f. How much of a danger is this spill for people getting their drinking water from each well?

g. Add a small amount of dye to the recharge zone and observe what happens to the simulated contaminant.

h. The colored area indicated by the dye (simulating a contaminant) is called a plume. How could soil conditions affect the speed at which the plume moves?

i. Were the results different from what you predicted?

2. Predict what would happen if a contaminant were released from a leaking underground storage tank (LUST).

a. Repeat questions and steps a. - h. above for this scenario (add a small amount of dye carefully to the LUST area only after the previously added dye has dispersed).

b. Would pumping of water from the well dug into the unconfined aquifer affect the movement of the contaminant plume? Use the supplied pump to test your answer.

3. Predict what would happen if the well drilled into the unconfined aquifer were contaminated.

a. Repeat questions and steps a. - h. above for this scenario (adding a small amount of dye to the well).

4. Predict what would happen if a contaminant were deep well injected into the confined aquifer.

a. Repeat questions and steps a. - h. above for this scenario (adding a small amount of dye to the well).

b. What is the likelihood of this contaminant contaminating other sources of water?

5. Predict what would happen if the a contaminant spill occurred in the river.

a. Would the shallow wells become contaminated?

b. Would the deep well (confined aquifer) become contaminated?

c. Would the lake become contaminated?

d. What is the source of most of the water in the river?

e. Simulate a contaminant spill in the river with a small amount of dye.

f. Observe and record the results.

g. Were the results different from what you predicted?

6. Predict what would happen if a contaminant spill occurred in the lake.

a. Would the shallow wells become contaminated?

b. Would the deep well (confined aquifer) become contaminated?

c. Would the river become contaminated?

d. What is the source of most of the water in the lake?

e. Simulate a contaminant spill in the lake with a small amount of dye.

f. Observe and record the results.

g. Were the results different from what you predicted?

7. How would the solubility of the contaminant in water affect the contamination of water?

a. Describe how a water soluble contaminant would act in the model (is the dye we used water soluble?)

b. Describe how a non-water soluble contaminant would act in the model (what could we use to simulate this type of contaminant?)

8. How would the density of the contaminant as compared to water affect its movement?

a. Describe how a contaminant less dense than water would act in the model (is the dye we used more dense or less dense than water?)

b. Describe how a contaminant more dense than water would act in the model (what could we use to simulate this type of contaminant?)

How to use Quickflow( demonstration software

1. Insert 3 1/2 “ floppy disk in appropriate drive.

2. Access MS-DOS prompt.

3. Type “a:qfdemo” (drive a [or whatever drive the floppy disk is in]: Quickflow( demonstration)

4. A plan view (view from above) will appear with a pull-down menu along the top. The grid shown contains “streamlines” (roughly vertical green lines, from top to bottom) that indicate the direction of water flow underground, and blue water table cross section lines (roughly horizontal, or across the screen) that indicate the level of groundwater at different depths. Three wells will already be installed on the map (marked RW-1, 2, and 3) - you need to remove them before you start.

5. Click and hold on “select” item from menu and choose “wells” option within that menu (Note: if mouse

is not functional, use arrows to highlight menu and menu items).

6. Click on one of the wells (these are pumping wells through which water is removed, as indicated by the “+” inside the orange circle, “-” inside orange circle indicates an injection well through which water or waste is introduced). The selected well should now be surrounded by a pink box.

7. Click and hold on “edit” and choose “delete selected item” option. That will delete that well. Repeat for the other two wells, or select one well and choose the “delete all like items” option from the “edit” pull down menu to delete all wells at once.

8. Once you have deleted (or added) a component (or components), an orange “recalculate” prompt will appear on the right of the screen. Click and hold on the “calculate” menu and choose the “recalculate” option (you should now have a grid with straight vertical green arrowed “streamlines”, indicating direction of flow of water underground, and straight horizontal blue water table lines, indicating the water table at various depths. Note: you must “calculate” and “recalculate” this each time you change a component or components to observe the resulting effects.

9. Click and hold on the “Add” menu. You can choose options to add “wells” (pumping or injection), “linesinks” (representing static recharge zones like sinkholes [“head linesinks”], or changing infiltration areas like rivers [“flux linesinks”], “ponds” (which can be sized smaller or larger by increasing or decreasing the size of the circle), more “streamlines”, or a “title”.

10. Once you add a component, a menu will appear in which you must specify the rate of water flow into or out of that component (generally, ”+” indicates flow out of a component and “-” indicates flow into the component). Until you have become very familiar with this program, you probably don’t want to modify any other parameters unless necessary (size and location will be determined automatically during your placement). You probably want to start by adding just one component, like a well or pond. Select “calculate” and choose “recalculate”option to implement changes in groundwater flow.

11. This will change the groundwater flow patterns to reflect the affects of your added components. Observe the changes in groundwater flow patterns caused by your added component.

12. You can modify the parameters chosen by clicking and holding on the “edit” menu and selecting “edit selected item” (e.g., to increase or decrease water flow into or out of the component).

13. To determine the movement of a potential contaminant through the system, you can click and hold on “select” and choose “particle trace” option to add either a “single”, “line” or “circle” of particle traces indicating the flow of a contaminant through your model.

15. For more complex groundwater modelling, a variety of other parameters can be modified under the “aquifer” menu (e.g., changing or “transient” flow rates, top and bottom of water table, porosity of soil, gradient of topographic slope, etc.) Have fun!

16. To exit program, click and hold on “quit” select “quit” and click on “yes” and “OK”. Close MS-DOS prompt.

Questions (related to Quickflow( demonstration software):

1. How does pumping from a well at high rates affect the water table? How does it affect the water flow (streamlines)? What is the change in the water table created pumping from a well called?

