GUIDANCE MANUAL
FOR
COMPLIANCE WITH THE
FILTRATION AND DISINFECTION REQUIREMENTS
FOR
PUBLIC WATER SYSTEMS
USING
SURFACE WATER SOURCES
for
Science and Technlogy Branch
Criteria and Standards Division
Office of Drinking Water
U.S. Environmental Protection Agency
Washington, D.C.
Contract No. 68-01-6989
DRAFT
by
Malcolm Pirnie, Inc. CWC-HDR, Inc.
100 Eisenhower Drive 3461 Robin Lane
Paramus, New Jersey 07653 Cameron Park, California 95682
October 8, 1987
-------
TABLE OF CONTENTS
1. INTRODUCTION 1-1
2. GENERAL REQUIREMENTS 2-1
2.1 Application 2-1
2.1.1 Types of Water Supplies 2-2
2.1.2 Applicability of the SWTR to Ground Water 2-3
2.2 Treatment Requirements 2-6
2.3 Operator Personnel Requirements 2-7
3. SYSTEMS NOT FILTERING 3-1
3.1 Source Water Quality Criteria 3-2
3.1.1 Coliform Concentrations 3-2
3.1.2 Turbidity Levels 3-5
3.2 Disinfection Criteria 3-6
3.2.1 Inactivation Requirements 3-6
3.2.2 CT Determination for Multiple Disinfectants 3-12
and Multiple Sources
3.2.3 Demonstration of Maintaining a Residual 3-16
3.2.4 Disinfection System Redundancy 3-17
3.3 Other Criteria 3-18
3.3.1 Watershed Control Program - 3-18
3.3.2 Sanitary Survey 3-19
3.3.3 No Disease Outbreaks 3-21
3.3.4 Long-term Coliform MCL 3-23
3.3.5 Total Trihalomethane (TTHM) 3-24
Regulations
4. CRITERIA FOR DETERMINATION OF FILTRATION AND DISINFECTION 4-1
TECHNOLOGY TO BE INSTALLED
4.1 Introduction 4-1
4.2 Selection of Appropriate Filtration Technology 4-1
4.2.1 General Description 4-2
4.2.2 Capabilities 4-3
4.2.3 Selection 4-7
4.3 Available Filtration Technologies 4-9
4.3.1 Introduction 4-9
4.3.2 General 4-10
4.3.3 Conventional Treatment 4-11
4.3.4 Direct Filtration 4-13
4.3.5 Slow Sand Filtration 4-15
4.3.6 Diatomaceous Earth Filtration 4-17
4.3.7 Alternate Technologies 4-18
4.3.8 Other Alternatives 4-19
4.4 Disinfection 4-20
4.4.1 General 4-20
4.4.2 Removal/Inactivation Requirements 4-20
4.4.3 Total Trihalomethane (TTHM) Regulations 4-22
4.4.4 Oxidant Needs 4-22
-------
TABLE OF CONTENTS (Continued)
5. CRITERIA FOR DETERMINING IF FILTRATION AND DISINFECTION 5-1
ARE SATISFACTORILY PRACTICED
5.1 Introduction 5~1
5.2 Turbidity Monitoring Requirements 5-2
5.3 Turbidity Performance Criteria 5-3
5.4 Disinfection Monitoring Requirements 5-6
5.5 Disinfection Performance Criteria 5-6
5.6 Other considerations 5-13
6. REPORTING 6-1
6.1 Reporting Requirements for Public Water Systems 6-1
Using Surface Hater Sources Not Providing
Filtration
6.1.1 Source Water Fecal Coliforms (FC) 6-1
6.1.2 Source Water Total Coliforms (TC) 6-2
6.1.3 Source Water Turbidity 6-3
6.1.4 Disinfection Conditions 6-3
6.1.5 Watershed Control Program 6-5
6.1.6 Sanitary Survey 6-6
6.1.7 Disease Outbreaks 6-6
6.1.8 Total Trihalomethane (TTHM) Regulations 6-7
6.1.9 Long-Term Total Coliform MCL
6.2 Reporting Requirements for Public Water Systems 6-7
Using Surface Water Sources that Provide
Filtration
6.2.1 Treated Water Turbidity 6-7
6.2.2 Disinfectant Conditions 6-9
7. COMPLIANCE 7-1
7.1 Introduction 7-1
7.2 Systems Without Filtration 7-2
7.2.1 Introduction 7-2
7.2.2 Source Water Quality Conditions 7-2
7.2.3 Disinfection Conditions 7-3
7.2.4 Watershed Control Program 7-4
7.2.5 Sanitary Survey 7-5
7.2.6 Disease Outbreaks 7-6
7.2.7 Long-term Total Coliform MCL 7-6
7.2.8 Total Trihalomethane (TTHM) Regulations 7-7
7.3 Systems Providing Filtration 7-7
7.3.1 Introduction 7-7
7.3.2 Systems Using Conventional Treatment, Direct 7-7
Filtration or Technologies Other than Slow
Sand and Diatomaceous Earth Filtration
7.3.3 Systems Using Slow Sand Filtration 7-8
7.3.4 Systems Using Diatomaceous Earth Filtration 7-8
7.3.5 Disinfectant Requirements 7~9
-------
TABLE OF CONTENTS (Continued)
7. COMPLIANCE (Continued)
7.4 Responses for Systems not Meeting the SWTR Criteria
7.4.1 Introduction
7.4.2 Systems Not Filtering
7.4.3 Systems Currently Filtering
8. PUBLIC NOTIFICATION
9. EXEMPTIONS
9.1 Minimum Requirements
9.2 Compelling Factors
9.3 Evaluation of Alternate Water Supply Sources
9.4 Protection of Public Health
9.5 Schedule of Compliance
9.6 Notification to EPA
LIST OF TABLES
Description
Removal Capabilities of Filtration Processes
Generalized Capability of Filtration Systems to
Accommodate Raw Water Quality Conditions
Summary of Total Costs of Treatment
LIST OF FIGURES
Description
Determination of Inactivetion for Multiple
Disinfectant Application to a Surface Water Source
Individually Disinfected Surface Sources Combined
at a Single Point
Multiple Combination Points for Individually
Disinfected Surface Sources
Flow Sheet for a Typical Conventional Water
Treatment Plant
4-3
Figure
No.
3-1
3-2
3-3
4-1
7-10
7-10
7-10
7-12
8-1
9-1
9-1
9-2
9-5
9-6
9-9
9-10
Following
Page
4-3
4-8
4-9
Following
Page
3-14
3-15
3-15
4-11
-------
TABLE OF CONTENTS (Continued)
LIST OF FIGURES (Continued)
Following
Description Page
4-2 Flow Sheet for a Typical Direct Filtration Plant 4-13
4-3 Flow Sheet for a Typical Direct Filtration Plant 4-14
with Flocculation
4-4 Flow Sheet for a Typical Direct Filtration Plant 4-14
with a Contact Basin
7-1 Surface Water Treatment Decision Tree 7-2
LIST OF APPENDICES
Appendix Description Page
A Use of Particulate Analysis for Source and Water
Treatment Evaluation A-l
B Institutional Control of Legionella B-l
C Tracer Test Procedures C-l
D A Survey of the Current Status of Residual Disinfectant D-l
Measurement Methods for all Chlorine Species and Ozone
E Inactivations Achieved by Various Disinfectants E-l
F Basis for CT Values p_l
G Protocol for Demonstrating Effective Chlorine-Ammonia G-l
Disinfection
H Sampling Frequency for Total Coliforms in the
Distribution System H_l
I Maintaining Redundant Disinfection Capability 1-1
J Watershed Control Program j_l
K Sanitary Survey K_T
L Small System Considerations L-l
M Pilot Study Protocol for Alternate Filtration Technology M-l
N Protocol for the Demonstration of Effective Treatment N-l
0 Protocols for Point-of-Use Treatment Devices
-------
1. INTRODUCTION
This draft Guidance Manual complements the proposed filtration and
disinfection treatment requirements for public water systems using surface
water sources (otherwise known as the Surface Water Treatment Requirements
(SWTR)). in effect, it is a proposed Guidance Manual, which may be
substantially changed in response to information received during the public
comment period and changes to the proposed rule before its final promulgation.
The purpose of this manual would be to provide guidance to United States
Environmental Protection Agency (USEPA) Regional Offices, individual states
and affected utilities in the implementation of the SWTR, and to help ensure
that actions taken toward implementation are consistent. This manual is
advisory in nature and is meant to supplement the criteria listed under the
proposed SWTR. For example, the SWTR sets treatment requirements which
encompass a large range of source water conditions. The guidance manual
suggests design, operating and performance criteria for specific surface water
quality conditions to provide the optimum protection of public health through
multiple barrier treatment. These recommendations are presented as guidelines
rather than an extension of the rule. They are offered to give the Primacy
Agency flexibility in establishing the most appropriate treatment requirements
for the waters within their jurisdiction. In order to facilitate the use of
this manual, it has been structured to follow the framework of the proposed
SWTR as closely as possible. In this manual, the term SWTR will always refer
to the criteria of the proposed requirements.
Section 2
This section provides guidance for determining whether a water supply
source is subject to the requirements of the SWTR; including the determination
of subsurface sources which are at risk to the presence of Giardia cysts or
other large microorganisms. The overall treatment requirements of the SWTR
are also presented, along with operator personnel requirements.
1-1
-------
Section 3
For systems which are subject to the requirements of the SWTR and which
do not currently provide filtration, this section provides guidance to the
Primacy Agency for determining if a given sources
- Meets the source water quality criteria
- Meets the disinfection requirements including:
- Maintenance of adequate disinfection
- Provision for disinfection system redundancy
- Maintains an adequate watershed control program
- Meets the sanitary survey requirements
- Has not had an identified waterborne disease outbreak
- Complies with the revised long-term colifonn Maximum Contaminant
Level (MCL)
- Complies with total trihalomethane (TTHM) regulations
Section 4
This section pertains to systems which do not meet the requirements of
Section 3 and therefore are required to install filtration. Guidance is given
for the selection of an appropriate filtration technology based on the source
water quality and the capabilities of the technology in achieving the required
performance criteria. In addition, recommended design and operating criteria
are provided for the available filtration technologies.
Section 5
To determine if filtration and disinfection are satisfactorily practiced,
Section 5 presents guidance to the Primacy Agency for determining compliance
with the turbidity and disinfection performance requirements. This section
includes the recommended use of CT (disinfectant residual concentration x
contact time) tables for chlorine, chlorine dioxide, ozone and chloramines.
Section 6
Section 6 provides guidelines to the Primacy Agency for establishing the
reporting requirements associated with the SWTR. The requirements include the
1-2
-------
report content and frequency, and are applicable to both filtering and
nonfiltering systems.
Section 7
This section provides guidance for determining whether or not systems are
in compliance with the requirements of the SWTR. Guidance is included for
monitoring, raw water quality, source protection, distribution system and
disinfection for nonfiltering system together with the monitoring, effluent
water quality, distribution system and disinfection conditions for filtration
systems. Guidance is given for corrective measures which can be taken by
systems which are not in compliance with these requirements. Examples are
included for actions which may be taken to remedy conditions which are not in
compliance with the SWTR requirements.
Section 8
This section of the manual presents guidance on public notification.
Included are examples of occurrences which would require notification,
language of notices and the method of notification.
Section 9
Section 9 provides guidance to the Primacy Agency for determining whether
or not a system is eligible for an exemption. The criteria for eligibility
for exemption include:
- Compelling factors (economic or resource limitations)
- No available alternate source
- The protection of public health
This section also covers an evaluation of the financial capabilities of a
water system, the review of the availability of alternate sources and measures
for protecting public health.
Appendices
The manual also contains several appendices which provide more detailed
guidance in specific areas. These include:
1-3
-------
Appendix A - Use of Particulate Analysis
for Source and Water Treatment Evaluation
A study involving 150 water sources resulted in the identification of
particulate matter which is indicative of a surface water. A paper
summarizing the results of the study is included in this appendix.
Appendix B - Institutional
Control of Legionella
Treatment provides protection from Legionella; however, it cannot assure
that re contamination or regrowth will not occur in the hot water or cooling
systems of buildings within the distribution system. This appendix provides
guidance for the monitoring and treatment which can be used by institutional
systems for the control of Legionella.
Appendix C - Tracer Test Procedures
In many cases the determination of contact times needed to evaluate the
CT maintained in the system will necessitate the use of tracer studies. This
appendix provides guidance for conducting these studies.
Appendix D - A Survey of the Current
Status of Residual Disinfectant
Measurement Methods for all Chlorine
Species and Ozone
This appendix is a copy of an executive summary of a report on the
analytical methods used to measure the residual concentrations of the various
disinfectants. The reliability and limitations of each of the methods are
also presented.
Appendix E - Inactivations Achieved
by the Various Disinfectants
This appendix presents the log inactivations of Giardia cysts and enteric
viruses which are achieved at various CT levels by chlorine, chlorine dioxide,
chloramines and ozone.
1-4
-------
Appendix F - Basis for CT Values
This appendix provides the background and rationale utilized in
developing the CT values for the various disinfectants. Included is a
currently unpublished paper by Clark et al., 1987, in which a mathematical
model was used in the calculation of CT values for free chlorine. The paper
is included in the appendix.
Appendix G - Protocol for Demonstrating
Effective Chlorine-Ammonia Disinfection
This appendix provides the recommended protocol for demonstrating the
effectiveness of chloramines as a primary disinfectant.
Appendix H - Sampling Frequency for
Total Coliforms in the Distribution System
The sampling frequency required in the proposed total coliform rule is
presented in this appendix.
Appendix I - Maintaining
Redundant Disinfection Capability
This appendix details the disinfection system conditions which should be
maintained by a system using chlorine, chlorine dioxide, ozone or chloramines,
to assure that compliance with the SWTR requirement for redundant disinfection
is met.
Appendix J - Watershed Control Program
This appendix provides a detailed outline of a watershed program which
may be adjusted by the Primacy Agency to serve the specific needs of a par-
ticular water system.
Appendix K - Sanitary Survey
This appendix provides guidance for a comprehensive sanitary survey of a
supply source, its treatment and delivery to the consumer. The contents for a
more general annual survey are included in Section 3.
1-5
-------
Appendix L - Small System Considerations
This appendix presents difficulties which may be faced by small systems
in complying with the SWTR along with guidelines for overcoming these diffi-
culties.
Appendix M - Pilot Study Protocol
for Alternate Filtration Technology
This appendix presents pilot study protocols to evaluate the effective-
ness of an alternate filtration technology in attaining the performance
requirements of the SWTR.
Appendix N - Protocol for the
Demonstration of Effective Treatment
This appendix provides guidance for conventional and direct filtration
plants to demonstrate that effective filtration is being maintained at
effluent turbidities between 1 Nephelometric Turbidity Unit (NTU) and 0.5 NTU.
Appendix 0 - Protocol for
Point-of-Use Treatment Devices
In some limited cases, it may be appropriate to install point-of-use
(POU) or point-of-entry (POE) treatment devices as an interim measure to
provide protection to the public health. This appendix provides a protocol
for evaluating and determining the efficacy of POU/POE treatment devices.
1-6
-------
2. GENERAL REQUIREMENTS
2.1 Application
The SWTR pertains to all public water systems which utilize a surface
water source. The SWTR defines a surface water as all waters which are open
to the atmosphere and subject to surface runoff (e.g., rivers, lakes, streams,
reservoirs, impoundments) and any subsurface sources such as springs,
infiltration galleries, wells or other collectors which are at risk of being
contaminated by a surface water. Historically, the term "surface water" has
generally meant "water which is located upon the surface of the earth."
Conversely, all water which existed underground was considered to be ground
water. While it has been known for some time that ground water is subject to
various forms of natural and man-made contamination, it has generally been
believed that ground waters in subsurface aquifers are free from the
pathogenic organisms that have been the traditional concerns of surface water
supplies. However, it is now known that some subsurface waters may be subject
to contamination from pathogenic organisms through the direct influence of a
surface water (Hoffbuhr, 1986).
Primarily, only those subsurface sources which are at risk to contamina-
tion from large microorganisms such as protozoa (specifically Giardia cysts)
will be subject to the requirements of the SWTR. It is not the intent of the
SWTR at this time to include subsurface sources which are not at risk from
Giardia cysts but which may be at risk to contamination from enteric viruses.
The treatment requirements for such systems will be covered under a future
regulation for ground waters.
The Primacy Agency has the responsibility for stipulating which water
supplies must meet the requirements of the SWTR. However, it is the
responsibility of the water supply system to provide the Primacy Agency with
the information, as requested to determine whether or not the utility is
subject to the SWTR. This section provides guidance to the Primacy Agency for
determining which water supplies are surface waters or directly influenced by
a surface water and are thereby subject to the SWTR.
2-1
-------
2.1.1 Types of Water Supplies
Surface water supplies that are often used as sources of drinking water
include two major classifications, namely running and quiescent waters.
Streams, rivers and brooks are subdivisions of running water while lakes,
reservoirs, impoundments and ponds are subdivisions of quiescent waters. The
exposure of surface waters to the atmosphere results in vulnerability to
precipitation events, surface water runoff and contamination with various
parameters resulting from activities in their surrounding areas. These
sources are subject to the requirements of the SWTR.
The traditional concept that all water in subsurface aquifers is con-
sidered to be free from pathogenic organisms is because soil is an effective
filter that removes microorganisms and other relatively large particles by
straining and antagonistic effects on the natural bacterial population
(Bouwer, 1978). The pathogenic bacteria retained in the soil find themselves
in a hostile environment, are not able to multiply and eventually die.
•*
However, some underground sources of drinking water may be subject to contam-
ination by pathogenic organisms from the direct influence of nearby surface
waters. A microbiological analysis program conducted on 70 water systems in
Colorado identified several parameters which may indicate the direct influence
of a surface water on a water supply. These parameters are: diatoms, plant
debris, rotifers, coccidia, insect parts and Giardia cysts (Hoffbuhr, 1986),
This study represents the best available information to date and suggests that
v J^
the main water quality characteristics that distinguish ground water from
surface water are the existence of plant matter and certain algae and micro-
biological organisms in surface water which normally are absent from ground
water (Hoffbuhr, 1986). A paper summarizing the results of this study is
included in Appendix A.
A subsurface source of water should be considered subject to requirements
of the SWTR if the source is at risk to the introduction of Giardia cysts and
other pathogenic organisms generally larger than 7 micrometers in diameter.
Section 2.1.2 presents a recommended procedure for determining whether or
not a source will be subject to the requirements of the SWTR.
1. Giardia cysts range in size from 7 to 14 urn. Therefore, 7 urn
represents the lower limit of Giardia cyst size. (Hoffbuhr, 1986)
2-2
-------
2.1.2 Applicability of the SWTR
It is the responsibility of the water purveyors to supply the Primacy
Agency with the information requested to determine which water supplies within
its jurisdiction would be subject to the requirements of the SWTR. A two
tiered approach has been developed as the recommended method of determining
whether a water supply source is at risk. This approach is consistent with
the intent of the definition in the SWTR, which is to identify water supply
sources which may be at risk of contamination by Giardia, or as previously
explained, pathogens greater than 7 micrometers in diameter.
The two tiers are as follows:
Tier 1 - Initial evaluation.
Tier 2 - A review of microbiological/biological analysis of the source
water.
Tier 1 - Initial Evaluation
It is recommended that all water supply sources be evaluated at the
Tier 1 level. An initial evaluation should be made of the water supply source
and a determination made as to the type of source. Specifically:
a. Sources which are open to the atmosphere and subject to surface
runoff meet the definition of a surface water and no further evalua-
tion is required.
b. With the exception of wells, for all other sources which are not
open to the atmosphere, or are not subject to surface water runoff,
including springs and infiltration galleries, the evaluation should
proceed to Tier 2.
c. In the majority of cases, wells can be considered to not be at risk
to contamination by Giardia cysts. However, there may be some
special cases that the Primacy Agency is aware of, such as wells in
Karst limestone aquifers, which may be potentially at risk to
Since the Primacy Agency will need to make this determination for
all water supply sources within its jurisdiction within 12 months of
adoption of the SWTR, detailed and exhaustive evaluations of each
water supply source may not be feasible. It is anticipated that the
majority of the water supply sources will require only a Tier 1
evaluation in order to make the determination.
2-3
-------
contamination by Giardia cysts. For these special cases, it is
recommended that the evaluation proceed to Tier 2. '
For many water supply sources (i.e., known surface water sources such as
rivers, lakes, and streams), this evaluation may not require the physical
presence of the Primacy Agency representative. An alternative for conducting
a Tier 1 evaluation is a mailed questionnaire to the systems. Only those
systems which indicate that their source does not meet the definition of a
surface water and whose source is not a well would be required to move to
Tier 2.
Tier 2
Water supplies which have already been determined to be surface waters or
wells will not be evaluated at this level. This evaluation should be applied
only to springs, infiltration galleries and other supplies which the Primacy
Agency feels may be at risk, and consists of a microbiological/biological
analysis of the source water.
It is recommended that this sampling and analysis be conducted during
periods when stream flows and water tables are highest such as in the spring
and fall. This should cover the period(s) when contamination by these orga-
nisms would most likely occur. The evaluation should include a minimum of
weekly samples prior to a storm event and twice weekly samples for two weeks
following the storm event.
A microbiological/biological analysis should be performed on the samples.
Most of these analyses involve filtering the water samples, extracting the
3. A study conducted on 150 water systems identified that some wells
contained particulate matter indicative of surface water. Thereby
suggesting that the well were being influenced by a nearby surface
water. (Hoffbuhr, 1986)
2-4
-------
solids from the filter and examining them under a microscope for the presence
of the microbiological/biological organisms listed below.(4)
The detection of Giardia cysts, coccidia, or other particulate matter
such as diatoms, rotifers, plant debris, insect parts or shells of diatoms
which require surface conditions for their survival, confirm that the source
is subject to the requirements of the. SWTR. If none of these parameters
are detected during the microbiological/biological investigation, then the
source is not at risk, the SWTR does not apply and the investigation is
complete.
In general, water supply sources in which the presence of the indicator
organisms has been confirmed should be considered to be subject to the re-
quirements of the SWTR. However, in some cases such as springs, a detailed
site evaluation may be appropriate. Specifically, the site evaluation may
indicate that the source is at risk due to a condition or situation which can
be corrected, enabling water quality to meet the Tier 2 criteria to demon-
strate that the SWTR does not apply.
4. The test procedures for microbiological and biological analyses are
presented in Standard Methods for the Examination of Water and
Wastewater, 16th edition, (Standard Methods) specifically methods
912K, and 1002.
5. Coccidia are host specific parasites 10-20 micrometers in size,
which are found in animals and fish. Giardia is a protozoan
pathogen which ranges in size from 7-14 micrometers, and is excreted
by a variety of mammals. These organisms are not indigenous to the
underground environment, and therefore do not generally multiply in
the absence of animal tissue and will eventually die in these
surroundings. If these microorganisms are detected in a ground
water, it may be assumed that they were introduced to the system via
direct influence of a surface source. Several biological parameters
which are indicators of surface water influence include diatoms,
rotifers, plant debris, and insect parts. Diatoms are a type of
algae which contain silica in their cell walls and require sunlight
for survival. Undigested fecal material from herbivorous mammals,
such as beavers and muskrats, usually consist of plant debris which
is therefore an indicator of animal activity. Rotifers are
microscopic animals, 150-600 micrometers in size which require
sunlight.
2-5
-------
At this point, a more detailed visual inspection and review of pertinent
data (such as construction of the source intake) should be made to identify
any defects which may allow such contamination and to determine corrective
action which may be taken to provide maximum protection of the source from
contamination, better enabling the water supply system to meet the SWTR
criteria evaluated during the Tier 2 investigation.
2.2 Treatment Requirements
According to the proposed SWTR, all community and noncommunity public
water systems which use a surface water source must ensure the consumers'
safety from pathogenic bacteria, viruses and protozoan cysts, through the
provision of treatment which achieves a minimum of 99.9 percent (3 log)
removal and/or inactivation of Giardia cysts, and a minimum of 99.99 percent
(4 log) removal and/or inactivation of enteric viruses. Filtration plus
disinfection or disinfection alone may be utilized to achieve these perfor-
mance levels, depending on the source water quality and site specific con-
ditions. The SWTR establishes these removal and/or inactivation requirements
for Giardia and enteric viruses because this level of treatment will also
provide protection from heterotrophic plate count (HFC) bacteria and
Legionella as required in the SDWA amendments.
Surface water systems which currently provide disinfection alone must
either meet source water quality criteria and site specific conditions, or
install a currently accepted filtration technology or an alternate technology
which meets the performance criteria. The source water quality criteria and
the site specific conditions which are required in the SWTR for systems
providing disinfection alone are presented in Section 3 of this manual. The
purveyor should collect and submit the required source water quality and
specific site conditions/data to the Primacy Agency for review and determina-
tion of whether additional treatment is required. The investigation of exist-
ing conditions may be both time consuming and expensive and does not ensure
that filtration will not be required. Given the uncertainties involved in the
above review, the system may elect to install a filtration technology as
presented in Section 4, rather than expend a large amount of time, effort and
finances to generate the necessary data for the system evaluation.
2-6
-------
Section 4 of this manual presents design and operating criteria for the
filtration technologies to achieve the finished water quality requirements of
the SWTR. The removal of Giardia cysts and enteric viruses achieved by
conventional treatment, direct filtration, slow sand filtration and diato-
maceous earth are dependent on the quality of the water being treated. Thus
in addition to the minimum requirements of the SWTR, Section 4 presents
guidelines for the effectiveness of the treatment processes for certain source
water quality conditions. The removals achieved by the different processes
under these conditions are presented along with guidelines for disinfection
which is needed to achieve the overall removal and/or inactivation of Giardia
and viruses required in the SWTR. Each of these filtration processes in
conjunction with the recommended disinfection can be assumed to achieve at
least a 3 log removal and/or inactivation of Giardia cysts and at least a
4 log removal and/or inactivation of enteric viruses. A system which utilizes
filtration technologies other than those cited above may follow the guidelines
presented in Section 4.3.7 to determine whether or not an alternate technology
provides the level of treatment necessary to meet the requirements of the
SWTR.
2.3 Operator Personnel Requirements
The SWTR requires that all systems must be operated by qualified person-
nel, and the Primacy Agency must set standards for the required operator
qualifications, in accordance with the system type and size. In order to
accomplish this, the Primacy Agency should develop a method of evaluating an
operator's competence in operating a water treatment system. States which do
not currently have a certification program are thereby encouraged to implement
such a program. An operator certification program provides a uniform base for
operator qualifications and an organized system for evaluating these qualifi-
cations.
It is recommended that plant operators have a basic knowledge of science,
mathematics and chemistry involved with water treatment and supply. The
minimum requirements for an operator should include an understanding of:
- The principles of water treatment and distribution and their charac-
teristics
2-7
-------
- The uses of potable water and variations in its demand
- The importance of water quality to public health
- The equipment, operation and maintenance of the distribution system
- The treatment process equipment utilized, its operational parameters
and maintenance
- The principles of each process unit (includes the scientific basis
and purpose of the operation and the mechanical components of the
unit)
- Performance criteria such as turbidity, total coliform, fecal
coliform, disinfectant residual, pH, etc. to determine operational
adjustments
- Common operating problems encountered in the system and actions to
correct them
- The current National Primary Drinking Water Regulations, the Secon-
dary Drinking Water Regulations and monitoring and reporting
requirements
- Methods of sample collection and sample preservation
- Laboratory equipment and tests used to analyze samples (where
appropriate)
- The use of laboratory results to analyze plant efficiency
- Record keeping
- Customer relations
- Budgeting and supervision (where appropriate)
Training in the areas listed above and others is available through the
American Water Works Association AWWA training course series for water supply
operations. The course series includes a set of four training manuals and one
reference book as follows:
- Introduction to Water Sources and Transmission (Volume 1)
- Introduction to Water Treatment (Volume 2)
- Introduction to Water Quality Analyses (Volume 4)
- Reference Handbook: Basic Science Concepts and Applications
2-8
-------
- Instructor Guide and Solutions Manual for Volume 1
- Instructor Guide and Solutions Manual for Volume 2
- Instructor Guide and Solutions Manual for Volume 4
- Introduction to Water Distribution (Volume 3) and its instructor
guide
These manuals are available through the American Water Works Association,
6666 West Quincy Avenue, Denver, Colorado 80235 USA, (303) 794-7711.
The State of California also offers a series of training manuals for
water treatment plant operators prepared by the California State University
School of Engineering in Sacramento. The manuals include:
1. Water Supply System Operation, 1 Volume
2. Water Treatment Plant Operation, 2 Volumes
3. Operation of Wastewater Treatment Plants, 3 Volumes
4. Operation and Maintenance of Wastewater Collection Systems, 1 Volume
These operator training manuals are available from California State
University, Sacramento, 6000 J Street, Sacramento, California 95819, phone
(916) 454-6142.
Completion of an established training and certification program will
provide the means of ensuring that the operators have received training in
their respective area, and are qualified for their position. The education
and experience requirements for certification should be commensurate with the
size and the complexity of the treatment system. At the present time, some
states have instituted a certification program while others have not. Follow-
ing is a summary of the basic contents of a certification program, which can
serve as a guide to the Primacy Agency in developing a complete program.
- Board of examiners for the development and implementation of the
program.
- Classification of treatment facilities by grade according to the
size and technology of the facilities.
- Educational and experience requirements for operators of the various
treatment facilities according to grade.
- A written/oral examination to determine the knowledge, ability and
judgement of the applicants with certification obtained upon receiv-
ing a passing grade.
2-9
-------
- Renewal program for the license of certification, including the
requirement of additional coursework or participation in workshops.
The certification program should provide technically qualified personnel
for the operation of the plant.
The extensive responsibility which is placed on the operating personnel
warrants the development of an outline of the responsibilities and authority
of the personnel members to aid them in the efficient operation of the plant.
The major responsibilities which should be delegated in the outline of re-
sponsibilities include: the normal day-to-day operations, preventive mainte-
nance, field engineering, water quality monitoring, troubleshooting, emergency
response, cross-connection control, implementation of improvements, budget
formulation, response to complaints and public/press contact. A reference
which the Primacy Agency may utilize in developing the outline is "Water
Utility Management Practices" published by AWWA.
2-10
-------
3.0 SYSTEMS NOT FILTERING
The provisions of the SWTR require that filtration or a participate
removal technology as approved by the Primacy Agency, must be included in the
treatment train unless certain criteria are met. These criteria are
enumerated in this chapter and include:
Source Water Quality Conditions
1. Coliform concentrations (total or fecal).
2. Turbidity levels.
Disinfection Criteria
1. System maintains at least 99.9 percent Giardia cyst inactivation and
99.99 percent enteric virus inactivation.
2. System maintains a residual of at least 0.2 mg/L at all times in
water entering the distribution system, demonstrated by continuous
monitoring. System must have redundant backup components with an
auxiliary power supply, automatic start-up and alarm to ensure
continuous disinfection.
3. System maintains a disinfectant residual in the distribution system
of at least 0.2 mg/L in no less than 95 percent of the samples each
month for any two consecutive months.
Site Specific Criteria
1. System maintains a watershed control program.
2. System has an on-site sanitary survey each year conducted by the
Primacy Agency, or a party approved by the Primacy Agency, to
demonstrate that the system has no sanitary defects.
3. System in its current configuration has not had an identified
waterborne disease outbreak as determined by State or local health
officials.
4. Compliance with the proposed total coliform long-term MCL for the
distribution system.
5. System serving more than 10,000 people is in compliance with the
Total Trihalomethane (TTHM) regulation.
The purpose of this section is to provide guidance to the Primacy Agency
for determining compliance with these provisions.
3-1
-------
3.1 Source Hater Quality Criteria
The first step in determining if filtration is required for a given sur-
face water supply is to determine if the supply meets the source water quality
criteria as specified in the SWTR. The site specific criteria pertaining to
systems which do not filter are not applicable unless the source water quality
criteria are met or unless the system is eligible for an exemption.
Sampling Location
The SWTR requires that the source water samples be collected at a
location just prior to the point of disinfection where the water is no longer
subject to surface runoff. When multiple sources are used, sampling should be
conducted at a location just prior to the disinfection sequence used for
calculating the CT. It is unimportant what is done to the water before this
point because this is the water which will be treated in accordance with the
requirements of the SWTR and is, therefore, the source water.
3.1.1 Coliform Concentrations; Specifically, the SWTR states that the
system must demonstrate that either the fecal coliform concentration is less
than 20/100 ml or the total coliform concentration is less than 100/100 ml in
the water prior to the point of disinfectant application in 90 percent of the
samples taken during any consecutive six month period. Where monitoring for
both parameters has been conducted, it is suggested that the analytical
results for both total coliforms and fecal coliforms should be reported and
the source may exceed the total coliform limit but not the fecal coliform
limit. In addition, it is suggested that if the turbidity of a surface water
source is greater than 5 NTU and is blended with a ground water to reduce the
turbidity, the high turbidity water prior to blending should meet the fecal
coliform source water quality criteria.
Ongoing monitoring is required to ensure that these requirements are
continually met. The samples may be analyzed using either the multiple tube
fermentation method or the membrane filter test (MF) as presented in the 16th
edition of Standard Methods.
Sampling Frequency
Minimum sampling frequencies are as follows:
3-2
-------
Population Served Samples/Week
<501 ' 1
501-3,300 2
3,301-10,000 3
10,001-25,000 4
>25,000 5
The sampling frequency must be increased to one measurement every day
during which the turbidity exceeds 1 NTU.
The minimum sampling frequency is sufficient for systems utilizing large,
quiescent water bodies including lakes and large reservoirs, as the source,
unless the watershed contains grazing areas, in which case additional
monitoring should be conducted, as stated below. Systems utilizing ponds and
streams which may be more readily affected by surface water runoff should
perform daily monitoring, for a three-day period immediately following storm
and runoff events. To determine the additional monitoring which may be
necessary, a system should review its current watershed activities and
historical source water quality data for a 6-month period. It is suggested
that for the existing historical data:
- If the historical data base available for coliform concentrations
contains less than four samples per month or less than 1/2 the
number of samples generated from the minimum monitoring program
previously outlined, the minimum sampling program should be aug-
mented to daily samples for a three-day period following storm or
runoff events.
- If the data base shows that not more than 10 percent of the source
water samples have shown the presence of. coliforms, the minimum
sampling frequency is adequate.
- If the data show that the coliform levels have remained less than
100 total coliforms/100 ml or less than 20 fecal coliforms/100 ml in
less than 90 percent of the samples during the 6 months, the minimum
sampling should be augmented to one sample/day for a three-day
period following a storm or runoff event.
- All systems which contain grazing areas in the watershed should
increase the source water monitoring to daily samples for a three-
day period following a storm or runoff event.
Systems which conduct this increased sampling after storm events should
review the test results to determine if the storms are affecting the water
quality. Systems which exhibit less than 10 percent of the fecal or total
coliform samples above 20/100 ml or 100/100 ml, respectively, after six storm
3-3
-------
events, may resume minimum monitoring, including daily monitoring when tur-
bidity levels exceed 1 MTU.
Following the initial determination by the Primacy Agency based on either
historical data or a newly generated data base, systems must continue to
conduct the miniaium sampling to fulfill the ongoing requirement of meeting the
source water quality criteria. It is recommended that in addition to the
minimum sampling frequency, systems be required to conduct daily sampling for
a three day period following at least one storm event per season.
The SWTR requires the Primacy Agency to determine which systems must
install filtration within 12 months of adopting the regulation. It is recog-
nized that the potential exists for the Primacy Agency to be so inundated with
data within the 12-month period that making the determination within the time
constraints of the SWTR would not be possible. To avoid this, the Primacy
Agency is encouraged to seek ways of making the determination within a shorter
time span wherever possible. To facilitate this determination, the following
recommendations are made:
Utilization of a Historical Data Base
Many systems already routinely monitor their source water for total
and/or fecal coliform concentration. Consequently, this historical data base
may be sufficient for the Primacy Agency to make the determination of whether
or not the system meets the source water quality criteria. The historical
data base is considered sufficient for making this determination if:
- The raw water sampling location is upstream of the point of
disinfectant application as previously defined.
- The samples represent at least the minimum sampling frequency
previously mentioned.
- The sampling period covers at least the major seasonal water quality
events such as spring runoff, summer low flow conditions, etc.
Generating a Data Base
For systems which do not have an adequate historical data base, the
determination can be made within a 6-month period with the monitoring program
previously sited, covering seasonal water quality conditions. For example, if
it is known that the poorest water quality conditions occur during spring
runoff and summer low flow conditions, monitoring during those months may
3-4
-------
provide sufficient information to make the determination. The sampling
frequency for the monitoring program must first be determined.
