A practical guide to particle counting for drinking water treatment

212 Pages·2001·5.912 MB·English

by  Mike Broadwell

A Practical Guide to
Particle Counting
for
Drinking Water
Treatment
© 2001 by CRC Press LLC
A Practical Guide to
Particle Counting
for
Drinking Water
Treatment
Mike Broadwell
LEWIS PUBLISHERS
Boca Raton London New York Washington, D.C.
© 2001 by CRC Press LLC
L1306/frame/front matter Page iv Friday, June 23, 2000 1:36 PM
Library of Congress Cataloging-in-Publication Data
Broadwell, Mike
A practical guide to particle counting for drinking water treatment/Mike Broadwell.
p. cm.
Includes index.
ISBN 1-56670-306-9 (alk. paper)
1. Particle counting (Water treatment plants)
2. Drinking water — Purification. I. Title.
TD368 .B76 2000
628.1′62—dc21 00-032265
CIP
This book contains information obtained from authentic and highly regarded sources. Reprinted material
is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable
efforts have been made to publish reliable data and information, but the author and the publisher cannot
assume responsibility for the validity of all materials or for the consequences of their use.
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or mechanical, including photocopying, microfilming, and recording, or by any information storage or
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Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are
used only for identification and explanation, without intent to infringe.
© 2001 by CRC Press LLC
Lewis Publishers is an imprint of CRC Press LLC
No claim to original U.S. Government works
International Standard Book Number 1-56670-306-9
Library of Congress Card Number 00-032265
Printed in the United States of America 1 2 3 4 5 6 7 8 9 0
Printed on acid-free paper
© 2001 by CRC Press LLC
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Preface
Particle counting is one of the most exciting and important technologies in
drinking water treatment. Its benefits far outweigh the problems encountered when
any relatively new technology is introduced into a new area of application.
It is my intent to provide in this book a comprehensive yet practical guide to
understanding the technology of particle counting and its application to drinking
water treatment — a book that will be useful to the plant operator as well as the
consulting engineer who has to specify the equipment and incorporate it into the
overall plant design.
The book consists of three parts. The first provides a broad overview of particle
counting, including the basic principles of operation, applications in the treatment
process, and the fundamentals of installation, operation, maintenance, data collec-
tion, and system integration.
Part II covers equipment specifications in detail. It provides the information nec-
essary to make intelligent choices when selecting equipment for a given application.
Part III presents equipment currently available on the market, assessed in terms
of the material covered in Parts I and II. It provides comparisons based on the
technical specifications covered in Part II.
The necessary information is provided within these pages for making an
informed, intelligent choice when selecting a particle counting system, and a guide
for using the technology to the greatest benefit.
Mike Broadwell
Atlanta, Georgia
© 2001 by CRC Press LLC
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About the Author
Mike Broadwell has over 12 years experience in water treatment instrumentation
and control, specializing in particle counting. He worked for two of the leading
particle counter manufacturers as field applications engineer and product manager
for drinking water treatment, during which time he worked with treatment plants
and consulting engineers in all but a half dozen states in the U.S.
In addition to extensive field experience, he has directed the development of a
line of particle counting equipment from inception, including some of the circuit
design and engineering.
Mr. Broadwell provides independent consultation for particle counting technol-
ogy and its application to drinking water treatment as well as marketing consultation
for process instrumentation. He holds a degree in electrical engineering from the
Georgia Institute of Technology.
Mr. Broadwell maintains a presence on the internet at www.ParticleCount.com.