2. How does injecting water into a well affect the water table? How does it affect the water flow?

3. How does flow into a lake, river, or stream affect the water table? How does it affect the water flow?

4. How does adding a sinkhole (recharge zone) effect the water table? How does it affect the water flow?

5. Assume that you have a contaminant spill near a pumping well (use the particle trace function). How does the contaminant move? As the contaminant spill is moved further away from the well, what happens?

6. Does the flow of water indicated by the streamlines affect whether the contaminant affects the well?

7. Assume that a contaminant is being drawn into a well by the water flow. Can you place another well (either injection or pumping) so that the contaminant is prevented from contaminating the first well? If so, describe how.

HSC 252 - Water Quality and Treatment

Laboratory Exercise #3: Groundwater Sources, Testing and Filling/Sealing of Wells.

Objective:

The purpose of this exercise is to provide you with an opportunity to observe some of the methods

used to access groundwater through wells, analyze of water for contaminants, and fill and seal

abandoned wells. When you have completed this lab, you should be able to describe the processes of

tapping aquifers through wells, various methods of water analysis for contaminants, and the process of

filling/capping abandoned wells to prevent groundwater contamination.

Related information:

Groundwater is a primary source of drinking water for a majority of people in the U.S.

Well types include drilled, jetted, driven, and hand dug.

Well casings may be plastic (PVC) or steel.

Wells must be capped and open spaces surrounding casing filled to limit surface contamination.

Chemical and microbiological analyses of water determine if water is safe for drinking.

Abandoned wells should be filled and capped to prevent surface contamination of aquifers.

Procedure:

Students meet in the lab for video presentations. You should take notes over the material

covered in these videos (material may be covered on exams).

Demonstrations of well components, filling, and sealing:

Six-inch steel well casing with pitless adaptor and bonnet.

1 ¼-inch steel driven well point with screen.

Bentonite clay samples (different particle sizes for different applications)

Videos to be shown:

1. Water testing for Well Owner - Why We Insist, Normal Water Well Association.

3. How to fill and seal a well.

HSC 252 - Water Quality and Treatment

Laboratory Exercise #4: Surveying Techniques and Elements of a Sanitary Survey.

Objective:

The purpose of this exercise is to provide you with an opportunity to learn about and use some of

the instruments and techniques used to conduct sanitary surveys for wells. Upon completion of this lab

exercise, you should be able to identify, describe the function of several common instruments and

techniques used to conduct sanitary surveys. You should be able to use these instruments and

techniques to make determinations of distance in the field. You should also be aware of minimum

distances and elevation differences among elements in a sanitary survey, including wells, septic tank

systems, and surface waters.

Instruments and techniques to be observed and used:

Builder’s level (or transit) - used to sight along a level plane from one point to another.

Stadia rod - used to provide a sighting point for the builder’s level to determine elevation differences.

Hand level - used to make rough measurements of differences in elevation.

100-foot reel tape - used to measure distances between two points.

Pace factor - when established for a particular individual, may be used to measure rough distances.

Procedure:

Students meet in the lab for a brief introduction to the proper use of surveying instruments.

You should take notes over the material covered during this exercise (material may be covered on exams).

Minimum distances, elevations among wastewater, drinking water, and surface waters:

Septic tank to well - 50 feet.

Septic tank to surface water - 25 feet.

Drain field to well - 75 feet.

Drain field to surface water - 25 feet.

Well must also be higher in elevation than drain field to prevent runoff contamination.

Use this area for calculation of pace factor and diagram of survey results.

1. Determination of pace factor. Pace the distance between the two points indicated (100 feet) and count the number of paces (walk naturally). Repeat three times. Calculate the average. Divide into 100. This is your personal pace factor in feet. To determine distance, count the number of steps and multiply by your pace factor. This is the distance in feet. Example: if your average is 33 steps, 100/33 = 3.03 feet per step. If you step off 50 paces to measure distance, 50 ( 3.03 = 150.15 feet (approximately 150 feet).

(1)

(2)

(3)

(4)

Average:

2. Diagram of survey results (include all relevant data):

Questions:

1. Are there any problems with the layout of the home, septic tank, drain field, and well concerning minimum distances and elevation differences?

2. How would you address these problems? (e.g., what would you do to correct them, based on factors such as cost, regulatory agencies, etc.)

3. List, describe, and justify the elements that should be included in a sanitary survey.

HSC 252 - Water Quality and Treatment

Laboratory Exercise #5: Chemical Analyses of Water

Objective(s):

The purpose of this exercise is to provide you with an opportunity to perform a number of

basic chemical analyses on a water sample of unknown origin. A variety of colorimetric assays will be

used to determine specific physicochemical properties of water. Upon completion of this

exercise, you should be able to conduct a variety of physicochemical analyses on water samples given the

appropriate equipment, supplies, and instructions.

Analyses conducted and supplies provided at each station:

1. Alkalinity: titration flask and stand with titration dropper, distilled water, phenolphthalein indicator

solution, sulfuric acid standard solution, bromcresol green/methyl red indicator powder pillows,

placemat.

2. Carbon dioxide: titration flask, titration dropper, 25-ml graduated cylinder, timer, phenolphthalein indicator solution, sodium hydroxide standard solution.

3. Fluoride: 25-ml graduated cylinders (2), colorimeter bottles (2), distilled water for

blank, SPADNS reagent, Hach DR/700 colorimeter with 575 nm filter.

4. Color: colorimeter bottles (2), Hach DR/700 colorimeter with 450 nm filter.

5. Hardness: titration flask with dropper, pipette with bulb, dropper, Buffer solution hardness I, ManVer II hardness indicator powder pillows, TitraVer hardness titrant.