3.1.2 Turbidity Levels; The SWTR requires that, prior to disinfection,
the turbidity of the water must not exceed 5 NTU, unless the following
conditions are met:
a. There are not more than two periods in any 12 consecutive months and
not more than five periods in any 120 consecutive months during
which the turbidity exceeds 5 NTU. A period is defined as any
number of consecutive days in which at least one turbidity
measurement exceeds 5 NTU each day, and;
b. The Primacy Agency determines that the event or events leading to
the period(s) exceeding 5 NTU are unusual or unpredictable, and;
c. During the periods when the turbidity exceeds 5 NTU, the system
informs its customers to boil the water before consumption.
Utilizing the same sampling location requirements as stated in Sec-
tion 3.1, the determination of compliance is based upon the collection of grab
samples at least every four hours. It is recommended that the initial
determination of compliance with the turbidity criteria be based upon data
from 6 consecutive months or an equivalent period of sampling as is required
for the coliform determination. As presented in Section 3.1.1, the Primacy
Agency is encouraged to make the initial determination of compliance with the
turbidity criteria in less than the 6-month period wherever possible. This
includes the use of a historical data base wherever possible.
Any system which exceeds the 5 NTU maximum limit at any time should
notify the Primacy Agency at the time of occurrence.
In order to determine if the periods in which the turbidity exceeds 5 NTU
are unusual or unpredictable, it is recommended that in addition to the
The SWTR permits the use of continuous turbidity monitoring as a
substitute for grab sample monitoring if the measurement is
validated for accuracy with grab sample measurements on a regular
basis as determined by the Primacy Agency. Validation should be
performed at least twice a week based on the procedure outlined in
Part 214A in the 16th Edition of Standard Methods.
3-5
-------
historical turbidity data, the water purveyor should collect and provide to
the Primacy Agency current and historical information on flows, reservoir
water levels, climatologieal conditions, and any other information that the
Primacy Agency deems relevant. This information should be evaluated to
determine if the event was unusual or unpredictable.
If the period (s) of turbidity greater than 5 NTU have been shown to be
the result of unusual or unpredictable events such as hurricanes, floods,
avalanches or earthquakes, the Primacy Agency may permit the system to avoid
filtration if the system issues a boiled water notice or the system agrees to
stop the delivery of water which exceeds the source water quality limits by:
- Utilization of an alternate source which is not a surface water and
does not have to meet the requirements of the SWTR.
- Utilization of an alternate source which is a surface water and
which does meet the requirements of the SWTR.
- Utilization of storage to supply the community until the source
water quality meet the criteria.
3.2 Disinfection Criteria
3.2.1 Inactivation Requirements
The SWTR requires that systems which do not filter must practice disin-
fection for the protection of public health. Systems which potentially
contain any sources of human enteric viruses within the watershed must demon-
strate by ongoing monitoring that they are achieving disinfection conditions
expected to provide a 99.9 percent (3 log) inactivation of Giardia cysts and a
99.99 percent (4 log) inactivation of enteric viruses at all times of the
year. Systems which contain no sources of enteric viruses within their
watershed are only required to provide a 3 log inactivation of Giardia cysts.
Potential sources of these viruses include sewage discharges, septic tank
discharges, swimming, boating, camping, fishing, hiking, hunting or any other
human usage or habitation which may result in human waste disposal within the
watershed.
There are a number of disinfectants which can be used. These include
ozone, chlorine, chlorine dioxide and chloramines. The SWTR establishes CT
3-6
-------
[residual concentration (ng/L) x contact time (min)] levels for these
disinfectants which will achieve the required inactivation, as explained in
the following subsection.
It has been found through studies that Giardia cysts are ouch more
resistant to chlorine, chlorine dioxide and ozone than are enteric viruses
(Hoff, 1986). Therefore, for these disinfectants, it is sufficient to demon-
strate that a CT level which achieves a 3 log inactivation of Giardia cysts is
being maintained. These CT values will provide much more than a 4 log
inactivation of enteric viruses as required by the SWTR. In accordance with
this, the CT requirements presented for chlorine, chlorine dioxide and ozone
are for the 3 log inactivation of Giardia cysts. The SWTR also requires that
the public be provided with protection from Legionella as well as Giardia
cysts and enteric viruses. Inactivation levels have not been set for
Legionella because the required inactivation of Giardia cysts will provide
protection from Legionella. However, this level of disinfection cannot
assure that all Legionella will be inactivated and that no recontami nation or
regrowth in recirculating hot water systems of buildings or cooling systems
will occur. Appendix B provides guidance for the monitoring and treatment
which can be used by institutional systems for the control of Legionella.
Definition of CT
The SWTR defines CT as the residual concentration(s) in mg/L multiplied
by the respective contact time(s) in minutes from the point(s) of disinfectant
application to a point prior to the first customer. In pipelines, the contact
time is calculated by dividing the internal volume of the pipeline by the peak
Kuchta et al. (1983) reported a maximum CT requirement of 22.5 for a
99 percent inactivation of Legionella in a 21 C tap water at a pH of
7.6-8.0 when using free chlorine. Using first order kinetics, a
99.9 percent inactivation requires a CT of 33.8. Table A-5 presents
the CTs needed for free chlorine to achieve a 99.9 percent
inactivation of Giardia cysts at 20 C. This table indicates that
the CT required for a 3 log inactivation of Giardia at the
temperature and pH of the Legionella test ranges from 67 to 108
depending on chlorine residual. This is 2 to 3 times higher than
that which is needed to achieve a 3 log inactivation of Legionella.
3-7
-------
hour flow rate through that pipeline. Within mixing basins and storage
reservoirs, the contact time must be determined by tracer studies or an
equivalent demonstration. Guidance for conducting tracer studies is provided
in Appendix C. The residual disinfectant concentration is measured daily,
during peak hourly flow for each disinfection sequence prior to the first
customer in the distribution system at -or immediately following the point at
which the contact time is determined. Appendix D contains measurement methods
for the various disinfectant residuals.
Meeting the CT Requirements
The SWTR establishes CTs for chlorine, chlorine dioxide, ozone and
chloramines which will achieve various inactivations of Giardia cysts and
enteric viruses. The CTs established are presented in Appendix E. For a
system to determine whether it is meeting the CT requirements, the
disinfectant residual and temperature (and pH for systems using chlorine) must
be measured daily at peak hourly flow prior to the first customer, and the
travel time from the point of disinfection to this point must be determined.
The CTs actually obtained for the system each day should be compared to the
values in the table for the pH and temperature of the water, to determine if
the CT required has been achieved.
When using free chlorine as a disinfectant, the efficiency of inactiva-
tion is influenced by the temperature and pH of the water. The SWTR provides
the CT requirements for free chlorine at various temperatures and pHs which
may occur in a source water. These values are presented in Table £-1 through
Table E-7 in Appendix E. The basis for these values is discussed in Appen-
dix F.
As indicated in Table E-2, at a raw water temperature of 5 C and a pH of
7.0, a chlorine concentration of 1.4 mg/L would require a CT of 175 to provide
a 3 log inactivation of Giardia cysts. Therefore, to meet the CT requirement
under those conditions would require a contact time of 125 minutes prior to
the first customer.
For the purpose of the SWTR, the pH of the water is assumed to have an
insignificant effect on the disinfection efficiency of chlorine dioxide and
the only parameter significantly affecting the CT requirements associated with
the use of chlorine dioxide is temperature. Out of concern for toxicological
3-8
-------
effects, EPA's current guideline is that the sun of residual, measured as
chlorine dioxide, chlorate and chlorite be less than 1.0 mg/1 at all consumer
taps. It is possible that this guideline may be lowered as more health
effects data becomes available. These concerns further subtract from the
feasibility of using chlorine dioxide as a residual for distribution systems.
As a result of this, systems which use chlorine dioxide are not required to
measure the pH of the disinfected water. Table E-8 in Appendix E presents the
chlorine dioxide CT values required for different temperature ranges. The
basis for these CT values is discussed in Appendix F.
As indicated in Tables E-8 and E-9, the CT requirements for chlorine
dioxide are substantially lower than those required for free chlorine,
(chlorine dioxide is a more effective primary disinfectant). However,
chlorine dioxide is not as stable as free chlorine or chloramines in a water
system and may not be capable of providing the disinfectant residual required
throughout the distribution system. Therefore, the use of chlorine dioxide
may present the need of applying a residual disinfectant such as chlorine or
chloramines that will persist in the distribution system and provide the
residual protection which is required by the SWTR.
A third disinfectant which can be used to inactivate Giardia and viruses
is ozone. As with chlorine dioxide, it is assumed that ozone's performance is
not significantly affected by the pH of the water, and the SWTR does not
require the measurement of the finished water pH. This assumption is
considered reasonable given the basis for the CT value and the applied safety
factor (see Appendix F). Tables E-10 and E-ll present the CT requirements for
ozone at different source water temperatures.
The CT for an ozonation system should be calculated based on the ozone
residual (mg/L) in the contactor effluent multiplied by the detention time of
the contactor. The ozone residual is measured at the exit from the contactor
rather than at the first customer because the ozone degrades quickly in water
3-9
-------
and no residual will remain at the first customer. For systems which add
the ozone in stages throughout the contactor, the exiting ozone concentration
and the contact time are both divided in half prior to calculating the CT
provided. This eliminates giving credit for ozone which is added just prior
to the sample collection point. The basis for the CT values presented for
ozone are presented in Appendix F.
The short life of ozone in a water system presents the need for a system
utilizing ozone as a primary disinfectant to apply a residual disinfectant
such as chlorine or chloraraines in order to maintain a disinfectant residual
in the distribution system. The residual disinfectant is to be added after
the primary disinfectant. However, when ozone is in contact with either
chlorine or chloramines, reaction between the two may result in the mutual
destruction of the disinfectants. In order to prevent the two disinfectants
from mutually destroying each other, the residual disinfectant should be
applied after the ozone residual has fully dissipated.
A fourth disinfectant which can be used for the inactivation of micro-
organisms is chloramine. There are limitations to its use as a primary
disinfectant. Chloramines are less effective as primary disinfectants than
are free chlorine, chlorine dioxide and ozone. In addition, chloramines are
less effective in inactivating enteric viruses than they are for Giardia
cysts. Therefore, a utility which utilizes chloramines as the primary
3. The residual can be measured using the Indigo Method which is a
submitted standard method (Bader & Hoigne, 1981). This method is
preferable to current standard methods because of the selectivity of
the indigo-reagent in the presence of most interferences found in
ozonated waters. Indigo trisulfonate is the indicator used in this
test method. The ozone degrades an acidic solution of indigo
trisulfonate in a 1:1 proportion. The decrease in absorbance is
linear with increasing ozone concentrations over a wide range.
Malonic acid can be added to block interference from chlorine.
Interference from permanganese, produced by the ozonation of
manganese, is corrected by running a blank in which ozone is
destroyed prior to addition of the indigo reagent. The samples can
be analyzed using a spectrophotometer at a 600 run wavelength which
can detect residuals as low as 2 ug/L or a visual color comparison
method which can measure down to 10 ug/L ozone.
3-10
-------
disinfectant mist maintain a CT sufficient to achieve a 4 log inactivation of
viruses, unless the system has no potential sources of human enteric viruses
within the watershed. However, the CTs required for a 4 log inactivation of
viruses with chloramine (see Table E-13) indicate that the use of chloramines
as a primary disinfectant is impractical for systems with potential sources of
enteric viruses. However, lesser CTs may be provided for a chloramine disin-
fection upon demonstration of its effectiveness as presented in Appendix G.
The effectiveness of chloramine as a disinfectant is dependent on temper-
ature, as are ozone and chlorine dioxide. Table E-12 in Appendix E presents
the CT requirements for chloramines to achieve a 3 log inactivation of Giardia
cysts. The basis for these CT values are presented in Appendix F.
The CT values presented in Tables E-12 and E-13 were obtained from
laboratory testing using preformed chloramines; that is, ammonia and chlorine
were reacted to form chloramines before the addition of the microorganisms.
Under field conditions, chlorine is usually added first followed by ammonia
addition further downstream. Also, even after the addition of ammonia, some
free chlorine residual may persist for a long period of time. Therefore,
there is a time period prior to the formation of chloramines during which free
chlorine is present. Since this free chlorine contact time is not duplicated
in the laboratory when testing preformed chloramines, the slow inactivation
rates obtained by such tests may provide conservative values when compared to
those CTs actually obtained in the field.
It is anticipated that many of the systems which do not provide filtra-
tion will have difficulty in providing the contact time necessary to satisfy
the CT requirements prior to the first customer. For example, as previously
indicated, a system using free chlorine at a water temperature of 5 C, a pH of
7.0 and a chlorine residual of 1.4 mg/L would require 125 minutes of contact
time to meet the CT requirement. Options which are available to these systems
include:
- Installation of storage facilities that will provide the required
contact time under maximum flow conditions.
- Use of an alternate disinfectant such as ozone or chlorine dioxide
which requires CT values lower than those required for free
chlorine.
3-11
-------
For some systems, the difficulty in obtaining the required CT values may
only be a seasonal problem. A system that has raw water temperatures which
reach 20 C during the summer months at a pH •= 7,0, may have sufficient contact
time to meet the CT of 62 at a chlorine concentration of 1 mg/L. However,
assuming the same pH and chlorine concentration, it may not have sufficient
contact time to meet the CT requirement at 5 C (165) or at 0.5 C (231). Under
those conditions, it may be appropriate for such a system to utilize ozone or
chlorine dioxide on a seasonal basis, since they are stronger oxidants.
As indicated in Table E-12, the CT values for chloramines are high enough
that they may be unattainable for most systems. Systems which currently
utilize chloramines as a primary disinfectant may need to use either free
chlorine, chlorine dioxide or ozone in order to obtain adequate disinfection.
However, systems using chloramines as a primary disinfectant may chose to
demonstrate the adequacy of the disinfection. Appendix G presents a method
for making this demonstration.
3.2.2 CT Determination for Multiple Disinfectants and Multiple Sources
For systems which apply disinfectant(s) in sequence, the total
inactivation achieved is the "sum" of the inactivations between each of the
points of disinfection. The CT for each section is based on the travel time
through that section during peak hourly flow and the residual disinfectant
concentration, measured during peak hourly flow, prior to the next point of
disinfectant application. The pH and temperature of the water are measured on
a daily basis at the location of the residual measurements, and the CTs are
calculated daily. The inactivation achieved in each section is based on the
CT, the pH and temperature of the water for the respective sections, referring
to Tables E-l through £-13 in Appendix E. These tables present the log
inactivation of Giardia cysts and enteric viruses achieved by CTs at various
water temperatures and pHs. The percent inactivations corresponding to the
log inactivations are as follows:
0.5 log - 68 %
1 log * 90%
1.5 log « 96.8%
2 log - 99%
2.5 log = 99.7%
3 log = 99.9%
4 log = 99.99%
3-12
-------
This is determined from the following formula:
y • 100 - 100 (1)
10X
where: y « % inactivation
x * log inactivation
for example:
x « 2.5 log inactivation
y - 100 - 100
io2'5
y « 99.7 % inactivation
Once the percent inactivation achieved in each section has been deter-
mined, the overall percent inactivation achieved by the sequential
disinfectant application (either the same or different disinfectants) is
determined by the formula below:
Gtn - Gtn-l + Gn
100
where
n - number of points of disinfectant application
G • the percent inactivation achieved by the nth disinfectant
n
G • the total percent inactivation achieved by the n disinfec-
ta tants
G » the total percent inactivation achieved by the n-1 disinfec-
tn'1 tants
G « 0 to represent that there is no inactivation prior to the
first disinfectant
The following is an example of the determination of the overall percent
inactivation achieved by sequential disinfection.
A community of approximately 6,000 people obtains its water supply from a
lake which is 10 miles from the city limits. There are two 1/2 MG storage
tanks located along the transmission line to the city. The water is disin-
fected with chlorine dioxide at the exit from the lake and with chlorine at
3-13
-------
the exits from the first and second storage tanks. The average water demand
of the community is 1 MGD with a peak hourly demand of approximately 2 MGD.
For the calculations of the overall percent inactivation, the supply system is
divided into three sections as shown on Figure 3-1 s
Section 1 - from the lake to the effluent from the first storage tank,
Section 2 - from the effluent from the first storage tank to the effluent
from the second tank
Section 3 - from the effluent of the second storage tank to the first
customer
The overall inactivation is computed daily for the peak hourly flow
conditions. On the day of this example calculation, the peak hourly flow was
2 MGD. The pH, temperature and disinfectant residual of the water were
measured at the end of each section just prior to the next point of
disinfection and the first customer during the hour of peak demand. The water
travels through the 12-inch transmission main at 237 ft/min at 2 MGD. The
detention times of the storage tanks were determined to be 290 min and 285 min
as the result of tracer studies.
The breakdown of the inactivation calculation is as follows:
Section 1 Section 2 Section 3
length (ft) 15,840 26,400 10,560
contact time (min)
pipe
tank
total
disinfectant
residual (mg/L)
temperature C
PH
This information is then used in conjunction with the tables in Appendix E to
determine the CT and the log Giardia inactivation achieved. Equation 1 was
then used to determine the percent inactivation.
67
290
357
chlorine
dioxide
0.1
5
8
111
285
396
chlorine
0.2
5
8
45
0
45
chlorine
0
5
8
3-14
-------
1st CUSTOMEF
"1 STORAGE STORAGE '
/ i
rTANK 1 * TANK 2 '
I
I
CHLORINE CHLORINE CHLORINE
DIOXIDE
SECTION
SECTION
SECTION
s -v
1 2 3
FIGURE 3-1
DETERMINATION OF INACTIVATIOM
FOR MULTIPLE DISINFECTANT
APPLICATION TO A SURFACE
WATER SOURCE
-------
Section 1 Section 2 Section 3
CT 36 79 18
table A-8 A-2 A-2
log inactivation 2 1
-------
point of blending; i.e., Sections A, B and C on Figures 3-2 and 3-3. It is
recognized that this is a conservative approach for determining the CT
provided. Systems which seek to obtain credit for both the CTs provided prior
to and following blending must be addressed on a case-by-case basis.
3.2.3 Demonstration of Maintaining a Residual
Maintaining a Residual Entering the System
It is required that a residual of at least 0.2 mg/L is maintained in the
water entering the distribution system at all times. Continuous monitoring at
a point prior to the entrance to the distribution system is required to ensure
that the residual is provided. The system must record the lowest disinfectant
residual measured each day of the month and this residual must not be less
than 0.2 mg/L. Duplicate residual monitoring devices with an automatic
switchover and alarm in case of monitor failure should be provided to ensure
that a continuous record of the residual is kept.
Maintaining a Residual Within the System
The SWTR requires that a disinfectant residual of at least 0.2 mg/L be
maintained throughout the distribution system, with measurements taken at a
minimum frequency equivalent to that required by the proposed total coliform
rule as in Appendix H. The same sampling locations as required for the
proposed coliform regulation must be used for measuring the disinfectant
residual.
The rule requires that for any two consecutive months the disinfectant
residuals must not be less than 0.2 mg/L in more than 5 percent of the samples
for each of the months. A system would not fail this requirement if it could
maintain disinfectant residuals of at least 0.2 mg/L in at least 95 percent of
the samples in the second month, even if these residual conditions were not
met in the first month. Disinfectant residual can be measured as total
chlorine, free chlorine, combined chlorine or chlorine dioxide. The SWTR
defines which analytical methods may be used to make these measurements. For
example, there are several test methods which can be used to test for the
chlorine residual in the water, including amperometric titration, DPD colori-
metric, DPD ferrous titrimetric method and iodometric method. The procedures
3-16
-------
1st CUSTOMER
FIGURE 3-2 INDIVIDUALLY DISINFECTED
SURFACE SOURCES COMBINED
AT A SINGLE POINT
k a 4- c
\ A II
U A ll
f 1
1
1
1
.^
D...— - i • r i
•b d e
j 1 st CUSTOMER
«^~\
DISINFECTANT FIGURE 3-3 MULTIPLE COMBINATION POINTS
APPLICATION FQR INDIVIDUALLY DISINFECTED
COMBINATION POINT SURFACE SOURCES
SAMPLING POINTS
-------
for these test methods axe contained in the 16th edition of Standard
Methods. Appendix D provides a review and summary of all disinfectant
residual measurement techniques which are available.
Options which are available to systems to correct the problem of being
unable to maintain a disinfectant residual within their distribution system
include:
- Routine flushing or cleaning of the pipes (either mechanically by
pigging or by the addition of chemicals to dissolve the deposits) of
the distribution system to remove accumulated debris which may be
exerting a disinfectant demand
- Flushing and disinfection of the portions of the distribution system
in which a residual is not maintained
- Installation of satellite disinfection field facilities with booster
chlorinators within the distribution system
Additional information is available in the AWWA Manual of Water Supply
Practices and Water Chlorination Principles and Practices.
3.2.4 Disinfection System Redundancy
In addition to the aforementioned disinfection requirements, the water
supply systems must also be evaluated for disinfection system redundancy and
for the control of disinfection practices. A system which provides
disinfection as the only treatment for the water is required to provide
redundant system components to ensure that continuous disinfection is provided
at all times. This can be accomplished by providing:
- Both a primary and a secondary disinfection system in which all
components have capacities equal to or greater than design values
- Two chemical supply units of disinfectant which can be used alter-
nately - e.g.f two cylinders of chlorine gas, two tanks of
hypochlorite solution
- Where generation of the disinfectant is needed (such as ozone),
units capable of supplying the design feed rate should be on-line
Also, there are portable test kits available which can be used in
the field to detect residual upon the approval of the Primacy
Agency. These kits may employ titration or colorimetric test
methods. The colorimetric kits employ either a visual detection of
a residual through the use of a color wheel, or the detection of the
residual through the use of a hand held spectrophotometer.
3-17
-------
with a backup unit available for down time. The backup unit should
have a capacity equal to or greater than that of the unit(s) it will
replace„
- Automatic switchover equipment which will change the feed fro® one
storage unit to the other before the first empties or becomes
inoperable
- Duplicate feed systems with each system having full design capacity
- An alternate power supply such as a standby generator with the
capability of running all the electrical equipment at the disinfec-
tion station. The generator should be on-site and functional with
the capability of automatic start-up on power failure
- An automatic shut down to prevent the undisinfected water from
entering the distribution system if there is a system failure
Appendix I contains more specific information for the Primacy Agency for
determining compliance with this requirement.
3.3 Other Criteria
In addition to meeting source water quality criteria and disinfection
criteria, nonfiltering systems utilizing surface water supplies must meet
other criteria. Specifically:
- Maintain a watershed control program
- Conduct a yearly sanitary survey
- Determine that no waterborne disease outbreaks have occurred
- Comply with the revised annual coliform MCL
- Comply with disinfection by-product regulation
Guidelines for meeting these other criteria are presented in the follow-
ing sections.
3.3.1 Watershed Control Program
A watershed control program is a surveillance and monitoring program
which is conducted to protect the quality of a surface water source. It is
desirable to have an aggressive and detailed watershed control program to
effectively limit or eliminate potential contamination by human enteric
viruses. A watershed program may impact parameters such as turbidity, certain
organic compounds, enteric viruses, and total and fecal coliforms and areas of
wildlife habitation. However, the program is expected to have little or no
impact on parameters such as naturally occurring inorganic chemicals,
3-18
-------
naturally occurring organic materials, and pathogens transmitted by wildlife
with the exception of preventing animal activity near the source water intake
prior to disinfection.
It may be difficult to quantify the effect of a watershed program since
there are many variables which influence water quality that are beyond the
control or knowledge of the water supplier. As a result, the benefit of a
watershed control program or specific control measures must in many cases be
based on accumulated cause and effect data and on the general knowledge of the
impact of control measures rather than on actual quantification. According to
the SWTR, a watershed control program should include as a minimum:
1. A description of the watershed including its hydrology and land
ownership
2. Identification and control of watershed characteristics and activi-
ties in the watershed which may have an adverse effect on the water
quality
3. A program to gain ownership or control of the land within the
watershed, for the purpose of controlling activities which will
adversely affect the biological quality of the water
Appendix J contains a more detailed guide to a comprehensive watershed
program.
3.3.2 Sanitary Survey
The watershed control program and the on-site sanitary survey are inter-
related preventive strategies. The sanitary survey is actually a program
which includes and surpasses the requirements of a watershed program. While
the watershed program is mainly concerned with the water source, the sanitary
survey includes some additional requirements for source water quality control
and is also concerned with treatment, distribution, monitoring and emergency
contingencies. As defined by the USEPA, a sanitary survey is an on-site
review of the water source, facilities, equipment, operation and maintenance
of a public water system for the purpose of evaluating the adequacy of such
source, facilities, equipment, operation and maintenance for producing and
distributing safe drinking water.
According to the SWTR, a sanitary survey is required to be conducted on a
yearly basis by the system or by a party approved by the Primacy Agency. The
survey should be conducted by competent individuals such as sanitary and civil
3-19
-------
engineers, sanitarians, and technicians who have experience and knowledge in
the operation, maintenance, and design of a water system, and who have a sound
understanding of public health principles and waterborne diseases. Guidance
for the contents of a sanitary survey are included in the following paragraphs
and Appendix K.
At the onset of determining whether or not a source is to be classified
as a surface water, utilities are required to conduct a detailed, comprehen-
sive survey. Appendix K presents a comprehensive list of water system
features that the person conducting the survey should be aware of and review
as appropriate. This initial investigation establishes the quality of the
water source, its treatment and delivery to the consumer. Once this deter-
mination is made, a less comprehensive survey should be conducted yearly to
ensure that quality of the water and service is maintained. The annual survey
should include as a minimum the following:
A. Source Evaluation
1. Review of the effectiveness of the watershed control program
(Appendix J)
2. Review the physical condition and protection of the source
intake
3. Review of maintenance program to insure that all equipment
(pumps, pipelines and controls) is appropriate and has received
repair as needed which insures high probability for prevention
of system failure
B. Treatment Evaluation
1. Review of improvements and/or additions made during the pre-
vious year to fulfill inadequacies detected in earlier surveys
2. Review of equipment for physical deterioration
3. Review of operating procedures
4. Review of data records to insure that all required tests are
being conducted and recorded and disinfection is effectively
practiced
5. Review coliform data for plant effluent
6. Identification of any improvements which are needed in the
equipment, system maintenance and operation, or data collection
3-20
-------
C. Distribution System Evaluation
1. Review of storage facilities for construction condition
2. Determination that sufficient pressure has been maintained in
the system throughout the year
3. Verification that system equipment has received regular mainte-
nance
4. Review of additions/improvements incorporated during the year
to correct inadequacies detected in the initial inspection
5. Review of cross connection prevention program, including annual
testing of backflow prevention devices
6. Review of routine flushing program for effectiveness
7. Evaluation of the corrosion control program and impact on
distribution water quality
8. Review of the periodic storage reservoir flushing program for
adequacy
D. Management/Operation Evaluation
1. Review the operations to insure that any difficulties experi-
enced during the year have been adequately addressed
2. Review to decide whether a reorganization of management is
needed
3. Determine whether the budget is adequate
4. Review of staffing to insure adequate personnel are available
and they are adequately trained and/or certified
5. Verify that a regular maintenance schedule is followed
6. Review the systems records to verify that they are adequately
maintained
7. Review bacteriological data from the distribution system for
colifonn occurrence, repeat samples and action response
3.3.3 No Disease Outbreaks
Under the provisions of the SWTR, a surface water system which does not
filter must not have had an identified waterborne disease outbreak in its
current configuration which has been determined by the Primacy Agency to be
3-21
-------
attributable to a treatment deficiency. If an identified waterborne disease
outbreak has occurred in the past and the outbreak has been attributed to a
treatment deficiency, then the system must install filtration unless the
system has upgraded its treatment system to remedy the situation which led to
the outbreak, and the Primacy Agency has determined that the system is satis-
fying this requirement. The system may not be required to install filtration
if the disease outbreak has been determined by the Primacy Agency to be the
result of a distribution system problem rather than a treatment deficiency.
In order to determine whether the requirement is being met, the re-
sponsible federal, state and local health agencies should be surveyed to
obtain the current and historical information on waterborne disease outbreaks
which may have occurred within a given service area. Whether conducted by the
Primacy Agency or submitted by the water purveyor this information should
include:
A. Source of the Information:
1. Name of agency
2. Name and phone number of person contacted
B. Outbreak Data
1. Date of inquiry
2. Date(s) of occurrence(s)
3. Known or suspected incidents of waterborne disease outbreaks
4. Type or identity of illness
5. Number of cases
C. Status of Disease Reporting:
- Changes in regulations; e.g., giardiasis was not a reportable
disease until 1985
D. If a Disease Outbreak has Occurred:
1. Was the reason for the outbreak identified; e.g., inadequate
disinfection
2. Did the outbreak occur while the system was in its current
configuration
3. Was remedial action taken
4. Have there been any further outbreaks since the remedial action
was taken
3-22
-------
If a review of the available information indicates that the system or
network for disease reporting is inadequate within the Primacy Agency's area
of responsibility, efforts should be made to encourage the appropriate agen-
cies to upgrade the disease reporting capabilities within the area.
3.3.4 Long-Term Coliform MCL
Long-Tenn MCL
Systems must comply with the long-term coliform MCL on an ongoing basis
in order to avoid filtration. If the proposed long-term coliform MCL criteria
become promulgated, these requirements would be as follows:
a. The three test methods which can be used within the distribution
system are the membrane filter test (MF), the multiple tube fermen-
tation test reported in terms of the most probable number (MPN).^or
the presence of colifonns using the presence-absence test (P-A),
The procedures for these test methods are contained in the 16th
edition of Standard Methods.
b. Systems which analyze less than 60 samples/year for colifonns must
maintain coliform-positive results in five percent or less of the 60
most recent samples, calculated within seven days of the end of each
month of sampling
c. Systems which analyze 60 or more samples/year must maintain coli-
form-positive results in five percent or less of the samples from
the most recent 12 months of sampling, calculated within 7 days of
the end of each month
d. Systems which have not collected 60 samples by the effective date of
the regulation, must maintain fewer than one coliform-positive
sample in the most recent 39 or fewer samples or two coliform-
positive samples in the most recent 40-59 samples
6. The P-A is a modification of the MPN method in which a single
culture bottle is innoculated with a 100 ml sample. The test method
is currently listed as a tenative procedure? however, past research
has indicated that the P-A method has a detection efficiency which
surpasses that of the MPN test and is equivalent to that of the MF
method (Fujioka et al., 1986). The test procedure is also more
easily performed than the aforementioned methods.
7. It should be noted that systems using an unfiltered surface supply
are required to collect a minimum of 5 samples/month or
60 samples/year.
3-23
-------
e. Systems which have violated a, b or c remain in noncompliance until
coliforms are not detected in 5 percent or less of the most recent
20 or more samples
The culture medium of each positive sample must be analyzed for fecal coli-
forms and five repeat samples must be collected within 24 hours at the same
sampling location or the next closest sampling point. If any repeat sample is
total coliform positive but fecal colifonn negative, five additional repeat
samples are to be taken within 24 hours of being notified of the results. The
system must repeat this process until either coliforms are not detected in one
set of five repeat samples or the system determines that the monthly coliform
MCL has been exceeded and notifies the Primacy Agency. The results of the
repeat sample are to be included in the calculation of the MCL and can be used
to satisfy the minimum number of monthly colifonn samples required. The
frequency of monitoring to meet the above regulations is population based, as
indicated in Appendix H.
All systems must also analyze one sample near the first customer on all
days during which the turbidity in the source water exceeds 1 KTU. These
samples are to be included in the calculation of the percent positive samples.
Although a Maximum Contaminant Level Goal/Maximum Contaminant Level
(MCLG/MCL) for Heterotrophic Plate Count (HPC) has not been proposed, the
proposed coliform rule uses the HPC to test for interference with coliform
analysis. If a coliform sample produces a turbid culture in the absence of
gas production, using the multiple-tube fermentation technique, or produces a
turbid culture in the absence of an acid reaction using the presence-absence
(P/A) test, or produces confluent growth or a colony number that is too
numerous to count using the membrane filter technique, the system may either
accept the sample as coliform-positive or declare the sample invalid and
collect and analyze another water sample. The second sample is to be analyzed
for both total coliform and HPC. The sample is considered coliform-positive
if the coliform test is positive or the HPC count is greater than 500 colo-
nies/ml.
3.3.5 Total Trihalomethane (TTHM) Regulations
As indicated in the SWTR, for the system to continue to use disinfection
as the only treatment it must be in compliance with the total trihalomethane
3-24
-------
MCL regulation. The current regulation has established an MCL for trihalo-
methanes (THM) of 100 ug/L for systems serving a population greater than
10,000. However, it is anticipated that this level will be reduced in the
future and this should be considered when planning disinfectant application.
It is recognized that one alternative for utilities to meet the CT
requirements of the SWTR is to increase the disinfectant dose. However, for
many sources, this will result in an increased production of THMs. Any
increase which results in THM levels greater than the 0.1 mg/L limit is
unacceptable. However, considering that more stringent THM requirements are
expected in the future, it is recommended that disinfection application which
increases THMs to levels close to 0.1 mg/L should not be implemented. In such
cases, it is recommended that an alternate disinfectant which produces fewer
THMs should be used. Alternate disinfectant applications which may be used
include the use of ozone as a primary disinfectant with chlorine or chlora-
mines as a secondary disinfectant, or the application of chlorine dioxide as a
primary disinfectant with either chlorine or chloramines used as a secondary
disinfectant.
It is also suggested that Primacy Agencies request systems which change
their disinfection practices to provide evidence of the impact of such changes
on the THM formation. This may be simply a requirement to conduct THM samples
throughout the distribution system after the change in disinfection has been
implemented, or it may be a more extensive testing program.
3-25
-------
4. DESIGN AND OPERATING CRITERIA FOR
FILTRATION AND DISINFECTION TECHNOLOGY
4.1 Introduction
In accordance with the SWTR, public water systems must include filtra-
tion, or an approved particulate removal technology, in their treatment
process unless they are able to satisfy certain conditions. Those conditions
include compliance with source water quality criteria and site-specific
criteria, for which guidance is provided in Section 3 of this manual. Systems
not able to satisfy these conditions will be required to provide particulate
removal and meet criteria pertaining to operation, design (as specified in the
definitions of technologies in the SWTR and more specifically as determined by
the Primacy Agency), and performance.
This section provides guidance for those water systems which currently do
not have filtration equipment and must add it. Guidance is presented both as
minimum requirements and/or background information. Guidance on additional
alternatives for small systems is discussed in Appendix L.
The scope of this section includes items that must be considered by a
water supply system to install filtration, or upgrade existing filtration
processes. Guidance is provided on the following topics:
- Filtration Technology: Includes descriptions, capabilities, design
criteria and operating requirements for each technology, and a
listing of major factors to be considered in their selection,
including raw water quality considerations.
- Disinfection: Includes a description of the most applicable disin-
fection technologies used with filtration systems, and a presenta-
tion of the relative effectiveness of the disinfection technologies
with respect to inactivation of bacteria, cysts and enteric viruses.
- Alternate Technologies: Includes a description of some currently
available alternate filtration technologies.
- Other Alternatives: Includes a description of some nontreatment
alternatives including regionalization and use of an alternate
source.
4.2 Selection of Appropriate Filtration Technology
Filtration is generally provided by passing water through a bed of sand,
a layer of diatomaceous earth, or through a combination of coarse anthracite
4-1
-------
coal overlaying finer sand. Filters are classified and named in a number of
ways. For example, based on application rate, sand filters can be classified
as either slow or rapid; yet these two types of filters differ in many more
characteristics than just application rates they differ in their removal
process, bed material, method of cleaning, and operation. Based on the type
of bed material, filters can be classified as sand, diatomaceous earth,
dual-media (coal-sand), or even tri-media in which a third sand layer is
added.
4.2.1 General Descriptions
Definitions of the currently most applicable technologies, as contained
in the SWTR are as follows:
a. Conventional Treatment: A series of processes including coagu-
lation, flocculation, sedimentation and filtration.
b. Direct Filtration: A series of processes including coagulation (and
perhaps flocculation) and filtration, but excluding sedimentation.
c. Slow Sand Filtration: A designed process which involves passage of
raw water through a bed of sand at low velocity [generally less than
0.4 meters/hour] resulting in particulate removal by physical and
biological mechanisms and changes in chemical parameters by biologi-
cal actions.
d. Diatomaceous Earth Filtration: A process that meets the following
conditions.
- A precoat cake of diatomaceous earth filter media is deposited
on a support membrane (septum)
- The water is filtered by passing through the cake on the
septum; additional filter media, known as body feed, is contin-
uously added to the feed water, in order to maintain the
permeability of the filter cake.
