Fats, Roots, Oils, and Grease in Centralized and Decentralized Systems: Werf Report 03-cts-16t

261 Pages·2009·44.418 MB·English

by  Joel J. Ducoste, Kevin M. Keener, John W. Groninger

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03-CTS-16T
FATS, ROOTS, OILS, AND GREASE
(FROG) IN CENTRALIZED AND
DECENTRALIZED SYSTEMS
by:
Joel J. Ducoste
North Carolina State University
Kevin M. Keener
Purdue University
John W. Groninger
Southern Illinois University
Leon M. Holt
Town of Cary
2008
"'WERF
The Water Environment Research Foundation, a not-for-profit organization, funds and manages water quality
research for its subscribers through a diverse public-private partnership between municipal utilities, corporations,
academia, industry, and the federal government. WERF subscribers include municipal and regional water and
wastewater utilities, industrial corporations, environmental engineering firms, and others that share a commitment to
cost-effective water quality solutions. WERF is dedicated to advancing science and technology addressing water
quality issues as they impact water resources, the atmosphere, the lands, and quality of life.
For more information, contact:
Water Environment Research Foundation
635 Slaters Lane, Suite 300
Alexandria, VA 22314-1177
Tel: [phone]
Fax: [phone]
www.werf.org
[email protected]
This report was co-published by the following organization. For non-subscriber sales information, contact:
IWA Publishing
Alliance House, 12 Caxton Street
London SWIH OQS, United Kingdom
Tel: [phone]
Fax: [phone]
www.iwapublishing.com
[email protected]
Copyright 2008 by the Water Environment Research Foundation. All rights reserved. Permission to copy must be
o©b tained from the Water Environment Research Foundation.
Library of Congress Catalog Card Number: 2008924498
Printed in the United States of America
IWA P ISBN: 978-184339-523-211-84339-523-1
This report was prepared by the organization(s) named below as an account of work sponsored by the
Water Environment Research Foundation (WERF). Neither WERF, members of WERF, the
organization(s) named below, nor any person acting on their behalf: (a) makes any warranty, express or
implied, with respect to the use of any information, apparatus, method, or process disclosed in this
report or that such use may not infringe on privately owned rights; or (b) assumes any liabilities with
respect to the use of, or for damages resulting from the use of, any information, apparatus, method, or
process disclosed in this report.
North Carolina State University
This document was reviewed by a panel of independent experts selected by WERF. Mention of trade names or
commercial products does not constitute WERF nor endorsement or recommendations for use. Similarly, omission
of products or trade names indicates nothing concerning WERF's positions regarding product effectiveness or
applicability.
ii
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ACKNOWLEDGMENTS
The authors of this report are indebted to the following water utilities, companies, and
individuals for their cooperation and participation in this project:
Town of Cary, NC.
• Oxford Tobacco Research Station, NC
• Carolina Classic Manufacturing, Inc.
• Wilkes Enterprise, Inc
• Duke Roots, Inc.
• RootX Root Control Corp
• Solutions-IES
•
Research performed at North Carolina State University (NCSU) could not have been
accomplished without the help of students and lab technicians. Tarek Aziz, a Ph.D. candidate at
the time of this research, was responsible for a significant portion of the lab work. The principal
investigators (PIs) would also like to thank Barbara Oslund and Heather Markell from Solutions­
IES for the development, administration, and analysis of the FOG and ROOTs survey.
The root study research carried out at Oxford Tobacco Research Station could not have
been possible without the help of students and laboratory staff. Students that have worked to
setup the roots control pilot system include Colleen Bowker, Liz Dinatale, Ojochide Idichaba,
Akinawale Omofoye, and Justin Woods. The PIs are indebted to Dennis Metcalf from NCSU and
Fred Smith and his team at the Oxford Tobacco Research Station for the construction of the pilot
system and maintaining the green house for proper tree growth.
The PIs would like to thank Mike Hogan and Duke Roots Inc. for the treatment chemicals
and sending a treatment team to apply their product to the roots at the pilot system. Many thanks
also to Pat Monaghan of RootX Root Control Corp. for donating their chemical treatment
product for the root control study in this research project. The project team would also like to
thank the following cities, counties, sewer districts, and authorities for sending in FOG deposit
samples:
Pima County, AZ Ashville, NC
Anaheim, CA Charlotte, NC
Fullerton CA Gastonia, NC
Redding, CA Hendersonville, NC
San Jose, CA Greenville, SC
St. Petersburg, FL Nashville, TN
Libertyville, IL Fort Worth, TX
Glasgow, KY Salt Lake City, UT
Grand Rapids, MI Richland, W A
Springfield, MO Tacoma,. WA
Great Falls, MT Vancouver, WA
Fats, Roots, Oils, and Grease in Centralized and Decentralized Systems iii
Report Preparation
Principal Investigators:
Joel J. Ducoste, Ph.D., North Carolina State University
Kevin M. Keener, Ph.D., Purdue University
John W. Groninger, Ph.D., Southern Illinois University
Project Subcommittee
Mary Lappin, P.E. RC Liaison, Kansas City Water Services Department
Mark Kawamoto, P.E. PSC Chair, Orange County Sanitation District
Philip Friess, County Sanitation Districts of Los Angles County
Gayle Tupper, East Bay Municipal Utility District
Kevin Sherman, Florida Onsite Wastewater Association
Hugh T. Garrison, Metro Water Services, Nashville
Charles Vanderlyn, P.E., EPA
Us.