6. Iron: 25-ml graduated cylinder, colorimeter bottles (2), FerroVer powder pillows, timer, Hach DR/890 colorimeter.

7. Manganese: 25-ml graduated cylinder, colorimeter bottles (2), Citrate buffer powder pillows, Sodium periodate powder pillows, Hach DR/890 colorimeter.

8. Ammonia : Colorimeter bottles (2), Nessler reagent, Hach 2010 Spectrophotometer.

9. pH: Portable pH meter and probes, 25-ml beakers, distilled water, comparators (2), pH color scale, 10-

ml glass tubes for comparator, phenol red indicator solution.

Procedure(s):

Students should work in pairs and proceed from station to station, collecting and recording data.

1. Alkalinity:

a. Rinse titration flask with distilled water 3-4 times to clean.

b. Measure 5-ml of water sample into clean titration flask, add 5-ml dilution water into flask and

use stir-rod to mix.

c. Add one drop phenolphthalein indicator solution.

d. If pink color appears, titrate with sulfuric acid standard until color disappears, if not proceed to ( f.)

Note: titrations should be done slowly and carefully, adding one drop of titrant at a time (slow drip

from buret) while swirling the sample slowly over a white placemat so that color change is evident.

If you’re not sure that a color change has occurred, record the current concentration of titrant and

continue to titrate until color change is more evident, or you are certain that the first color change

was the end-point. Then, correct titrant concentration can be recorded and used to calculate the

concentration of the component for which you are analyzing the sample.

e. The phenolphthalein alkalinity is calculated by multiplying the ml of sulfuric acid used by 200 (expressed in mg/L calcium carbonate.)

f. Add one bromcresol green/methyl red indicator powder pillow and swirl to mix.

g. Continue titration with sulfuric acid standard solution until color changes from green to blue-green or pink (color change may not be very obvious, titrate slowly).

h. Total alkalinity is calculated by multiplying the ml sulfuric acid used in both titrations by 200 (expressed in mg/L calcium carbonate).

2. Carbon dioxide:

a. Measure 25-ml of water sample using clean graduated flask.

b. Add one drop phenolphthalein indicator solution. If pink color forms, no CO2 is present. If no pink color forms, proceed with (c.)

c. Titrate water sample with sodium hydroxide standard solution until light pink color develops and persists for 30-seconds (look down through cylinder onto white paper for easiest color observation.)

d. Carbon dioxide concentration is calculated by multiplying the ml of sodium hydroxide used by 40 (expressed in mg/L.)

3. Fluoride:

a. Measure a 10-ml sample into a clean graduated cylinder (to be treated).

b. Measure a 10-ml sample of distilled water into a clean graduated cylinder (to be used as blank).

c. Pipette 2 ml of SPADNS reagent into each graduated cylinder and swirl to mix.

d. General directions for use of Hach DR/700 colorimeter:

1. Press power button.

2. Adjust to appropriate setting (depending on filter and analysis being conducted) by using up or

down arrow buttons:

(a.) Fluoride: 57.01.1 (using 575 nm filter).

(b.) Color: 45.03.1 (using 450 nm filter)

(c.) Manganese: 52.01.1 (using 525 nm filter).

3. Transfer 10-ml of untreated sample (reagents not added, except for SPADNS reagent for Fluoride

analysis) to a clean colorimeter bottle, insert into cell holder (as a blank to zero colorimeter), and

close cover (make sure diamond on cuvette is facing forward). Note: small cuvettes (round bottles

for colorimeter) are marked at 10-ml with a line.

4. Press “ZERO” button.

5. Wait for 20 second countdown to complete (reading should indicate “0” for the parameter tested).

6. Transfer 10-ml of treated sample (with reagents added) from graduated cylinder to a clean

colorimeter bottle, insert into cell holder (make sure diamond on cuvette is facing forward), and

close cover.

7. Press “READ” and wait for results (in appropriate units, usually mg/L).

4. Color:

a. Fill a clean colorimeter bottle with 10-ml of distilled water (for zero blank).

b. Follow 3d step 1 and 2.

c. Place the blank in the cell holder. Close the lid.

d. Press “ZERO” button.

e. Place the water sample to be tested into the cell holder,

j. Press “READ”. The display will count down to 0. Then the display the apparent color results in platinum-cobalt (Pt/Co) units.

5. Hardness

a. Pipette 10-ml of water sample into titration flask.

b. Add 3 drops Buffer solution hardness I.

c. Add contents of one ManVer II hardness indicator powder pillow.

d. Titrate with TitraVer hardness titrant until color changes from pink to blue (titrate slowly near end- point.)

e. Total hardness is calculated by multiplying the ml of TitraVer hardness titrant used times 100 (expressed as mg/L calcium carbonate.)

6. Iron

a. Measure 25-ml of water sample into a clean 25-ml graduated cylinder.

b. Add contents of one FerroVer powder pillow. Swirl to mix completely. If iron is present, an orange color will develop. Let water sample stand for 2-5 minutes before measuring color.

c. General directions for use of Hach DR/890 colorimeter to measure Iron:

1. Press: “Exit”

2. Press: “PRGM” The display will show: “PRGM?”

3. Press: “3 3 ENTER”, the display will show “mg/L, Fe” and the “ZERO” icon.

4. Transfer 10-ml of untreated sample (reagents not added) to a clean colorimeter bottle, insert into cell holder (as a blank to zero colorimeter), and close cover tightly (make sure diamond on cuvette is facing forward). Note: small cuvettes (round bottles for colorimeter) are marked at 10-ml with a line.

5. Press “ZERO” button.

6. Wait for 20 second countdown to complete (reading should indicate “0” for the parameter tested).

7. Transfer 10-ml of treated sample (with reagents added) from graduated cylinder to a clean colorimeter bottle, insert into cell holder (make sure diamond on cuvette is facing forward), and close cover.