4-2
-------
e. Alternate Technologies: The available alternate filtration tech-
nologies include, but are not limited to:
- Package Plants{1)
- Cartridge Filters
4.2.2 Capabilities
Filtration processes provide various levels of turbidity and microbial
contaminant removal. However, when properly designed and operated and when
treating source waters of suitable quality, the above filtration processes
(with the exception of cartridge filters regarding virus removal) are capable
of achieving at least a 2 log (99 percent) removal of Giardia cysts and a
1 log (90 percent) removal of enteric viruses without disinfection (Logsdon,
1987b; USEPA, 1987; Roebeck, 1962).
A summary of the removal capabilities of the various filtration processes
is presented in Table 4-1. As indicated, conventional treatment without
disinfection is capable of achieving up to a 3 log removal of Giardia cysts
and up to a 3 log removal of enteric viruses. Direct filtration can achieve
up to a 3 log removal of Giardia cysts and up to a 2 log removal of enteric
viruses. Achieving the maximum removal efficiencies of those constituents
with these treatment processes requires the raw water to be properly
coagulated and filtered. Factors which can adversely impact removal
efficiencies include:
- Raw water turbidities less than 1 NTU
- Cold water conditions
- Non-optimum coagulation
- No coagulation
- Improper filter operation including:
Depending upon the type of treatment units in place, historical
performance and/or pilot plant work, these plants could be
categorized as one of the technologies in a-d above at the
discretion of the State. Several studies have already indicated
that some package plants effectively remove Giardia cysts. If such
plants provided adequate disinfection as demonstrated by satisfying
CT values, to achieve the minimum 3 log removal/inactivation of
Giardia cysts and 4 log removal/inactivation of viruses by the
complete treatment train, use of this technology would satisfy the
minimum treatment requirements.
4-3
-------
- No filter to waste
- Intermittent operation
- Sudden rate changes
- Poor housekeeping
- Operating beyond breakthrough
Studies of slow sand filtration have shown that this technology (without
disinfection) is capable of providing greater than a 3 log removal of Glardia
cysts and greater than a 3 log removal of enteric viruses. Factors which can
adversely impact removal efficiencies include:
- Poor source water quality
- Cold water conditions
- Increases in filtration rates
- Decreases in bed depth
- Improper sand size
- Inadequate ripening
Also, as indicated in Table 4-1, diatomaceous earth (DE) filtration can
achieve greater than a 3 log removal of Giardia cysts when sufficient precoat
and body feed are used. However, turbidity and total coliform removals are
strongly influenced by the grade of DE employed. Conversely, DE filtration is
not very effective for removing enteric viruses unless the surface properties
of the diatomaceous earth have been altered by pretreatment of the body feed
with alum or a suitable polymer. In general, DE filtration is assumed to
achieve only a 1 log removal of enteric viruses unless it has been
demonstrated otherwise. Factors which can affect the removal of Giardia cysts
and enteric viruses include:
- Precoat thickness
- Amount of body feed
- Grade of DE
- Improper conditioning of septum
Package plants can be used to treat water supplies for communities as
well as for recreational areas, state parks, construction camps, ski resorts,
remote military installations and others where potable water is not available
from a municipal supply. Operator requirements vary significantly with
specific situations. Under unfavorable raw water conditions they could demand
full-time attention. Package plants are most widely used to treat surface
supplies for removal of turbidity, color and coliform organisms prior to
disinfection. They are available in various capacities up to 6 mgd. Colorado
4-4
-------
TABLE 4-1
REMOVAL CAPABILITIES OF FILTRATION PROCESSES
(1)
Log Removals
Process
Conventional Treatment
Direct Filtration
Slow Sand Filtration
Diatomaceous Earth
Filtration
Giardia(2)
Cysts
2-3
2-3
2-3
2-3
(5)
(5)
Enteric
Viruses
1-3
1-2
1-3
1-2
(3)
(3)
(4)
(2)
Total(2)
Coliform
>4
1-3
1-2
1-3
Note:
1. Without disinfection
2. Logsdon, 1987b.
3. Roebeck et al 1962
4. Poynter and Slade, 1977
5. These technologies generally achieve greater than a 3 log removal.
-------
State University conducted a series of tests on one package plant over a
5-month period during the winter of 1985-86 (Horn and Hendricks, 1986).
Existing installations in Colorado had proven effective for turbidity removal,
and the tests at the university were designed to evaluate the system's
effectiveness in removing coliform bacteria and Giardia cysts from low
turbidity, low temperature source waters. The test results showed that the
filtration system could remove greater than 99 percent of Giardia cysts for
waters which had less than 1 NTU turbidity and less than 5 C temperatures, as
long as proper chemical treatment was applied, and the filter rate was
10 gpm/ft or less. In addition, an alternate water source having a turbidity
ranging from 3.9 to 4.5 NTU was used in 12 test runs with coagulant doses
ranging from 15 to 45 mg/L. The effluent turbidities from these runs were
consistently less than 0.5 NTU.
Surveys of existing facilities indicated that while package plants may be
capable of achieving effective treatment, many have not consistently met the
MCL for turbidity, and in some cases, coliforms were detected in the filtered
water (Morand et al., 1980; Morand and Young, 1983). The performance
difficulties were related to the short detention time inherent in the design
of the treatment units, the lack of skilled operators with sufficient time to
devote to operating the treatment facilities and the wide-ranging variability
in quality of the raw water source. Raw water turbidity was reported to often
exceeded 100 NTU at one site. Later, improvement in operational techniques
and methods resulted in substantial improvement in effluent quality. After
adjustments were made, the plant was capable of producing a filtered water
with turbidities less than 1 NTU, even when influent turbidities increased
from 17 to 100 NTU within a 2-hour period as long as proper coagulation was
provided.
One of the major conclusions of these surveys was that package water
treatment plants manned by competent operators can consistently remove turbid-
ity and bacteria from surface waters of a fairly uniform quality. Package
plants applied where raw water turbidities are variable require a high degree
of operational skill and nearly constant attention by the operators.
Regardless of the quality of the raw water source, all package plants require
4-5
-------
at least a minimum level of maintenance and operational skill and proper
chemical treatment if they are to produce satisfactory water quality.
Cartridge filters using microporous filter elements (ceramic, paper or
fiber) with pore sizes as small as 0.2 urn may be suitable for producing
potable water from raw water supplies containing moderate levels of turbidity,
algae and microbiological contaminants.
The advantage to small systems of these cartridge filters is that, with
the exception of disinfection, no other chemicals are required. The process
is one of strictly physical removal of small particles by straining as the
water passes through the porous cartridge. Other than occasional cleaning or
cartridge replacement, operational requirements are not complex and do not
require skilled personnel. Such a system may be suitable for some small
systems where, generally, only maintenance personnel are available for
operating water supply facilities. However, the use of cartridge filters
should be limited to low turbidity source waters since their use on moderate
or high turbidity waters will result in rapid headless buildup.
Long (1983) analyzed the efficacy of a variety of cartridge filters using
turbidity measurements, particle size analysis, and scanning electron micro-
scope analysis. The filters were challenged with a solution of microspheres
averaging 5.7 urn in diameter (smaller than a Giardia cyst), at a concentration
of 40,000 to 65,000 spheres per mL. Ten of 17 cartridge filters removed over
99.9 percent of the microspheres.
In tests using live infectious cysts from a human source, cartridge
filters were found to be highly efficient in removing Giardia cysts (Hibler,
1986). Each test involved challenging a filter with 300,000 cysts. The
average removal for five tests was 99.86 percent, with removal efficiencies
ranging from 99.5 percent to 99.99 percent.
The application of cartridge filters to small water systems using either
cleanable ceramic or disposable polypropylene cartridges, appears to be a
feasible method for removing turbidity and most microbiological contaminants,
although data are needed regarding the ability of cartridge filters to remove
viruses. Since disinfection by itself could achieve a 4 log inactivation of
viruses, if the cartridge filter removes greater than or equal to 3 logs of
Giardia, then the filter plus disinfection would achieve the overall minimum
4-6
-------
requirements. However, consideration should be given to the feasibility of
multiple barriers of treatment for each target organism, i.e., some Giardia
and virus removal by each barrier as a protection if one of the barriers
fails. The efficiency and economics of the process must be closely evaluated
for each application. Pretreatment in the form of roughing filters (rapid
sand or multi-media) or fine mesh screens may be needed to remove larger
suspended solids, which could result in the rapid buildup of headless across
the cartridges. (USEPA, 1987)
In general, conventional treatment, direct filtration, slow sand
filtration and diatomaceous earth filtration can be designed and operated to
achieve the maximum removal of those water quality parameters of concern.
However, for the purpose of selecting the appropriate filtration and disinfec-
tion technologies and for determining design criteria, these filtration
processes should be assumed to achieve a 2 log reduction in Giardia cysts and
a 1 log reduction of enteric viruses. This conservative approach will assure
that the treatment facility has adequate capabilities to respond to
non-optimum performance due to changes in raw water quality, plant upsets,
etc. The balance of the required removals and/or inactivation of Giardia
cysts and enteric viruses must therefore be achieved through the application
of appropriate disinfection. The performance of alternate technologies such
as cartridge filters, and possibly package plants, depending upon the unit
under consideration, however, cannot be stated with certainty at this time.
These performance uncertainties necessitate the use of. pilot studies in order
to demonstrate their efficacy for a given water supply.
4.2.3 Selection
For any specific site and situation, a number of factors will determine
which filtration technology is most appropriate. Among these are:
- Raw Hater Quality Conditions
- Site Specific Factors
- Economic Constraints
Raw Water Quality Conditions
The number of treatment barriers provided should be commensurate with the
degree of contamination in the source water. The four available technologies
vary in their ability to meet the performance criteria when a wide range of
4-7
-------
raw water quality is considered. While numerical values of raw water quality
that can be accommodated by each of the four technologies will vary from site
to site, general guidance can be provided. A table for selecting filtration
processes, based on total coliform count, turbidity, and color is presented
here as Table 4-2. It is not recommended that filtration systems other than
those listed in Table 4-2 be utilized when the general raw water quality
conditions exceed the values listed, unless it has been demonstrated through
pilot testing that the technology can meet the performance criteria under the
raw water quality conditions expected to occur at the site. The filtration
processes listed in Table 4-1 are capable of achieving the required
performance criteria when properly designed and operated if they are treating
a source water of suitable quality. One of the causes of filtration failures
is the use of inappropriate technology for a given raw water quality
(Logsdon, 1987b).
However, these criteria are general restrictions and not absolute limits.
Periodic occurrences of raw water coliform, turbidity or color levels in
excess of the values presented in Table 4-2 would not preclude the use of a
particular filtration technology. For example, the following alternatives are
available for responding to occasional raw water turbidity spikes:
- Direct Filtration
- Continuous monitoring and coagulant dose adjustment
- More frequent backwash of filters
- Use of presedimentation
- Use of a one hour contact basin between the rapid mix basin and
filters12'
- Slow Sand Filtration
- Use of a roughing filter
- Use of an infiltration gallery
- Diatomaceous Earth Filtration
- Use of a roughing filter
- Use of excess body feed
The contact basin serves as a silt and sand trap and can increase
plant reliability by adding lead time to smooth out sudden
variations in raw water turbidity. (USEPA, 1987) The additional
contact time can also help to condition the floe so that it becomes
more filterable.
4-8
-------
TABLE 4-2
GENERALIZED CAPABILITY OF FILTRATION SYSTEMS
TO ACCOMMODATE RAW WATER QUALITY CONDITIONS
General Restrictions
Total
Conforms Turbidity Color
Treatment (f/100 ml) (NTU) (CU)
Conventional with predisinfectlon (20,000 No restrictions (75(2*
Conventional without predi si nf ectlon (5,000 No restrictions (75
Direct filtration with flocculatlon (500 (7-14 (40
Direct filtration without flocculatlon (500 (7-14 (10
Slow sand filtration (800(5) (10 (5(3)
Diatomaceous earth filtration (50t3) (5(3) (5(3)
Notes:
1. Depends on algae population, alum or cationic polymer coagulation — (Cleasby et al., 1984.)
2. USEPA, 1971.
3. Letter-man, 1986.
*. Bishop et al., 1980.
5. Slezak and Sims, 1984.
-------
For the above alternatives, it is recommended that pilot testing be
conducted to demonstrate the efficacy of the treatment alternative.
The characteristics of each filtration technology are a major factor in
the selection process. Characteristics of significance include performance
capabilities (contaminant removal efficiencies), design and construction
requirements, and operation and maintenance requirements. Details regarding
each of the four filtration technologies are presented in the following sub-
section.
Site specific factors
As indicated in the SWTR, the selection of appropriate filtration tech-
nology must include consideration of site specific factors. These factors
include:
- Available land area
- Location of treatment plant relative to the source
- Sophistication of the technology
Although consideration of all possibilities is beyond the scope of this
manual, the above factors must be included in the evaluation to select a
filtration technology.
Economic Constraints
The costs associated with a filtration technology are recognized to have
a significant impact on selection and implementation. Cost estimates for the
filtration technologies presented in this document can be found in the USEPA
document "Technologies and Costs for the Removal of Microbial Contaminants
from Potable Hater Supplies." (USEPA, 1987) A summary of these cost
estimates are presented in Table 4-3.
4.3 Available Filtration Technologies
4.3.1 Introduction
As indicated in the SWTR, the historical responsibility of the states to
establish design and operating criteria for public drinking water plants will
continue. The purpose of the following sections is to provide guidance on how
the design and operating criteria may need to be changed in order to assure
that the performance criteria in the SWTR are met.
4-9
-------
The design criteria for the various filtration technologies found in the
1982 edition of the Recommended Standards for Water Works (Ten States Stan-
dards) are the minimum design criteria that a majority of states are currently
following. The design criteria contained in the Ten States Standards have
not been duplicated here. Rather, the reader is referred to the Ten States
Standards. The following additions and/or changes are recommended in order to
assure compliance with the performance criteria of the SWTR.
4.3.2 General
The following recommendations should be applied to all filtration plants:
A. All filtration plants should provide continuous turbidity monitoring
of the effluent turbidity from each individual filter. This recomr
mendation applies to all new and existing water treatment plants.
B. All new water treatment plants should include the capability of
filter to waste on each filter, and where possible, existing filtra-
tion plants should install a filter to waste capability.
C. In order to establish the filter-to-waste operating guidelines, the
following procedure is suggested:
a. Review the performance (effluent turbidity) data for each
filter and determine which filter has the poorest performance
historically (highest effluent turbidity).
3. Based upon the results of a survey conducted for the American Water
Works Association Research Foundation (AWWARF), some 38 states use
the Ten States Standards entirely or in modified form (AWWARF,
1986).
4. Although this is not part of the requirements of the SWTR, it is
recommended because of the possibility that not all filters in a
treatment plant will produce the same effluent turbidity. This may
be due to a variety of" conditions that include bed upsets, failure
of media support or underdrain systems, etc. Although the combined
effluent from all the filters may meet the turbidity requirements of
the SWTR, the turbidity level from an individual filter may
substantially exceed the limits. This may result in the passage of
Giardia cysts, or other pathogens.
5. For most high rate granular bed filters, there is a period of
conditioning, or break-in, immediately following backwashing, during
which turbidity and particle removal is at a minimum. In some cases
the addition of a suitable polymer to the backwash water or starting
the filter at a low rate and gradually increasing the rate may
reduce the amount of time required for the break-in of a filter.
4-10
-------
TABLE 4-3
SUMMARY OF TOTAL COSTS OF TREATMENT; t/1.000 GALLONS
(1)
Site Category
(2)
Treatment
Processes Design Flow
Average Ft on
Filtration13'
Conventional treatment package plants
1
0.026
0.013
944.5
(4)
2
0.068
0.045
277.*
3
0.166
0.133
195.1
*
0.50
0.40
113.6
5
2.50
1.30
72. 8
01 a
6
5.85
3.25
52.4
CO •»
7 8 9 10
11.59 22.86 39.68 109.9
6.75 11.50 20.00 55.5
en a ci e to fc 11 c
11
404
205
12
1,275
650
backwashing filters
Direct filtration using pressure
filters
Direct filtration using gravity
filters preceded by flocculation
Direct filtration using gravity
filters and contact basins
Diatomaceous earth filtration
Slow-sand filtration
Package ultrafiltration plants
322.7 137.2 79.1 48.8 39.2 45.8 36.9 28.2
150.2 90.5 58.4 46.8 50.5 39.8 28.6 23.6 2113
131.2 80.9 54.7 44.2 48.0 37.5 26.3 21.4 19.1
672.9 227.2 134.7 66.6 43.1 43.1 36.1 48.1 41.7 35.4
377.8
205.1 133.4 54.7 34.3 28.7 25.3
455.6 226.8 179.2 138.4
Notes:
1. Costs are in late 1986 dollars.
2. Category values, from top to bottom, are number, design flow (mgd), and average flow (mgd). Population ranges for each
category arei
1. 25 - 100 4. 1,001 - 3,300 7. 25,001 - 50,000 10. 100,001 - 500,000
2. 101 - 500 5. 3,301 - 10,000 8. 50,001 - 75,000 11. 500,001 • 1,000,000
3. 501 - 1,000 6. 10,001 - 25,000 9. 75,001 - 100,000 12. M,000,000
3. Each process group includes chemical addition and Individual liquid and solids handling processes required for operation;
excluded are raw water pumping, finished water pumping, and disinfection.
4. Indicates that costs are not currently available.
-------
b. Following backwashing of the filter with the poorest
performance, place that filter into service and collect grab
samples every minute for a period of at least 30 minutes.
c. Analyze the grab samples for turbidity and determine how long
the filter must be in operation before the effluent turbidity
drops to less than or equal to 0.5 MTU.
d. The filter to waste period is then defined as the time it takes
for the filter effluent of the worst filter to reach a turbid-
ity of less than or equal to 0.5 NTU following filter startup
at the normal production flow rate. If the raw water is less
than 1.0 NTU then at least, 50 percent turbidity removal across
the filter should be achieved before the filter is brought back
on-line.
e. Since not all filters may be capable of filtering to waste at
normal production flow rates, an alternative may be to define
the quantity of water which must be filtered to waste.
f. In addition, the filter-to-waste period should be determined
during each of the seasonal variations in water quality to
account for their impact on filter performance.
0. All water treatment plants should increase filtration rates
gradually when placing filters back into service following back
washing and/or after the filter-to-waste valve is closed.
4.3.3 Conventional Treatment
Conventional treatment is the most widely used technology for removing
turbidity and microbial contaminants from surface water supplies. Convention-
al treatment includes the pretreatment steps of chemical coagulation, rapid
mixing, flocculation and sedimentation followed by filtration. The filters
can be either sand, dual-media, or multi-media. Figure 4-1 is a flow sheet
for a conventional treatment plant.
Single media rapid sand filters are generally designed with a filtration
rate of 2 gpm/ft . Newer plants which use dual- or tri-media filters have a
design filtration rate of 4 to 6 gpm/ft . When properly operated, filter
6. Continuous turbidity monitoring can be used in place of grab
sampling.
4-11
-------
plants are generally capable of producing a low turbidity filtered water that
approaches a value of 0,1 to 0.2 NTU.
The extent and degree of pretreatment is determined by the quality of the
raw water supply and the type of filter used in the plant. For example, a raw
water with high turbidity and high concentrations of coliforms, requires more
pretreatment, prior to filtration than a raw water with low turbidity and low
coliform concentrations. Site-specific raw water quality conditions influence
the design criteria for each component of a conventional treatment system.
Design Criteria
The minimum design criteria presented in the Ten State Standards for
conventional treatment are considered sufficient for the purposes of the SWTR
except for the following additions:
a. A primary coagulant must be used at all times during which the
treatment plant is in operation.
b. The criteria for sedimentation should be expanded to include other
methods of solids removal including plate separation, dissolved air
floatation, and upflow-solids-contact clarifiers.
Operating Requirements
The operation of conventional and direct filtration plants is more
demanding than for DE or slow sand filter plants. Conventional and direct
filtration plants must be monitored carefully because failure to maintain
optimum coagulation can result in poor filter performance and breakthrough of
(8)
cysts and viruses. Although the detention time provided by the settling
basins results in some margin of safety, the loss of coagulation control at
the chemical feed and rapid mix points may not be noticed until the poorly
coagulated water reaches the filters and the process has failed. Failure to
7. Dependable removal of Giardia cysts can not be guaranteed if a clear
water (raw water turbidity less than 1 MTU) is filtered without
being properly coagulated (Logsdon, 1987b; Al-Ani et al., 1985).
8. As indicated in the preamble to the proposed SWTR, 33 percent of the
reported cases of giardiasis in waterborne disease outbreaks were
attributed to improperly operated filtration plants.
4-12
-------
•COAGULANTS
INFLUENT
I
RAPID MIX
i i»c-2 mm
DETENTION
FLOCCULATION
20-45 mm
SEDIMENTATION
1-4 noun
FILTRATION
RAPID SAND- 2 cpm/ll*
I DUAL AND TRl-MlXED
1 MEDIA- 4-6 CS«"H2
FIGURE 4-1 FLOW SHEET OF A TYPICAL CONVENTIONAL
WATER TREATMENT PLANT
-------
effectively monitor and control filter operation can result in undetected poor
filter performance (Logsdon, 1987a; Logsdon, 1987b).
Effective operation of a conventional treatment plant requires careful
monitoring and control of:
- Chemical Feed
- Rapid Mix
- Flocculation
- Sedimentation
- Filtration
For the purposes of the SWTR, effective operation of a conventional water
treatment plant can be summarized as follows:
a. The application of a primary coagulant and the maintenance of
effective coagulation and flocculation at all times when a treatment
plant is in operation.
b. Maintenance of effective filtration. Unless terminal headloss
occurs before the effluent turbidity exceeds 0.5 NTU, the filter
effluent turbidity should be used to initiate: 1) the start of a
filter run at the end of a filter-to-waste cycle, and 2) the start
of a backwash cycle when filter effluent again rises to 0.5 MTU or a
lower set point value which will ensure that., the plant finished
water quality will meet performance criteria.
4.3.4 Direct Filtration
A direct filtration plant can include several different pretreatment unit
processes depending upon the application. In its simplest form, the process
includes only in-line filters (oftentimes pressure units) preceded by chemical
coagulant application and mixing. The mixing requirement, particularly in
pressure filters, can be satisfied by influent pipeline turbulence. In larger
plants with gravity filters, an open rapid-mix basin with mechanical mixers is
typically used. Figure 4-2 illustrates the unit processes of a typical direct
filtration plant.
9. Some conventional water treatment plants which treat low turbidity
source waters (<1 NTU) reportedly discontinue the application of
coagulant(s) during periods of low turbidity since the raw water
already meets the turbidity MCL. However, studies have shown that
cyst removal for low turbidity waters is the most difficult to
achieve and requires optimum pretreatment (including coagulation) to
achieve effective removals (Al-Ani et al., 1985).
10. As an exception to this priority, filters which were removed from
service should always be backwashed upon start up.
4-13
-------
Another variation of the direct filtration process consists of the
addition of a coagulant to the raw water followed by rapid mixing and floccu-
lation, as illustrated on Figure 4-3. The chemically conditioned and floccu-
lated water is then applied directly to a dual or mixed-media filter. Floccu-
lation results in better performance of certain dual-media filter designs for
specific water supplies (USEPA, 1987).
Figure 4-4 is a flow sheet of a direct filtration process utilizing a
1-hour contact basin between the rapid mix basin and the filter. The contact
basin should be designed to promote low intensity mixing of the destabilized
colloidal material and suspended solids to increase the rate of particle
encounters and the formation of aggregates which are removed through
filtration. The contact basin also increases plant reliability by adding
detention time to smooth-out sudden variations in raw water turbidity.
Design Criteria
The 1982 edition of Ten State Standards requires pilot studies to
determine most of the design criteria. The requirement is considered
sufficient for the purposes of the SWTR with the following exceptions:
A. Primary coagulant must be used at all times when the treatment plant
is in operation.
Operating Requirements
Operating considerations and requirements for direct filtration plants
are essentially identical to those for conventional treatment plants. The
major difference is that a direct filtration plant will not have a clarifier,
and may or may not have a flocculation or contact basin. In addition, it is
recommended that all direct filtration plants, both new and existing, be
required to initiate a filter to waste period following backwashing.
11. Optimum coagulation is critical for effective turbidity and
microbiological removals with direct filtration (Al-Ani et al.,
1985).
12. As with conventional treatment, direct filtration produces a
relatively poor quality filtrate at the beginning of filter runs and
therefore requires a filter-to-waste period (Cleasby et al., 1984).
4-14
-------
INFLUENT
-COAGULANTS
RAPID MIX
s«c • 2 min
DETENTION
DUAL OR MIXED
MEDIA FILTER
4-5 gpm/ft2
FIGURE 4-2 FLOW SHEET FOR A TYPICAL
DIRECT FILTRATION PLANT
rCOAGULANTS
INFLUENT
1
RAPID MIX
c*c - 2 min
DETENTION
FLOCCULATION
15-30 mm
DUAL OR MIXED
MEDIA FILTER
4-6 gpm/tt2
FIGURE 4-3 FLOW SHEET FOR A TYPICAL DIRECT
FILTRATION PLANT WITH FLOCCULATION
-------
INFLUENT
1
-COAGl
' -
JLANTS
RAPID MIX
I stc • 2 mm
DETENTION
1-HR
CONTACT BASIN
>
,
DUAL OR MIXED
MEDIA FILTER
4-5 com/tt2
POLYMER
0.05-0.5 mg/l OR
ACTIVATED SILICA
FIGURE 4-4 FLOW SHEET FOR A TYPICAL DIRECT
FILTRATION PLANT WITH A CONTACT BASIN
-------
As with conventional treatment, the priorities for initiating the back-
washing of a filter should be filter effluent turbidity values, followed by
headless and run time. Effluent turbidity monitoring equipment should be set
to initiate filter backwash at an effluent value lower than 0.5 NTU, in order
to meet finished water quality requirements.
4.3.5 Slow Sand Filtration
Slow sand filters differ from single-media rapid-rate filters in a number
of important characteristics. In addition to the difference of flow rate,
slow sand filters:
A. Function using biological mechanisms as well as physical-chemical
mechanisms
B. Use smaller sand particles
C. Are not backwashed, but rather are cleaned by removing the surface
media
D. Have much longer run times between cleaning
E. Require a ripening period at the beginning of each run
Although rapid rate filtration is the water treatment technology used
most extensively in the United States, its use has often proved inappropriate
for small communities since rapid-rate filtration is a technology that requir-
es skilled operation by trained operators. Slow sand filtration requires very
little control by an operator. Consequently, use of this technology may be
more appropriate for small systems where source water quality is within the
guidelines recommended in Section 4.2.3.
As indicated in this section, slow sand filtration may be applicable to
other source water quality conditions with the addition of pretreatment such
as a roughing filter or presedimentation.
Design Criteria
The minimum design criteria presented in the Ten State Standards for slow
rate gravity filters are considered sufficient for the purposes of the SWTR
with the following exceptions:
4-15
-------
a. Raw water quality limitations should be changed to reflect the
values given in table 4-2.
b. The effective sand size should be between 0.15mm and 0.35nm rather
than the current 0.30 mm to 0.45 mm.
Operating Requirements
Maintenance of a slow sand filter requires two periodic tasks: removal
of the top 2 to 3 cm of sand and replacement of the sand (Bellamy et al.,
1985). The top 2 to 3 cm of the surface of the sand bed should be removed
when the headloss exceeds 1 to 1.5 m.
Slow-sand filters produce poorer quality filtrate at the beginning of a
run (right after scraping), and require a filter-to-waste (or ripening) period
of one to two days before being used to supply the system. The ripening
period is an interval of time immediately after a scraped filter is put back
on-line, when the turbidity or particle count results are significantly higher
than the corresponding values for the operating filter. Filter effluent
monitoring should be used to determine the end of the ripening period. For
example, a turbidimeter could be set at an NTU of 1.0 or less to initiate
start of the filter run.
When repeated scrapings of the sand have reduced the depth of the sand
bed to approximately one half of its design depth, the sand should be
replaced. Filter bed depths of less than 0.3 to 0.5 m (12 to 20 inches) have
been shown to result in poor filter performance (Bellamy et al., 1985). The
13. Without pretreatment, limitations exist in the quality of water that
is suitable for slow sand filtration (Logsdon, 1987b; Cleasby et
al., 1984; Bellamy et al., 1985; Fox et al., 1983).
14. Significant decreases in total coliform removals were shown at
effective sand sizes greater than 0.35 mm (Bellamy et al., 1985).
As defined in the AWWA Standard for Filtering Material, effective
size is the size opening that will pass 10 percent by weight of a
sample of filter material.
15. Removal of this top layer of the "Schmutzdecke" should restore the
filter to its operational capacity and initial headloss.
4-16
-------
replacement procedure should include removal of the remaining sand down to the
gravel support, the addition of the new sand to one half of the design depth
and placement of the sand previously removed on top of the new sand.
The amount of time for the biological population to mature in a new sand
filter (also called curing) and to provide stable and full treatment was found
to vary. The World Health Organization.(1980) reported that curing requires a
few weeks to a few months. Fox et al., (1983) found that "about 30 days* were
required to bring particle and bacterial effluents down to a stable level.
All researchers agree that a curing time for a new filter is required before
the filter operates at its fullest potential (Bellamy et al., 1985).
4.3.6 Diatomaceous Earth Filtration
Diatomaceous earth (DE) filtration, also known as precoat or diatomite
filtration, is applicable to direct treatment of surface waters for removal of
relatively low levels of turbidity and microorganisms.
Diatomite filters consist of a layer of DE about 3 mm (1/8 inch) thick
supported on a septum or filter element. The thin precoat layer of DE must be
supplemented by a continuous body feed of diatomite, which is used to maintain
the porosity of the filter cake. If no body feed is added, the particles
filtered out will build up on the surface of the filter cake and cause rapid
increases in headless. The problems inherent in maintaining a perfect film of
DE on the septum have restricted the use of diatomite filters for municipal
purposes, except under certain favorable raw water quality conditions, i.e.,
low turbidity and good bacteriological quality.
16. This procedure results in clean sand being placed in the bottom half
of the filter bed and biologically active sand in the top half
reducing the amount of time required for the curing period. It also
provides for a complete exchange of sand over time, alleviating
potential problems of excessive silt accumulation and clogging of
the filter bed (Bellamy et al., 1985).
4-17
-------
Design Criteria
The minimum design criteria presented in the Ten State Standards for
diatomaceous earth filtration are considered sufficient for the purposes of
the SWTR with the following exceptions:
A. The recommended quantity of precoat is 1 kg/m (0.2 pounds per
square foot) of filter area, and the minimum thickness of the
precoat filter cake is 3mm to 5mm (1/8 to 1/5-inch).
B. It is recommended that treatment plants be encouraged to provide a
coagulant coating [alum or suitable polymerJ of the body feed.
Operating Requirements
Operating requirements specific to DE filters include:
- Preparation of body feed and precoat
- Verification that dosages are proper
- Periodic backwashing and disposal of spent filter cake
- Periodic inspection of the septum(s) for cleanliness or damage
- Verification that the filter is producing a filtered water that
meets the performance criteria
4.3.7 Alternate Technologies
The SWTR indicates that filtration technologies other than those speci-
fied above, may be used following demonstration through the use of on-site
pilot studies that the alternate technology is at least as effective as
conventional treatment. Guidance for the pilot studies required to demon-
strate this effectiveness is given in Appendix M of this manual.
Alternate filtration technologies which are currently available include:
- Package Plants
- Cartridge Filters
17. Studies have shown that a precoat thickness of 1 kg/m (0.2 Ibs/ft )
was most effective in Giardia cyst removal and that the precoat
thickness was more important than the grade size in cyst removal
(DeWalle et al., 1964; Logsdon et al.f 1981; Bellamy et al., 1984).
18, Although enhancement of the DE is not required for Giardia cyst
removal, coagulant coating of the body feed has been found to
significantly improve percent removals of viruses, bacteria and
turbidity. (Brown et al., 1974; Bellamy et al., 1984).
4-18
-------
Package plants are not a separate technology in principle from the
preceding technologies. They are, however, different enough in design crite-
ria, operation and maintenance requirements that they must be handled as an
alternate technology. The exception to this would be as previously stated
under 4.2.I.e. The package plant is designed as a factory-assembled,
skid-mounted unit generally incorporating a single, or at the most, several
tanks. A complete treatment process typically consists of chemical coagula-
tion, flocculation, settling and filtration. Package plants generally can be
applied to flows ranging from about 25,000 gpd to approximately 6 mgd (USEPA,
1987).
The application of cartridge filters using either cleanable ceramic or
disposable polypropylene cartridges to small water systems may be a feasible
method for removing turbidity and some microbiological contaminants, although
data are needed regarding the ability of cartridge filters to remove viruses.
As previously indicated, pilot studies are required to demonstrate the
efficacy of this technology for a given supply. If the technology was
demonstrated to be effective through pilot plant studies at one site, then the
technology could be considered to be effective at another site which had
similar source water quality conditions. Pilot plant testing at the new site
might not be necessary.
Design Criteria
Upon completion of the pilot studies and assuming successful demonstra-
tion of performance, design criteria should be established and approved by the
Primacy Agency. Eventually, a sufficiently large data base will become
available to apply the alternate technology on other water supplies of similar
quality.
Operating Requirements
Upon completion of the pilot studies and assuming successful demonstra-
tion of performance, operating requirements should be established and approved
by the Primacy Agency.
4.3.8 Other Alternatives
Under certain circumstances, some systems may have other alternatives
available. These alternatives include:
- Regionalization
- Alternate sources
4-19
-------
A feasible option, especially for small water systems which must provide
filtration, may be to join with other small or large systems to form a. region-
al water supply system. Alternative water sources located within a reasonable
distance of a community which meet the requirements of the SWTR and other
applicable drinking water regulations may be developed to provide a satisfac-
tory solution to a community water quality problem. Alternative ground water
sources may be available depending upon the size and location of the system
and the costs involved.
4.4 Disinfection
4.4.1 General
The SWTR requires that disinfection be included as part of the treatment
of water for potable use. It has already been recommended that the number of
treatment barriers be commensurate with the degree of contamination in the
source water in accordance with Table 4-2. For example, as indicated in Table
4-2, when the total coliforms in the source water are greater than 5,000/100
ml, conventional treatment with predisinfection is recommended. However, the
selection of appropriate disinfection requires more detailed considerations
than those provided in Table 4-2. These considerations include:
- Source water quality and the overall removal/inactivation of Giardia
cysts and enteric viruses
- Formation of TTHMs
- Need for an oxidant for purposes other than disinfection, e.g.,
control of taste and odor, iron and manganese, color, etc.
4.4.2 Removal/inactivation Requirements
The SWTR requires a minimum 3 log removal/inactivation of Giardia cysts
and a minimum 4 log removal/inactivation of enteric viruses. For planning
purposes, filtration which is operated to meet the turbidity performance
requirements presented in Section 5 should be assumed to achieve a minimum 2
log removal of Giardia cysts and a 1 log removal of enteric viruses. Well
operated conventional treatment, diatomaceous earth and slow sand filtration
plants can be expected to achieve a 2.5 to 3 log removal of Giardia cysts and
direct filtration plants can be expected to achieve greater than a 2 log
removal of Giardia cysts. Nevertheless, it is still recommended that systems
4-20
-------
provide sufficient disinfection to achieve a minimum of 1 log inactivation of
Giardia cysts as a margin of safety. Depending upon circumstances (e.g.
source water less than 100/100 ml total colifonns, and disinfection
by-products or economic harships are problems), systems using conventional
treatment slow sand filtration or diatomaceous earth (but not direct
filtration) may seek to reduce their disinfection requirements to a minimum of
0.5 log inactivation if they are achieving a good filtered water quality on a
source water that contains low coliform levels. At no time should the
disinfection requirements be reduced to less than is needed to achieve a
0.5 log inactivation of Giardia cysts. Systems which achieved a 0.5 log
inactivation of Giardia cysts, using free chlorine, chlorine dioxide or ozone,
would also in effect be achieving a 4 log inactivation of viruses. This same
rule of thumb could not be applied to chloramines, which are less effective
for inactivating viruses than they are for Giardia cysts.
Although the SWTR requires a minimum of a 3 log removal/inactivation of
Giardia cysts and a minimum of a 4 log removal/inactivation of enteric
viruses, greater removals/inactivations may be appropriate depending upon the
degree of contamination within the source water. Based upon the geometric
mean of the raw water total coliform levels, it is recommended that for
systems which filter, sufficient disinfection be provided for the
. ,, . (19)(20)
following:
19. These values are presented here only as general guidelines. There
is currently little evidence which correlates the occurrance of
colifonns with Giardia or viruses in raw water supplies. The
assumption is that source waters with deteriorating microbiological
quality should receive increased disinfection. This assumption is
consistent with the multiple barrier concept. However, for water
supplies which contain significant levels of THM precursors in their
source water, strict reliance on these disinfection guidelines may
result in unacceptable increases in their THM levels. Therefore,
utilities which have difficulty meeting these guidelines would be
encouraged to monitor their source water for Giardia and viruses and
to adjust these values accordingly.