© 2001 by CRC Press LLC
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Table of Contents
Part I
Chapter 1 Particle Counting Basics
A. What is a Particle Counter?.......................................................................3
1. Particle Counters vs. Particle Sizers....................................................3
2. Types of Particle Counters...................................................................4
a. Light-Based Particle Counters.........................................................4
b. Electrical Conductivity Particle Counters.......................................4
B. Principles of Operation..............................................................................4
1. Light-Based Instruments.......................................................................4
a. Light-Scattering Sensor...................................................................4
b. Light-Blocking Sensor.....................................................................5
c. The Rest of the System...................................................................7
2. Conductivity-Based Instruments..........................................................9
C. Familiar Ground.......................................................................................10
1. Turbidimeters......................................................................................11
a. Relative Measurement...................................................................11
b. Absolute Measurement..................................................................11
2. Turbidimeter Operation......................................................................12
3. Particle Counters and Turbidimeters..................................................13
a. Similarities.....................................................................................13
b. Differences.....................................................................................13
4. Particle Counters and Turbidimeters Are Complementary................14
D. Grab Sample or Continuous Online?......................................................14
Chapter 2 Applications for Drinking Water Treatment
A. Why Use Particle Counters for Drinking Water Treatment?..................15
B. Cryptosporidium and Giardia.................................................................16
C. Particle Counters and Cryptosporidium and Giardia.............................16
D. Surrogate Measurement...........................................................................17
E. Log Removal............................................................................................18
F. Improving Filter Performance.................................................................19
1. Filter Run Time..................................................................................21
G. Process Optimization...............................................................................23
1. Flocculation.........................................................................................25
2. High Rating Filters.............................................................................26
H. Process Applications................................................................................26
1. Conventional Treatment......................................................................26
2. Direct Filtration..................................................................................27
3. Pilot Plants..........................................................................................27
4. Membrane Plants................................................................................28
5. Packaged Treatment Plants.................................................................29
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I. Groundwater............................................................................................29
J. Wastewater Applications..........................................................................29
1. Tertiary Treatment..............................................................................30
2. Reuse...................................................................................................30
3. Ultraviolet (UV) Disinfection.............................................................30
Chapter 3 Installation, Operation, and Maintenance
A. Choosing Proper Sample Locations........................................................31
1. Representative Sample........................................................................32
2. Short Sample Lines............................................................................33
3. Sample Line Materials........................................................................33
4. Valves, Pumps, and Manifolds...........................................................33
5. Temporary or Shared Sample Locations............................................34
6. Practical Considerations.....................................................................35
B. Sample Flow............................................................................................35
1. Maintaining Constant Head................................................................35
2. Mounting the Constant-Head Overflow Weir for Best Operation.....37
3. Other Flow Devices............................................................................37
a. Direct-Reading Rotometers...........................................................37
b. Low-Flow Detector........................................................................38
c. Electronic Flowmeters...................................................................38
d. Determining the Best Approach....................................................39
C. Operation and Maintenance.....................................................................40
1. Maintenance Schedule........................................................................40
2. Unscheduled Maintenance Problems.................................................41
3. Maintenance Log................................................................................41
4. Maintenance Checklist.......................................................................42
5. Flow Maintenance..............................................................................42
6. Cleaning..............................................................................................43
a. Coatings on Flow Cell Windows...................................................43
b. Clogs and Flow Cell Obstruction..................................................43
7. Maintaining Sample Tubing...............................................................44
8. Strainers..............................................................................................45
9. Pilot Plants and Other Special Applications......................................45
D. Calibration................................................................................................46
1. Particle Counter Calibration...............................................................46
2. Particle Counter Calibration Verification...........................................47
3. Maintaining Calibration......................................................................47
Chapter 4 Collecting Data
A. Data Collection........................................................................................50
B. Data Presentation.....................................................................................51
1. Trend Display.....................................................................................51
2. Trend Particle Counters with Other Plant Data.................................52
3. Other Data Displays...........................................................................52
4. Data Reporting....................................................................................52
5. Historical Data....................................................................................52
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C. System Structure......................................................................................53
1. Turnkey System..................................................................................53
2. Turnkey System with Additional Inputs............................................54
3. Particle Counter Tied Directly to the Plant SCADA System............54
a. Particle Counters Integrated Directly into SCADA......................54
b. Hybrid Approaches........................................................................56
4. 4 to 20 mA Problems Current Loops.................................................57
a. Digital vs. Analog..........................................................................57
b. Specific Sources of Error in 4 to 20 mA Current Loops.............58
c. Special 4 to 20 mA Problems in Particle Counting.....................58
Chapter 5 Grab Sampling
A. Particle Counter Grab-Sampler Operating Principles.............................61
B. Grab-Sample Particle Counting vs. Online Counting.............................62
1. Reasons for Choosing Grab Samplers Over
Online Particle Counters....................................................................62
2. Drawbacks to Grab-Sample Particle Counting..................................63
a. Sample Handling...........................................................................63
b. Grab Sampling Presents a Partial Picture.....................................64
c. Data Handling................................................................................64
3. Benefits of Grab Samplers.................................................................64
4. Alternatives to Grab Sampling...........................................................65
C. Grab-Sampler Sample Handling.............................................................65
1. Sample Preparation.............................................................................66
2. Sample Storage and Shipping............................................................66