8. Press “READ” and wait for results (in appropriate units, usually mg/L).

d. Iron concentration should be displayed and recorded in mg/L.

7. Manganese

a. Measure a 25-ml water sample into a clean 25-ml graduated cylinder.

b. Add contents of one Citrate buffer powder pillow and swirl to mix completely.

c. Add contents of one sodium periodate powder pillow and swirl to mix. If manganese is present, a pink-violet color will develop. Allow 1-5 minutes for maximum color development.

d. General directions for use of Hach DR/890 colorimeter to measure Manganese:

1. Press: “Exit”

2. Press: “PRGM” The display will show: “PRGM?”

3. Press: “4 1 ENTER”, the display will show “mg/L, Mn” and the “ZERO” icon.

4. Transfer 10-ml of untreated sample (reagents not added) to a clean colorimeter bottle, insert into cell holder (as a blank to zero colorimeter), and close cover tightly (make sure diamond on cuvette is facing forward.

5. Press “ZERO” button, wait for 20 second countdown to complete (reading should indicate “0” for the parameter tested).

6. Transfer 10-ml of treated sample (with reagents added) from graduated cylinder to a clean colorimeter bottle, insert into cell holder (make sure diamond on cuvette is facing forward), and close cover.

7. Press “READ” and wait for results (in appropriate units, usually mg/L).

e. Manganese concentration should be displayed and recorded in mg/L.

8. Ammonia (HACH Spectrophotometer 2010)

a. Turn on power for Hach DR/2010 spectrophotometer (if not already on). The screen will show “DR/2010”, “Self-Test V1.6” and “Enter Program #) automatically.

b. Press “380 ENTER”. The display will show “DIAL nm to 425”.

c. Rotate the wavelength dial until the display shows “425 nm”.

d. When the correct wavelength is dialed in the display will quickly show: “Zero Sample” then “mg/L NH3-N Ness)

e. Measure 25-ml of water sample into a clean 25-ml graduated cylinder.

f. Fill a second 25-ml graduated cylinder (the blank) with deionized water.

g. Add three drops of Mineral Stabilizer to each cylinder and swirl to mix.

c. Add three drops of Polyvinyl Alcohol Dispersing Agent to each cylinder and swirl to mix.

d. Add 4 drops of Nessler Reagent to each cylinder and swirl to mix.

e. Wait for 1 minute. Pour each solution into a cuvette (square bottle).

f. Place the blank in the cell holder, close the light shield.

g. Press: “ZERO”

h. Place the treated sample in the cell holder, close the light shield.

i. Press: “READ”. The display will count down to 0. Then the display will show the results in mg/L ammonia nitrogen (NH3-N).

9. pH (Note: two methods will be used for pH – (1.) pH meter and (2.) comparator).

1. pH meter -

a. Transfer about 20-ml of distilled water to a 50-ml beaker.

b. Transfer about 20-ml of sample to be tested to a 50-ml beaker.

c. Rinse the pH electrode in distilled water.

d. Transfer pH electrode to sample to be tested and swirl gently.

e. Allow about 1-2 minutes for reading to stabilize and record.

f. Replace electrode in distilled water for use by next group.

2. Comparator -

a. Place phenol red disk in comparator.

b. Fill one viewing tube (flat-bottom test tube) to upper (10-ml) mark with water sample to be tested.

c. Fill second viewing tube to upper (10-ml) mark with distilled water.

d. Add 0.5-ml (10 drops) phenol red indicator solution to viewing tube containing the water sample to

be tested, and swirl or stir to mix.

e. Insert viewing tube containing sample to be tested in right-hand opening of comparator. Note: front

of comparator is the side with the door and three viewing openings.

f. Insert viewing tube with distilled water into left-hand opening of comparator.

g. Hold color comparator to sunlight and view through two openings in front. Rotate phenol red color disk until a color match is obtained. Read pH through scale window (below viewing openings).

Table 1: Acceptable and excessive levels of various chemical indicators of water quality (Salvato).

| |Acceptable (mg/L) |Excessive (mg/L) |

|Alkalinity |30-100 |> 500 |

|Carbon dioxide |5-10 |> 10 |

|Color |< 100 |> 100 |

|Fluoride |0.7-1.2 |> 4 |

|Hardness |60-150 |300-500 |

|Iron |0.05-0.1 |> 0.3 |

|Manganese |0.01-0.05 |> 0.05 |

|Ammonia |0.2-2.0 |>2.0 |

|pH |7.0-10.0 |< 7.0, > 10.0 |

Results

Table 1: Results of physicochemical analyses of unknown water sample.

|Group # |#1 |#2 |#3 |#4 |#5 |

|Analysis | | | | | |

|total coliform | | | | | |

|(m-Endo) | | | | | |

|(CFU/100 ml) | | | | | |

|total coliform | | | | | |

|(m-MUG) | | | | | |

|(CFU/100 ml) | | | | | |

|E. coli | | | | | |

|(m-MUG) | | | | | |

|fecal | | | | | |

|coliform (m-FC) | | | | | |

|(CFU/100 ml) | | | | | |

Questions:

1. Why are coliform called indicator microorganisms? What do they indicate? What are the SDWA standards for total coliform in drinking water?

2. Do you see any substantial differences in indicator microorganism concentrations among different types of media (e.g., m-Endo vs. m-MUG)? Why or why not?

3. If your sample turned out to be Too Numerous To Count (TNTC), what should you do to determine the concentrations of indicator microorganisms? What is the appropriate range of Colony Forming Units (CFU’s) on a 50 mm petri dish?

4. If you had an estimated 500 colonies of total coliform per 100 ml of a water sample, what would you do to obtain a range of microorganisms in the correct range? (be specific).