20. An explanation of the geometric mean is provided in the 16th edition
of Standard Methods.
4-21
-------
Raw water Giardia eyst Enteric virus
Total coliforms inactivation inactivation
(#/100ml) dog)
<100 1 3
<500 1.5 3.5
<1000 2 4
<5000 2.5 4.5
<10000 3 5
CT tables for each of the disinfectants for the various removals listed
in item C above are presented in Appendix E. These tables should be reviewed
in order to determine the minimum dosage and contact time required for the
selected disinfectant in preparation for ascertaining the chemical feed and
storage requirements.
4.4.3 Total Trihalomethane (TTHM) Regulations
In addition to complying with disinfection requirements, systems must
conform to the TTHM regulation. Currently, this regulation includes an MCL
for TTHMs of 0.1 mg/L for systems which serve greater than 10,000 people.
More stringent regulations are expected to be issued in the near future by the
USEPA, and these would also pertain to systems serving less than 10,000
people. Therefore, the selection of an appropriate disinfectant must include
consideration of current and possible future regulations.
4.4.4 Oxidant Needs
In the treatment of surface waters, an oxidant/disinfectant is often
needed for purposes other than disinfection. For example, preoxidants are
frequently used to help control taste and odors, iron and manganese removal,
and to control growth within the treatment plant. Therefore, the selection of
an appropriate disinfectant/oxidant must take these other objectives into
account.
21. When the disinfectants chlorine, chlorine dioxide and ozone are
used, meeting the CT requirements for achieving the indicated level
of Giardia cyst inactivation will easily satisfy the CT requirements
for achieving the indicated level of enteric viruses inactivation.
For these disinfectants, only a 0.5 log inactivation of Giardia
cysts is needed to achieve a 4 log inactivation of enteric viruses.
4-22
-------
Based upon the above considerations, bench scale studies and/or pilot
studies are recommended as part of the selection process for a disinfectant.
These studies should address, as a minimum:
a. Water quality objectives(removal requirements, taste and odor
control, etc.)
b. Points of chemical application
c. Dosage requirements
d. Mixing requirements
e. Impacts on other treatment processes, (e.g., use of alternate
oxidant may require the use of a filter aid to prevent turbidity
breakthrough on the filters)
f. Impacts on compliance with current and future TTHM regulations
g. Ability of selected disinfectant and the method of application to
meet future regulations -/
4-23
-------
5. CRITERIA FOR DETERMINING IF FILTRATION AND
DISINFECTION ARE SATISFACTORILY PRACTICED
5.1 Introduction
In addition to the design and operating conditions outlined in Section 4
of this manual, the SWTR requires that new and existing filtration plants meet
specified performance criteria in order to assure that filtration and
disinfection are satisfactorily practiced. These criteria include:
Design and Operating Criteria (presented in Section 4)
Disinfection Monitoring Requirements
Turbidity Monitoring Requirements
Turbidity Performance Criteria
Disinfection Performance Criteria
The overall objective of these criteria is to control the following water
quality constituents specified in the SWTR:
- Giardia
- Enteric viruses
- Turbidity
- HPC
- Legionella
Filtration which is practiced according to the design and operating
criteria presented in Section 4 of this manual is very effective in achieving
a 2 to 3 log removal of Giardia cysts. However, filtration is generally less
effective (1 to 2 log removals) in removing enteric viruses. Disinfection
with chlorine, chlorine dioxide, or ozone provides effective inactivation of
enteric viruses, and should be considered the primary treatment barrier for
virus removal. Chloramines are not effective for inactivation of viruses.
Based upon these considerations, the purposes of the performance criteria
in the SWTR are to assure high probabilities that:
a. Filtration plants are well operated and achieve maximum removal
efficiencies of the constituents listed above.
b. To assure that disinfection will provide adequate inactivation of
viruses, HPC and Legionella, and added protection against Giardia
cysts.
5-1
-------
5.2 Turbidity Monitoring Requirements
Sampling Location
The SWTR requires that the turbidity samples be representative of the
system's filtered water. The purposes of the proposed turbidity requirements
for systems utilizing filtration are:
a. To provide an indication of Giardia cyst and general particulate
removal for conventional treatment, direct filtration and general
particulate removal for diatomaceous earth and slow sand filtration.
b. To provide an indication of possible interference with disinfection.
The sampling locations which would satisfy the requirements of the SWTR
would include:
a. Combined filter effluent prior to entry into a clearwell
b. Clearwell effluent
c. Plant effluent or immediately prior to entry into the distribution
system
The selection of one of these three sampling locations for demonstrating
compliance with the turbidity performance criteria may be left up to the
preferrence of the system or, if appropriate, specified by the Primacy Agency.
Sampling Frequency
The SWTR requires that the turbidity of the filtered water must be
determined:
a. At least once every four hours that the system is in operation, or
b. The Primacy Agency may reduce the sampling frequency to once per day
for systems using slow sand filtration or filtration treatment other
than conventional treatment, direct filtration or diatomaceous earth
filtration.
A system may substitute continuous turbidity monitoring for grab sample
monitoring if it validates the continuous measurement for accuracy on a
regular basis using a protocol approved by the Primacy Agency. It is
recommended that the calibration of continuous turbidity monitors be verified
at least twice per week according to the procedures established in Method 214A
of the 16th edition of Standard Methods.
5-2
-------
Additional Monitoring
As indicated in Section 4.3.2, it has been recommended that systems
should equip each filter with a continuous turbidity monitor. This
recommendation is not part of the requirements of the SWTR and is not required
for establishing compliance. Rather, it is recommended as a tool for the
systems to use to better monitor their treatment efficiency and to provide a
method of detecting filter performance deterioration.
There are two basic types of filter performance deterioration that can
occur within the life of a filter:
- Those that result from nonroutine operating conditions such as media
deterioration, mud ball formation, underdrain failure, surface
cracking and cross-connections, and
- Those where water quality deteriorates under normal operations,
i.e., turbidity increases routinely observed at both ends of a
filter run.
Routine monitoring of filter effluent turbidity and observation of
backwash sequences under an appropriate schedule can indicate both forms of
filter performance deterioration.
If continuous monitoring of each filter effluent cannot be implemented,
then it is recommended that at least the following be conducted. On a
quarterly basis:
- Monitor each filter, either by grab samples or continuous monitors,
through the course of a routine cycle of operation, i.e., from
restart to backwash, and
- Visually inspect each filter for indications of physical
deterioration of the filter.
These are general suggestions. The Primacy Agencies are encouraged to
work with the systems to determine the best overall monitoring program(s) for
their particular filtration plants in order to assess the status of the filter
units.
5.3 Turbidity Performance Criteria
Conventional Treatment or Direct Filtration
Based upon the requirements of the SWTR, the minimum turbidity perfor-
mance criteria for systems using conventional treatment or direct filtration
are:
5-3
-------
- Filtered water turbidity must be less than or equal to 0.5 NTU in
95 percent of the measurements taken every month.
- At the discretion of the Primacy Agency, filtered water turbidity
levels of less than or equal to 1 NTU in 95 percent of the
measurements taken every month may be permitted on a case-by-case
basis if the system can demonstrate by on-site studies that it is
achieving effective removal and/or inactivation of Giardia lamblia
cysts, or cyst-sized particles. For this demonstration, systems are
allowed to include disinfection in the determination of the overall
performance by the system.
- Filtered water turbidity may not exceed 5 NTU at any time.
If conventional and direct filtration treatment plants (i.e., with
coagulation) are operated to achieve the minimum turbidity performance
criteria, it could be assumed that they are well operated and achieving at
least a 2 log removal of Giardia cysts and a 1 log removal of viruses. The
balance of the overall 3 and 4 log removal/inactivation requirements should be
achieved through disinfection.
Although the minimum turbidity performance criterion was set at 0.5 NTU,
treatment facilities using conventional treatment or direct filtration, whose
raw water supplies have turbidity levels of 1 NTU or less, should be
(4)
encouraged to achieve filtered water turbidity levels of less than 0.2 NTU.
1. Recommended protocol for this demonstration is presented in
Appendix N.
2. The literature indicates that well operated conventional treatment
and direct filtration plants can achieve up to a 3 log reduction of
Giardia cysts and enteric viruses. (Al-Ani et al., 1985; Logsdon,
1987b, Roebeck et al., 1962) Limiting the credit to 2 log for
Giardia cysts and 1 log for enteric viruses provides a margin of
safety for those plants which are not providing optimum treatment
and is consistent with the multiple barrier concept.
3. Some treatment systems may wish to demonstrate that they are
achieving better removals by filtration in order to reduce their
chemical disinfection requirements to avoid a conflict with the TTHM
regulation.
4. Research has demonstrated the difficulty in obtaining effective
removals of Giardia cysts and enteric viruses with low turbidity
source waters (Logsdon, 1987b; Al-Ani et al., 1985).
5-4
-------
Slow Sand Filtration
For systems using slow sand filtration, the turbidity performance re-
quirements are:
- The filtered water turbidity must be less than or equal to 1 NTU in
95 percent of the measurements for each month.
- At the discretion of the Primacy Agency, a higher filter effluent
turbidity may be allowed on a case-by-case basis, if the filter
effluent, prior to disinfection, consistently meets the long-term
coliform MCL and the turbidity level never exceeds 5 NTU.
- Filtered water turbidity may not exceed 5 NTU at any time.
Slow sand filtration plants, with appropriate design and operating
conditions and which meet the minimum turbidity performance criteria are
considered to be well operated and achieving at least a 2 log removal of
Giardia cysts and 1 log removal of enteric viruses. The balance of the
overall 3 and 4 log removal/inactivation requirements should be achieved by
disinfection.
Diatomaceous Earth Filtration
For systems using diatomaceous earth filtration, the turbidity perfor-
mance criteria are:
a. The filtered water turbidity must be less than or equal to 1 NTU in
95 percent of the measurements for each month.
b. The turbidity level of representative samples of filtered water must
at no time exceed 5 NTU.
Diatomaceous earth systems, with appropriate design and operating
conditions and which meet the minimum turbidity performance criterion are to
be considered well operated and achieving a minimum 2 log removal of Giardia
cysts and a 1 log removal of enteric viruses prior to disinfection. The
balance of the overall 3/4 log removal/inactivation of Giardia cysts and 4 log
inactivation of enteric viruses should be achieved by disinfection.
5. As indicated in Section 4, pilot studies have shown that with proper
nurturing of the schmutzdecke, operation at a maximum loading rate
of 0.2 m/h will provide optimum removal of Giardia cysts and enteric
viruses (Logsdon, 1987b; Bellamy et al., 1985).
5-5
-------
Other Filtration Technologies
As specified in the SWTR, the turbidity performance criteria for filtra-
tion technologies, other than the ones presented above, are the sane as for
conventional treatment and direct filtration.
So4 Disinfection Monitoring Requirements
The SWTR requires that each system continuously monitor the disinfectant
residual of the water as it enters the distribution system. Each system must
also measure and record the lowest disinfectant residual entering the
distribution system each day and the disinfectant residual in the distribution
system at the same frequency and locations for which total coliform
measurements are made pursuant to the requirements in the revised coliform
rule (proposed at the same time as the SWTR).
In addition to these monitoring requirements, it is recommended that
water supply systems seeking to include disinfection prior to filtration in
determination of CT values should identify the type of disinfectant,
disinfectant dose, point of application, and sampling location being used for
residual measurement. Continuous monitoring of the disinfectant residual at
this point is recommended. An evaluation of different analytical
techniques for measuring disinfectant residual is given in Appendix D.
5.5 Disinfection Performance Criteria
For systems which provide filtration, the disinfection requirements of
the SWTR arei
a. The system must comply with all design and operating requirements
specified by the state.
In addition to the application of disinfectants prior to entry into
the distribution system, many water treatment plants utilize
chlorine, chlorine dioxide or ozone as predisinfectants/oxidants,
and some facilities may have multiple application points within the
treatment plant. Depending upon the water quality conditions at the
point of application, credit for CT may be given for this
disinfection step. A description of these conditions and guidance
for giving partial CT credit are presented in Section 5.5 of this
manual.
5-6
-------
b. The system must demonstrate, by continuous monitoring and recording,
that a disinfectant residual of at least 0.2 mg/L is continually
maintained in the water delivered to the distribution system.
c. The residual disinfectant concentrations of samples from the
distribution system may not be less than 0.2 mg/L in more than
5 percent of the samples, each month, for two consecutive months.
The SWTR requires that as a minimum, the overall treatment must achieve a
3 log removal and/or inactivation of Giardia cysts and a 4 log removal and/or
inactivation of enteric viruses. However, the treatment provided should be
commensurate with the degree of contamination in the source water, which in
some cases may require greater removals and/or inactivation than those
specified as minimum. In Section 4.4.1, recommended removals and/or
inactivation of Giardia cysts and enteric viruses following filtration are
presented as a function of raw water total coliform levels. These guidelines
should be used to determine the appropriate disinfection performance criteria.
As indicated in Section 4.4.1 and in Section 5.3, filtration which is
operated to achieve the minimum turbidity performance criteria should be
assumed to achieve a minimum 2 log removal of Giardia cysts and a 1 log
removal of enteric viruses, with the balance of the inactivation requirements
being accomplished through disinfection.
The purpose of this section is to provide guidance to the Primacy Agency
in determining the appropriate disinfection performance criteria. To
accomplish this, the following information is presented:
- Definition and methods of calculating CT values
- Recommended CT values for free chlorine, chlorine dioxide, ozone,
and preformed chloramines for various inactivation rates for Giardia
cysts and enteric viruses at different pH and temperature values.
Definition and Methods of Calculating CT Values
As presented in Section 3.2, CT is defined as the residual disinfectant
concentration in mg/L multiplied by the contact time in minutes. In general,
the contact time is defined as the time for the water to move between the
point of disinfectant application and the first customer, or prior to the
first customer at the downstream sampling location such as the clearwell
effluent which is being used to define the contact time. In pipelines, the
contact time is calculated by dividing the internal volume of the pipeline by
5-7
-------
the peak hourly flow rate through the pipeline each day. Within mixing basins
and storage reservoirs, the contact time must be determined by tracer studies
(7)
or an equivalent demonstration.
The disinfectant concentration is generally defined as the residual
disinfectant concentration at a point near the first customer or at the
downstream location used in determining the contact time. For filtration
systems which practice predisinfection, and wish to receive credit toward
satisfying the overall removal and/or inactivation requirements, the following
recommendations are made:
- For predisinfection, if the water to which the disinfectant is being
applied has a turbidity of less than 5 NTU, then disinfection credit
for Giardia inactivation can be given for the detention time within
the plant at maximum flow rate between the application point and the
point at which the residual is measured, as determined by tracer
studies or equivalent demonstration and prior to the application of
other disinfectants.
- For predesinfection credit for the inactivation of viruses, the
water to which the disinfectant is being applied must be less than
1 NTU. Inactivation credit can then be given for the detention time
within the plant at maximum flow rate between the application point
and the point at which the residual is measured, as determined by
tracer studies or equivalent demonstration and prior to the
application of other disinfectants.
- For disinfectants added to other points in the treatment process,
e.g., post settling/prefiltration, the credit for the detention time
will be based on the measured detention time between the point of
application and the point of application of any additional disinfec-
tants.
Because disinfectant residuals for both ozone and chlorine dioxide may be
short-lived, a sampling location for residual measurement upstream of the
filters may be required.
Guidance for conducting tracer studies is provided in Appendix C.
A lower turbidity level is suggested for obtaining credit for virus
inactivation than that which is suggested for achieving Giardia
inactivation credit because of the relative size difference of the
organisms. Considering that viruses are so much smaller than
Giardia cysts it is more likely that the turbidity may interfere
with the inactivation of the viruses, resulting in the lower
turbidity level.
5-8
-------
The most practical approach for ozone may be to measure the residual in
the water as it leaves the contactor. Consequently, all credit for contact
tine would be limited to the contact time within the contactor. For
multi-phase ozone contactors, in which ozone is applied at sequential stages,
the CT should be determined based upon one half of the measured residual and
one half of the contact time. The CT is being limited in this case, because
some of the ozone residual which is measured will have been applied
immediately upstream of the point of measurement.
For chlorine dioxide, sampling and residual analyses at various points in
the treatment process downstream of the point of application may be necessary
to establish the point at which no residual is present. Subsequent sampling
and residual analyses conducted upstream of this point can be used to deter-
mine the CT credit by utilizing the demonstrated detention time between the
point of application and the sampling location. Methods for calculating CT
are presented in Section 3.2.
Recommended CT Values
In general, systems with filtration plants should provide sufficient
disinfection to achieve the inactivation rates listed in Section 4.4.1.
Compelling reasons to seek reduced disinfection requirements for a well
operated filtration plant, as noted in Footnote No. 6 in Section 5.4, include:
- Conflict with THM MCL or other disinfection by-product regulation
- Technical feasibility
- Affordability as discussed in Section 9
If a system has demonstrated that it is achieving greater than a 3 log
removal of Giardia cysts and it has demonstrated the need for reduced disin-
fection requirements, the Primacy Agency may permit the disinfection to be
reduced to the CT requirements for 0.5 log inactivation of Giardia cysts. A
0.5 log inactivation of Giardia cysts, as determined by CT values using
chlorine, ozone, or chlorine dioxide, would be able to achieve a 4 log
inactivation of viruses. Factors to be considered for allowing such a minimum
level of disinfection include:
a. If the system uses conventional treatment and achieves filtered
water turbidities well below the minimum performance criteria
b. System uses slow sand filtration
5-9
-------
c. That the raw water total coliform concentration is generally less
than 100/100 ml or the fecal coliform concentration is generally
less than 20/100 ml
At no time should the disinfection requirements be reduced below this level.
The CT values for the various inactivation levels for free chlorine,
chlorine dioxide, ozone and preformed chloramines for both Giardia cysts and
for enteric viruses at various pH and temperature values are presented in
Appendix E. These values are given to permit a more accurate method of
determining the required CT value for a well operated plant or for the use of
predisinfection. In addition, these values permit the assessment of
appropriate CT requirements for poor source water quality conditions as
defined in Section 4.4.1. The basis for calculating the CT values, presented
here for the various disinfectants, appears in Appendix F.
When determining the appropriate CT value for a water system, the
applicable values for both Giardia cyst inactivation and enteric virus
inactivation should be determined and the higher value should be utilized.
Free Chlorine
As previously indicated in Section 3.2, when using free chlorine as a
disinfectant, the efficiency of inactivation is influenced by the temperature
and pH of the water. The inactivation of Giardia cysts by free chlorine at
various temperatures and pHs are presented in Appendix E Table E-l through
Table E-6. The CT values for the inactivation of enteric viruses by free
chlorine are presented in Table E-7.
To determine whether a system is meeting these requirements, the free
chlorine residual, pH and temperature must be measured, either just prior to
the first customer, or at the point at which contact time is to be measured.
The contact time from the point of application of the disinfectant to the
first customer should be measured. The CTs actually achieved in the system
should then be compared to the values in the table for the pH and temperature
of the source water.
Ozone
CT values for the inactivation of Giardia cysts by ozone are presented in
Table E-10 for various temperatures and inactivation rates. As indicated in
this table, the CT requirements for ozone are substantially lower than those
5-10
-------
required for free chlorine. This reflects the fact that ozone is a more
powerful disinfectant. CT requirements for inactivation of enteric viruses
using ozone are presented in Table £-11. As a result of the short life of
ozone, the application of a persistent disinfectant such as chlorine or
chloramines is needed to maintain the required disinfectant residual in the
distribution system.
Chlorine Dioxide
CT values for the inactivation of Giardia cysts by chlorine dioxide are
presented in Table £-8 and the CT values for the inactivation of enteric
viruses are presented in Table £-9. The disinfection efficiency of chlorine
dioxide is not significantly affected by the pH of the water. Therefore, the
only parameter affecting the CT requirements associated with the use of
chlorine dioxide is temperature.
Preformed Chloramines
CT values for the inactivation of Giardia cysts by preformed chloramines
are presented in Table £-12. The high CT values associated with the use of
preformed chloramines indicate the difficulties involved in attaining adequate
inactivation with their use as the primary disinfectant. Rather, chlorine,
ozone, or chlorine dioxide should be used for primary disinfection, and
chloramines for residual disinfection, as necessary. Systems may use
coliphage MS to indicate virus inactivation (see Appendix G)j however, no
easy method to show Giardia cyst inactivation is available.
5.6 Other Considerations
Monitoring for HPC is not required under the SWTR. However, such
monitoring nay provide a good operational tool for:
- Measuring microbial breakthrough
- Evaluating process modifications
- Detecting loss of water main integrity
- Detecting bacterial regrowth conditions within the distribution
system
- Determining interference with the coliform measurements (AWWA, 1987)
5-11
-------
Therefore, routine monitoring of HPC on the plant effluent and within the
distribution system is recommended whenever the analytical capability is
available inhouse or nearby. Systems which do not have this capability should
consider using a semiquantitative bacterial water sampler kit (dip stick).
As presented in the preamble to the SWTR, the EPA believes that it is
inappropriate to include HPC as a treatment performance criterion in the
proposed rule since small systems would not have in-house analytical
capability to conduct the measurement, and they would need to send the samples
to a private laboratory. Unless the analysis is conducted rapidly, HPC may
multiply and the measurement may be misrepresentative.
It is suggested that an HPC level <10 organisms /ml in the finished water
is easily maintained with proper disinfection (Geldreich et al, 1987). It is
also suggested that levels greater than 10 organisms/ml in the distribution
system indicate a microbial regrowth problem which needs to be resolved
(Geldreich et al, 1987).
Legionella is another organism which is not included as a treatment
performance criterion. Inactivation information on Legionella is limited.
The available information indicates that the filtration and disinfection
requirements of the SWTR will remove or inactivate substantial levels of
Legionella which might occur in source waters. Since these organisms are
similar in size to coliform organisms, removal by filtration should be similar
to those reported for total coliforas. In addition, the available
disinfection information indicates that the CT requirements for inactivation
of Legionella are lower than those required for the inactivation of Giardia
cysts.<9)
These treatment requirements do not guarantee that these organisms
will not be present in numbers sufficient to colonize hot water
systems within homes and institutions (Muraca et al., 1986).
Guidance for control of Legionella by institutions is provided in
Appendix B.
5-12
-------
6. REPORTING
6.1 Reporting Requirements for Public Water Systems Using
Surface Water Sources Not Providing Filtration
6.1.1 Source Water Fecal Colifonn (FC)
Introduction
The source water quality criteria and required sampling frequencies for
fecal coliforms can be found in Section 3.1.1 of this manual. The source
water must be analyzed for either fecal or total coliforms. This section
outlines the format of the report on source water quality for fecal coliforms
which must be sent to the Primacy Agency on a monthly basis. The individual
sample results must be retained by the utility for a minimum of 5 years.
Individual sample results do not have to be reported; however, a summary of
the results as outlined below must be sent to the Primacy Agency within
10 days of the end of each month, and the summary will then be used to deter-
mine whether compliance has been met. For the purposes of this section, a
6-month period is either a full six months or the equivalent as explained in
Section 2.
Monthly Report Format
1. Report the number of samples analyzed during the month.
2. Report the number of results which are less than or equal to 20 fec-
al coliform/100 ml.
3. Report the cumulative number of results since the start of the
6-month compliance period.
4. Report the cumulative number of months for which fecal coliform
concentrations were determined since the start of the 6-month
compliance period.
5. Report the cumulative number of results less than or equal to
20 fecal coliforms/100 ml, since the start of the 6-month compliance
period.
6. Report the percentage of passing results, which is (line 5/line 3) x
100.
7. If the system is not in compliance (see Section 7.2.2), report a
source water violation to the state, within 48 hours of the viola-
tion.
6-1
-------
Reporting Frequency
The preceding results should be reported to the Primacy Agency on a
monthly basis within 10 days of the end of each month, with violations report-
ed within 48 hours of the occurrence.
6.1.2 Source Water Total Coliforms (TC)
Introduction
The source water quality criteria for total coliforms can be found in
Section 3d = l of the this manual along with required sampling frequencies.
The source water must be analyzed for either fecal or total coliforms. This
section outlines the format of the report on total coliforms in the source
water that must be sent to the Primacy Agency on a monthly basis. The indivi-
dual sample results must be retained by the utility for a minimum of 5 years.
Individual sample results do not have to be reported; however, a summary of
the results as outlined below must be sent to the Primacy Agency within
10 days of the end of each month, which will then be used to determine whether
compliance has been met.
Monthly Report Format
1. Report the number of samples analyzed during the month.
2. Report the number of results which are less than or equal to 100 to-
tal coliforms/100 ml during the month.
3. Report the cumulative number of total coliform results since the
start of the 6-month compliance period.
4. Report the cumulative number of months for which total coliform
concentrations were determined since the start of the 6-month
compliance period.
5. Report the cumulative number of results less than or equal to
100 total coliforms/100 ml since the start of the 6-month compliance
period.
6. Report the percentage of passing results, which is (line 5/line 3)
x 100.
7. If the system is not in compliance (see Section 3,1.1), report a
source water violation to the state within 48 hours.
6-2
-------
Reporting Frequency
The preceding results should be reported to the Primacy Agency within
10 days of the end of each month, with violations reported within 48 hours of
the occurrence.
6.1.3 Source Water Turbidity
Introduction
The source water quality criteria and the minimum sampling frequency for
turbidity can be found in Section 3.1.2 of this manual. This section outlines
the format of the report, for turbidity that must be sent to the Primacy
Agency on a monthly basis. The individual sample results must be retained for
a minimum of 5 years. However, only a summary of the results must be sent to
the Primacy Agency, which will then determine whether or not compliance has
been met.
Monthly Report Format
1. Report the maximum instantaneous turbidity level for the system
operation during the month.
2. Report the date and value of any measurement which exceeds 5 NTU.
3. Report the dates and number of periods during which the turbidity
exceeds 5 NTU, as defined in 3.1.2 in the previous 12 months.
4. Report the dates and cumulative number of periods during which the
turbidity exceeded 5 NTU in the previous 120 months beginning
138 months after promulgation of the SWTR.
5. Report the dates during which the customers were notified to boil
the water being consumed.
6. It is suggested that weather conditions on days the turbidity
exceeds 5 NTU, i.e., hurricane, flood, etc. are also reported.
Reporting Frequency
1. If an instantaneous turbidity level exceeds 5 NTU, report this to
the state immediately, and issue a boil water notice.
2. A summary of turbidity results, as described above, must be reported
to the state within 10 days of the end of each month.
6.1.4 Disinfection Conditions
Introduction
The disinfection criteria include requirements for providing a 99.9 per-
cent inactivation of Giardia cysts and a 99.99 percent inactivetion of enteric
6-3
-------
viruses, as contained in Section 3.2. This section outlines the test results
which must be sent to the Primacy Agency to be used to determine whether
compliance has been met. These results are to be sent to the Primacy Agency
within 10 days of the end of each month the system is in operation and should
be retained by the utility for a minimum of 5 years.
Monthly Report Format
1. Report the date and duration of each instance when the disinfectant
residual in water supplied to the distribution system is less than
0.2 mg/L.
2. Report the disinfectant(s) used and the sequence of application.
3. Report the daily disinfectant concentration at peak hourly flow
prior to the first customer and just prior to any points of
additional disinfectant application before the first customer.
4. Systems using chlorine must report the daily pR of the disinfected
water at peak hourly flow just prior to the next point of chlorine
addition for all chlorination points prior to the first customer.
5. Report the daily temperature of the disinfected water at peak hourly
flow for each point of disinfectant application prior to the first
customer.
6. Report the daily disinfectant contact time at peak hourly flow in
minutes for each disinfection sequence prior to the first customer.
7. Report the actual daily CT value, using the above information, for
each portion of the distribution system between points of
disinfection prior to the first customer.
8. Systems with only one disinfection sequence, report the daily
determination of the CT value for the corresponding daily pH
(chlorine only) and temperature measurements, which is necessary to
achieve 99.9 percent inactivation of Giardia and 99.99 percent
inactivation of enteric viruses, as determined in Section 3.2.
9. Report the date of each instance in which the actual CT value is
less than the required CT value necessary to achieve 99.9 percent
Giardia cyst and 99.99 percent enteric virus inactivation.
10. It is suggested that systems with multiple disinfection sequences,
should report the overall percent inactivation of Giardia cysts (for
ozone, chlorine dioxide and chlorine systems) or enteric viruses
(for chloramine systems) as calculated in Section 3.2.2.
6-4
-------
11. Systems using multiple disinfection should report days on which the
3 log inactivation of Giardia cysts and 4 log inactivation of
enteric viruses is not achieved.
12. Report the disinfectant residual concentration present in each
sample from the distribution system in which total coliforms were
detected.
13. Report the analytical method used to determine the residual.
14. Report the total number of samples analyzed for disinfectant residu-
al.
15. Report the total number of samples in which less than 0.2 mg/L of
disinfectant residual was detected.
16. Report the percent of disinfectant residual measurements in the
distribution system which are less than 0.2 mg/L (line 15/line 14)
x 100.
Reporting Frequency
1. The CT values and supporting data must be reported monthly within
10 days of the end of each month.
2. The results of the disinfectant residual determinations in the
distribution system must be reported within 10 days of the end of
each month.
3. Report to the state within 48 hours of the occurrence each instance
when a residual is not present in the water supplied to the
distribution system.
6.1.5 Watershed Control Program
Introduction
According to the SWTR, a yearly report of the watershed control program
conducted in accordance with the program presented in Section 3.3.1 must be
submitted to the Primacy Agency. The report is to be submitted to the Primacy
Agency within 10 days of the end of each federal fiscal year. The Primacy
Agency will review the report to determine whether or not compliance has been
met. This section outlines the report content.
Report Format
The report should:
1. Summarize all activities in the watershed(s) for the previous year.
2. Identify activities or situations of actual and potential concern in
the watershed(s).
6-5
-------
3. Describe how the utility is proceeding to address them.
Report Frequency
The report must be submitted to the Primacy Agency on a yearly basis
within 10 days of the end of each fiscal year.
6.1.6 Sanitary Survey
Introduction
Guidelines for a general sanitary survey are contained in Section 3.3.2,
and a comprehensive sanitary survey is presented in Appendix H. The SWTR
requires each system to provide the State with an annual report of the yearly
sanitary survey, unless the sanitary survey is conducted by the State. The
report is to be submitted within 10 days of the end of the federal fiscal
year.
Report Format
It is suggested that:
1. A report of the comprehensive survey containing the findings,
suggested improvements and dates by which to complete improvements
is to be prepared following the initial system review.
2. To lessen the burden on utilities, a report containing results of
the general survey can be submitted in subsequent years.
Reporting Frequency
The report is to be submitted to the Primacy Agency on a yearly basis
within 10 days of the end of each fiscal year, unless the survey is conducted
by the Primacy Agency.
6.1.7 Disease Outbreaks
Introduction
The definition of a waterborne disease outbreak is contained in
part 141.2 of the SWTR. The records of an outbreak are to be maintained
permanently.
Report Format
It is suggested that the report of the outbreak contain:
1. Date of occurrence
2. Type of illness
3. Number of cases
4. System conditions at the time of the outbreak, including
disinfectant residuals, pH, temperature, turbidity, and
bacteriologicol results.
6-6
-------
Report Frequency
Any disease outbreaks in the serviced community which are linked to the
drinking water oust be reported by the water supplier to the Primacy Agency
within 48 hours. It is suggested that the public is notified within this tine
frame as well.
6.1.8 Total Trihalomethane (TTHM) Regulations
Reporting requirements of the TTHM regulation are to be followed.
6.1.9 Long-Term Total Coliform MCL
Reporting requirements of the long-term total coliform MCL must be
followed.
6.2 Reporting Requirements for Public
Hater Systems Using Surface Hater
Sources that Provide Filtration
6.2.1 Treated Hater Turbidity
A. Systems Using Conventional Treatment, Direct Filtration, or tech-
nologies other than Slow Sand and Diatomaceous Earth Filtration
Introduction
The effluent turbidity criteria and required sampling frequencies for
these technologies is contained in Section 5.3 of this manual. This section
outlines the SHTR required contents of the report which is to be sent to the
Primacy Agency within 10 days of the end of each month. The Primacy Agency
will then determine whether compliance has been met. These results are to be
kept on record by the utility for a minimum of five years.
Report Format
1. Report the total number of filter plant effluent instantaneous
turbidity measurements made during the month.
2. Report the number of filtered water turbidity measurements that are
less than or equal to 0.5 NTU (or higher value up to 1 NTU as
approved by the Primacy Agency following satisfactory demonstration
of effective treatment by the system).
3. Report the percentage of filter water turbidity measurements that
are less than or equal to 0.5 NTU [(line 2/line 1) x 100].
4. Report the date and value of any turbidity measurements which exceed
5 NTU.
6-7
-------
Reporting Frequency
The preceding results should be reported to the Primacy Agency within 10
days of the end of the monthly compliance period. Any violations are to be
reported to the Primacy Agency within 48 hours.
B. Systems Using Slow Sand Filtration
Introduction
The effluent turbidity criteria and required sampling frequencies for
these technologies are contained in Section 5.3 of this manual. This section
outlines the SWTR required contents of the report which is to be sent to the
Primacy Agency within 10 days of the end of each month. The Primacy Agency
will then determine whether compliance has been met. These results are to be
kept on record by the utility for a minimum of five years.
Monthly Report Format
1. Report the total number of filter plant effluent instantaneous
turbidity measurements made during the month.
2. Report the number of filtered water turbidity measurements that are
less than or equal to 1 NTU, and the dates of these occurrences.
3. Report the percentage of filter water turbidity measurements that
are less than or equal to 1 NTU [(line 2/line 1) x 100].
4. Systems which have less than 95 percent of the filter effluent
turbidity levels less than or equal to 1 NTU must report:
a. Dates and results of total coliform sampling of the filter
effluent prior to disinfection. These are to be collected at
the game frequencies specified in Appendix H.
5. Report the date and value of any turbidity measurements which exceed
5 NTU.
Reporting Frequency
The preceding results should be reported to the Primacy Agency each month
within 10 days of the end of the monthly compliance period. However, if the
filter plant effluent instantaneous turbidity level exceeds 5 NTU at any time,
report the violation to the Primacy Agency within 48 hours.
C. Systems Using Diatomaceous Earth Filtration
Introduction
The effluent turbidity criteria and required sampling frequencies for
this technology is contained in Section 5.3 of this manual. This section
6-8
-------
outlines the contents of the report which is to be sent to the Primacy Agency
within 10 days of the end of each month. The Primacy Agency will then deter-
mine whether compliance has been met. These results are to be kept on record
by the utility for a minimum of five years.
Monthly Reporting Format
1. Report the total number of filter plant effluent turbidity
measurements made during the month.
2. Report the number of filter plant effluent turbidity measurements
that are less than or equal to 1 NTU.
3. Report the percentage of filter plant effluent turbidity
measurements less than 1 MTU which is (line 2/line 1) x 100.
4. Report the date and value of any turbidity level which exceeds
5 NTU.
Reporting Frequency
The preceding results should be reported to the Primacy Agency each month
within 10 days of the end of the monthly compliance period. Any filter plant
effluent turbidity level(s) which exceed 5 NTU should be reported to the
Primacy Agency within 48 hours.
6.2.2 Disinfectant Conditions
Introduction
Distribution water quality criteria and sampling frequency can be found
in Section 3.2.3 of this manual. This section outlines the contents of the
report which is to be sent to the Primacy Agency. These results should be
reported to the Primacy Agency within 10 days of the end of each month.
Individual results are to be retained for a minimum of one year. This section
also recommends data to be reported to document the actual CTs which are
maintained. Section 5.5 presents- guidelines for CTs for filtering systems.
Report Format
1. Report the value of the lowest daily measurement of disinfectant
concentration in mg/L in water supplied to the distribution system
prior to the first customer.
2. Report the date of each instance when the disinfectant residual in
water supplied to the distribution system prior to the first
customer is less than 0.2 mg/L.
6-9
-------
3. Report the total number of samples and values of disinfectant
residual for each sample measured in the distribution system.
4. Report the number of disinfectant residual measurements in the
distribution system which are greater than or equal to 0,2 mg/L.
5. Report the percent of disinfectant residuals in the distribution
system which are greater than or equal to 0.2 mg/L (line 4/line 3).
Recommended Reporting Not Required by the SWTR
1. Report the average raw water turbidity.
2. Report the average raw water total or fecal coliform levels.
3. Report the percent inactivation of Giardia cysts and enteric
viruses, required by the Primacy Agency.