3. Running the Sample...........................................................................67
4. Sample Dilution..................................................................................67
a. Concentration Limits of the Particle Counter...............................68
b. Dilution Test..................................................................................68
c. Diluents and Background Counts..................................................69
D. Data Handling..........................................................................................70
E. Preparing a Workable Approach..............................................................70
1. Operator Training...............................................................................70
2. Procedures...........................................................................................71
3. Data Presentation................................................................................71
4. Preventing Entropy.............................................................................71
5. Maintaining a Consistent Sampling Pattern.......................................71
F. Conclusion...............................................................................................71
Part II
Understanding the Technology
Chapter 6 Specifications
A. Sensitivity................................................................................................75
B. Signal-to-Noise Ratio..............................................................................75
C. Resolution................................................................................................77
D. Coincidence..............................................................................................77
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E. Sizing Range............................................................................................78
F. Sample Flow Range.................................................................................78
G. Flow Cell Dimensions.............................................................................79
H. Volumetric................................................................................................79
Chapter 7 Particle Sensor Construction
A. Flow Cell.................................................................................................81
B. Cell Windows...........................................................................................81
C. Sample Fittings........................................................................................82
D. Laser/Optical Assembly...........................................................................83
Chapter 8 Particle Counter Electronics
A. Laser Driver.............................................................................................85
B. Detector Circuit.......................................................................................85
C. Counting Electronics...............................................................................86
1. Voltage Comparator............................................................................87
2. Setting Comparator Size Thresholds..................................................89
3. Analog-to-Digital Conversion............................................................89
4. Pulse Height Analysis.........................................................................90
D. Power Supply...........................................................................................90
Chapter 9 Auxiliary Features
A. Diagnostic Signals, Alarms, and Displays..............................................93
B. Sample Flow Regulation.........................................................................94
C. Analog Inputs..........................................................................................94
D. Discrete Inputs.........................................................................................95
E. Analog Outputs........................................................................................95
1. 4 to 20 mA Basics..............................................................................95
2. Signal Power and Isolation.................................................................96
3. Output Scaling....................................................................................96
F. Discrete Outputs......................................................................................97
G. Enclosure..................................................................................................97
Chapter 10 Serial Data Output
A. Basics of Serial Communications...........................................................99
B. Definitions..............................................................................................100
C. SCADA Interface...................................................................................101
D. Particle Counter Communication Protocol...........................................102
1. Data Configuration...........................................................................102
2. Timing and Control..........................................................................102
3. Remote Programming.......................................................................103
E. Communications Drivers.......................................................................103
F. Sorting Out the Options........................................................................104
1. Dynamic Data Exchange (DDE)......................................................104
2. Networked File Sharing...................................................................104
3. Central Controller Unit....................................................................105
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Chapter 11 Computerized Data Collection
A. Computer Basics....................................................................................107
1. Platforms...........................................................................................107
2. Operating Systems............................................................................107
3. Processor...........................................................................................108
4. Memory.............................................................................................108
5. Storage Media...................................................................................109
a. Hard Disk.....................................................................................109
b. Floppy Diskette............................................................................109
c. CD ROM......................................................................................110
d. Other Permanent Storage Media.................................................110
6. Communications Ports......................................................................110
a. Serial Port....................................................................................110
b. Parallel Port.................................................................................111
c. Network Card...............................................................................111
d. USB..............................................................................................111
7. Additional Components....................................................................112
a. Motherboard.................................................................................112
b. Mouse and Keyboard...................................................................112
c. Display.........................................................................................113
d. Modem.........................................................................................113
B. Computer Requirements for Particle Counting Systems......................113
1. Computer Selection Guidelines........................................................114
a. Purpose.........................................................................................114
b. Performance.................................................................................114
c. Computer Brand...........................................................................115
2. Recommended Computer for Particle Counting Systems...............115
a. Power Conditioning.....................................................................116
b. Operating System........................................................................116
c. Computer Components................................................................116
d. Backup.........................................................................................116
e. Support Software.........................................................................117
f. Modem..........................................................................................117
g. Networking..................................................................................117
C. Data Management..................................................................................117
1. Reporting...........................................................................................118
D. Upgrading Equipment and Software.....................................................119
E. Networking and Remote Communications...........................................120
Chapter 12 Putting It All Together
A. The Treatment Plant..............................................................................121
1. Size and Future Plans.......................................................................121
2. Staff...................................................................................................122
3. Treatment Process.............................................................................122
B. Equipment Features...............................................................................122
1. Packaging..........................................................................................123
© 2001 by CRC Press LLC