HSC 252 - Water Quality and Treatment

Laboratory Exercise #7: Site Visit to Normal Water Treatment Facility

Objective:

The purpose of this exercise is to provide you with an opportunity to tour a water treatment

facility for a moderate size community with a groundwater source. You should observe, and be able

to list and describe various treatment processes including aeration, coagulation and lime-soda ash softening, filtration, fluoridation, and chlorination. You should also observe laboratory control and data monitoring and recording techniques.

Related information:

Groundwater is pumped from wells in the Normal area.

Cascade aeration releases hydrogen sulfide (rotten-egg smell), and oxidizes iron and manganese.

Clarifiers use alum (AlSO4) as a coagulant, and lime-soda ash as coagulant aids and water softeners.

Recarbonation process adds CO2 to remove excess lime.

Filtration beds use dual media (anthracite and sand.)

Sodium hexametaphosphate (SHMP) is added to water prior to distribution to control corrosion.

Water is routinely monitored for chlorine and fluorine levels, microorganisms (coliform), turbidity, etc.

Procedure:

Students meet in lab and walk to Normal Water Treatment Facility. You should bring

a pad and pencil or pen to take notes to use for preparing for the first lab exam. Use the layout of the plant provided to label each step of the process as we proceed through the treatment facility.

Brief outline of treatment process:

1. Groundwater is pumped from 14 wells into plant.

2. Water is cascaded over aeration disks to remove H2 S, Fe, and Mn.

3. Lime is delivered into water and water is mixed in clarifiers, allowing coagulation and settling of

flocculant (sludge is collected and may be used for land application.)

4. Clarified water is drawn from top of clarifier and recarbonation process restores CO2 levels.

5. Water is passed through gravity forced, dual media filtration beds.

6. Chlorine, fluorine, sodium hexametaphosphate added prior to distribution.

7. Water is distributed to the community.

Description of steps in water treatment process:

1. Aeration: Excessive iron in water can cause reddish-brown discoloration of laundry, water fixtures, and drinking water. Manganese may also cause a brown discoloration. Aeration oxidizes iron and manganese. Free carbon dioxide keeps calcium in solution, contributing to hardness. Carbon dioxide also forms carbonic acid that is corrosive to pipes. Plastic disks retain iron and manganese, while carbon dioxide is released into the atmosphere.

9. Clarification and lime-soda softening: Excessive calcium and magnesium contribute to water

hardness. Lime-soda softening reduces hardness. Soda ash facilitates magnesium removal. Alum is

added to facilitate coagulation and flocculation and reduce pH. The solids contact clarifier introduces

chemicals, mixes, facilitates flocculation, and collects sludge for later removal.

10. Recarbonation: Added carbon dioxide removes excess lime, reduces pH (due to carbonic acid

formation), and prevents additional calcium hardness that may form incrustation of scale in distribution

system.

4. Filtration: Dual media (sand and anthracite) filters remove residual suspended precipitated particulates. Turbidity is monitored as a measure of the efficiency of the filtration process.

5. Chlorination: Chlorine disinfects the treated water prior to distribution to prevent bacterial contamination. Residual chlorine guards against later incidental contamination.

6. Fluoridation: Optimal fluoride concentrations of approximately 1.0 mg/l are established through addition of fluoride (in the form of hydrofluosilicic acid) to water in order to prevent dental caries.

7. Sodium hexametaphosphate: This is used as a corrosion inhibitor that reacts with iron oxides which form a film on the interior of iron pipe. Sodium hexametaphosphate also sequesters iron, manganese, and calcium, preventing deposition of rust or scale.

Questions:

1. What problems are associated with the raw water used at the Normal Water Treatment Facility?

2. How are these problems being addressed?

3. How would you rate the overall quality level of the water produced? Why?

4. Assume a treatment rate of 4,000 gpm. How many gallons of water are treated during a 24 hour period?

How many pounds of lime would be added to reach a concentration of 10 mg/l?

How many pounds of soda ash would be added to reach a concentration of 5 mg/l?

HSC 252 - Water Quality and Treatment

Laboratory Exercise #8: Site Visit to Bloomington Water Treatment Facility

Objective:

The purpose of this exercise is to provide you with an opportunity to tour a water treatment

facility for a moderate size community with a surface water source. You should observe, and be able

to list and describe various treatment processes including clarification (ferric sulfate-lime-polymer, using

various types of clarifiers), and filtration (using activated charcoal.) You should also observe laboratory

control and data monitoring and recording techniques.

Related information:

Surface water is taken from Lake Bloomington and Lake Evergreen.

Clarifiers use ferric sulfate, lime, and cationic polymer to facilitate coagulation and sedimentation.

Recarbonation process adds CO2 to remove excess lime.

Filtration beds use sand and activated charcoal (removes taste and odor components.)

Sodium hexametaphosphate is added to water prior to distribution to control corrosion.

Water is routinely monitored for chlorine and fluorine levels, microorganisms (coliform), and turbidity.

Procedure:

Students meet in Room 102 and drive to Bloomington Lake. You should bring

a pad and pencil or pen to take notes to use in composing a one-page summary of our visit. Use the layout of the plant provided to label each step of the process as we proceed through the treatment facility.

Brief outline of treatment process:

1. Surface water is pumped from Lake Bloomington.

2. Water is mixed with cationic polymer, lime, and ferric sulfate (coagulants and aids).

3. Water is mixed in 5 clarifiers, allowing coagulation and settling of flocculant (sludge is collected and may be used for land application.)

4. Clarified water is drawn from top of clarifier and recarbonation process restores CO2 levels in recarbonation basins (sodium hexametaphosphate also added here.)