4. Report the primary disinfectant used.
5. Report the daily pH (for systems using chlorine) and temperature
measurements for the disinfected water following each point of
disinfection.
6. Report dosage and point of application for all disinfectants used.
7. Report sampling location(s), disinfectant residual(s) and contact
time used for determining the CT achieved.
8. Report the daily CT(s) used to calculate the percent inactivation of
Giardia cysts and viruses.
9. If more than one disinfectant is used, report the CT(s) and
inactivation(s) achieved for each disinfectant and the total percent
inactivation achieved.
10. Report the percent inactivation determined prior to filtration and
the data used to make this determination.
11. Report any difference between the measured CT(s) and the CT required
to meet the overall minimum treatment peformance requirement
specified by the Primacy Agency.
Reporting Frequency
The preceding results should be reported to the Primacy Agency within
10 days of the end of each month. Report each instance when a measurable
residual is not maintained at the first customer to the Primacy Agency within
48 hours of the occurrence.
6-10
-------
7. COMPLIANCE
7.1 Introduction
The SWTR requires the Primacy Agency to make a determination on a monthly
basis that each system is in compliance with the SWTR based on information
received from the system. The purpose of this section is to provide guidance
to the Primacy Agency in making this determination.
If a Primacy Agency fails to comply with the schedule for adopting the
criteria and applying them to determine who must filter, systems would be
required to comply with the "objective" or self-implementing criteria, i.e.,
the requirements that are clear on the face of the rule and do not require the
judgment of the Primacy Agency, within 30 months of the promulgation of this
rule or install filtration within 48 months. As soon as the Primacy Agency
adopts the criteria, the system would have to comply with all the require-
ments.
The proposed rule has self-implementing requirements which pertain to
both unfiltered and filtered water systems. These are listed in para-
graph 141.76(a)(1)(2)(4)(5)(6) and 141.76(b) (1)(2)(4)(5)(6), respectively?
they would go into effect for each public water system within 48 months
following the promulgation of this rule (unless the Primacy Agency has imposed
more stringent requirements). The subjective criteria (such as those pertain-
ing to watershed control and design and operating conditions), listed in
141.76(a)(3) and (b)(3), would go into effect following the establishment of
these criteria by the Primacy Agency. Systems which are not in compliance
with the objective criteria for avoiding filtration 30 months after promulga-
tion would be required to install filtration and meet the objective perfor-
mance criteria (listed in paragraph 141.76) for the filtration technology they
choose within 48 months after promulgation.
Any system failing to meet the criteria listed in 141.76(1)(1)(2) or
(b) (1) (2) or (b) (1) (2) within 48 months following promulgation of this rule,
would be in violation of a treatment technique requirement. Any system
failing to meet the subjective criteria, listed in 141.76(a)(3) or (b)(3),
following the determination made by the Primacy Agency, would also be in
violation of a treatment technique requirement. Any system failing to meet
7-1
-------
the criteria pertaining to analytical, monitoring, and reporting requirements,
listed in 141.76(a)(4)(5)(6) or 141.76Cb)(4)(5)(6) would.be in violation of a
testing procedure requirement, monitoring requirements, or reporting require-
ment o
The 48-month time limit is based on the 1986 SDWA amendments which
require: (1) Primacy Agencies to adopt criteria for determining which systems
must filter within 18 months following EPA's promulgation of such criteria;
(2) Primacy Agencies to determine which systems must filter within 12 months
following such adoption of criteria, and (3) systems to install filtration
within 18 months of the determination that filtration is required. Figure 7-1
illustrates how to determine whether a system is in compliance with the SWTR.
7.2 Systems Without Filtration
7.2.1 Introduction
Systems which do not provide filtration must comply with several require-
ments of the SWTR. As indicated in Section 141.76 of the SWTR, these include:
- Source Water Quality Conditions
- Disinfection Criteria
- Watershed Control Program
- Sanitary Survey
- Disease Outbreaks
- Total Coliform Occurrence
- TTHM Regulation
If these criteria are not met within 30 months following the promulgation
of the SWTR, the system would be required to filter. If the criteria are not
met within 48 months following the promulgation of the SWTR, the system would
be in violation of a treatment technique requirement and subject to the public
notification requirements associated with such a violation.
7.2.2 Source Water Quality Conditions
A. Source Water Fecal Coliform
Any system which indicates in its monthly report that more than 10 per-
cent of the raw water samples for the previous 6 months had fecal coliform
levels greater than 20/100 ml will be required to install filtration as part
of its treatment process, within 48 months of the promulgation of the SWTR or
it will be in violation of a treatment technique requirement.
7-2
-------
SURFACE WATER TREATMENT
MO
| SYSTEM USES SURFACI
| YE!
, NOT APPLY
FILTRATION N PLACE 7
NO f
t
MEETS SOURCE V\
QUAUTY & SITE-5
CONDCT10NS?
YES
YES
t
fATER MEETS DESIGN. OPERATION
iPECFIC No ^. EXEMPTION «* ™° PERFORMANCE CRTTFR1
CRITERIA SATISFED 7
YES 1
EXEMPTION
(TEMPORARY)
t
INO i
1 NO
I VIOLATION |-^ '
1 YES
NSTALL FILTRATION
OK
MOOFY TREATMENT
-
A
YES
DECISION TREE
FIGURE 7-1
-------
B. Source Water Total Coliforms (TC)
Any system which indicates that for the previous 6 months, more than
10 percent of the raw water samples had total coliform levels greater than or
equal to 100/100 ml will be required to install filtration as part of the
treatment process within 48 months of the promulgation of the SWTR, unless the
system also measures fecal coliforms and the fecal levels are within the
acceptable limits. If the system does not meet this criteria it is in viola-
tion of a treatment technique requirement.
C. Source Water Turbidity
To avoid filtration, a system would be required on an ongoing basis to
demonstrate that the turbidity of the water prior to disinfection does not
exceed 5 NTU, based on the collection of grab samples at least every four
hours. Continuous turbidity monitoring could be substituted for grab sample
monitoring if this measurement was validated for accuracy with grab sample
measurements on a regular basis, with a protocol approved by the Primacy
Agency. If the public water system used continuous monitoring, the system
would use turbidity values taken every four hours to determine whether it met
the turbidity raw water limit. A system would be allowed to exceed the 5 NTU
limit, no more than two periods during twelve consecutive months or five
periods during 120 consecutive months, provided that the system informed its
customers to boil their water before consumption during the period the tur-
bidity exceeds 5 NTU and the Primacy Agency determined that the exceedance
occurred because of unusual or unpredictable circumstances. A "period" would
be defined as the number of consecutive days in which at least one turbidity
measurement each day exceeded 5 NTU. If these criteria are not met within
30 months of the promulgation of the SWTR, filtration must be installed within
18 months following the 30-month period, or the system will be in violation of
a treatment technique requirement and public notification is required.
7.2.3 Disinfection Conditions
The utility must demonstrate that 1) a residual of at least 0.2 mg/L is
continually maintained in the water at the point of entry to the distribution
system, 2) the system achieves a 99.9 percent inactivation of Giardia cysts
and a 99.99 percent inactivation of viruses each day during peak hourly flow,
and 3) a disinfectant residual greater than or equal to 0.2 mg/L is present,
7-3
-------
in at least 95 percent of the monthly distribution system samples. If the
system does not meet all of these requirements, the system must install
filtration, within 48 months of the promulgation of the SWTR or it is in
violation of a treatment technique.
7.2.4 Watershed Control Program
The purpose of a watershed control program is to minimize the potential
for contamination of the source water by enteric viruses, Giardia lamblia
cysts and other biological contaminants. This objective is reached by the
elimination or control of all activities which may adversely impact the
quality of the source waters, and through ownership and written agreements
with land owners within the watershed. Guidelines for a watershed control
program are included in Section 3.3.1 and Appendix J of this manual.
Conditions of noncompliance with the requirements of a watershed control
program include:
A. Not having a watershed control program in place.
B. The watershed control program which is followed is not adequate to
meet the Primacy Agency's requirements, as suggested below.
Systems which do not provide a watershed control program must either
implement a program or install filtration within 48 months of the SWTR or they
will be in violation of a treatment technique.
The determination of the adequacy of a given watershed control program
will be subjective in most cases. The questions which must be answered in
order to determine the adequacy of a given watershed control program according
to the SWTR are:
A. Are the characteristics of the watershed thoroughly understood,
including:
- The existing agreements, ownership patterns, watershed loca-
tion, hydrology, etc.?
8. Have conditions which may have an adverse effect on water quality
been identified, such as:
- Naturally occurring sources, including animal populations,
effects of precipitation, etc.?
7-4
-------
- Man-made sources of contamination, inclining point and nonpoint
sources such as sewage discharge, .logging, barnyards,
grazing, etc.?
C. Have the priorities been set to address the impacts of these condi-
tions or activities? Are there programs to control these conditions
or activities and are they effective? For example,:
- Are logging practices acceptable?
- Are waste discharges being controlled?
- Have grazing activities been limited or removed?
Additional questions which may be considered include;
D. Is there a regular patrol of the watershed to review animal and
human activity?
- Are animal populations adequately controlled?
- Is recreation limited?
E. Have malfunctioning septic systems been identified and steps taken
to correct them?
F. Is there an effective organizational structure for the watershed
control program?
Section 7.4 addresses measures which can be taken by the utility to
attain compliance if some of the requirements of the program are not currently
met.
7.2.5 Sanitary Survey
The purpose of the sanitary survey is to identify deficiencies in a
system which when corrected may ensure the provision of safe drinking water.
Each system must provide to the Primacy Agency an annual report of the yearly
sanitary survey unless the sanitary survey is conducted by the Primacy Agency.
Performing an annual comprehensive survey may not be practical for all systems
because of the large size of the system. Thus, it is suggested that a de-
tailed comprehensive survey is conducted at the onset of the review of the
1.
Filtration may be required if sewage discharges or on-site disposal systems
are present in the watershed.
7-5
-------
system as presented in Appendix I, with basic surveys as detailed in Sec-
tion 3.3.2 of this manual conducted on an annual basis.
The basic noncompliance with respect to the sanitary survey is the
failure to make the required improvements or repairs suggested by the Primacy
Agency as a result of the previous sanitary survey. The suggestions may
include repairs on intake structures, pipelines, pumps, disinfection equip-
ment, etc., or the implementation of certain treatment processes such as the
use of an alternate disinfectant, or a variation in the application of the
disinfectant.
Failure to maintain compliance with the watershed control program as in
Section 7.2.4 also results in a violation of a treatment technique with
respect to the sanitary survey, as does failure to maintain adequate treatment
and records of data and system operations as required in the SWTR. If a
system does not meet the requirements of a sanitary survey, filtration must be
installed within 48 months of the promulgation of the SWTR or the system is in
violation of a treatment technique.
7.2.6 Disease Outbreaks
- A utility which has had a waterborne disease outbreak attributed to a
treatment deficiency and which has not upgraded its system satisfactorily to
prevent such further occurrence must install filtration within 48 months of
the promulgation of the SWTR, or the system is in violation of a treatment
technique. If after the effective date of the SWTR, a system is allowed by
the Primacy Agency to operate without filtration and a waterborne disease
outbreak is attributed to that system, it is in violation of a treatment
technique and must install filtration. However, if a waterborne disease
outbreak is attributed to a deficiency in the distribution system, the system
is not in violation of the SWTR.
7.2.7 Long-term Total Coliform MCL
Systems which collect 60 or more samples per year in the distribution
system (all surface water systems which do not filter are required to collect
at least 60 samples per year) and detect total coliforms in more than 5
percent of the distribution system samples over a 12-month period, are in
violation of a treatment technique and filtration is required. In such cases,
7-6
-------
it is suggested that the system disinfection be altered to gain compliance
prior to installing filtration.
7.2.8 Total Trihalomethane (TTHM) Regulations
The SWTR requires that the system be in compliance with the current TTHM
regulation. If the yearly running average TTHMs exceed 0.1 ng/L in a system
serving more than 10,000 people, the system must install filtration within
48 months of the promulgation of the SWTR or the system is in violation of a
treatment technique. Measures which can be taken to meet the required THM
levels within 30 months of the promulgation of the SWTR include the removal of
THM precursors, or the use of an alternate disinfectant which will produce
lower concentrations of THMs.
It should be noted that in the future, THM regulations are likely to
apply to all community systems, including those with populations less than
10,000. Also, regulations for other disinfection by-products are under
development and will be promulgated before 1991. Thus, it is recommended that
regardless of system size, any systems with THM levels near 0.1 mg/L begin
plans to install filtration.
7.3 Systems Providing Filtration
7.3.1 Introduction
Filtration may be achieved through many different methods which require
different turbidity performance levels for compliance. This section will be
subdivided according to the requirements for the various technologies.
7.3.2 Systems Using Conventional Treatment,
Direct Filtration or Technologies Other
than Slow Sand and Diatomaceous Earth Filtration
Utilities which operate these systems must maintain a filter effluent
turbidity of less than or equal to 0.5NTU. As indicated in Section 5.3 of
this manual, the turbidity measurements to satisfy the requirements of the
SWTR may be taken at the combined filter effluent prior to entry into a
clearwell, at the clearwell effluent or at the plant effluent prior to entry
into the distribution system. If more than 5 percent of the monthly effluent
samples contain a turbidity greater than 0.5 NTU, the system is in violation
of a treatment requirement. In cases where the Primacy Agency has determined
7-7
-------
that a higher turbidity level is acceptable for the system as a result of
on-site studies demonstrating effective removals/inactivations of Giardia
cysts at a filtered water turbidity level up to 1 NTU, the system will not be
in violation unless more than 5 percent of the monthly effluent samples have
turbidity levels greater than 1 NTU. In addition, if the turbidity of the
filter plant effluent at any time exceeds 5 NTU, the system is in acute
violation of a treatment requirement and is required to issue a boil water
notice to the public. Requirements presented in Section 7.3.5 and 7.3.6 must
also be met.
7.3.3 Systems Using Slow Sand Filtration
Utilities using slow sand filtration treatment must maintain an effluent
turbidity equal to or less than 1 NTU. If more than 5 percent of the effluent
samples contain greater than 1 NTU turbidity, the system is in violation of a
treatment technique requirement of the SWTR. In cases where the Primacy
Agency has determined that a higher turbidity level is acceptable for the
system as a result of on-site studies demonstrating effective removals/inacti-
vations of Giardia cysts at a filtered water turbidity level up to 5 NTU, the
system will not be in violation unless an effluent sample exceeds a turbidity
of 5 NTU. Systems operating at a filtered water turbidity between 1 NTU and
5 NTU, must sample the filter effluent prior to disinfection in the same
manner and frequency as in the Proposed Total Coliform Rule, the results must
comply with the proposed long-term colifonn MCL for one year and the dates and
results of the sampling are submitted to the Primacy Agency. If a turbidity
greater than or equal to 5 NTU is detected at any time, the system is in
violation of a treatment technique requirement, and a boil water notice must
be issued to the public. Requirements presented in Section 7.3.5 and 7.3.6
must also be met.
7.3.4 Systems Using Diatomaceous Earth (DE) Filtration
The SWTR requires that systems using DE filtration maintain an effluent
turbidity equal to or less than 1 NTU. If more than 5 percent of the monthly
effluent samples contain turbidities greater than 1 NTU, the system is in
violation of this requirement. In addition, if any filter effluent turbidity
exceeds 5 NTU, the system is in acute violation of a treatment technique and a
boil water notice must be issued to the public. Requirements presented in
Section 7.3.5 and 7.3.6 must also be met.
7-8
-------
7.3.5 Disinfectant Requirements
For systems which provide filtration:
- Failure to continuously maintain a disinfectant residual of at least
0.2 mg/L in the water entering the distribution system (demonstrated
by continuous monitoring) is in violation of a treatment technique,
and public notice is required.
- Failure to maintain continuous monitoring of the disinfectant
residual entering the distribution system is in violation of a
monitoring requirement.
- Failure to maintain a residual of 0.2 or greater in at least 95
percent of the distribution system samples each month for two
consecutive months is in violation of a treatment technique.
- Failure to sample the distribution system at the frequencies and
locations specified in the total coliform rule is a violation of a
monitoring requirement.
- Failure to use an approved analytical technique as presented in
Section 141.74 C is in violation of a monitoring requirement.
As presented in Section 141.74, the approved analytical procedures
include:
- Amperometric titration method
- DPD ferrous titrimetric method
- DPD colormetric method
- Leuco crystal violet method
- Indigo method
In addition to these minimum requirements, Section 5 of this manual
presented the importance of maintaining a sufficient disinfectant dosage and
contact time to achieve the minimum overall 3 log removal and/or inactivation
of Giardia cysts and 4 log removal and/or inactivation of enteric viruses.
Failure to meet these requirements as specified by the Primacy Agency would be
a violation of a treatment technique requirement. The SWTR requires that
Primacy Agencies establish design and operating regulations to assure that
systems are achieving a 3 log removal and/or inactivation of Giardia cysts and
a 4 log removal and/or inactivation of enteric viruses. Unless the system
meets these requirements it is in violation of a treatment technique. In the
event that the Primacy Agency does not adopt these requirements as part of
their design and operating conditions as contained in Section 141.72(B)(1),
7-9
-------
failure to meet these requirements cannot be considered a violation of a
treatment technique.
7.4 Responses for Systems not Meeting the SWTR Criteria
7.4.1 Introduction
Systems which presently fail to meet the SWTR criteria because of their
present configuration or operating condition may have the capability of
upgrading the system's design and/or operation and maintenance in order to
achieve compliance. The purpose of this section is to present options which
may be followed to achieve compliance.
7.4.2 Systems Kot Filtering
Systems not filtering can be divided into two categories:
A. Those systems not meeting the SWTR criteria before 30 months with
the ability to upgrade to meet them.
B. Those systems failing to meet the SWTR criteria after 30 months and
filtration is required. If the installation of filtration is not
possible within the following 18 months to gain compliance, to avoid
a violation to a treatment technique requirement, the system may
request an exemption and take interim measures to provide reasonably
safe water.
Systems in Category A
Example A - Response Situation
Conditions System is not meeting the source water fecal and/or total
coliform concentrations but has not received judgment on the adequacy of
its watershed control.
Response Options;
- Monitor for fecal coliforms rather than total coliforms if this is
not already done. Fecal coliforms are a direct indicator of fecal
contamination where total coliforms are not. If total coliform
levels are exceeded but fecal levels are not, the system meets the
criteria.
- Take appropriate action in the watershed to insure fecal and total
coliform concentrations are below the criteria, such as elimination
of animal activity near the source water intake.
7-10
-------
Example B - Response Situation
Conditiont System meets the source water quality criteria, watershed
control requirements, and is maintaining a disinfectant residual within
the distribution system, but is not able to meet the CT requirements due
to lack of contact time prior to the first customer.
Response Options;
- Increase the application of disinfectant while monitoring THM levels
to ensure they remain below the MCL.
- Add additional contact time through storage to obtain an adequate
CT.
- Apply a more effective disinfectant such as ozone.
Systems in Category B
Example A - Response Situation
Condition; System meets the source water turbidity but not the fecal
coliform requirements. A sewage treatment plant discharges into the
source water. A determination has been made that the system does not
have adequate watershed control.
Response Options;
- Purchase water from a nearby purveyor or use an alternate source
such as ground water if available.
- Take steps to install filtration, applying for an exemption as
presented in Section 9 where appropriate.
Example B
Condition; The source water exceeds a turbidity of 5 NTU for an average
of four periods per year.
Response Options;
- During the periods when the turbidity exceeds 5 NTU, issue a public
notice to boil all water for consumption. The utility continues
sampling the distribution system for chlorine residual and total
coliforms, and initiates measurement of the HPCs in the distribution
system. This data and the raw water turbidity is used to determine
when to lift the boil water notice. The notice is lifted when;
- The historical (prior to high turbidity) disinfectant residual
concentration is reestablished in the distribution system.
7-11
-------
- The total colifonn requirements are met.
- The HPC count is less than 500.
- The turbidity of the raw water is less than 5 NTU.
- Purchase water from a nearby purveyor or use an alternate source
such as ground water if available.
- Take steps to install filtration, applying for an exemption as
presented in Section 9 where appropriate.
7.4.3 Systems Currently Filtering
Systems which are currently filtering must meet the SWTR criteria within
48 months of the SWTR to be in compliance, after which the criteria must be
continually met for the system to be in compliance.
Example A - Response Situation
Condition; A direct filtration plant is treating a surface water which
is not compatible with this treatment process. The system is not achiev-
ing its required turbidity performance or disinfection criteria.
Response. Options;
- Increase disinfectant application while monitoring THM levels to
ensure that the MCL is not exceeded.
- Use an alternate disinfectant.
- Optimize coagulant dose.
- Reduce filter loading rates.
- Evaluate the effect on performance of installing flocculation and
sedimentation ahead of the filters.
Example B - Response Situation
Condition: A filtration plant is using surface water which is compatible
with its treatment system. The system is not achieving disinfection
performance criteria required by the Primacy Agency to achieve a 1 log
inactivetion of Giardia cysts; however, it is meeting the requirements of
the total coliform rule.
Response Options;
- Increase disinfectant dosages.
- Add a stronger alternate disinfectant such as ozone.
7-12
-------
Install storage facilities to increase disinfectant contact time.
Ensure optimum filtration efficiency by:
Use of a filter aid.
Reduction in filter loading rates.
More frequent backwashing of filters.
7-13
-------
8. PUBLIC NOTIFICATION
The SWTR specifies that the public notification requirements of the Safe
Drinking Water Act (SDWA) and the implementing regulations of 40 CFR Paragraph
141.32 must be followed. These regulations divide public notification re-
quirements into two tiers. These tiers are defined as follows:
1. Tier 1:
a. Failure to comply with MCL
b. Failure to comply with prescribed treatment technique
c. Failure to comply with a variance or exemption schedule
2. Tier 2:
a. Failure to comply with monitoring requirements
b. Failure to comply with a testing procedure prescribed by a
NPDWR
c. Operating under a variance/exemption. This is not considered a
violation but public notification is required.
The SWTR classifies violations of Paragraphs 141.70, 141.71, 141.72 and
141.73 (as specified in Paragraph 141.76) as Tier 1 violations and violations
of Paragraphs 141.74 and 141.75 as Tier 2 violations. In addition, the public
notification rule classifies certain violations as "acute" Tier 1 violations.
The "acute" Tier 1 violations of the SWTR are:
1. When the turbidity of the water prior to disinfection of an unfil-
tered supply, or the turbidity of filtered water, exceeds 5 NTU at
any time.
2. There is a failure to maintain a disinfectant residual of at least
0.2 mg/L in the water being delivered to the distribution system.
There are certain general requirements which all public notices must
meet. All notices must provide a clear and readily understandable explanation
of the violation, any potential adverse health effects, the population at
risk, the steps the system is taking to correct the violation, the necessity
of seeking alternate water supplies (if any) and any preventative measures the
consumer should take. The notice must be conspicuous, not contain any unduly
technical language, unduly small print or similar problems. The notice must
include the telephone number of the owner or operator or designee of the
public water system as a source of additional information concerning the
violation where appropriate. The notice must be multi-lingual.
8-1
-------
In addition, the public notification rule requires that when providing
information on potential adverse health effects in public notices of viola-
tions of MCLs, violations of treatment techniques, notices of granting and the
continued existence of exemptions and variances from maximum contaminant
levels and failure to comply with a variance or exemption schedule, the owner
or operator of a public water system must include certain mandatory health
effects language. For violations of filtration and disinfection requirements,
the mandatory health effects language is:
Microbiological Contaminants
The United States Environmental Protection Agency (EPA) sets drinking
water treatment technique requirements for microbiological contaminants
(such as viruses, bacteria, and some other microorganisms) which are of
health concern. To reduce any potential risk of microbial contamination
of drinking waters, drinking water treatment facilities are required to
treat drinking water by filtering or disinfecting, which removes or
destroys microbiological contaminants. Violation of the required treat-
ment technique indicates that the water has been treated improperly and
may expose people who drink that water to contaminants which can cause
various types of illness such as hepatitis, giardiasis, and gastro-
enteritis. These illnesses can cause different symptoms, including
diarrhea, jaundice, abdominal cramps, nausea, headaches, fatigue, and
weight loss.
Further, the owner or operator of a community water system must give a
copy of the most recent notice for any Tier 1 violations to all new billing
units or hookups prior to or at the time service begins.
The medium for performing public notification and the time period in
which notification must be sent varies with the type of violation and is
specified in 141*32. For Tier 1 violations (i.e., violations of Paragraphs
141.70, 141.71, 141.72 and 141.73), the owner or operator of a public water
system must give notice:
1. By publication in a local daily newspaper as soon as possible but in
no case later than 14 days after the violation or failure. If the
area does not have a daily newspaper, then notice shall be given by
publication in a weekly newspaper of general circulation in the
area.
2. By, either direct mail delivery of hand delivery, of the notice
either by itself or with the water bill not later than 45 days after
the violation or failure. The state may waive this requirement if
it determines that the owner or operator has corrected the violation
within the 45 days.
8-2
-------
If, however, the violation is an "acute" Tier 1 violation as defined
above, a copy of the notice must be furnished to the radio and television
stations serving the area as soon as possible, but in no case later than 72
hours after the violation.
Following, the initial notice, the owner or operator must give notice at
least once every three months by mail delivery (either by itself or with the
water bill), or by hand delivery, for as long as the violation or failure
exists.
There are two variations on these requirements. First, the owner or
operator of a community water system in an area not served by a daily or
weekly newspaper must give notice within 14 days after the violation by hand
delivery or continuous posting of a notice of the violation. The notice must
be in a conspicuous place in the area served by the system and must continue
for as long as the violation exists. Notice by hand delivery must be repeated
at least every three months for the duration of the violation.
Secondly, the owner or operator of a noncommunity water system (i.e., one
serving a transitory population) may give notice by hand delivery or continu-
ous posting of the notice in conspicuous places in the area served by the
system. Notice must be given within 14 days after the violation. If notice
is given by posting, then it must continue as long as the violation exists.
Notice given by hand delivery must be repeated at least every three months for
as long as the violation exists.
For Tier 2 violations (i.e., violations of 40 CFR 141.74 and 141.75)
notice must be given within three months after the violation by publication in
a daily newspaper of general circulation, or if there is no daily newspaper,
then in a weekly newspaper. In addition, the owner or operator shall give
notice by mail (either by itself or with the water bill) or by hand delivery
at least once every three months for as long as the violation exists. Notice
of a variance or exemption must be given every three months from the date it
is granted for as long as it remains in effect.
If the area is not served by a daily or weekly newspaper, the owner or
operator of a community water system must give notice by continuous posting in
conspicuous places in the area served by the system. This must continue as
long as the violation does or the variance or exemption remains in effect.
8-3
-------
Notice by hand delivery must be repeated at least every three months for the
duration of the violation or the variance of exemption.
For noncommunity water systems,, the owner or operator may give notice by
hand delivery or continuous posting in conspicuous places; beginning within
3 months of the violation or the variance or exemption. Posting must continue
for the duration of the violation or variance or exemption and notice by hand
delivery must be repeated at least every 3 months during this period.
The state may allow for owner or operator to provide less frequent notice
if EPA has approved the state's substitute requirements.
To provide further assistance in preparing public notices, a few examples
have been provided. However, each situation is different and will call for a
variation in the content and tone of the notice. All notices must comply with
the general requirements specified above.
Example 1 - Acute Tier 1 Violation
A system which does not apply filtration, experiences a breakdown in the
chlorine feed systems and the switchover system fails to activate the backup
systems. This is an acute Tier 1 violation which may pose an acute risk to
human health. A number of hours pass before the operator discovers the
malfunction.
The operator upon discovery of the malfunction, contacts the local tele-
vision and radio stations and announces that the public is receiving untreated
water. The announcement may read as follows:
We have just received word from the local water supplier that a malfunc-
tion of the disinfection system has allowed untreated water to pass into
the distribution system. Thus, the public water system providing your
drinking water is in violation to a treatment technique requirement. The
United States Environmental Protection Agency (EPA) sets drinking water
treatment technique requirements for microbiological contaminants (such
as viruses, bacteria, and some other microorganisms) which are of health
concern. To reduce any potential risk of microbial contamination of
drinking waters, drinking water treatment facilities are required to
treat drinking water by filtering or disinfecting, which removes or
destroys microbiological contaminants. Violation of the required treat-
ment technique indicates that the water has been treated improperly and
may expose people who drink that water to contaminants which can cause
various types of illness such as hepatitis, giardiasis, and gastro-
enteritis. These illnesses can cause different symptoms, including
8-4
-------
diarrhea, jaundice, abdominal cramps, nausea, headaches, fatigue, and
weight loss.
However, the temporary breakdown in disinfection may have allowed micro-
organisms to pass into the distribution system. The operation of the
system has been restored so that no further contamination of the distri-
bution system will occur. Any further changes will be announced.
In order to protect your personal health, all water which is used for
drinking or cooking must be boiled at a full rolling boil for 1 minute.
The boiling will kill any organisms which may be in the water. You are
urged to continue this treatment for the next three days. If you develop
any of these symptoms, you are advised to contact your physician.
Additional information is available at the following number: 1-800-235-WATER.
A direct mailing of the notice is provided within 45 days of the occurrence.
Example 2 - Acute Tier 1 Violation
A system supplies an unfiltered surface water to its customers. During a
period of unusually heavy rains caused by a hurricane in the area, the tur-
bidity of the water exceeds 5 NTU. The turbidity data during which the heavy
rains occur is as follows:
Day NTU Day NTU Day NTU Day NTU
1 0.4 0.5 0.4 5 7.6
0.4 0.4 0.6 3.1
0.5 0.4 4 0.7 2.7
0.7 0.6 7.6 0.7
1.1 3 0.7 11.3 0.8
0.9 0.4 9.6 0.5
2 0.8 0.4 7.2 6 0.5
0.5 0.5 5.0
The following public notice was prepared and submitted to the local
newspaper, television and radio stations within 72 hours of the first turbid-
ity exceedence of 5 NTU.
The occurrence of heavy rains in our watershed is causing a rise in the
turbidity of our drinking water supply.
Turbidity is a measurement of particulate matter in water. It is of
significance in drinking water because irregularly shaped particles can
both harbor microorganisms and interfere directly with disinfection which
destroys microorganisms. While the particles causing the turbidity may
not be harmful or even visible at the concentrations measured, the net
effect of a turbid water is to increase the survival rate of
8-5
-------
microorganisms contained in the water. This is of concern because
several diseases are associated with waterborne microorganisms.
Because of the high turbidity levels, our drinking water system is in
violation of a treatment requirement set by the Environmental Protection
Agency (EPA).
The United States Environmental Protection Agency (EPA) sets drinking
water treatment technique requirements for microbiological contaminants
(such as viruses, bacteria, and some other microorganisms) which are of
health concern. To reduce any potential risk of microbial contamination
of drinking waters, drinking water treatment facilities are required to
treat drinking water by filtering or disinfecting, which removes or
destroys microbiological contaminants. Violation of the required treat-
ment technique indicates that the water has been treated improperly and
may expose people who drink that water to contaminants which can cause
various types of illness such as hepatitis, giardiasis, and gastro-
enteritis. These illnesses can cause different symptoms, including
diarrhea, jaundice, abdominal cramps, nausea, headaches, fatigue, and
weight loss.
In order to protect yourself from illness, all water used for drinking,
cooking and washing dishes must be boiled at a rolling boil for one
minute.
The system is being closely monitored and a notice will be issued when
the water returns to an acceptable quality and no longer needs to be
boiled.
Additional information is available at the following number: 1-800-626-
1BOIL.
The utility continues sampling the distribution system for chlorine
residual and total coliforms, and initiates measurement of the HPCs in the
distribution system. This data and the raw water turbidity is used to deter-
mine when to lift the boil water notice. The notice is lifted when:
- The historical (prior to high turbidity) disinfectant residual
concentration is reestablished in the distribution system.
- The total coliform requirements are met.
- The HPC count is <500.
- The turbidity of the raw water is less than 5 NTU.
The system enters into a dialogue with the Primacy Agency on whether the
turbidity event was unusual or unpredictable and whether filtration should be
installed.
8-6
-------
Example 3 - Nonacute Tier 1 Violation
A conventional treatment plant is treating a surface water. A malfunc-
tioning alum feed system resulted in an increase of the filter effluent
turbidities. The effluent turbidity was between 0.5 and 1.0 NTU in 20 percent
of the samples for the month. The utility issued a notice which was published
in a local daily newspaper within 14 days after the violation. The notice
read as follows:
During the previous month, the water treatment plant experienced diffi-
culties with the chemical feed system. The malfunctions caused an
effluent turbidity level above 0.5 NTU in 80 percent of the samples for
the month. The current treatment standards require that the turbidity
must be less than 0.5 NTU in 95 percent of the monthly samples. Our
drinking water system has thus been in violation to a treatment technique
requirement.
The United States Environmental Protection Agency (EPA) sets drinking
water treatment technique requirements for microbiological contaminants
(such as viruses, bacteria, and some other microorganisms) which are of
health concern. To reduce any potential risk of microbial contamination
of drinking waters, drinking water treatment facilities are required to
treat drinking water by filtering or disinfecting, which removes or
destroys microbiological contaminants. Violation of the required treat-
ment technique indicates that the water has been treated improperly and
may expose people who drink that water to contaminants which can cause
various types of illness such as hepatitis, giardiasis, and gastro-
enteritis. These illnesses can cause different symptoms, including
diarrhea, jaundice, abdominal cramps, nausea, headaches, fatigue, and
weight loss.
The chemical, feed and switchover systems of our system have been re-
paired and are in working order and turbidity levels are meeting the
standard. It is unlikely that illness will result from the turbidity
exceedences previously mentioned because continuous stringent disin-
fection conditions were in effect and the system was in compliance with
other microbiological drinking water standards pertaining to microbio-
logical contamination. However, a doctor should be contacted in the
event of illness. For additional information call, 1-800-726-WATER.
8-7
-------
9. EXEMPTIONS
9.1 Minimum Requirements
EPA believes that in order to obtain an exemption from the SWTR, a system
should meet certain minimum requirements. These should be applied before
looking at other factors such as affordability. These minimum requirements
are listed below.
Systems which do not provide filtration
- Practice disinfection to achieve at least a 2 log inactivation of
Giardia cysts; or comply with the disinfection requirements for the
distribution system as defined in Section 141.72b of the SWTR.
- Comply with both the monthly and long-term coliform MCL or issue
boil water orders to their customers; or provide bottled water (or
another alternate water source) or point of use treatment devices
for their customers in which representive samples comply with all
the MCL National Primary Drinking Water Regulations.
It is recommended that in order to obtain an extension to the initial
exemption period, the system would need to be in compliance with both the
monthly and long-term coliform MCL, satisfy the above disinfection criteria
and not have any evidence of waterborne disease outbreaks attributable to" the
•
system at the end of that first exemption period. If at any point during the
extended exemption period the system did not meet these conditions ,' the
system should be subject to an enforcement action.
Systems which provide filtration •
- Practice disinfection to achieve at least a 1 log inactivation of
Giardia cysts; or comply with the disinfection requirements for the
distribution system as defined in Section 141.72b of the rule.
- Comply with both the monthly and long-term coliform MCL or issue
boil water orders or provide bottled water (or other alternate
supply) or point of use treatment devices for their customers; and
- Take all practical steps to improve the performance of its
filtration system.
It is recommended that in order to obtain an extension to the initial
exemption period, the system would need to be in compliance with both the
monthly and long-term coliform MCL, satisfy the above disinfection criteria
and not have any evidence of waterborne disease outbreaks attributable to the
9-1
-------
system at the end of that first exemption period. If at any point during the
extended exemption period the system did not meet these conditions , the
system should be subject to an enforcement action. In addition, the system
must continue to be taking steps to improve the performance of its filtration
system to achieve the criteria specified in the SWTR.
Once these minimum requirements are applied, the Primacy Agency should
look at the other factors as described in Sections 9.2, 9.3, and 9.4.
9.2 Compelling Factors
Compelling factors are any conditions which would render compliance with
the requirements of the SWTR impractical. These problems or constraints are
associated most often with small systems, and the major compelling factor is
economic. It is suggested that another compelling factor may be the
unavailability of qualified operators. Small systems may not have any
certified operators within commuting distance from the plant. Also, it may
not be practical for the system to relocate a certified operator within
commuting distance, since plant operations would not require a full time
operator. Additional considerations for small systems are presented in
Appendix L.
If system improvements necessary to comply with the SWTR incur costs
which the Primacy Agency determines pose an undue economic hardship, the
system fulfills the criteria of demonstrating a compelling hardship which
makes it unable to meet the treatment requirements. The system may obtain an
exemption if the criteria in 9.3 and 9.4 are also met.