Steering Subcommittee
Frank Brockman, Cobb County
Ben Horenstien, East Bay Municipal Utilities District
Mike Dunbar, South Coast Water District
John Redner, PE, County Sanitation Districts of Los Angles County
Jim Peters, PE, DEE, Florida Water Environment Association Utility Council
Quyen Tram, PE, Toho Water Authority
Brian Wheeler, Toho Water Authority
Nick Arhontes, PE Orange County Sanitation District
Terrie Mitchell, Sacramento Regional County Sanitation District
Drew Mihocko, City of Philadelphia Water Department
Tim McKim, PE, Reedy Creek Energy Services
Adel Hagekhalil, City of Los Angeles
Christine Mikulice, County of San Francisco Water Pollution Control
Gail Chester, Ph.D., PE, Central Contra Costa Sanitary District
Brett Goodman, Gainesville Regional Utility
Rick Oliver, Jensen Precast
Water Environment Research Foundation
Director of Research Daniel M. Woltering, Ph.D.
Senior Program Director: Amit Pramanik, Ph.D., BCEEM
Program Director: Lauren Fillmore
Program Manager: Jane Caste line
iv
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ABSTRACT AND BENEFITS
Abstract:
Fats, oil, and grease (FOG) are generated every day by food preparation and cleaning
activities at commercial establishments and, on a smaller scale, by residential sewer customers.
Another common problem -- known to all plumbing and utility maintenance personnel -- is dense
mats of root hair in sewer lines. As the mat forms, the slower wastewater flow exacerbates the
rate of accumulation and promotes the deposit of FOG materials onto pipe walls, thereby further
reducing capacity. FOG or root accumulations in the sanitary sewer collection system, ifnot
periodically cleaned, result in reduced capacity that may lead to sanitary sewer overflows (SSO).
Analyzing the chemical and physical makeup of FOG deposits in the sewer collection
system is a crucial step in determining what compounds should be limited in the effluent
discharge of grease interceptors. This report identifies the major chemical constituents and
physical characteristics of FOG deposits retrieved from sewer collection systems across EPA
regions. The researchers measured total oil and grease, metals and mineral content; they
compiled shear and compressive strength data; and they developed fatty acid profiles. In
addition, researchers performed surface chemistry analyses on sewer pipes and tree roots to
determine if there is a preferential deposition of FOG on specific surface types.
Based on the analyses, the researchers characterized FOG deposit formation as similar to
the formation of soaps through fat saponification. In the maj ority of the deposits, unsaturated
fatty acids are not a major contributor to FOG blockages.
The invasion of sewer pipes by tree roots presents a major cost to the utilities and to
private property owners. When a root encounters sewer pipe conditions (high moisture and
nutrients), the root system tends to envelope that section of sewer pipe, particularly when the
surrounding soils are poor in nutrients or low in water content. Roots grow by elongation, which
allows them to enter small openings in sewer joints and cracks.
Municipalities currently utilize root control practices involving chemical or mechanical
methods. This report compares two of those chemical root control methods and a mechanical
control method. Researchers tested root control in a pilot-scale sewer system that included three
types of trees. They performed surface roughness and polarity measurements of common piping
materials, examined different tree root material and determined the impact of root-types on
preferential deposition of FOG in the sewer mains.
Benefits:
Characterizes the chemical and physical makeup of FOG deposits in collection systems.
•
Presents a hypothesis that FOG deposits are formed primarily by saponification and are
• metal soaps.
Determines if different piping and root-type materials have different susceptibility to
• blockages caused by FOG.
Identifies the best root control methods to reduce root intrusions in sewer systems.
•
Keywords: Fats, oils, grease, FOG, soaps, root intrusion, sewer system, blockage, sanitary sewer
overflows, SSO, root control, operation & maintenance, O&M.
Fats, Roots, Oils, and Grease in Centralized and Decentralized Systems v
TABLE OF CONTENTS
Acknowledgements ........................................................................................................................ iii
Abstract and Benefits .......................................................................................................................v
List of Tables ............................................................................................................................... viii
List of Figures ix
................................................................................................................................