5. Water is passed through gravity forced, filtration beds (sand and activated charcoal.)

6. Chloramine and fluoride added prior to distribution.

7. Water is distributed to the community through high service pumps.

Questions:

1. How is the Bloomington Water Treatment Facility different from Normal Water Treatment Facility?

2. What special problems do these differences cause?

3. How is the Bloomington Water Treatment Facility addressing these problems?

4. Assuming a treatment rate of 10,000 gpm, how many gallons of water are treated per day?

How many pounds of chlorine should be added to maintain a total chlorine level of 5 mg/l?

How many pounds of fluoride should be added to maintain a fluoride level of 1.0 mg/l?

HSC 252 - Water Quality and Treatment

Laboratory Exercise #9: Jar Tests for Coagulation, Flocculation, and Sedimentation.

Objective(s):

The purpose of this exercise is to provide you with an opportunity to perform a “jar test” on a water sample to determine appropriate concentrations of coagulants and coagulant aids to maximize precipitation and sedimentation of suspended and dissolved solids in the water sample. After completing this lab, you should be able to describe the processes of coagulation, flocculation, precipitation, and sedimentation as related to chemical coagulants and coagulant aids. You should also be able to conduct a jar test to determine optimum concentrations of coagulants and coagulant aids for a water sample, collect data, and interpret the data generated.

Materials needed:

1. Stirring apparatus.

2. 500-ml beakers (“jars”).

3. Water sample.

4. Standard solutions of coagulants (e.g., aluminum sulfate [alum], and ferrous sulfate).

5. Standard solution of coagulant aid (e.g., lime [calcium oxide]) or polymers.

6. Graduated cylinders for measuring standard solutions.

7. Comparator and phenol red indicator for determining pH.

8. Settleometers (Imhoff cones).

Procedure:

1. Obtain a clean 500-ml beaker and fill with 300 ml of the water sample to be tested. Determine pH (initial) of sample by using comparator (see exercise #3) and record in Table 1 below.

2. Your instructor will tell you which chemical formulation to use (groups #1-6).

a. Group #1 - 5 mg/L alum (aluminum sulfate), 10 mg/L lime (calcium oxide).

b. Group #2 - 10 mg/L alum, 5 mg/L lime.

c. Group #3 - 15 mg/L alum, 2 mg/L lime.

d. Group #4 - 4 mg/L ferrous sulfate, 8 mg/L lime.

e. Group #5 - 16 mg/L ferrous sulfate, 6 mg/L lime.

f. Group #6 - 20 mg/L ferrous sulfate, 15 mg/L lime.

3. For each mg/L required, add 1.0 ml of a 1.0 g/L standard solution to the 300 ml water sample to be tested using a 10-25 ml graduated cylinder (Note: this is an approximate concentration to avoid measuring very small weights of dry chemicals).

5. Determine pH of solution by using comparator. Record pH (final) in Table 1 below.

6. Place beaker under stirring apparatus (Note: stirring paddles can be moved up and down by releasing set screw on top of stirring apparatus). Begin stirring by turning on toggle switch on front of apparatus. Speed should be adjusted to 100 rpm for one minute (using speed adjustment knob on top of apparatus), then reduced to 50 rpm for 20 minutes (make sure all groups start their stirring at the same time).

7. Observe sample for coagulation, precipitation, and flocculation of suspended and dissolved solids during stirring.

8. After stirring period is completed, remove sample from stirrer, transfer to settleometer, and allow to settle for 15 minutes.

9. Measure and record volume of settleable solids (sediment) in ml/L.

Results:

Table 1: Concentrations and weights of coagulants and aids, pH, and settleable solids in water sample.

|Group # |#1 |#2 |#3 |#4 |#5 |#6 |

| | | | | | | |

|Analyses |(alum) |(alum) |(alum) |(FeSO4) |(FeSO4) |(FeSO4) |

|Coagulant | | | | | | |

|(1.0 g/L standard solution volume | | | | | | |

|in ml) | | | | | | |

|Lime | | | | | | |

|(concentration) | | | | | | |

|Lime | | | | | | |

|(1.0 g/L standard solution volume | | | | | | |

|in ml) | | | | | | |

|pH (initial) | | | | | | |

| | | | | | | |

|pH (final) | | | | | | |

| | | | | | | |

|Settleable solids | | | | | | |

|(ml/L) | | | | | | |

Questions:

1. What function does a coagulant serve in water treatment? Name two other coagulants (other than those used in this lab).

2. What function does a coagulant aid serve in water treatment? What is the relationship between lime concentration and pH? Name two other coagulant aids (other than that used in this lab).

4. What function does the stirring apparatus serve in treating the water? Why were two speeds used?

5. Which coagulant concentration was most efficient for each coagulant? Which concentration of coagulant aid was most efficient? Which combination of coagulant and aid was most efficient?

Would this be true for every water sample? Explain why or why not.

6. Relate the steps in a water treatment facility to the steps used in lab. Why is a jar test useful? Are

there any problems with the data generated by a jar test, or is it always completely reliable? Why?

7. How many pounds of alum would be necessary to treat 5.0 MGD at a concentration of 5.0 mg/L?

HSC 252 - Water Quality and Treatment

Laboratory Exercise #10: Chlorine Analyses of Water

Objective(s):

The purpose of this exercise is to provide you with an opportunity to perform several different

types of analyses for chlorine in an unknown water sample. Total, free, and combined chlorine levels

will be determined using several different methods. Chlorine level determination will be made using

three different comparators: Hach, Hellige, and Taylor. The Hach colorimeter will be used to determine

chlorine levels. The amperometric titration method may also be used to determine chlorine levels. Upon

completing this exercise, you should be able to define total, free, and combined chlorine and conduct

several different types of chlorine analyses on water samples given the appropriate equipment, supplies,

and instructions.