The USEPA document, "Technologies and Costs for the Removal of Microbial
Contaminants from Potable Water Supplies," contains costs associated with
available treatment alternatives (USEPA, 1987). Costs found in this document,
or those generated from more site specific conditions, can be used as the
basis for determining the ability of a system to afford treatment.
Specifically, in this manual when calculating the total production costs, each
cent per thousand gallons of treated water is equivalent to $1.5 per year per
household, assuming a water usage of 100 gallons per capita per day, and four
9-2
-------
people per household. The total cost will need to be adjusted according to
water usage for cases where the usage differs from 100 gallons per capita per
day, or for the number of people per household if that number differs from
four.
The following examples are presented to provide guidance in determining
whether a system can afford to upgrade its system or install filtration.
Example 1
A water system which supplies an average daily flow of 0.05 mgd to a
small urban community, receives its water supply from a lake. The system
currently provides disinfection with chlorine but does not provide filtration.
The system reviewed its source water quality and found the characteristics to
be as follows:
Total coliforms 1,000/100 ml
Turbidity 10 - 13 NTU
Color 6 - 9 CU
Based upon the criteria found in the SWTR, this source requires filtra-
tion and a review of the water quality criteria presented in Table 4-2,
indicates that the treatment technique which is most applicable to these
source conditions is conventional treatment. A conventional package treatment
1. Determined as follows:
4 persons x 100 gal x 365 day • 146,000 gal
household person-day year household-year
146,000 gal x 1C » $1.5/household-year
household-year 1,000 gallon
or ($1.5/household-year) / (C/1,000 gallons)
at a usage of 146,000 gal
household year
9-3
-------
plant with a capacity of 0.068 MGD may be purchased and put on line at a cost
of $416/household/year not including the cost of any pilot studies which may
be required by the state.
Thus the cost estimate for implementing filtration indicates that the
increase in the average annual household water bill would be approximately
§416. The incomes of people in the community and the current water bills can
be reviewed by the Primacy Agency along with these estimated costs to
determine if an undue economic hardship is incurred by these treatment
methods. Upon determination that an economic hardship is incurred, the
Primacy Agency may grant an exemption from filtration, provided that no other
water source meeting the standards is available at a lower cost, and that the
system can assure the protection of the health of the community. However, if
the water supply system for a nearby community meets the drinking water
standards and there is the ability to hook up to that system, an exemption
would not be granted provided the total cost would be less than that of the
above treatment.
Example 2
A large urban community with a median annual income of $25,000 per
family, is supplied with water from lakes and reservoirs. The community
places an average daily demand of 3 mgd on the supply system. .The watershed
of the system is moderately populated and used for farming and grazing. The
system currently provides filtration using diatomaceous earth filtration and
disinfection with ehloramines.
A review of the source and finished water quality was conducted to evalu-
ate the plant's performance. The source water quality was determined to be:
Total coliforms 30 - 40/100 ml
Turbidity 2-3 NTU
Color 1 - 2 CU
2. Table VI-3 (USEPA, 1987) lists the total cost as 277.40/1,000 gal
(277.40/1,000 gal) ($1.5/household-year) c $416/household-year
( 0/1,000 gallons )
9-4
-------
Diatomaceous earth is therefore an acceptable filtration method.(3)
However, review of the finished water showed that a residual in the distri-
bution system is only maintained 80 percent of the tine. In addition to this,
coliforms were detected in 10 percent of the samples taken over the twelve
month period. Inspection of the chlorination equipment showed the equipment
is deteriorated. Review of the monthly reports showed that the coliforms
appeared in the distribution system shortly after the chlorinators malfunc-
tioned. This observation led to the conclusion that new disinfection facili-
ties were needed.
The source water quality and available contact time after disinfection
were then used to determine the most appropriate disinfectant for the system.
As described in Section 5.5, ozone, chlorine or chlorine dioxide can be used
as primary disinfectants given these conditions. A preliminary review of
costs for applying the various disinfectants showed chlorine to be the most
(4)
economical at a cost Of $4.2/household/year (USEPA, 1987). This cost does
not include backup equipment; however, even with providing duplicate equipment
doubling this cost to $8.4/household/ year, the improvement incurs minimal
cost and it is unlikely that the Primacy Agency will grant the system an
exemption based on economic hardship.
9.3 Evaluation of Alternate Water Supply Sources
Once compelling factors are demonstrated, systems must next demonstrate
that there is no reasonable alternate water supply available to the system.
In order to show this, the system must evaluate the possibility of utilizing
an alternate source. These alternate sources include:
- The use of ground water
- Connection to a nearby water purveyor
3. As determined from Table 4-2 of Section 4.
4. Table VT-12 (USEPA, 1987) lists a total cost of 2.8^/1,000 gal for a plant
capacity of 5.85 MGD.
( 2.8C ) ($1.5/household-year) m $4.2/household-year
(1,000 gal) ( C/1,000 gal )
9-5
-------
- Utilization of an alternate surface water supply
When considering the use of ground water, the purveyor must determine the
capacity of the underlying aquifer for supplying the demand. The water
quality characteristics of the aquifer must be evaluated to determine what
treatment may be needed to meet existing standards. The cost of the well
construction and treatment facilities must then be determined and converted
into a yearly cost per household.
The connection to a nearby purveyor involves contacting the purveyor to
determine their capacity and willingness to supply the water. Once it has
been determined that the alternate source meets all applicable drinking water
standards, the cost of the transmission lines, distribution system, and other
facilities (e.g. disinfection, repumping, etc.) must then be determined and
amortized into a yearly cost per household.
If the cost for an alternate source is found by the Primacy Agency to
present an economic hardship, and the purveyor can demonstrate that there will
be no unreasonable risk to health as cited in Section 9.4, the Primacy Agency
may grant an exemption to the SWTR for the purveyor and develop a schedule of
compliance.
9.4 Protection of Public Health
Systems which apply for exemption from the SWTR must demonstrate to the
Primacy Agency that the health of the community will not be put at risk by the
granting of such an exemption. A system will provide protection for the
public health by meeting the minimum suggested EPA requirements in
Section 9.1. However, a Primacy Agency may specify additional measures or
standards a system must meet to protect public health. These measures
necessarily will depend on the particular circumstances and systems with
currently unfiltered surface water supplies which fail to meet the source
water quality criteria will be required to install filtration as part of their
treatment process. However, it may take 3 to 5 years or more before the
filtration system can be designed, constructed and begin operation. During
this period interim measures which the system could take include one or more
of the following:
a. Use of higher disinfectant dosages without exceeding the TTHM MCL
9-6
-------
b. Installation of a replacement or additional disinfection system
which provides greater disinfection efficiency and which can be
integrated into the new filtration plant
c. Increasing the monitoring and reporting to the Primacy Agency
d. Increasing protection of the watershed
e. Increasing the frequency of sanitary surveys
f. Temporarily purchasing water from a nearby water system
g. For small systems, temporary installation of a mobile filtration
(packaged) plant
h. Increasing contact time by rerouting water through reservoirs
In some cases systems may be able to increase their disinfection dosages
during the interim period to provide additional protection against pathogenic
organisms. This alternative should be coupled with a requirement for increa-
sed monitoring for coliforms, HPC and disinfectant residual within the distri-
bution system. However, this alternative is not recommended if the increase
in disinfectant dosage will result in a violation of the TTHM regulation.
Systems which are planning to install filtration may be able to utilize a
more efficient disinfectant that can later be integrated into the filter
plant. Currently ozone and chlorine dioxide are considered to be the most
efficient in reducing/inactivating Giardia cysts and enteric viruses.
For all systems which do not meet the source water quality criteria and
must install filtration, it is recommended that during the interim period the
Primacy Agency increase its surveillance of the system and require increased
monitoring and reporting requirements to assure adequate protection of the
public health.
Any required increases in . watershed control and/or sanitary survey
prerequisites will not alleviate the need for more stringent disinfection
requirements and increased monitoring of the effectiveness of the system
employed. Their purpose would be to identify and control all sources of
contamination so that the existing system will provide water of the best
possible quality.
For some systems, it may be possible to purchase water from a nearby
system on a temporary basis. This may involve no more than the use of
9-7
-------
existing interconnections or it may require the installation of temporary
connections.
Trailer mounted filtration units (package plants) are sometimes available
from state agencies for emergencies or may be rented or leased from equipment
manufacturers.
Systems may also be required to issue a boil water notice, supply bottled
water or install point-of-entry (POE) treatment devices. For the reasons
listed below, these alternatives should only be utilized if the previously
mentioned alternatives are not feasible:
- There is no way to assure that every consumer will adhere to the
boil water decree.
- In many states bottled water is subject only to the water quality
requirements of the FDA as a beverage and not to the requirements of
the Safe Drinking Water Act.
- Point-of-entry treatment devices are not currently covered by
performance or certification requirements which would assure their
effectiveness or performance.
Should the installation of POE devices be required, it is recommended
that the selection of the appropriate treatment device be based upon a labora-
tory or field scale evaluation of the devices. A guide for testing the
effectiveness of POE units in the microbiological purification of contaminated
water is provided in Appendix Q0
Several issues arise with the use of POE devices. These include
establishing who or what agency has the responsibility for ensuring compliance
with standards; retains ownership of the treatment units; performs monitoring,
analyses and maintenance; manages the treatment program and maintains
insurance coverage for damage and liability. It should also be considered
that there is no significant increase in risk over centrally treated water.
These issues should be borne in mind when POE as a treatment alternative
is being considered.
Systems with currently unfiltered surface water supplies which meet the
source water quality criteria, but do not meet one or more of the other re-
quirements for watershed control, sanitary survey, compliance with annual
coliform MCL or disinfection byproducts regulation(s), will be required to
install filtration unless the deficiencies are corrected within 30 months of
9-8
-------
promulgation of the SWTR. Interim protection measures include those previous-
ly listed.
Systems with currently unfiltered surface water supplies which meet the
source water quality criteria and the site specific criteria but which do not
meet the disinfection requirements, will be required to install filtration
unless the disinfection requirements (adequate CT and/or disinfection system
redundancy) can be met. During the interim period, the available options
include:
a. Temporary installation of a mobile treatment plant
b. Temporary purchase of water from a nearby purveyor
c. Increased monitoring of the system
d. Installation of temporary storage facilities to increase the disin-
fectant contact time
Currently filtered supplies which fail to meet the turbidity or disinfec-
tion performance criteria presented in Section 5 will be required to evaluate
and upgrade their treatment facilities in order to attain compliance. During
the interim period the available options for improving the finished water
quality include:
a. Use of a filter aid to improve filter effluent turbidities
b. Increased disinfectant dosages and/or the addition of an alternate
disinfectant such as ozone
c. Reduction in filter loading rates with subsequent reduction in plant
capacity
d. Installation of temporary storage facilities to increase disinfec-
tant contact time
9.5 Schedule of Compliance
The granting of an exemption is accompanied by a schedule of action which
is set by the Primacy Agency. The schedule establishes a time frame for the
water system to comply with the treatment technique requirement for which the
exemption was granted. The schedule also includes the implementation of
interim control measures including some which may be required immediately,
9-9
-------
until the required treatment facilities can be installed, guidelines for which
are discussed in Section 9.4.
The schedule establishes the most expeditious time frame for compliance
with the treatment technique requirements that is practical. The Primacy
Agency must provide public notification and allow for a public hearing before
a schedule is implemented. The SWTR is promulgated under Section 1412(c) of
the SDWA which states that the schedule must require compliance within
12 months after the issuance of the exemption. The Primacy Agency may extend
the final date for compliance provided in any schedule for up to three years
after the date of the issuance of the exemption if the public water system
establishes that:
- the system cannot meet the standard without capital improvements
which cannot be completed in the period of the exemption.
- the system has entered into agreements to obtain necessary financial
assistance.
- the system has entered into an enforceable agreement to become part
of a regional supply system and the system is talcing all practical
steps to meet the standard.
Systems serving less than 500 customers and need financial assistance,
may be granted an extension of the three year exemption for one or more
additional 2-year periods provided that the system establishes that is is
taking all practical steps to meet the schedule.
As stated in Section 9.1, EPA believes that in order for a system to be
eligible to receive any extensions to the exemption period(s), the system must
be in compliance with both the monthly and long-term coliform MCL and there
must be no evidence linking the system to waterborne disease outbreaks. In
addition, systems which are providing filtration but whose filtration system
does not meet the criteria of the SWTR, must also be continuing to take all
practical steps to improve the performance of its filtration system in order
to be eligible for an extension.
9.6 Notification to EPA
The SDWA requires that each Primacy Agency which grants an exemption
shall notify EPA of the granting of this exemption. The notification must
9-10
-------
contain the reasons for the exemption, including the basis for the finding
that the exemption will not result in an unreasonable risk to public health
and document the need for the exemption. The EPA will provide additional
details on the reporting requirements for the Primacy Agency in later
documents.
9-11
-------
REFERENCES
-------
REFERENCES
Ali-Ani, M.; McElroy, J. M.; Hibler, C. P.; Hendricks, D. W. Filtration of
Giardia Cysts and other Substances, Volume 3: Rapid Rate Filtration.
EPA-600/2-85-027, U.S. Environmental Protection Agency, WERL, Cincinnati,
Ohio, April, 1985.
American Public Health Association; American Water Works Association; Water
Pollution Control Federation. Standard Methods for the Examination of Water
and Wastewater, 16th ed., pp. 134-6, 298-310, 827-1038, 1985.
American Water Works Association Research Foundation (AWWARF). A Summary of
State Drinking Water Regulations and Plan Review Guidance. June, 1986.
Bader, H.; Hoigne, J. Determination of Ozone in Water by the Indigo Method,
Water Research 15; 449-454, 1981.
Bellamy, W. D.; Lange, K. P.; Hendricks, D. W. Filtration of Giardia Cysts and
Other Substances. Volume 1: Diatomaceous Earth Filtration. EPA-600/2-84-114,
U.S. Environmental Protection Agency, Cincinnati, Ohio, 1984.
Bellamy, W. D.; Silverman, G. P.; Hendricks, D. W. Filtration of Giardia Cysts
and Other Substances. Volume 2: Slow Sand Filtration. EPA-600/2-85-026, U.S.
Environmental Protection Agency, MERL, Cincinnati, Ohio, April, 1985.
Berman, D.; Hoff, J.C. Inactivation of Simian Rotavirus SA 11 by Chlorine,
Chlorine Dioxide and Monochloramine. Appl. Environ. Microbiol, 48:317-323,
1984.
Bishop, S.; Craft, T. F.; Fisher, D. R.; Ghosh, M.; Prendiville, P.W.;
Roberts, K. J.; Steimle, S.; Thompson, J. The Status of Direct Filtration,
Committee Report. J.AWWA, 72(7):405-411, 1980.
Bouwer, H. Ground Water Hydrology. McGraw Hill Book Co., New York,
pp. 339-356, 1978.
Brown, T. S.; Malina, J. F., Jr.; Moore, B. D. Virus Removal by Diatomaceous
Earth Filtration - Part 1 & 2. J.AWWA 66(2):98-102, (12):735-738, 1974.
Clark, R. M.; Read, E. J.; Hoff, J. C. Inactivation of Giardia lamblia by
Chlorine: A Mathematical and Statistical Analysis. Unpublished Report,
EPA/600/X-87/149, DWRD, Cincinnati, OH, 1987.
Cleasby, J. L.; Hilmoe, D. J.; Dimitracopoulos, C. J. Slow-Sand and Direct
In-Line Filtration of a Surface Water. J.AWWA, 76(12):44-55, 1984.
Cotruvo, J. A.; Vogt, C. D. USEPA Office of Drinking Water, Regulatory
Aspects of Disinfection. AWWA Seminar Proceedings, AWWA Conference, pp. 27-32,
June, 1984.
-1-
-------
DeWalle, F. B.; Engeset, J.; Lawrence, W. Removal of Giardia lamblia Cysts by
Drinking Water Plants. EPA-600/52-84-069, United States Environmental
Protection Agency, MERL, Cincinnati, Ohio, May 1984.
Fox, K. R.,- Miltner, R. J.; Logsdon, G. S.; Dicks, D. L.; Drolet, L. F. Pilot
Plant Exploration of Slow Rate Filtration. Presented at the AWWA Annual
Conference Seminar, Las Vegas, Nevada, June 1983.
Fujioka, R.; Kungskulniti, N.; Nakasone, S. Evaluation of the Presence -
Absence Test for Colifonns and the Membrane Filtration Method for Heterotro-
phic Bacteria. AWWA Technology Conference Proceedings, November, 1986.
Geldreich, E.; Nash, H.; Reasoner, D.; Taylor R. Necessity of Controlling
Bacterial Populations in Potable Waters: Community Water Supply. J.AWWA,
64:596-602, 1972.
Geldreich, E.; Greenberg, A.; Haas, C.; Hoff, R.; Karlin, J.; Means, E.;
Moser, R.; Regunathan, P.; Reich, K. and Victoreen, H. Microbiological
Considerations for Drinking Water Regulation Revisions, Committee Report,
Organisms in Water Committee. JAWWA, 79(5):81, 1987.
Hibler, C. P. Evaluation of the 3M Filter 124A in the FS-SR 122 Type 316 S/S
#150 Housing for Removal of Giardia Cysts. Department of Pathology, Colorado
State University, Performance Report submitted to 3M Corporation, 1986.
Hoffbuhr, J. W.; Blair, J.; Bartleson, M.; Karlin, R. Use of Particulate
Analysis for Source and Water Treatment Evaluation. AWWA Water Quality
Technology Conference Proceedings, November 1986.
Hoff, J. C. Inactivation of Microbial Agents by Chemical Disinfectants.
EPA-600/52-86-067, U.S. Environmental Protection Agency, Water Engineering
Research Laboratory, Drinking Water Research Division, Cincinnati, Ohio,
September, 1986.
Horn, J. B.; Hendricks, D. W. Removals of Giardia Cysts and other Particles
from Low Turbidity Waters Using the Culligan Multi-Tech Filtration System.
Engineering Research Center, Colorado State University, Unpublished, 1986.
Kelly, Gidley, Blair and Wolfe, Inc. Guidance Manual - Institutional
Alternatives for Small Water Systems. AWWA Research Foundation Con-
tract 79-84, 1986.
Kuchta, J. M.; States, S. J.; McNamara, A. M.; Wadowsky, R. M.; Yee, R. B.
Susceptibility of Legionella pneumophila to Chlorine in Tap Water. Appl.
Environ. Microbiol., 46(5): 1134-1139, 1983.
Letterman, R. D. The Filtration Requirement in the Safe Drinking Water Act
Amendments of 1986. U.S. EPA/AAAS Report, August 1986.
Logsdon, G. S.; Symons, J. M.; Hoye, Jr., R. L.; Arozarena, M. M. Alternative
Filtration Methods for Removal of Giardia Cysts and Cyst Model. J.AWWA,
73:111-118, 1981.
-2-
-------
Logsdon, G. S. Report for Visit to Carrollton, Georgia, USEPA travel report,
February 12, 1987a.
Logsdon, G. S. Comparison of Some Filtration Processes Appropriate for
Giardia Cyst Removal. USEPA Drinking Water Research Division; Presented at
Calgary Giardia Conference, Calgary; Alberta, Canada, February 23-25, 1987b.
Long, R. L. Evaluation of Cartridge Filters for the Removal of Giardia
lamblia Cyst Models from Drinking Water Systems. J. Environ. Health,
45(5):220-225, 1983.
McCabe, L.; Symons, J.; Lee, R.; Robeck, G. Study of Community Water Supply
Systems. J.AWWA, 62:11:670, 1970.
Morand, J., M.; C. R. Cobb; R. M. Clark; Richard, G. S. Package Water
Treatment Plants, Vol. 1, A performance Evaluation. EPA-600/2-80-008a, USEPA,
MERL, Cincinnati, Ohio, July, 1980.
Morand, J. M.; Young, M. J. Performance Characteristics of Package Water
Treatment Plants, Project Summary. EPA-600/52-82-101, USEPA, MERL,
Cincinnati, Ohio, March, 1983.
Muraca, P.; Stout, J. E.; Yu, V. L. Comparative Assessment of Chlorine, Heat,
Ozone, and UV Light for Killing Legionella pneumophila Within a Model Plumbing
System. Appl. Environ. Microbiol., 53(2):447-453, 1987.
Payment, P.; Trudel, M.; Plante, R. Elimination of Viruses and Indicator
Bacteria at Each Step of Treatment During Preparation of Drinking Water at
Seven Water Treatment Plants. Appl. Environ. Microbiol., 49:1418, 1985.
Poynter, SFB; Slade, J. S. The Removal of Viruses by Slow Sand Filtration,
Prog. Wat. Tech. Vol. 9, pp. 75-88, Pergamon Press, 1977. Printed in
Great Britain.
Regli, S.; Berger, P., (eds.). Workshop on Filtration, Disinfection, and
Microbial Monitoring, April 15-17, 1985, Baltimore, MD. EPA 570/9-87-001,
Office of Drinking Water, 1987.
Regli, S.; Amirtharajah, A.; Hoff, J.; Berger, P. Treatment for Control of
Waterborne Pathogens: How Safe is Safe Enough? In: Proceedings, 3rd
Conference on Progress in Chemical Disinfection, G.E. Janauer (Editor),
April 3-5, 1986. State University of New York, Binghampton, NY, in press.
Robeck, G. G.; Clarke, N. A.; Dostal, K. A. Effectiveness of Water Treatment
Processes in Virus Removal. J. AWWA, 54(10):1275-1290, 1962.
Slezak, L. A.; Sims, R. C. The Application and Effectiveness of Slow Sand
Filtration in the United States. J.AWWA, 76(12):38-43, 1984.
-3-
-------
U. S. Environmental Protection Agency, Office of Drinking Water, Criteria and
Standards Division. Manual for Evaluating Public Drinking Water Supplies,
1971.
U. S. Environmental Protection Agency, Office of Drinking Water. Technologies
and Costs for the Removal of Microbial Contaminants from Potable Water
Supplies. AWWA Water Quality Technology Conference, November 1986.
U. S. Environmental Protection Agency, Office of Drinking Water. Public
Notification Handbook for Drinking Water Suppliers, May 1978.
World Health Organization Collaborating Center. Slow Sand Filtration of
Community Water Supplies in Developing Countries. Report of an International
Appraiser Meeting, Nagpur, India, Bulletin Series 16, September 15-19, 1980.
-4-
-------
APPENDIX A
USE OF PARTICULATE ANALYSIS FOR
SOURCE AND WATER TREATMENT EVALUATION
Reprinted from 1986 Annual
Conference Proceedings, by
permission
Copyright C 1986, American
Work Works Association
-------
USE OF PARTICULATE ANALYSIS FOR SOURCE
AND WATER TREATMENT EVALUATION
Jack W. Hoffbuhr, P.E.
Deputy Director
Water Management Division
U.S. E.P.A., Region 8
Denver, Colorado 8202-2413
John Blair, P.E.
District Engineer
Colorado Department of Health
Grand Junction, Colorado 81501
Michael Bartleson
Director of Water Treatment Operations
City of Broomfield
Broomfield, Colorado 80020
Richard Karlin, P.E.
Chief, Drinking Water Section
Colorado Department of Health
Denver, Colorado 80220
Coliform bacteria and turbidity have been traditional procedures for
evaluating the quality of source waters and the effectiveness of treatment
processes. Many water systems have used these measures exclusively to deter-
mine the microbiological quality of their finished water. This sense of
security has been severly diminished in recent years due to the increasing
frequency of reported waterborne disease outbreaks where water quality was
judged to be excellent by the traditional measures. It is evident that
additional tools are needed to determine the quality of source and treated
waters. The recent enactment of the 1986 Amendments to the Safe Drinking
Water Act (SDWA) also highlights this need.
Background
Giardia Lamblia has become a most famous (or infamous) parasite to the
water utility industry. Its presence in source waters across the U.S. and
role in numerous waterborne outbreaks has:
1. Emphasized the importance of the multiple barrier concept in water
treatment;
-1-
-------
2. Illustrated the need for additional techniques to evaluate the
quality of water; and
3. Caused a major increase in sampling and analysis for Giardia
lamblia.
These points were clearly emphasized in epidemiological and engineering
studies conducted by the Colorado Department of Health (1). These studies
also indicated that all surface waters are susceptible to contamination by
Giardia. As a result, the Department of Health adopted regulations requiring
filtration of all surface water sources.
Ground water sources weren't included since it was felt that they were
protected by the natural barrier provided by the layers of earth. However, it
quickly became apparent that not all ground waters are created equally. Wells
and springs that are properly sited, designed and constructed certainly
provide a larger degree of protection from contamination due to surface
influences. However, many alluvial wells plus wells and springs that are
poorly constructed don't provide that same level of protection.
Infiltration galleries fall into a gray area since they can collect
surface and ground water. In most cases, they are heavily influenced by
surface water conditions.
It was clear that a technique was needed to determine if the so-called
ground waters were susceptible to surface water and, therefore, Giardia
contamination. Sanitary surveys can identify problem areas and potential
pathways of contamination but aren't conclusive evidence. Turbidity and
coliform results, as shown by the previous study aren't reliable indicators
(1).
Sampling to determine the presence of only Giardia cysts isn't helpful
either since not finding Giardia in a single sample doesn't obviate the
potential for contamination. However, the sampling and analysis procedure for
Giardia does offer a useful alternative. A variety of other particulate
matter is trapped on the sampling filter and appears on the microscope slide
along with any Giardia cysts. These particulates can be identified and
evaluated to provide a valuable insight into the quality of the water.
To further explore the usefulness of this procedure the Colorado Depart-
ment of Health conducted a study of 70 water systems in Colorado. (A special
-2-
-------
study examined 10 systems in depth (2)). The Region 8 office of the Environ-
mental Protection Agency conducted a study of 80 systems in Wyoming using the
same procedures (3). The objectives of the studies were to (1) identify
particulate types that, by their presence in water, indicate surface water
contamination and (2) to determine the efficacy of water treatment systems.
This paper discusses the results obtained pertaining primarily to the first
objective.
Methods
The 150 systems selected for the studies included surface water sources,
wells, springs and infiltration galleries. This paper presents the results of
16 systems representing a cross-section of both studies.
Untreated source water was sampled at each site using a one micron
cartridge filter apparatus and the protocols for pathogenic protozoans de-
scribed in the 16th edition of Standard methods (4). All samples were shipped
packed in ice and analyzed within 48 hours. The Colorado samples were an-
alyzed by the Health Department's Parasitology Laboratory. Split samples were
analyzed by Dr. Charles Hibler at Colorado State University for quality
control. The Wyoming samples were all analyzed by Dr. Hibler. In all cases
the particulate analysis was conducted using the zinc sulfate flotation
techniques (4,5). This procedure does not produce 100 percent cyst recovery
or precise particulate analysis, but it does provide results which provide
invaluable information about the quality of the sampled water.
The particulate analyses provided results for 14 particulate categories
which have been summarized into 12 groups for purposes of this paper. The
particulates, except for Giardia, were enumerated using the general quantities
shown in Table 1. For Giardia cysts the numbers shown are estimated total
numbers of cysts in the samples.
Discussion of Results
The particulate categories shown in Table 2 constitute a broad spectrum
of what could be found in water. Not all of them are good indicators of
surface water contamination of ground water. By considering these categories
in detail a more concise list of possible indicators can be developed.
-3-
-------
Sediment - Includes all the particulate matter in a sample. Since
this group is so inclusive, it is not a good indicator.
Amorphous Debris - Consists of pieces of silica, decaying vegeta-
tion, micro-organisms and unrecognizable matter with a wide size
range. Since this material is non-specific and ubiquitous in all
water sources it is not a good indicator.
Algae - Comprises a large group of microorganisms which have a wide
variety of sizes and shapes. Algae have been found in all types of
water sources, therefore, as a group they are not a good indicator.
Diatoms - A particular type of algae that contain silica in their
cell walls. Since diatoms require sunlight they are not normally
found in ground water, therefore they are a good indicator.
Plant Debris - This category consists of undigested fecal material
from herbivorous mammals such as beavers and muskrats. This catego-
ry should be an excellent indicator of animal activity in the
watershed and of surface water influence.
Giardia - This infamous protozoan pathogen ranges in size from
7-14 microns. The organism is transported by beavers, muskrats,
dogs, humans and other mammals. In the cyst form the organism is
fairly resistant to environmental conditions and chlorine. Giardia
cysts are excellent indicators of surface water influence.
Free-living and Parasitic Nematodes - Worm-like microorganisms that
can exist in a wide variety of water environments including filter
beds, infiltration galleries and wells, therefore, they are not good
indicators.
Coccidia - Host specific parasites found in animals and fish. They
range in size from 10 to 20 microns and make excellent indicators of
surface water influence.
Pollen - Powder-like material produced by plants and found every-
where, therefore not a good indicator.
Protozoa (other than Giardia cysts) - Microorganisms which live in a
variety of water sources, therefore they are not good indicators.
Crustacea - Large microorganisms ranging in size from 250 to 500 mi-
crons, with eggs from 50 to 150 microns. Since they can live in
many types of water sources they are not good indicators of surface
water influence. However, their presence in finished water can
indicate poor treatment performance.
Insects - This category includes insects, insect parts, larvae and
eggs. Since many insects live in or near surface water they can be
good indicators.
-4-
-------
- Rotifers - Microscopic animals commonly found in surface waters
ranging in size from 150 - 600 microns. They require sunlight so
are good indicators of surface water influence.
Based on these points, the list of particulate types that can indicate a
surface water impact on ground water are shown in Table 3. A key to their
usefulness is that they are the same size or larger than Giardia cysts. If
they are not removed by natural processes in the earth or by treatment pro-
cesses, Giardia cysts probably would not be removed either. Therefore, the
presence of these indicator particulates in wells, springs, infiltration
galleries or treatment plant effluents indicates that these water systems are
also at risk of becoming contaminated by Giardia cysts.
The particulate data from the studies were reviewed to determine if the
above reasoning was valid. Table 4 shows data from 16 of the water systems
surveyed. The symbols used are the same as those in Table 1.
The streams contained a broad spectrum of all the particulate types
including Giardia cysts. The influence of animals on these sources is in-
dicated by the presence of plant debris, coccidia and Giardia. It is clear
that if adequate treatment isn't provided to these sources that the respective
water systems would be at risk.
The infiltration galleries (except for gallery 5) also contained a wide
range of particulate matter including plant debris and Giardia cysts. This
indicates that little filtering action was being accomplished by galleries 6,
7, and 8. These installations had collection systems buried from a few inches
to about six feet below the streams. Gallery 5 had a collection system
constructed 10 feet deep and 20 feet away from and parallel to the stream
which allowed for better filtration. Many times infiltration galleries are
constructed as low cost alternatives to more complete treatment. It is
evident that such installations may be providing a false sense of security.
The well data indicate a much different pattern. The wells only con-
tained a few particulate types and, with the exception of well 12, none of the
types indicated surface water intrusion. The characteristics of these wells
are listed by Table 5. Wells 9 and 11 would have the most potential for
contamination (assuming the geologic formations are roughly the same and good
construction practices were followed) since they are closest to surface water.
-5-
-------
Well 12 did exhibit some plant debris and should be investigated further.
Well 9 showed the smallest amount of particulate matter. However, a sample
taken during the spring runoff contained plant debris and Giardia cysts which
illustrate an important consideration. Since surface water quality can
fluctuate widely, judgments based on one sample can lead to serious errors.
The springs showed even less particulate matter than the wells.
Spring 14 did contain rotifers and spring 16 some plant debris indicating
surface water influence. The sanitary surveys revealed that the catchment
areas in both cases were not fenced and there was evidence of heavy animal and
human traffic, illustrating the importance of proper source protection.
Overall, the data support the indicators shown by Table 3. The six
particulate types are present in surface waters and absent in properly pro-
tected ground waters. The results of these studies indicate that particulate
analysis can provide an excellent tool in evaluating source water quality, the
potential for surface water contamination of ground water and the effective-
ness of infiltration galleries.
Conclusions
1. Particulate analysis can provide valuable information for evaluating
source water quality, the potential for surface water contamination
of ground waters and the effectiveness of infiltration galleries.
2. Diatoms, rotifers, coccidia, plant debris, insect parts and Giardia
cysts are valid indicators of surface water contamination of ground
water systems.
3. Infiltration galleries are providing a false sense of security in
many instances particularly if the collection system is directly
under the stream. Infiltration galleries must be carefully evalu-
ated to determine if treatment beyond chlorination is needed.
4. Sampling for particulate analysis should be done seasonally to gain
an understanding of the fluctuation of surface water quality and the
impact on ground water.
5. Particulate analysis can also provide information on the effective-
ness of water treatment processes in removing particulate matter.
Acknowledgements
The authors express their sincere thanks to Mr. Kurt Albrecht of the
Colorado Department of Health's Laboratory Division and Dr. Charles Hibler and
-6-
-------
his staff at Colorado State University's Pathology Laboratory. Mr. Albrecht
spent many hours analyzing the samples. Dr. Hibler and his staff analyzed
numerous samples and provided expert advice on the studies.
References
1. Karlin, R.V. and Hopkins, R.S., "Engineering Defects Associated With
Colorado Giardiasis Outbreaks June 1980 - June 1982." Proc. AWWA
ACE, Las Vegas, Nev. (June 1983).
2. Bartleson, M.E. "Particulate Indicators for Assessing Protected
Ground Water Sources and Water Treatment Efficacy." Report to
Colorado Dept. of Health, Denver, Co. (June 1986).
3. Wiley, B.R., Barman, D.J., and Benjes, Jr., H.H. "Survey and
Evaluation of 80 Public Water Systems in Wyoming - Project Summary."
Culp/Wesner/Culp, Denver, Co. (January 1986).
4. Standard Methods for the Examination of Water and Wastewater, APHA,
AWWA & WPCF, Washington, D.C. (16th ed., 1985)-
5. Logsdon, G.S., et. al. "Control of Giardia Cysts By Filtration:
The Laboratory's Role." Proc. AWWA WgTC, Norfolk, Va. (December
1983).
-7-
-------
TABLE 1
PARTICULATE ANALYSIS QUANTITY DESIGNATIONS
Symbol
EH
H
M
S
0
R
VR
T
Verbal Rating
Extremely heavy
Heavy
Moderate
Small
Occasional
Rare
Very rare
Trace
Description
4 or more particles per microscope
field
3 particles per microscope field
2 particles per microscope field
1 particle per microscope filed
1 particle every 3 or 4 microscope
fields
2 to 3 particles in entire slide
1 particle in entire slide
Visual observation, typically used
only for sediment
None Not detected
-------
TABLE 2
SUMMARY OF PARTICULATE TYPES
Sediment Coccidia
Large Amorphous Debris Pollen
Fine Amorphous Debris Protozoa
Algae Crustacea
Diatoms Insect Parts & Larvae
Plant Debris Rotifers
Giardia
Free Living & Parasitic Nematodes
-------
TABLE 3
PARTICIPATE TYPES INDICATING SURFACE WATER
Diatoms Plant Debris
Rotifers Insect Parts & Larvae
Coccidia Giardia
-------
TABLE 4
RESULTS OF PARTICULATE ANALYSES
Source
Infiltration
Particulate Type
Amorphous Material
Protozoa
Algae
Diatoms
Plant Debris
Nematodes
Rotifers
Crustacea
Coccidia
Insect Parts
Pollen
Giardia Cysts
Streams
1
H
T
T
H
O
T
N
N
T
R
N
4
2
M
T
T
T
O
M
N
T
T
VR
N
20
3
O
R
R
0
H
N
R
R
R
R
N
98
4
0
R
O
O
S
O
R
O
N
O
O
129
Galleries
5
M
T
M
R
0
T
N
N
N
R
N
N
6
M
T
H
H
T
T
N
T
R
H
T
80
7
M
T
EH
T
T
T
R
N
N
N
N
20
8
O
N
R
O
M
0
N
O
O
O
0
71
9
S
N
T
N
N
N
N
N
N
N
N
N
Wells
10
M
R
H
N
N
O
N
N
N
N
N
N
11
S
R
N
N
N
N
N
N
N
N
N
N
12
H
T
N
N
T
N
N
N
N
N
N
N
13
R
R
T
N
N
N
N
N
N
N
N
N
Springs
14
R
N
N
N
N
N
R
N
M
N
N
N
15
O
R
O
N
N
N
M
N
N
N
O
N
16
T
N
N
N
T
T
N
N
N
N
T
N
-------
TABLE 5
WELL CHARACTERISTICS
Source
9
10
11
12
Depth, ft.
100
40
60
72
Distance From Stream, ft.