Executive Summary ...................................................................................................................E S-1
1.0 Introduction 1-1
..................................................................................................................
1.1 Background 1-1
..........................................................................................................
1.2 Significance to Wastewater Utilities 1-2
....................................................................
1.3 Literature Review 1-2
.................................................................................................
1.4 Research Scope and Objectives 1-5
...........................................................................
2.0 Survey Assessment of Pretreatment Coordinators ..................................................... 2-1
2.1 Survey Assessment of Pretreatment Professionals 2-1
..............................................
2.2 Survey Development 2-1
............................................................................................
2.3 Survey Distribution 2-1
..............................................................................................
2.4 Sample Requests 2-2
..................................................................................................
2.5 Data Compilation 2-2
.................................................................................................
2.6 Survey Assessment Results 2-3
..................................................................................
2.7 Implications of Survey Results 2-11
..........................................................................
3.0 ................................................................................................... 3-1
Material and Methods
3.1 FOG Deposit Measurement Methods 3-1
..................................................................
3.2 Measurement of Surface Roughness and Polarity of Piping and Root Material.. 3-2
..
3.3 Application of Root Control Methods 3-6
.................................................................
3.4 Surface characterization Methods 3-16
......................................................................
4.0 Characterization of Fog Deposits in Sewer Collection Systems ................................ 4-1
4.1 Introduction 4-1
..........................................................................................................
4.2 Physical Properties of FOG Deposits 4-2
..................................................................
4.3 Moisture Content and Elemental Fatty Acid Composition in FOG Deposits 4-2
......
4.4 Mineral and Metal Composition of FOG Deposits 4-5
..............................................
4.5 Summary of FOG Deposit Results 4-7
......................................................................
vi
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5.0 Evaluation of Surface Characteristics 5-1
.........................................................................
5.1 Assessment of Surface Roughness and Surface Polarity of Black Willow
Tree Roots 5-1
............................................................................................................
5.2 Assessment of Surface Roughness and Surface Polarity of PVC Pipe MateriaL .. 5-2
5.3 Summary of Surface Characteristics Results ....................................................... 5-4
6.0 Assessment of Root Control Method on Root Regrowth ........................................... 6-1
6.1 Introduction .......................................................................................................... 6-1
6.2 Observation of Root Growth in Pilot System ...................................................... 6 1
-
6.3 Evaluation of Root Control Methods 6-5
...................................................................
6.4 Summary of Root Control Method ...................................................................... 6-6
7.0 Conclusions and Recommendations 7-1
.............................................................................
7.1 Conclusions 7-1
..........................................................................................................
7.2 Future Research Considerations 7-1
..........................................................................
References R-l
....................................................................................................................................
Appendix A: Survey Questions .................................................................................................. A-I
Fats, Roots, Oils, and Grease in Centralized and Decentralized Systems vii
LIST OF TABLES
1-1 Grease Interceptor Effluent Measurements 1-2
.........................................................................
1-2 Surveyed Variables Tested with MRBE and RMASE 1-3
........................................................
2-1 Number of Collection Systems Reported in the Survey by System Capacity Size 2-5
.............
2-2 Age Distribution of Pipes from Survey 2-7
...............................................................................
2-3 Reported Tree Types that Were Part of Root Intrusion Blockages 2-11
...................................
3-1 Metal and Minerals Data Obtained from Sample 7 FOG Deposit 3-2
.......................................
3-2 Propose Experimental Design for Evaluation of Surface Roughness and Contact Angle
of Tree Roots and Piping Materials 3-3
.....................................................................................
3-3 Revised Experimental Design for Evaluation of Surface Roughness and Contact Angle
of Tree Roots and Piping Materials 3-3
.....................................................................................
3-4 Composition of Oil-Water Solutions ................................................................................... 3-4
4-1 Physical Properties of FOG Deposits (mean SD) ............................................................. 4-2
±
4-2 Fatty Acid Profiles of Common Cooking Oils and Animal Fats (13) ................................. 4-3
4-3 Elemental Fatty Acid Composition in FOG Deposits .......................................................... 4-4
4-4 Mineral and Metal Composition of FOG Deposits .............................................................. 4-6
5-1 Percent oil Adhered to Willow Roots in Solutions of Oil, Water, and Soap
(average of three replicates)* 5-1
...............................................................................................
5-2 Percent Oil Adhered to Sanded (220 grit) PVC Pipe in Solutions of Oil, Water, and Soap
(average of two replicates)* 5-3
.................................................................................................
5-3 Surface Roughness (Ra and Rz) and Contact Angle of Sanded PVC Samples
(average of two replicates) 5-3
...................................................................................................
viii
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