Analyses conducted and supplies provided at each station:

1. DPD (N, N-Diethyl-p-Phenylenediamine) method, using Hach comparator: Water sample, Hach comparator, titration flask, comparator tubes (2), 25-ml graduated cylinder, DPD powder pillows for total and free chlorine determination, placemat.

2. DPD method, using Hellige comparator: Water sample, Hellige comparator (with DPD color disc),

comparator tubes (2), plastic stirring rod, titration flask, 25-ml graduated cylinder, DPD tablets #1, 2, 3, 4, placemat.

3. DPD method, using Hach direct-reading colorimeter: Water sample, Hach colorimeter, colorimeter bottles (2), plastic stirring rod, 25-ml graduated cylinder, titration flask, DPD free and total chlorine reagents (powder pillows).

4. DPD method, using Taylor liquid DPD chlorine reagent: Water sample, Taylor comparator, Taylor comparator tubes (2), stirring rod, DPD liquid reagents #1, 2, 3.

5. Amperometric titration (digital): Water sample, digital amperometric titration unit, beaker for

sample, buffer solutions (pH 4.0, 7.0), phenylarsene oxide (PAO) titrant cartridge, potassium iodide

powder pillows.

Procedure(s):

Students should work in pairs and proceed from station to station, collecting and recording data.

1. DPD (N, N-Diethyl-p-Phenylenediamine) method, using Hach comparator.

a. Place chlorine DPD method disc into comparator.

b. Add 25-ml of water sample to titration flask.

c. Add one DPD total chlorine reagent powder pillow (swirl to mix.) Red color indicates presence of chlorine.

d. Transfer sample to comparator tube, filling to 10-ml mark, place in right-hand opening.

e. Place 10-ml of untreated water sample in other comparator tube and insert into other opening.

f. Compare colors and rotate disc until a color match is obtained. Read total chlorine in mg/l.

g. Repeat above using DPD free chlorine reagent. Read results as free chlorine in mg/l.

h. Determine combined chlorine by subtracting free chlorine from total chlorine in mg/l.

2. DPD method, using Hellige comparator.

a. Repeat above procedure using Hellige comparator and 10-ml water sample.

b. Determine free chlorine by using DPD reagent #1 (free chlorine) tablet first (crush tablet to mix.)

c. Using same sample as above, determine total chlorine by adding DPD reagent tablet #3 (total Cl).

d. Determine combined chlorine by the determining the increase in color from #1 to #3.

e. Also determine combined chlorine by using 1 DPD reagent tablet #4 (combined Cl).

f. Determine monochloramine chlorine by using 1 DPD tablet #2 (monochloramine form).

3. DPD method, using Hach direct-reading colorimeter.

Free chlorine determination:

a. Fill a 10-ml colorimeter bottle with 10-ml of untreated water (blank).

b. Turn on power on colorimeter.

c. Press UP ARROW key until display reads program number 52.06.1.

d. Place blank in cell holder, close top, and press ZERO (display will count down to zero, then show 0.00 mg/l and zero prompt will turn off).

e. Place a 25-ml sample of water to be tested into a clean titration flask.

f. Add the contents of 1 DPD free chlorine powder pillow and swirl to mix.

g. Transfer 10-ml of prepared sample to a 10-ml colorimeter bottle.

h. Place 10-ml prepared sample into cell holder, close top, and press READ button.

i. Free chlorine is displayed in mg/l.

Total chlorine determination:

a. Complete steps (a.) through (d.) above (set program number to 52.07.1).

b. Place a 25-ml sample of water to be tested into a clean titration flask.

c. Add the contents of 1 DPD total chlorine powder pillow, swirl for 20 seconds, then wait 3 minutes.

d. Transfer 10-ml of the prepared sample to a 10-ml colorimeter bottle (round).

e. Place 10-ml prepared sample into cell holder, close top and press READ button.

f. Total chlorine is displayed in mg/l.

Combined chlorine determination:

a. Subtract free chlorine concentration from total chlorine concentration in mg/l.

4. DPD method, using Taylor liquid DPD chlorine reagents.

a. Fill Taylor sample tube to mark with water to be tested.

b. Add 5 drops liquid DPD reagent #1, mix by stirring with stir rod.

c. Add 5 drops liquid DPD reagent #2, mix by stirring with stir rod.

d. Compare color immediately and report as free available chlorine in mg/l.

e. Using same sample as in above, add 5 drops liquid DPD reagent #3, mix with stir rod.

f. Compare color and report as total chlorine in mg/l.

g. Subtract free chlorine from total chlorine and report as combined chlorine in mg/l.

5. Amperometric titration (using digital amperimetric titrator).

1. Free chlorine

a. Gently add 200-ml of water sample to be tested to the clean beaker on the beaker stand using a

clean graduated cylinder. Note: probe and delivery tube should extend into the sample to be tested.

b. Add 1.0-ml (20 drops) of pH 7.0 Phosphate Buffer Solution.

c. Set delivery tube counter to zero and adjust the LED digital readout on the Digital Amperometric

Titrator to 1.00.

d. Using the Digital Titrator delivery knob, dispense the titrant in small increments of 5-10 digits.

Note: the readings on the LED digital readout should decrease.

e. Continue to titrate slowly until the reading does not decrease further.

e. At the lowest reading on the LED digital display, record the corresponding digits on the Digital

Titrator. Note: the LED display reading may increase slightly after reaching it’s lowest point – so

record the Digital Titrator Digits regularly.

f. Calculate the mg/L of free chlorine using the following formula:

Digits at end-point X 0.01 = mg/L free chlorine as Cl2.