20
300
20
100
-------
APPENDIX B
INSTITUTIONAL CONTROL OF LEGIONELLA
-------
APPENDIX B
INSTITUTIONAL CONTROL OF LEGIONELLA
Introduction
Legionella is a genus name for bacteria commonly found in lake and river
waters. Some species of this genus have been identified as the cause of the
disease legionellosis. In particular, Legionella pneumophila has been
identified as the cause of Legionnaires disease, the pneumonia form of
legionellosis and with Pontiac Fever, a nonpneumonia disease. Outbreaks of
legionellosis are primarily associated with inhalation of water aerosols or,
less commonly, with drinking water containing Legionella bacteria with
specific virulence factors not yet identified. Foodborne outbreaks have not
been reported (USEPA, 1985).
As discussed in this document, treatment requirements for disinfection of
a municipal water supply are thought to provide at least a 3 log reduction of
Legionella bacteria (see Section 3.2.2). However, some recontamination may
occur in the distribution system due to cross connections and during
installation and repair of water mains. It has been hypothesized that the low
concentrations of Legionella entering buildings due to these sources may
colonize and regrow in hot water systems (USEPA, 1985). Although all of the
criteria required for colonization are not known, large institutions, such as
hospitals, hotels, and public buildings with recirculating hot water systems
seem to be the most susceptible. The control of Legionella in health care
institutions, such as hospitals, is particularly important due to the
increased susceptibility of many of the patients.
The colonization and growth of Legionella in drinking water primarily
occurs within the consumer's plumbing systems after the water leaves the
distribution system. Therefore, the control of these organisms must be the
consumer's responsibility. This appendix is intended to provide guidance to
these institutions for the detection and control of the Legionella bacteria.
Monitoring
It is suggested that hospitals, and other institutions with potential for
the growth of Legionella, conduct routine monitoring of their hot water
B-l
-------
systems at least quarterly.(1) The analytical procedures for the -detection of
these organisms can be found in Section 912.1 "Legionellaceae" of the 16th
edition of Standard Methods. Samples should be taken at, or closely
following, the hot water storage reservoir and from a number of shower heads.
It is recommended that showers with the least frequent usage be included in
the sampling program. Follow-up testing is suggested for all positive
indications prior to the initiation of any remedial measures. If the the
presence of Legionella is confirmed, then remedial measures should be taken.
Although the regrowth of Legionella is commonly associated with hot water
systems, hot and cold water interconnections may provide a pathway for cross
contamination. For this reason, systems detecting Legionella in hot water
systems should also monitor their cold water systems.
Treatment
Because the primary route of exposure to Legionella is probably
inhalation, rather than ingestion, it is recommended that disinfection
procedures include an initial shock treatment period to disinfect shower heads
and hot water taps where the bacteria may colonize and later become airborne.
The shock treatment period should also include disinfection of hot water
tanks. After this time, a point-of entry treatment system can be installed to
provide continual disinfection of the hot water system.
Initial Disinfection
The most applicable method for the initial disinfection of shower heads
and water taps is heat eradication. The fittings can be removed and held at
temperatures greater than 60 C for at least 24 hours. Disinfection of fit-
tings can also be achieved by soaking or rinsing with a strong chlorine
solution. When soaking the fittings, a minimum chlorine strength of 50 mg/L
should be used for a period of no less than 3 hours. Rinsing with chlorine
should be performed with more concentrated solutions. Care must be taken not
1. Monitoring frequency based on the reported rate of Legionella
regrowth observed during disinfection studies (USEPA, 1985).
B-2
-------
to corrode the finished surface on the fittings. Commercially available
bleaches, for example, are typically 5.25 percent chlorine by weight.
Long-Term Disinfection
Heat - Numerous studies have shown that increasing the hot water tempera-
ture to 50 - 70 C over a period of several hours may help to reduce and
inhibit Legionella populations. However, some instances of regrowth after 3
to 6 months have been reported. In these cases, the authors have concluded
that a periodic schedule of short-term temperature elevation in the hot water
may be an effective control against legionellosis (USEPA, 1985; Muraca, 1986).
Disinfection by this method also requires periodic flushing of faucets and
shower heads with hot water. Although heat eradication is easily implemented
and relatively inexpensive, a disadvantage is the potential need for periodic
disinfection. The potential for scalding from the unusually hot water also
exists (USEPA, 1985; Muraca, et al. 1986).
Chlorination - Several studies have suggested that a free chlorine
residual of 4 mg/L will eradicate Legionella growth. There is, however, a
possibility for recontamination in areas of the system where the chlorine
residual drops below this level. A stringent monitoring program is therefore
required to ensure that the proper residual is maintained throughout the
system and under varying flow conditions. It may also be necessary to apply a
large initial chlorine dose to maintain the 4 mg/L residual. This may cause
problems of pipe corrosion and, depending on water quality, high levels of
trihalomethanes (THMs).
Ozone - Ozone is the most powerful oxidant used in the potable water
industry. One study indicated that an ozone dosage of 1 to 2 mg/L was suffi-
cient to provide a 5 log reduction of Legionella (Muraca, et al. 1986). Ozone
is generated by passing a high voltage current of electricity through a stream
of dry air or oxygen. The use of high voltage electricity requires proper
handling to avoid creating hazardous conditions. The ozone is applied by
bubbling the ozone containing gas through the water in a chamber called a
contactor.
One of the disadvantages of this system is its complexity. It requires a
dry air or oxygen source, a generator, and a contactor sized to provide 2 to 5
minutes of contact time and an ambient ozone monitor. All materials in
B-3
-------
contact with the ozone must be constructed of special ozone resistant mat-
erials to prevent leakage. Leak detection is also required because of the
toxic nature of ozone and possible explosive conditions if pure oxygen is used
for generation.
Another disadvantage of ozonation is the rapid decomposition of ozone
residuals. The half-life of ozone in drinking water is typically around 10
minutes. This makes it difficult, if not impossible, to maintain a residual
throughout the water system and may require the use of a supplementary
disinfectant such as chlorine or heat. For these reasons it is not thought
that ozonation is viable for institutional applications.
Ultraviolet Irradiation - Ultraviolet (UV) light, in the 254 nanometer
wavelength range can be used as a disinfectant. UV systems typically contain
low-pressure mercury vapor lamps to maximize output in the 254 ran range.
Water entering the unit passes through a clear cylinder while the lamp is on,
exposing bacteria to the UV light. Because UV light can not pass through
ordinary window glass, special glass or quartz sleeves are used to assure
adequate exposure.
The intensity of UV irradiation is measured in microwatt-seconds per
square centimeter (uW-s/cm2). Several studies have shown a 90 percent reduc-
tion of Legionella with a UV dosage of 1000 - 3000 uW-s/cm2, compared to 2000
to 5000 uW-s/cm2 for E. coli, Salmonella and Pseudomonas (USEPA, 1985). In
another study, a 5 log reduction of Legionella was achieved at 30,000
uW-s/cm2; and the reduction was more rapid than with both ozone and chlorine
disinfection (Muraca, et al. 1986).
The major advantage of UV disinfection is that it does not require the
addition of chemicals. This eliminates the storage and feed problems associ-
ated with the use of chlorine, chlorine dioxide and chloramines. In addition,
the only maintenance required is periodic cleaning of the quartz sleeve and
replacement of bulbs. UV monitors are available which measure the light
intensity reaching the water and provides a signal to the user when
maintenance is required. These monitors are strongly suggested for any
application of UV irradiation for disinfection. It should be noted, however,
that these monitors measure light intensity which may not be directly related
to disinfection efficiency. The UV lamps should therefore not be operated
past the manufacturers use rating even with a continuous UV monitor installed.
B-4
-------
Another disadvantage of UV disinfection, as with ozonation, is that a
residual is not provided. A supplementary disinfectant may therefore be
required to provide protection throughout the system. In addition, turbidity
may interfere with UV disinfection by blocking the passage of light to the
microorganisms.
Other Control Methods - In addition to chemical and heat disinfection,
there are system modifications which can be made to inhibit Legionella growth.
Many institutions have large hot water tanks heated by coils located midway in
the tank. This type of design may result in areas near the bottom of the tank
which are not hot enough to kill Legionella. Designing tanks for more even
distribution of heat may help limit bacterial colonization. In addition,
sediment build-up in the bottom of storage tanks provides a surface for
colonization. Periodic draining and cleaning may therefore help control
growth. Additionally, other studies have found that hot water systems with
stand-by hot water tanks used for meeting peak demands, still tested positive
for Legionella despite using elevated temperature (55 C) and chlorination
(2 ppm) (Fisher-Hoch, et al. 1984.) Stringent procedures for the cleaning,
disinfection and monitoring of these stagnant tanks should be set up and
followed on a regular basis.
In another study, it was reported that black rubber washers and gaskets
supported Legionella growth by providing habitats protected from heat and
chlorine. It was found, after replacement of the black rubber washers with
Proteus 80 compound washers, that it was not possible to detect Legionella
from any of the fixtures (Colbourne, et al. 1984).
Conclusions
Legionella bacteria have been identified as the cause of the disease
legionellosis, of which the most serious form is Legionnaires Disease.
Although conventional water treatment practices are sufficient to provide
disinfection of Legionella, regrowth in buildings with large hot water
heaters, and especially with recirculating hot water systems, is a significant
problem. This problem is of particular concern to health care institutions,
such as hospitals, where patients may be more susceptible to the disease.
B-5
-------
This guideline suggests a program of quarterly monitoring for Legionella.
If the monitoring program suggests a potential problem with these organisms, a
two stage disinfection program is suggested consisting of an initial period of
shock treatment followed by long term disinfection.
Four methods of disinfection for the control of Legionella were presented
in this appendix; heat, chlorination, ozonation, and ultraviolet irradiation.
All four of the methods have proven effective in killing Legionella.
Ultraviolet irradiation and heat eradication are the suggested methods of
disinfection due, primarily, to advantages in monitoring and maintenance.
However, site specific factors may make chlorination or ozonation more feas-
ible for certain applications. In addition, it is recommended that all
outlets, fixtures and shower heads be inspected and all black rubber washers
and gaskets replaced with materials which do not support the growth of
Legionella organisms.
One problem associated with the application of point-of-entry treatment
systems is the lack of an approved program for certifying performance claims.
However, the National Sanitation Foundation (NSF), Ann Arbor, MI an
unofficial, non-profit organization, does have a testing program to verify
disinfection efficiencies and materials of construction. Certification by the
NSF, or other equivalent organizations, is desirable when selecting a
treatment system.
References
Colbourne, J.; Smith, M. G.; Fisher-Hoch, S. P. and Harper, D. Source of
Legionella pneumophila Infection in a Hospital Hot Water System: Materials
Used in Water Fittings Capable of Supporting L. pneumophila Growth. In:
Thornsberry, C.; Balows, A.; Feeley, J. C. and Jakubowski, W. Legionella -
Proceedings of the 2nd International Symposium. American Society for
Microbiology, pp. 305-307, 1984.
Fisher-Hoch, S. P.; Smith, M.G.; Harper, D. and Colbourne, J. Source of
Legionella pneumonia in a Hospital Hot Water System, pp. 302-304 in
Thornsberry, C.; Balows, A.; Feeley, J.C. and Jakubowski, W. Legionella
Proceedings of the 2nd International Symposium, American Society for
Microbiology, pp. 302-304, 1984.
B-6
-------
Muraca, P.; Stout, J. E. and Yu, V. L. Comparative Assessment of Chlorine,
Heat, Ozone, and UV Light for Killing Legionella pneumophila Within a Model
Plumbing System. Appl. Environ. Microbiol. 53(2):447-453, 1986.
U.S. Environmental Protection Agency, Office of Drinking Water. Control of
Legionella in Plumbing Systems, Health Advisory (1985).
B-7
-------
APPENDIX C
TRACER TEST
PROCEDURES
-------
APPENDIX C
TRACER TEST PROCEDURES
Introduction
The detention time (T) used for determining the CT in a pipeline can be
calculated theoretically assuming plug flow through the pipe at peak hourly
flow. However, in mixing basins and storage reservoirs, the contact time must
be determined by tracer studies. This appendix presents procedures for
performing the required tracer studies in order to determine the contact time.
Separate tests are recommended for mixing basins and storage reservoirs
because of the magnitude of difference in detention times between the two, and
because of the practical difficulties which may arise from simultaneously
operating both units under worst-case conditions. Except for differences in
operating conditions, the procedures for performing tracer tests in both units
are similar.
Test Frequency
Because detention time (T) is proportional to flow rate (Q) it is neces-
sary to develop a relationship between these parameters which can be used to
determine T under peak hourly flow conditions. It is therefore recommended
that tracer tests be performed at several (at least 4) flow rates. The flow
rates tested should be separated by approximately equal intervals with one
point near average flow, two greater than average, and one at a less than
average flow. The flows should also be selected so that it is not necessary
to extrapolate to more than 110 percent of the highest flow tested.
Detention time may also be influenced by differences in water temperature
within the treatment plant. For plants with potential for thermal stratifi-
cation, additional tracer studies are suggested under the various seasonal
conditions which are likely to occur.
Similar procedures should be used for developing a Q vs. T relationship
in storage tanks, with the additional constraint that the water level in the
tank should be maintained at a near constant level during the test period.
The detention time determined by the tracer tests will only be valid for
C-l
-------
calculating CT when the tank is operating at water levels greater than or
equal to the level at which the testing was performed.
The contact times that have been determined by the tracer studies under
the various seasonal conditions should remain valid for as long as no physical
changes are made to the mixing basin(s) or storage reservoir(s).
Tracer Selection
The first step in any tracer test is selection of a chemical to use as
the tracer. The most common tracers used in drinking water plants are
chloride, rhodamine Wt, and fluoride. All of these chemicals are readily
available, conservative (i.e., they are not consumed or removed during treat-
ment) , approved for potable use, and easily monitored. Fluoride is probably
the most frequently used tracer for potable water applications.
Tracer Addition
There are two common methods of tracer addition employed in water treat-
ment evaluations. They are:
- The slug dose method
- The step method
With the slug dose method, a large instantaneous dose of tracer is added
to the water and timed as it passes through the mixing basin or storage
reservoir. A disadvantage of this technique is that very concentrated
solutions are needed for the dose. Intensive mixing may therefore be required
to minimize potential density-current effects. Alternatively, with the step
method, which is discussed in this appendix, tracer addition is continued
until the concentration at the desired end point reaches a steady state level,
typically two to three times the theoretical detention time (Hudson, 1981).
The tracer should be added at the same point in the treatment train as
the disinfectant to be used in the CT calculations. If multiple disinfection
points are used, the tracer should be added at the earliest (farthest up-flow)
application point. For testing storage reservoirs, the tracer should be
applied as close to the tank influent as possible. In all cases, the tracer
should be dosed in sufficient concentration to easily monitor a residual
throughout the test.
C-2
-------
Data Collection
Beginning at time zero (when tracer addition begins) tracer residuals
should be monitored at all points where the disinfectant residual will be
measured for CT calculations. For plants with multiple points of application
for the disinfectant(s), the residual should be monitored just prior to each
application point. The sampling frequency at each point should be sufficient
to adequately define a plot of residual versus time. Sampling should continue
until the residual concentration levels off at a constant value.
Data Reduction
The results of each tracer test can be summarized in a table of time and
residual concentration. The residual concentration (C) should be normalized
by dividing by the applied tracer concentration (C ) and plotted versus time,
as illustrated on Figure C-l. The detention time to be used in calculating CT
is the time corresponding to C/C = 0.10. Ninety percent of the water passing
through the system will have a detention time greater than or equal to this
value (Levenspiel, 1972).
Detention times should be determined by the above procedure for each of
the flow rates tested. The detention times should then be plotted versus flow
rate as shown on Figure C-2. This plot of Q vs. T is what should be used to
determine T for daily compliance with the CT requirements.
References
Hudson, H. E., Jr. Water Clarification Processes; Practical Design and
Evaluation, Van Nostrand Reinhold Company, New York, 1981.
Levenspiel, O. Chemical Reaction Engineering, John Wiley & Sons, New York,
1972.
C-3
-------
1.0
0.8
C 0.6
Co
0.4
0.2
T - 90 MIN
30 60 90 120 150 180 210 240
TIME (MIN)
FIGURE C-1 TRACER TEST RESULTS
-------
(MIN)
200,-
150
100
50
AVERAGE
MAXIMUM
EXTRAPOLATION
345
Q (MGD)
6
8
FIGURE C-2 DETENTION TIME VS. FLOW
-------
APPENDIX D
A SURVEY OF THE CURRENT STATUS OF RESIDUAL DISINFECTANT
MEASUREMENT METHODS FOR ALL CHLORINE SPECIES AND OZONE
Copyright ® 1987 by American
Water Works Association
Research Foundation and
American Water Works
Association
Reprinted by permission of
AWWA Research Foundation
-------
A SURVEY OF THE CURRENT STATUS OF RESIDUAL DISINFECTANT
MEASUREMENT METHODS FOR ALL CHLORINE SPECIES AND OZONE
by
Gilbert Gordon
Department of Chemistry
Miami University
Oxford, OH 45056
William J. Cooper
Drinking Water Research Center
Florida International University
Miami , Florida 33199
Rip G. Rice
Rice, Incorporated
Ashton, Maryland 20861
Gilbert E. Pacey
Department of Chemistry
Miami University
Oxford, Ohio 45056
Prepared for:
AWWA Research Foundation
6665 W. Quincy Avenue
Denver, CO 80235
November 1987
Published by the American Water Works Association
-------
DISCLAIMER
This study was funded by the American Water Works Association
Research Foundation (AWWARF). AWWARF assumes no responsibil-
ity for the content of the research study reported in this
publication, or for the opinions or statements of fact
expressed in the report. The mention of tradenames for
commercial products does not represent or imply the approval
or endorsement of AWWARF. This report is presented solely
for informational purposes.
Although the research described in this document has been
funded in part by the United States Environmental Protection
Agency through a Cooperative Agreement, CR-811335-01, to
AWWARF, it has not been subjected to Agency review and
therefore does not necessarily reflect the views of the
Agency and no official endorsement should be inferred.
Copyright » 1987
by
American Water Works Association Research Foundation
Printed in U.S.
-------
FOREWORD
This report is part of the on-going research program of the AWWA Research
Foundation. The research described in the following pages was funded by
the Foundation in behalf of its members and subscribers in particular and
the water supply industry in general. Selected for funding by AWWARF's
Board of Trustees, the project was identified as a practical, priority need
of the industry. It is hoped that this publication will receive wide and
serious attention and that its findings, conclusions, and recommendations
will be applied in communities throughout the United States and Canada.
The Research Foundation was created by the water supply industry as its
center for cooperative research and development. The Foundation itself
does not conduct research; it functions as a planning and management
agency, awarding contracts to other institutions, such as water utilities,
universities, engineering firms, and other organizations. The scientific
and technical expertise of the staff is further enhanced by industry
volunteers who serve on Project Advisory Committees and on other standing
committees and councils. -An extensive planning process involves many
hundreds of water professionals in the important task of keeping the
Foundation's program responsive to the practical, operational needs of
local utilities and to the general research and development needs of a
progressive industry.
All .aspects of water supply are served by AWWARF's research agenda:
resources, treatment and operations, distribution and storage, water
quality and analysis, economics and management. The ultimate purpose of
this effort is to assist local water suppliers to provide the highest
possible quality of water, economically and reliably. The Foundation's
Trustees are pleased to offer this publication as contribution toward that
end.
This project reviewed all disinfectant residual measurement methods for
free chlorine, chloramines, ozone and chlorine dioxide with special
attention to interferences that could be experienced by the water utility
industry. Recommendations, practical guidance, and cautions on the
selection of appropriate residual measurement techniques are summarized
(Please see Preface for information on full report).
Je/ome 3. Gi Ibert (""Jajpes F. Manwanng, P.E.
Caiman, Board of Trustees ^-fxecutive Director
AWWA Research Foundation AWWA Research Foundation
-------
PREFACE
This document summarizes the AWWA Research Foundation's 816 page
publication "Disinfectant Residual Measurement Methods." That
publication (Publication Number 90528) can be ordered from the AWWA
Customer Services Department, 6666 W. Quincy Avenue, Denver, CO 80235;
telephone, (303) 794-7711.
The purpose of this summary document is to provide the water utility
laboratory analyst with guidance in selecting disinfectant residual
measurement methods. Either this document or the full report is
recommended as a companion to Standard Methods for the Examination of
Water and Wastewater.
-------
ACKNOWLEDGEMENTS
The authors wish to express their appreciation to the American Water Works
Association - Research Foundation for the opportunity to carry out this
detailed review of the literature.
Furthermore, the authors would like to pay tribute to the really important
people — all those who did the original work and made this secondary
source of information possible.
Finally, the authors wish to express their appreciation to the members of
the Project Advisory Committee:
1) Mark Carter, Ph.D.
Rocky Mountain Analytical Laboratories
2) J. Donald Johnson, Ph.D.
University of North Carolina
3) Leown A. Moore
Drinking Water Research Division—EPA
4) R. Rhodes Trussell, Ph.D.
James M. Montgomery Consulting Engineers, Inc.
G.G.
W.J.C.
R.G.R
G.E.P-
-------
EXECUTIVE SUMMARY
BACKGROUND
The objective of this Report is to review and summarize all disinfectant re-
sidual measurement techniques currently available for free chlorine (along with
the various chloramines), combined chlorine, chlorite ion, chlorine dioxide,
chlorate ion, and ozone.
Presently, both chlorine dioxide and ozone are gaining considerable favor as
alternatives to chlorine disinfection (1). The analytical chemistry for these
disinfectants when compared with chlorine is even more complex and less readily
understood as evidenced by various surveys (2-5) and detailed research carried
out in various laboratories (6-10).
Chlorine dioxide is manufactured at the site of its use by reactions involv-
ing sodium chlorite, chlorate ion, chlorine gas and/or hypochlorite ion and sul-
furic acid or hydrochloric acid (11-12). Consequently, chlorate ion, chlorite
ion, hypochlorite ion and/or hypochlorous acid frequently will be found occur-
ring as by-products or unreacted starting materials. These materials are strong
oxidizing agents which are very reactive and behave in many ways similar to
chlorine dioxide itself.
There are more than 2,000 water treatment plants today using ozone, and less
than half of them are applying ozone solely for disinfection. The large major-
ity of water treatment plants use ozone as a chemical oxidant. Many of the
plants applying ozone for disinfection also are using ozone, in the same plant,
for chemical oxidation. Analyses for residual ozone in water are applicable
only in the treatment plant, either in the ozone contactor(s) or at their
outlets. Residual ozone is never present in the distribution system; however,
its by-products may be.
There have been numerous attempts to evaluate the relative advantages and
disadvantages associated with the measurement of free and combined chlorine.
Different criteria are frequently used for the evaluation of the analytical
•easurements and often suggestions for the improvement of test procedures have
gone largely ignored. No comprehensive and objective review of the literature
appears to be available. This Report is aimed at providing such a review along
with guidance and recommendations as to what criteria water utilities should use
in selecting residual monitoring techniques based on circumstances by category.
OBJECTIVES
1. To review and summarize all residual measurement techniques
currently available for free chlorine--taking into account
the roles of chloramines.
2. To review and summarize all residual measurement techniques
currently available for combined chlorine.
-------
3. To briefly review the present understanding of the chlorine-
ammonia chemistry and in particular, in relationship to the
measurement of chlorine and combined chlorine.
4. To review and summarize all residual measurement techniques
currently available for chlorine dioxide, chlorite ion and
chlorate ion.
5. To review and summarize the analytical procedures currently
used by operating water utilities to control ozone treatment
processes, considering disinfection as well as the many oxid-
ative applications of ozone in water treatment applications.
6. To discuss common interferences associated with the measurement
of each'of the disinfectants/oxidants described above (free
chlorine, combined chlorine, chlorite ion, chlorine dioxide,
chlorate ion, and ozone).
7. To provide guidance and recommendation for water utilities in
selecting residual monitoring techniques for each of the above
disinfectants/oxidants.
8. To recommend future research for development of monitoring and
analytical methods to improve accuracy, and reduce time and cost
requirements for the measurement of the above disinfectants.
In the full report, we present as complete as possible an examination of the
world-wide body of literature on analytical methods used by the water utility
industry in order to elaborate on the various problems, advantages, disadvan-
tages and known interferences for each of the currently used analytical methods.
Foremost in our objectives has been a better understanding of the reliabil-
ity of various measurements which have been carried out. Since there are inher-
ent limitations in all measurements, it becomes apparent that there are specific
needs for some indication of the reliability of the result, i.e., what is the
precision and accuracy of the reported value, and are these acceptable?
The volatility of most of the disinfectants makes sampling and sample
handling a major contributor to imprecision and inaccuracies. "Standard
additions" is a questionable technique; it should be avoided if possible, since
the pipetting and dilution process causes potential loss of disinfectant.
The relative usefulness of each method, along with descriptions of known
interferences such as turbidity, organic matter, ionic materials, solids, color,
buffering capacity, as well as the nature of the sample and the time between
collection of the sample and the actual analysis, are described in this report.
It must be emphasized, however, that almost invariably each of the methods
described is based on the total oxidizing capacity of the solution being
analyzed and is readily subject to interferences from the presence of other
potential oxidizing agents and/or intermediates from concomitant chemical
reactions. Under ideal conditions some of the methods are accurate to better
-------
than ±1%--especially in the absence of common interferences--whereas other
methods are almost semi-quantitative in nature with many common species
interfering with both the precision and accuracy of the measurements.
We have also included chlorate ion as a residual species in that only
recently have reliable analytical methods begun to appear in the literature
(5,6,10). -We also report on the chemistry of the chlorine-ammonia system and
the associated breakpoint reactions, because one of the most common inteferences
in the measurement of free chlorine is monochloramine.
The most important development for this report has been the decision to in-
clude a preliminary section describing an "idealized" analytical method. The
need for this section became apparent as our writing progressed describing each
of the analytical methods for chlorine. Specific items included in this "ideal-
ized" method are accuracy, precision, reproduciblity, lack of interferences,
ease of use of the method, lack of false positive values, and so forth.
The benefit of the "idealized" analytical method is to allow individual com-
parisons and to allow the choice between various methods based on individual
method shortcomings. For example, a particular method might have as its only
difficulty interference by manganese and iron. In many circumstances, this type
of interference might be a major problem. However, should the water supply
under consideration not have any manganese or iron, it is quite likely that the
method might be very usable--and as a matter of fact well might be the best
method of choice.
In other cases, speed of analysis rather than potential interferences (or
choice of some other important characteristic) might be the guiding factor in
choosing an analytical method. In this way rational choices can be made based
on potential and/or real difficulties and/or interferences and as compared to an
"idealized" method -- rather than a possibly controversial existing method.
Table I has been constructed as a quick reference guide to the available
methods for the determination of water disinfection chemicals and byproducts.
Included are pertinent analytical characteristics such as detection limits,
working range, interferences, accuracy and precision estimates. The current
status of the method, as gleaned from this report, is given. The necessary
operator skill level is given to aid the laboratory manager in assessing the
manpower requirements for a particular method. Additional information
concerning the reasons for the current status is contained in the Recommendation
Section of the Executive Summary and the complete report.
As each of the methods is described in detail in the full report, specific
conclusions are drawn--along with appropriate recommendations--by comparing the
method against the "idealized" analytical method for that species.
One additional benefit of this direct comparison is the possibility of add-
ing or subtracting a method to the list of Standard Methods for the Examination
of Water and Wastewater (13), based on a rational set of criteria. It should
also be possible in the future to decide on the viability of various methods
based on their meeting specific criteria rather than based only on comparisons
between analytical laboratories (and personalized subjective reactions to the
various methods themselves
-------
TABLE I. CHARACTERISTICS AND COMPARISONS OF ANALYTICAL METHODS®
Species' DETECTION WORKING EXPECTED EXPECTED
TYPE OF TEST MEASURED LIMIT RANGE ACCURACY PRECISION SKILL'
(METHOD)* DIRECTLY (mg/L) (mg/L) (± %) (± %) LEVEL
FREE CHLORINE
"Ideal" C12 + HOC1/OC1- 0.001 0.001-10 0.5 0.1 1
UV/VISIBLE C12 + HOC1/OC1- - 1 1 - 100 NR NR 3
Continuous C12 + HOCl/OCl' 1.5 1.5-300 NR NR 3
AMPEROMETRIC TITRATION:
Forward C12 + HOCl/OCl" 0.00181 > 10 NF NF 2
0.02 - 0.032 > 10 NF 3-50 2
Back C12 + HOC1/OC1- 0.002 > 10 3-50 NF 2
Continuous C12 + HOCl/OCl" 0.005 > 10 NR 1.0 2/3
IODOMETRIC TITRATION:
Standard (Total Chlorine) 0.073 0.1-10 NR NR 2
0.354 0.5-10 NR NR 2
DPD
FAS Tit'n C12 + HOCl/OGl' 0.004s 0.01-10 NF 2-7 1
0.0114 0.01 - 10 NF 2-7 1
Color'mtrc C12 + HOCl/OCl" 0.016 0.01 - 10 1 - 15 1-14 1
Steadifac C12 + HOCl/OCl' 0.018 0.01-10 NF NR 1/2
LCV
Black and
Whittle C12 + HOC1/OC1- 0.01 0.25-3 NF NR 1
Whittle &
Lapteff C12 + HOC1/OC1- 0.01 0.25-10 NR 0-10 2
-------
TABLE I. CHARACTERISTICS (confd)
STABILITY FIELD CURRENT
REAGENT PRODUCTS INTERFERENCES pH RANGE TEST AUTOMATED STATUS
5 YRS
NA
NA
1-2 yrs
1-2 yrs
1-2 yrs
1-2 yrs
1 yr
1 yr
powder
stable6
powder
stable6
powder
stable6
powder
stable6
months
months
> 1 DAY
NA
NA
NA
NA
NA
NA
10 min
or less
10 min
or less
30 min
30 min
30 min
30 min
NR
NR
NONE
C1NH2 - C13N
backgnd Abs
C1NH2 - C1SN
C1NH2 - C1SN
C1NH2 - C1SN
C1NH2 - C1SN
C1NH2 - C1SN
All oxidizing
species
All oxidizing
species
C1NH2 - CljN
oxid species
C1NH2 - C13N
oxid species
C1NH2 - C13N
oxid species
C1NH2 - C13N
oxid species
C1NH2 - C13N
oxid species
Oxidizing
species
Independent
pH Dependent
pH Dependent
pH Dependent
pH Dependent
pH Dependent
pH Dependent
pH Dependent
pH Dependent
Requires
buffer
Requires
buffer
Requires
buffer
Requires
buffer
Requires
buffer
Buffering
YES
NO
NO
YES
YES
YES
YES
NO
NO
NO
NO
YES
YES
YES
YES
YES
NO
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
RECOMMENDED
RECOMMENDED
(LAB TEST)
CONT'D STUDY
RECOMMENDED
RECOMMENDED
RECOMMENDED
RECOMMENDED
RECOMMENDED
(LAB TEST)
RECOMMENDED
(LAB TEST)
RECOMMENDED
(LAB TEST)
RECOMMENDED
(LAB TEST)
RECOMMENDED
(FIELD TEST)
RECOMMENDED
(FIELD TEST)
ABANDON
RECOMMENDED
(LAB TEST)
-------
TABLE I. CHARACTERISTICS AND COMPARISONS OF ANALYTICAL METHODS® (cont'd)
TYPE OF TEST
(METHOD)^
Species* DETECTION WORKING EXPECTED EXPECTED
MEASURED LIMIT RANGE ACCURACY PRECISION SKILL0
DIRECTLY (mg/L) (mg/L) (± %) (± %) LEVEL
FACTS
Color'mtrc C12 + HOCl/OCl' 0.1
METHYL ORANGE C12 + HOC1/OC1" NR
0-TOLIDINE C12 + HOC1/OC1- NR
3,3'-DIMETHYLNAPHTHIDINE ^
C12 + HOC1/OC1- 0.05
0-DIANISIDINE C12 + HOCl/OCl" 0.1
CHEMILUMINESCENCE
Hydrogen
Peroxide C12 + HOC1/OC1" NR
0.25 - 10 5 - 20 1-11
Spect'photo C12 + HOCl/OCl" 0.012 0.05-10 NF
Luminol OCL"
Lophine OCL"
ELECTRODE METHODS
Membrane HOCL
0.0007
0.14
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
0.2 - 20 NR
NR
NR
NR
2 - 6
NR
NR
NR
NR
0.004 0.04-1 NR 1.6
2/3
2/3
Bare-wire C12 + HOC1/OC1" 0.1 0.1-3 NR 1-25
Potent'mtrc C12 + HOC1/OC1' 0.005 0.01-1 1-6 7-10 2
Agl
Volt'mtrc C12 + HOCl/OCr 0.01 0.1-10 NR
NR
-------
TABLE I. CHARACTERISTICS (confd)
STABILITY
REAGENT PRODUCTS INTERFERENCES pH RANGE
FIELD CURRENT
TEST AUTOMATED STATUS
2 years7 30 min Oxidizing
at high C13 species
2 years7 30 min Oxidizing
at high C12 species
NF
NF
NF
NF
Oxidizing
species
Oxidizing
species
Buffering
critical
Buffering
critical
Buffering
required
Buffering
required
YES NO RECOMMENDED
YES NO RECOMMENDED
YES NO ABANDON
YES NO ABANDON
NF 15-20 min Oxidizing
species
NF 55 min
Oxidizing
species
NR
NR
NO
NO
NO
NO
ABANDON
ABANDON
NR
sec
None
Independent NO POSSIBLE ABANDON
NR
NR
sec
sec
Oxidizing
species
None
pH Dependent NO POSSIBLE CONT'D STUDY
pH Dependent NO YES CONT'D STUDY
NA
NA
NA
NA Oxidizing
Gas species
NA Oxidizing
species, Cl"
3 months NA
Oxidizing
species Cl"
NA Oxidizing
species, Cl"
Dependent POSSIBLE POSSIBLE CONT'D STUDY
on pH
NR POSSIBLE POSSIBLE CONT'D STUDY
pH Dependent YES YES RECOMMENDED
Buffer POSSIBLE POSSIBLE CONT'D STUDY
required
-------
TABLE I. CHARACTERISTICS AND COMPARISONS OF ANALYTICAL METHODS® (cont'd)
Species* DETECTION WORKING EXPECTED EXPECTED
TYPE OF TEST MEASURED LIMIT RANGE ACCURACY PRECISION SKILL'
(METHOD)' DIRECTLY (mg/L) (mg/L) (± %) (± %) LEVEL
TOTAL CHLORINE8
"Ideal" C12 + HOC1/OC1- 0.001 0.001-10 0.5 0.1 1
NH2C1 NHC12 NC13
AMPEROMETRIC TITRATION:
Forward C12 + HOCl/OCl" 0.00181 > 10 NF NF 2
NHjCl NHC12 NC1S
C12 + HOC1/OC1- 0.02 -0.032 > 10 NF 3 - 50 2
NH2C1 NHC12 NC13
Back C12 + HOC1/OC1- 0.002 > 10 3 - 50 NF 2
NH2C1 NHC12 NC13
Continuous C12 + HOC1/OC1' 0.005 > 10 NR 1.0 2/3
NHjCl NHC12 NCla
IODOMETRIC TITRATION:
Standard C12 + HOCl/OCl" 0.073 0.1-10 NR NR 2
NH2C1 NHC12 NC13
C12 + HOC1/OC1- 0.35* 0.5-100 NR NR 2
NH2C1 NHC12 NC13
DPD
FAS Tit'n C12 + HOC1/OC1- 0.004s 0.01-10 NF 2-7 1
NH2C1 NHC12 NCI,
C12 + HOC1/OC1- 0.11« 0.01-10 NF 2-7 1
NH2C1 NHC12 NC13
Color'mtrc C12 + HOC1/OC1- 0.0016 0.01-10 1 - 15 1 - 14 1
NH2C1 NHC12 NC13
LCV
Black &
Whittle C12 + HOC1/OC1- 0.005 0.25-3 NF 4-10 1
NH2C1 NHC12 NC13
-------
TABLE I. CHARACTERISTICS (cont'd)
STABILITY FIELD CURRENT
REAGENT PRODUCTS INTERFERENCES pH RANGE TEST AUTOMATED STATUS
5 YRS > 1 DAY
1 - 2 yrs NA
1-2 yrs NA
1 - 2 yrs NA
1 - 2 yrs NA
1 yr 10 min
1 yr 10 min
powder 30 min
stable8
powder 30 min
stable6
powder 30 min
stable6
months NR
NONE
Oxidizing
Species
Oxidizing
Species
Oxidizing
Species
Oxidizing
Species
All oxidizing
species
All oxidizing
species
Oxidizing
Species
Oxidizing
Species
Oxidizing
Species
Oxidizing
Species
Independent YES
of pH
pH Dependent YES
pH Dependent YES
pH Dependent YES
pH Dependent YES
pH Dependent NO
pH Dependent NO
Requires NO
buffer
Requires YES
buffer
Requires YES
buffer
Requires YES
buffer
YES RECOMMENDED
YES RECOMMENDED
YES RECOMMENDED
YES RECOMMENDED
YES RECOMMENDED
NO RECOMMENDED
(LAB TEST)
NO RECOMMENDED
(LAB TEST)
NO RECOMMENDED
(LAB TEST)
NO RECOMMENDED
(FIELD TEST)
NO RECOMMENDED
(FIELD TEST)
NO ABANDON
-------
TABLE I. CHARACTERISTICS AND COMPARISONS OF ANALYTICAL METHODS® (cont'd)
Speclest DETECTION WORKING EXPECTED EXPECTED
TYPE OF TEST MEASURED LIMIT RANGE ACCURACY PRECISION SKILL"
(METHOD)* DIRECTLY (mg/L) (mg/L) (± %) (± %) LEVEL
Whittle &
Lapteff C12 + HOC1/OC1- 0.01 0.25-10 NF 4-10 2
NH2C1 NHC12 NC1S
FACTS
Color'mtrc C12 + HOCl/OCl" 0.1 0.25-10 5 - 20 1 - 11 1
NH2C1 NHC12 NC1S
Spect'photo C12 + HOC1/OC1- 0.012 0.05-10 NF NR 1
NH2C1 NHC12 NC1S
ELECTRODE METHODS
Pot'metrie C12 + HOC1/OC1- 0.005 0.01-1 1 - 6 7 - 10 2
NHjCl NHC12 NC13
MONOCHLORAMINE9
"Ideal- NH2C1 0.001 0.001 - 10 0.5 0.1 1
UV/VISIBLE NH2C1 - 1 1 . 100 NR NR 3
AMPEROMETRIC TITRATION:
Forward
Back
DPD
FAS Tit'n
Color'mtrc
NH2C1
NHaCl
NH2C1
NH2C1
NR
NR
NR
NR
> 10
> 10
0.01 - 10
0.01 - 10
NF 0-10
NF NF
NF 2-7
NF 5-75
2
2
1
1
10
-------
TABLE I. CHARACTERISTICS (confd)
STABILITY FIELD CURRENT
REAGENT PRODUCTS INTERFERENCES pH RANGE TEST AUTOMATED STATUS
months NR
Oxidizing
Species
Buffering YES
NO RECOMMENDEDD
(LAB TEST)
2 YRS
2 YRS
30 min
at high
C12
30 min
at high
Cl,
Oxidizing
Species
Oxidizing
species
Buffering
critical
Buffering
critical
YES NO RECOMMENDED
YES NO RECOMMENDED
3 months NA
Oxidizing pH Dependent YES
Species, Cl"
YES RECOMMENDED
5 YRS > 1 DAY
NONE
Independent YES
YES
RECOMMENDED
NA
NA C12NH - C13N pH Dependent NO
backgnd Abs
NO RECOMMENDED
(LAB TEST)
1-2 yrs NA C12NH - C1SN pH Dependent YES YES
1-2 yrs NA C12NH - C1SN pH Dependent YES YES
RECOMMENDED
RECOMMENDED
powder
stable8
powder
stable8
30 min
30 min
C1NH2 - C1SN
oxid species
C1NH2 - C13N
oxid species
Requires NO NO RECOMMENDED
buffer (LAB TEST)
Requires YES NO RECOMMENDED
buffer (FIELD TEST)
11
-------
TABLE I. CHARACTERISTICS AND COMPARISONS OF ANALYTICAL METHODS® (cont'd)
TYPE OF TEST
(METHOD)*
Speciest DETECTION WORKING EXPECTED EXPECTED
MEASURED LIMIT RANGE ACCURACY PRECISION SKILL0
DIRECTLY (mg/L) (mg/L) (± %) (± %) LEVEL
LCV
Whittle &
Lapteff
NH2C1
NR
0.25-10 NF 0-43 2
ELECTRODE METHODS
Silver iodide
Voltammetric
NH2C1
NR
0.1 - 10 NR NR
DICHLORAMINE9
"Ideal"
NHC1,
0.001 0.001 - 10 0.5 0.1
UV/VISIBLE
NHC1,
- 1
1 - 100
NR NR
AMPEROMETRIC TITRATION:
Forward NHC12
Back NHC1,
NR > 10 NF 0 2
NR > 10 3 - 50 NF 2
DPD
FAS Tit'n
Color'mtrc
NHC1,
NHC1,
NR 0.01 - 10 NF NF 1
NR 0.01 - 10 NF 0 - 100 1
LCV
Whittle &
Lapteff
NHC1,
NR
0.25 - 10
NF 10 - 150 2
12
-------
TABLE I. CHARACTERISTICS (cont'd)
STABILITY FIELD CURRENT
REAGENT PRODUCTS INTERFERENCES pH RANGE TEST AUTOMATED STATUS
months NR Oxidizing Requires YES NO RECOMMENDED
species buffer (LAB TEST)
NA
NA Oxidizing Requires POSSIBLE POSSIBLE CONT'D STUDY
species buffer
5 YRS > 1 DAY
NA
NA
NONE
C1NH2 & C1SN
backgnd Abs
Independent
of pH
YES
pH Dependent NO
YES RECOMMENDED
NO RECOMMENDED
(LAB TEST)
1-2 yrs NA C1NH2 & C1SN pH Dependent YES
1-2 yrs NA CINHj. & C13N pH Dependent YES
YES RECOMMENDED
YES RECOMMENDED
powder 30 min
stable9
powder 30 min
stable6
C1NH2 & C13N Requires NO NO
oxid species buffer
CINHj & C1SN Requires YES NO
oxid species buffer
RECOMMENDED
(LAB TEST)
RECOMMENDED
(FIELD TEST)
months
NR
Oxidizing Requires YES NO RECOMMENDEDD
species buffer (LAB TEST)
13
-------
TABLE I. CHARACTERISTICS AND COMPARISONS OF ANALYTICAL METHODS® (confd)
TYPE OF TEST
(METHOD)'
TRXCHLORAMINE9
•Ideal"
UV/VISIBLE
Speciest DETECTION WORKING EXPECTED EXPECTED
MEASURED LIMIT RANGE ACCURACY PRECISION SKILL'
DIRECTLY (mg/L) (mg/L) (± %) (± %) LEVEL
NCI, 0.001 0.001 - 10 0.5 0.1
NCI,
AMPEROMETRIC TITRATION:
Forward NC1S
NR
NR
NR
> 10
NR NR
NF 5 - 100
DPD
FAS Tit'n
Color'mtrc
LCV
Whittle &
Lapteff
NC13
NCI,
NCI,
CHLORINE DIOXIDE
•Ideal- C103
IODOMETRIC C102
AMPEROMETRIC CIO,
DPD
UV
Manual C10S
CIO,
NR 0.01 - 10 NR NR 1
NR 0.01 - 10 NR NR 1
NR
0.25 - 10 NR NR
0.001 0.001 - 10 0.5 0.1 1
0.002 0.002 - 95 1 - 2 1-2 2
0.012 0.02 - ?? 1 - 15 1 - 15 3
C102l°-11 0.008 0.008 - 20 10 7-15 2
0.05
0.25
0.05 - 500
0.25 - 142
14
-------
TABLE I. CHARACTERISTICS (confd)
STABILITY FIELD CURRENT
REAGENT PRODUCTS INTERFERENCES pH RANGE TEST AUTOMATED STATUS
5 YRS > 1 DAY
NONE
Independent YES
YES RECOMMENDED
NA
NA C1NH2 - C12NH pH Dependent NO
backgnd Abs
HOC1/OCL-
NO RECOMMENDED
(LAB TEST)
1-2 yrs NA
C1NH2 - C12NH pH Dependent NO
YES RECOMMENDED
(LAB TEST)
powder 30 min
stable6
powder 30 min
stable6
C1NH2 - C12NH Requires NO NO
oxid species buffer
C1NH2 - C12NH Requires YES NO
oxid species buffer
RECOMMENDED
(LAB TEST)
RECOMMENDED
(LAB TEST)
months
NR
Oxidizing Requires YES NO RECOMMENDED
species buffer (LAB TEST)
5 YRS
1 YR
good
> 1 DAY
NONE
Subject to Oxidizing
oxidation species
Subject to Metal ions &
oxidation nitrite ion
solid < 30 min
stable6
Oxidizing
species
Independent YES
2-5 NO
7 NO
7 NO
YES RECOMMENDED
NO NOT RECOMMENDED
NO CURRENTLY USED
NO NOT RECOMMENDED
none
none
none
none
Other UV
absorbers
none
Independent NO YES
Independent NO YES
RECOMMENDED
(LAB TEST)
RECOMMENDED
(LAB TEST)
15
-------
TABLE I. CHARACTERISTICS AND COMPARISONS OF ANALYTICAL METHODS® (cont'd)
TYPE OF TEST
(METHOD)*
ACVK12
o-TOLIDINE
INDIGO BLUE
CHEMILUMINESCENCE
Luminol
GDFIA13
ELECTROCHEM.