2. 2. Total chlorine

a. Gently add 200-ml of water sample to be tested to the clean beaker (clean) on the beaker stand using

a clean graduated cylinder. Note: probe and delivery tube should extend into the sample to be tested.

b.Add the contents of one Potassium Iodide powder pillow to the beaker and swirl to dissolve.

c. Add 1.0-ml of pH 4.0 Acetate Buffer Solution.

c. Set delivery tube counter to zero and adjust the LED digital readout on the Digital Amperometric

Titrator to 1.00 (allow to stabilize before proceeding).

d. Using the Digital Titrator delivery knob, dispense the titrant in small increments of 5-10 digits.

Note: the readings on the LED digital readout should decrease.

e. Continue to titrate slowly until the reading does not decrease further. Note: the LED display reading

may increase slightly after reaching it’s lowest point – so record the Digital Titrator Digits regularly

as they decrease. Record at least three points on the downward curve and three points after reaching

the lowest point.

f. Record the corresponding digits on the Digital Titrator at the lowest reading on the LED digital display.

g. The mg/L of total chlorine corresponds to the Digital Titrator digit reading at it’s lowest point.

h. The combined chlorine is determined by subtracting the free chlorine from the total chlorine,

and is reported in mg/l.

Results: Total, combined, and free chlorine levels as determined by Hach, Hellige, and Taylor comparators, Hach colorimeter, and Digital Amperometric Titration.

|Group # |# 1 |# 2 |# 3 |# 4 |# 5 |# 6 |#7 |

| 1. Hach - | | | | | | | |

| Total Chlorine | | | | | | | |

| Combined Chlorine | | | | | | | |

| Free Chlorine | | | | | | | |

| 2. Hellige - | | | | | | | |

| Total Chlorine | | | | | | | |

| Combined Chlorine | | | | | | | |

| Free Chlorine | | | | | | | |

| 3. Taylor - | | | | | | | |

| Total Chlorine | | | | | | | |

| Combined Chlorine | | | | | | | |

| Free Chlorine | | | | | | | |

|B. Colorimeter | | | | | | | |

| Hach - | | | | | | | |

| Total Chlorine | | | | | | | |

| Combined Chlorine | | | | | | | |

| Free Chlorine | | | | | | | |

|C. Amperometric | | | | | | | |

|titration | | | | | | | |

| Total Chlorine | | | | | | | |

| Combined Chlorine | | | | | | | |

| Free Chlorine | | | | | | | |

HSC 252: Water Quality and Treatment

Questions: Chlorine lab - 4 points each (20 points total)

1. Were results for different types of analyses consistent? Were results from different groups and labs consistent? Why or why not?

2. What is breakpoint? Why is it important?

3. What types of chloramines are formed by chlorination in the presence of ammoniacal compounds? What else is formed if organic matter is present?

4. If your total chlorine were 5 ppm and your free chlorine 2 ppm, what would you expect your combined chlorine levels to be (include the equation)?

5. How many pounds of total chlorine would you have to add to a 5 million gallon clear well to ensure a free residual chlorine of 0.5 ppm if the combined chlorine levels have been at about 2 ppm?

HSC 252 - Water Quality and Treatment

Laboratory Exercise #11: Site Visit to Horton Pool.

Objective:

The purpose of this exercise is to provide you with an opportunity to tour a water treatment

facility for an indoor pool facility. You should observe, and be able to list and describe various treatment

processes including pressure sand filtration, soda ash pH adjustment, and chlorination. You should also

observe data monitoring techniques (e.g., Taylor chlorine and pH determinations, ORP meter).

Related information:

Volume of the pool is 220,000 gallons.

Maximum bather load is 334 persons.

Clarification process uses six high-rate pressure sand filters housed in fiberglass shells.

When filtering at 613 gpm, the turnover rate is six hours, when filtering at 736 gpm, the turnover rate is five hours (turnover rate = volume of the pool divided by the filtration rate, and must be less than six hours).

Head loss on filters is measured by pressure gauges (on top of filters). A loss of 6 to 7 feet of head indicates backwashing is necessary. Backwash rates are 15 gpm/sq. Ft. Wastewater goes to sewers.

Chlorine gas is introduced to disinfect water. Free residual chlorine levels will be determined by the Taylor method.

pH is lowered by chlorine addition, so soda ash is added to counteract the acidity.

Procedure:

Students meet in the lab and walk to Horton pool.

Brief outline of treatment process (see outline on back of sheet):

1. Water is pumped into pool from city water supply.

2. Make-up tank is filled to provide water to supplement water loss (evaporation, etc.) Normally, water is recycled from pool and little additional water is needed.

3. Hair catcher strains out hair, bandages, etc. that could damage pumps.

4. Dual (alternating) pumps supply water to pressure sand filters (inlet at top, outlet at bottom). Flow rate monitor determines turnover rate. pH and chlorine levels are determined by an automatic monitoring device (Strantrol(). Chlorine is monitored indirectly by redox potential (conversion chart needed).

5. Water is heated if necessary. Temp. range of water should be ( about 5 degrees F. ambient air temp.

6. Chlorine is added by aspiration effect of water drawn through supply pipes (shuts down automatically if no water is drawn through pipes to prevent excess chlorination).

7. pH is readjusted to about 7.4 using soda ash addition (for comfort purposes).

Questions:

1. Compare the treatment systems for drinking water and pool water. How are they similar?

How are they different?

2. What should the pH of the pool water be? Why?

3. What should the free chlorine levels in the pool be in mg/L? How does this compare to levels in drinking water? Why are they different?

4. Assume that the volume of a pool is 200,000 gallons, the incoming water free chlorine level is

0.2 mg/l, and the pH is 9.0.

Assume that the flow rate is 650 gpm. What is the turnover rate in hours? Is this acceptable?

Assuming the municipal water has 0.2 ppm free chlorine, how many pounds of chlorine should be added to bring the free chlorine level to 0.7 mg/l?

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