Ft Microelec.
Vit. Carbon
Voltam. Mem.
Rotating Volt.
Membrane C102 0.30 0.30 - 3 NR 6.4 2/3
CHLORITE ION
"Ideal" C102- 0.001 0.001 - 10 0.5 0.1 1
AMPEROMETRIC
lodometrtc C102" 0.05 0.05-95 5 5 2
IODOMETRIC
Sequential C102- 0.011 > 1 1 1 3
Modified C102- 0.3 0.5 - 20 0.5 1-3 3
DPD C102- 0.01 0.01-10 5 5 2
16
Speciest
MEASURED
DIRECTLY
C102
C102
C102
C102
i
C102
C102
C102 + C102-
C102
C102
DETECTION WORKING EXPECTED EXPECTED
LIMIT RANGE ACCURACY PRECISION SKI
(mg/L) (mg/L) (± %) (± %) LEV
0.04
0.003
0.1
0.01
0.3
0.005
1.3
32
0.25
0-25 NR NR
0.003 - 1 10 5
NR NR NR
NR NR 1.5
0.3-1 NR 8
0.005 - 74 2 1
NR 7 NR
NR NR NR
NR NR NR
1
1
1
1
1
1
2/3
3
2
-------
TABLE I. CHARACTERISTICS (confd)
STABILITY
REAGENT
NR
6 months
NR
good
1 DAY
1 DAY
none
none
none
PRODUCTS
NR
NR
NR
good
< 1 sec
< 1 sec
none
none
none
FIELD
INTERFERENCES pH RANGE TEST
minimal
unknown
Oxidizing
species
0, C17
NR
C12
cio2-
cio2-
HOC1
8.1-8.4 NO
7 YES
NR NO
> 4 NO
NR NO
> 12 NO
5-5.5 NO
3.5-7 NO
7.8 NO
CURRENT
AUTOMATED STATUS
NO
NO
NO
NO
NO
YES
NO
NO
NO
CONT'D STUDY
NOT RECOMMENDED
NOT RECOMMENDED
NOT RECOMMENDED
NOT RECOMMENDED
RECOMMENDED
CONT'D STUDY
CONT'D STUDY
CONT'D STUDY
CONT'D STUDY
none
none
HOC1
5 - 5.5
NO
NO
CONT'D STUDY
5 YRS > 1 DAY
NONE
Independent YES
YES RECOMMENDED
1 YR Subject to Oxidizing
oxidation species
2 - 5
NO
NO NOT RECOMMENDED
good Subject to Metal ions &
oxidation nitite ion
good Subject to Metal ions &
oxidation nitite ion
Solid < 30 min
stable6
Oxidizing
species
NO NO RECOMMENDED AT
HIGH CONC.
NO
NO
NO
CONT'D STUDY
NO NOT RECOMMENDED
17
-------
TABLE I. CHARACTERISTICS AND COMPARISONS OF ANALYTICAL METHODS® (cont'd)
TYPE OF TEST
(METHOD)*
CHLORATE ION
"Ideal"
FIA
DPD
OZONE
"Ideal"
IODOMETRIC
ARSENIC BACK
TITRATION
FACTS
DPD
INDIGO
Spect'photo
Species*
MEASURED
DIRECTLY
cio,-
IODOMETRIC
Sequential C103~
Modified- C10,'
cio,-
cio,-
DETECTION WORKING EXPECTED EXPECTED
LIMIT RANGE ACCURACY PRECISION SKILL'
(mg/L) (mg/L) (± %) (± %) LEVEL
0.001 0.001 - 10 0.5 0.1
0.064 > 1 2 2-5 3
0.3 0.3-20 1 1-3 3
0.08 0.08 - 0.8 3.5 1 2
0.01 0.01 - 10 5 5 2
0.01 0.01 - 10 0.5 0.1 1
0.002 0.5-100 1 - 35 1 - 2 2
0.002 0.5-65 1=5 1-2 2
0.02 0.5-5 5 - 20 1 - 5 2
0.1 0.2-2 5-20 5 2
0.001 0.01 - .1 1 0.5 1
0.006 0.05 - .5 1 0.5 1
0.1 > 0.3 1 0.5 1
18
-------
TABLE I. CHARACTERISTICS (confd)
STABILITY
REAGENT PRODUCTS INTERFERENCES pH RANGE
FIELD CURRENT
TEST AUTOMATED STATUS
5 YRS
good
good
1 year
Solid
stable6
5 YRS
1 YR
1 YR
2 YRS
Solid
stable8
good
good
good
> 1 DAY
Subject to
oxidation
Subject to
oxidation
1 day
< 30 min
> 1 DAY
subject to
oxidation
subject to
oxidation
no fading
first 5 min
< 30 min
good
good
good
NONE Independent
Metal ions & 7
nitrite ion
Metal ions & 2
nitrite ion
Oxidizing < 1
species
Oxidizing 7
species
NONE Independent
All ozone < 2
by products
and oxidants
Oxidizing 6.8
species
Oxidizing 6.6
species
Oxidizing 6.4
species
C12, Mn ions 2
Br, I2
C12, Mn ions 2
Br2 I2
C12, Mn ions 2
YES
NO
NO
NO
NO
YES
NO
NO
NO
NO
NO
NO
NO
YES
NO
NO
RECOMMENDED
NO RECOMMENDED AT
HIGH CONC.
CONT'D STUDY
YES USED AFTER ALL
C102 C102- GONE
NO NOT RECOMMENDED
YES RECOMMENDED
NO ABANDON
CONT'D STUDY
NO NOT RECOMMENDED
NO NOT RECOMMENDED
YES RECOMMENDED
YES RECOMMENDED
YES RECOMMENDED
Br2 I2
19
-------
TABLE I. CHARACTERISTICS AND COMPARISONS OF ANALYTICAL METHODS® (cont'd)
Speciest
TE OF TEST MEASURED
.METHOD)* DIRECTLY
INDIGO (cont'd)
Visual 03
GDFIA 03
LCV 03
ACVK 03
o-TOLIDINE 03
BISTERPYRIDINE 0.
DETECTION WORKING EXPECTED EXPECTED
LIMIT RANGE ACCURACY PRECISION SK!
(mg/L) (mg/L) (± %) (± %) LF
0.1 0.01 - 0.1 5 5
> 0.1 5 5
0.03 0.03 - 0.4 1 0.5
other ranges
possible
0.005 NR NR NR
0.25 0.05 - 1 NR NR
NOT QUANTITATIVE NR NR
0.004 0.05 - 20 2.7 2.1
1
1
2
1
1
1
3
CARMINE INDIGO
< 0.5
NR
NR
NR
ELECTROCHEM
Amperometric
Amperometric
iodometric
Bare electrode
Membrane elect.
Differential
Pulse Dropping
Mercury
Differential
Pulse Polar-
ography
Potentiometric
Total - 1
oxidants
Total - 0.5
Oxidants
03 0.2
0, 0.062
03 NR
03 0.003
0, NR
NR
NR
NF
NF
NR
NR
NR
5
5
5
5
NR
NR
NR
5
5
5
5
NR
NR
NR
2
2
2
1
3
3
1
20
-------
TABLE I. CHARACTERISTICS (cont'd)
STABILITY FIELD CURRENT
REAGENT PRODUCTS INTERFERENCES pH RANGE TEST AUTOMATED STATUS
good
good
good
Stable
NR
NR
Good
good
good
good
Stable
NR
NR
Good
C12 , Mn ions 2
Br2 I2
C12 , Mn ions 2
Br2 I2
C12 at > Img/L 2
52- SO3" Cre* 2
Mn > 1 mg/L 2
C12 > 10 mg/L
Metal ions, NOj" 2
C12 < 7
YES NO
YES NO
NO YES
NO NO
NO NO
YES NO
NO YES
RECOMMENDED
RECOMMENDED
COMPARISON
STUDIES
NEEDED
CONT'D STUDY
CONT'D STUDY
ABANDON
RECOMMENDED
(LAB TEST)
NR
NR
NR
NO
NO
CONT'D STUDY
none
NA
Oxidizing
species
NO YES RELATIVE
MONITORING
1 YR Subject to Oxidizing
oxidation species
4 - 4.5
NO
none
none
none
none
none
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
4
NR
NO
NO 1
NO
NO
NO
YES
'OSSIBIJ
NO
NO
YES
NO NOT RECOMMENDED
CONT'D STUDY
RESEARCH LAB
CONT'D STUDY
CONT'D STUDY
21
-------
TABLE I. CHARACTERISTICS AND COMPARISONS OF ANALYTICAL METHODS®
TYPE OF TEST
(METHOD)*
UV
Species* DETECTION WORKING EXPECTED EXPECTED
MEASURED LIMIT RANGE ACCURACY PRECISION SKILL'
DIRECTLY (mg/L) (mg/L) (± %) (± %) LEVEL
0.02
> 0.02
0.51* 0.5
ISOTHERMAL
PRESSURE CHANGE
4 x 10-8 4 x 10-6 - 10 0.5
0.5
OZONE GAS PHASE
"Ideal" 03
UV Os
Stripping
Absorption
lodometry 0,
Chemiluminescence 03
Gas phase titration 03
Rhodamine B/
Gallic Acid 03
Amperometry 03
1 1 - 50,000 111
0.5 0.5 - 50,000 2 2.5 1/2
0.002
0.005
0.005
0.001
NR
0.5 - 100
0.005 - 1
0.005 - 30
NR
NR
1 - 35
7
8
NR
NR
1 - 2
5
8.5
5
NR
2
1/2
2
1
1
* for page numbers in the full report, refer to the Alphabetical Index
t direct determination of the species measured without interferences
* Operator Skill Levels: 1 - minimal, 2 - good technician,
3 - experienced chemist
NA Not applicable
NR Not reported
NF Not found
1 Using research grade electrochemical equipment
2 Using commercial titrator
3 Spectrophotometric endpoint detection
4 Visual endpoint detection.
5 Using test kit
6 Liquid reagent is unstable
7 Stablility is very dependent on the purity of the 2-propanol used
22
-------
TABLE I. CHARACTERISTICS (confd)
STABILITY
REAGENT PRODUCTS INTERFERENCES pH RANGE
none
NA Other
Absorber
none good
none
Independent
Independent
FIELD CURRENT
TEST AUTOMATED STATUS
NO YES ESTABLISH
MOLAR ABSORB-
TIVITY
NO YES COMPARISON
STUDY
none
none
none
none
none
none
Independent YES YES
NA YES YES
RECOMMENDED
RECOMMENDED
good good
stable < 1 sec
stable stable
S02 N02
none
none
NA
NA
NA
YES NO ABANDON
YES YES RECOMMENDED
YES NO NOT RECOMMENDED
problems
none none
NR
NR
NA
NA
YES POSSIBLE NOT RECOMMENDED
YES YES NOT RECOMMENDED
8 Total Chlorine is all chlorine species with +1 oxidation state
9 Very little actual work has been carried out on selective determination
of chloramines. The values reported are from extrapolated studies that
had objectives other than the selective determination of chloramines.
Most methods are indirect procedures which are not recommended
10 Indirect method
11 1/5 of C102 determined
12 Acid chrome violet potassium (ACVK)
13 Gas diffusion flow injection analysis (GDFIA)
14 Based on current molar absorbtivity and proper sample handling tecniques.
Current best estimates of molar absorbtivity of 2900-3300 give a
possible error of > 10%.
c Taken from Gordon, Cooper, Rice, and Pacey, AWWA-RF Review on
"Disinfectant Residual Measurements Methods" (1987)
23
-------
Chapter 4 (Indexed Reference Citations) has been included in this report in
order to assist readers in locating particular papers of interest. The 48
categories for chlorine, chloramines, and the oxy-chlorine species, along with
the additional 60 categories for ozone, should make the task of finding in-
dividual papers of interest considerably less cumbersome. Papers which describe
several methods have been included in each of the appropriate categories. All
together, the 1,400 references cited in Chapters 1-3 number more than 2,000
individual citations when distributed in the indexed form of Chapter 4.
Chapter 5 is an alphabetical listing of the individual references citations.
Finally, a detailed Index has been included in order to assist readers in
locating subjects of specific interest. We hope the readers will find these
additional chapters as useful as have we in preparing this report.
RECOMMENDATIONS
General Statements on Comparisons.
There have been and will continue to be reports of methods comparison. One
of the most important considerations for a method is accuracy, i.e. the ability
of the method to determine the correct concentration of a disinfectant in
solution. An equally important consideration is precision, i.e. how well does
the analytical method reproducibly measure the same concentration. Frequently
experiments are conducted to determine the "equivalency" of the methods. From
such results, methods may be found to be equivalent, but the only analytical
considerations tested were accuracy, as judged by a Referee Method, and
precision, judged for each method based on the experimental design.
No considerations were given to specificity or analyst preference. Yet one
of the most difficult tasks in the area of disinfection analytical methods
development is comparison testing. It is recommended that a protocol be
developed to initiate comparison of the disinfectants. This protocol should
include all of the factors delineated in the "Ideal Method" and should be
undertaken in both laboratory controlled conditions and at selected water
treatment plants around the country.
Chlorine Chemistry.
Clearly, the conversion to moles, equivalents, or normality from units of
mg/L (as C12) or mg/L (as other oxidants) can easily be confused (and
confusing). Our recommendation is that all oxidizing agents be reported in molar
units (M) and, if necessary, in mg/L of that oxidizing agent as measured (i.e.
mg/L (as C12) or mg/L (as C102") or mg/L (as C10S~). Furthermore, we recommend
that oxidizing equivalents per mole of oxidant be reported to minimize
additional potential confusion. For example, when C102 is reduced to C102',
this corresponds to one equivalent/mole; on the other hand, when C102 is reduced
to Cl", this corresponds to five equivalents/mole. A summary of molecular
weights and oxidizing equivalents for the various chlorine species, oxychlorine
species and ozone is given in Table II.
24
-------
TABLE II. EQUIVALENT WEIGHTS FOR CALCULATING CONCENTRATIONS ON THE
BASIS OF MASS.
Species
Chlorine
Monochloramine
Dichloramine
Trichloranine
Chlorine dioxide
Chlorine dioxide
Chlorite ion
Chlorate ion
Ozone
Ozone
Molecular
Weight
g/mol
70.906
51.476
85.921
120.366
67.452
67.452
67.452
83.451
47.998
47.998
Electrons
Transferred
2
2
4
6
1
5
4
6
2
6
Equivalent
Weight
g/eq
35.453
25.738
21.480
20.061
67.452
13.490
16.863
13.909
23.999
8.000
Several mechanisms have been proposed for the decomposition of dichloramine,
but the complete mechanism at the breakpoint has not been resolved. Clearly, the
chemistry is complicated and varies markedly with solution composition. A
detailed understanding of the specific reactions involved requires a detailed
knowledge of the concentration of all chloramine species in the system.
Nitrogen-containing organic compounds may be present in surface water and
ground-water. Because of analytical complexities, very few detailed studies
have been undertaken to determine the individual compounds present and the
concentration at which they exist. Kjeldahl nitrogen analysis is used
frequently, but this does not provide any detailed information with regard to
individual compounds. The area of organic nitrogen and the determination of
specific compounds in natural waters is one of the increasing interest and
requires considerably more research in characterization and methods development.
ultraviolet Methods.
In general, because the molar absorptivities are quite low for chlorine and
chloramine species, ultraviolet methods are not considered useful in routine
monitoring of chlorine residuals. In addition to the low molar absorptivities,
there is often background absorbance that may interfere with the measurement in
various natural waters. However, these measurements are of use in standardizing
the chlorine species in distilled waters and are often used in experimental work
25
-------
related to chlorine speciation. This method does have considerable potential
for the determination of relatively high concentrations of halogens,
particularly in relatively clean 'water. This method might find use in
monitoring chlorine species in water treatment plants. However, with a more
elaborate multiwavelength spectrophotometer and computer-controlled spectral
analysis, it might be possible to analyze several halogens simultaneously.
It is also possible that additional methods using permeable membranes could
be developed for the simultaneous determination of chlorine species in aqueous
solution. Additional work is necessary in this area. Although the molar
absorptivities of the species is not of a magnitude as to lend it to the routine
determination of the dilute (less than 10"6 M) chlorine and chlorine-ammonia
species, it is potentially helpful in determining the concentration of standard
solutions. Absorption spectrophotometric analysis has and will continue to be
very important in the area of chlorine chemistry. It can be used in the
unambiguous determination of relatively high concentrations of the species in
relatively pure water.
Continuous Amperometric Titration Method.
Interferences appear to be reduced using the continuous amperometric method
because the reagents are added to the sample just prior to contacting the
indicating electrode. Thus, when compared to the amperometric titration, the
amount of interference by iodate ion, bromate ion, copper(II), iron(III), and
manganese(IV) is reduced by approximately one-tenth. No reports appear to be
available in the literature on the determination of mixed oxidants using the
amperometric method. Such experiments need to be carried out. In addition, few
experiments have been reported which clearly demonstrate that the electrodes
remain uncontaminated for drinking water or waste water systems. In the absence
of such comparisons, the accuracy of any electrode procedure may be
questionable.
However, the amperometric titration determination of chlorine species re-
mains the standard for routine laboratory measurements. Given proper analyst
training and experience, the commercially available instrumentation is sensitive
and precise. This method should remain as the method for laboratory use and
accuracy comparisons. It requires more analyst experience than colorimetric
methods, but can be relied on to give very accurate and precise measurements.
It should be noted that care must be exercised when using one titrator for the
measurement of both free and combined chlorine. Small quantities of iodide ion
can lead to errors when differentiating between free and combined chlorine.
Careful rinsing with chlorine demand free water (CDFW) is a must! Additional
development of automated back-titration equipment with the goal of lowering the
limit of detection and improving the reproducibility would be highly beneficial.
lodometric Titration Method.
The iodometric titration is useful for determining high concentrations of
total chlorine. The most useful range is 1 mg/L (as C12) or greater. It is a
common oxidation-reduction titration analytical method and provides a reference
procedure for total chlorine. Although not necessarily used routinely, most
laboratories use it as a. reference method and it is not likely ever to be
eliminated from use.
26
-------
Colorinetric Methods.
It Is reported in Standard Methods (13) that nitrogen trichloride can be
measured using the DPD method; however, the method has not been confirmed by
independent investigations and should be used only as a qualitative method.
Additional research is necessary to determine the effectiveness of the DPD
method for nitrogen trichloride. The effect of the presence of mercuric
chloride in the reagents for minimizing the breakthrough of monochloramine into
the free chlorine reading with the DPD method has been shown. It is very
important that the addition of mercuric chloride to the buffer be followed to
minimize the direct reaction of monochloramine with DPD. This phenomenon is not
thoroughly understood. This effect should be studied more thoroughly and the
principle may be applicable to all of the colorimetric methods.
The use of thioacetamide was evaluated for monochloramine (using DPD-
Steadifac). It was shown under these conditions to eliminate any positive
inteference in the free residual measurement. These results are not as yet
understood, but the implication is that the chemistry of oxidation is different
for monochloramine and free chlorine. These results suggest that more work is
necessary to better define the reactions involved, and this may lead to a more
usable analytical procedure. This procedure is recommended for use in waters
that are suspected to be relatively high in combined chlorine.
The DPD-Ethyl Acetate Extraction Procedure is a modification of the DPD
chemistry. The method is based on the oxidation of iodide ion by active
chlorine followed by extraction of the iodine species into ethyl acetate. This
procedural modification may be of use in the determination of total residual
chlorine in both the field and laboratory. Additional work is necessary before
it can be used to any great extent. It does not appear to offer substantial
advantages to the already well tested colorimetric method for laboratory
measurements.
The DPD methods have become the most widely used procedures for the measure-
ment of chlorine. This is not likely to change. The DPD color reagent, in
liquid form, has been shown to be quite unstable and is not recommended for use.
It is sensitive to oxidation by oxygen and thus requires a control measurement.
Clearly, it is better to use dry reagents.
Leuco Crystal Violet, LCV.
No studies have been reported that examine the interference of chlorine
dioxide and/or ozone in the LCV method. It is anticipated that these oxidants
would interfere in the method, and studies should be conducted to quantify these
potential interferents.
Syringaldazine; FACTS.
A study using syringaldazine in a continuous method to differentiate free
from combine chlorine has been reported. It was concluded that it could be used
•nd was useful in controlling free chlorination. Further work would have to be
conducted to use this or any colorimetric method in continuous analyzers.
27
-------
Chemiluminescence.
Several papers have appeared that detail the reaction of hydrogen peroxide
and hypochlorous acid and the resulting chemiluminescence. The mechanism has
been relatively well established and the chemiluminescence is thought to occur
as a result of the formation of singlet oxygen. The light emitted is red (635
nm), and occurs most readily in alkaline solution. This reaction is rather
insensitive to low concentrations and is not suitable for the determination of
hypochlorous acid in aqueous solution. However, the studies that have been
reported can serve as a guide for those interested in pursuing other methods for
the determination of hypochlorous acid by chemiluminescence. It is not sensitive
enough to be considered as an analytical method for chlorine in water treatment.
A study has been reported that details the use of luminol for the
measurement of hypochlorite ion. The optimum pH for analysis was between 9.0 and
11.0 Luminol also has been used for the determination of hydrogen peroxide.
4,5,6,7,-tetramethoxyluminol is 30 % more sensitive than luminol. Either of
these compounds may be more sensitive in the determination of free chlorine. As
these compounds have not been tried it appears that additional studies are
necessary. From the limited data available, it appears that this reaction has
considerable promise as an analytical method. It may very well be the most
sensitive method to date.
It is reported that lophine, in a reaction with hypochlorite ion, produces
light. Very few details were given in the study for this reaction. It appears
that lophine also may be good as a chemiluminescence reaction system for free
chlorine. Additional work should be undertaken to better characterize the
details of this reaction.
Luminol and some of its derivatives, or lophine, may be well suited for the
very sensitive measurements of chlorine species. Additional research should be
undertaken to develop the use of chemiluminescence for use in the determination
of chlorine in water. The potential exists for rapid, simple, and specific
methods for chlorine and possibly other oxidants. With the advent of fiber
optic sensors and their application in chemiluminescence methods, this
technology will be important in the future.
Fluorescence.
The use of rhodamine B has been reported as a low level fluorometric method
for the determination of bromine. This method is qualitatively specific for
bromine, although chlorine will react to decrease the fluorescence. The advant-
age of this method is that it is capable of determining oxidants at very low
concentrations. This method could be applied to chlorine analysis by first
using the free chlorine to oxidize the bromide ion to bromine, an irreversible
reaction, followed by the determination of bromine. This method was not
developed fully and very little work has been undertaken since the first
publication. It does appear to have considerable potential and future research
in the area of methods development should not exclude additional work on this
fluorometric procedure.
28
-------
Other Electrode Methods.
Additional studies are required to better understand the limitations of
membrane electrode methods. It appears that they may have prominent roles to
play in chlorine residual measurements in the future.
In a series of experiments carried out for the determination of free
chlorine in tap water, it was observed that there was a statistically
significant difference between the results of the amperometric titration and the
•embrane electrodes. It was thought to be a problem in the membrane electrodes.
However, on reconsideration, it is possible that the electrodes were actually
giving a free chlorine reading and the amperometric titration was reading the
sum of free and organically combined chlorine. The study was conducted on water
which is relatively high in organic nitrogen. It is possible that considerable
chlorine is present as organically combined chlorine and interferes in the
amperometric titration procedure, but does not interfere with the membrane
electrode measurements. This question must be resolved. Carefully designed
experiments to expicitly resolve these differences would be most appropriate.
There have been no reports of experiments using bare-electrode amperometric
analyzers where other oxidants such as chlorine dioxide, chlorite ion, chlorate
ion or ozone have been tested with the bare-electrode. Additional studies are
required to expand these bare-electrode amperometric studies to quantitate
interferences with oxidants other than those tested, and to expand to other
natural waters.
Since the accuracy of the potentiometric electrodes is affected, if
temperature corrections are not used, it is recommended that temperature be
either controlled or measured simultaneously. Additional independent measure-
ments of accuracy should be undertaken for the potentiometric electrodes.
It appears that the potentiometric electrode can be used for the
determination of total residual oxidant. It is suitable for continuous
measurements and appears to give results that are acceptable when compared to
the amperometric titrator.
General Summary and Recommendations for Chlorine.
In comparing all of the methods to the "Ideal Method" we find that none come
very close to our ideal standard. Continued development of the various methods
will, however, come closer and closer to the ideal.
For the present, the amperometric titration techniques will remain the
laboratory standard used for the basis of comparisons of accuracy. These
methods, with proper precautions can differentiate between the common inorganic
chorine/chlorine ammonia species, and in general suffer from as few inter-
ferences as any of the methods.
Of the three common colorimetric procedures, DPD, LCV. and FACTS, the DPD is
by far the most commonly used method. From the available literature it is clear
that the DPD procedure has a number of weaknesses. In particular, the colored
product is a free radical which limits the stability of the colored reaction
product. The direct reaction with monochloramine, to form a product identical
29
-------
to the reaction with free chlorine, is also a drawback. This problem can be
reduced by the addition of thioacetamide. Liquid reagent instability precludes
their use in most cases; care should be taken to determine blanks frequently.
The present LCV method that appears in Standard Methods (13) is outdated and
has been substantially improved upon by Whittle and Lapteff (14). This method
allows for the differentiation of the common free and combined inorganic
chlorine species. However, because only one comparison study has been
conducted, additional collaborative testing is recommended.
The FACTS test procedure appears to be very useful for the determination of
free chlorine in the presence of relatively high concentrations of combined in-
organic chlorine. A severe drawback of the FACTS test procedure is the insolu-
bility of the syringaldazine in either 2-propanol or water. This leads to dif-
ficulties in reagent preparation, and presumably to the color stability problem
encountered at the higher concentrations of chlorine (greater than 6-8 mg/L
(as C12)). Although a method for the use of the FACTS test for total chlorine
has been reported, it should be tested further.
Electrode methods have been developed employing several different concepts.
The membrane electrodes appear to have potential as specific methods for hypo-
chlorous acid. Common interferences are other nonionized molecules such as
chlorine dioxide and ozone. Fotentiometric electrodes for the determination of
total chlorine are improving in both detection limit and stability. These
electrodes appear to have promise in the area of process control. Their
inclusion as methods for routine use in the laboratory and field is warranted.
Both fluorescence and chemiluminescence methods also show promise for the
specific determination of free chlorine at very low concentrations. Within this
area of spectrofluorometric methods, there is considerable work yet to be
initiated. Continued development work is warranted and recommended in this
promising area.
From the review of analytical procedures for the determination of chlorine
in aqueous solution, it is readily apparent that only a few of the methods are
used routinely. Nevertheless, there is certain to be a continued interest in
developing new and better methods of analysis. We would strongly recommend that
new methods be presented in terms of the "Ideal Method" and that whenever pos-
sible, comparisons with real samples and interlaboratory comparisons be made.
Flow injection analytical techniques are becoming very common. Continued
development should lead to the automation of many colorimetrie and fluorometric
analytical methods for the measurement of free and combined chlorine and its
various species in water. With the current emphasis on automation, the methods
that are to be developed and those already developed can readily exceed present
standards of accuracy and precision. Automation will also lead to operator
independent methods and should lead to improvements in process control and
monitoring.
Chlorine Analytical Methods Comparative Studies.
The reader is cautioned against accepting the results of any or all of the
above tests without some reservations. Where possible we have tried to add com-
30
-------
nents, parenthetically, based upon our knowledge of the field. It is very im-
portant in reviewing data from comparison tests that the analyst be aware of the
objectives of the comparison testing. For example, a test may be judged
unacceptable because of an unacceptable lower limit of detection that is beyond
the need for concern for other investigators.
In general when testing several test procedures it is important to identify
the objective of the testing. Equally important is the use of the data. In
reporting the results of the above tests, it should be kept in mind that many
manufacturers of chemicals for analytical methods and Test Kits change their
procedures as a result of the testing. The concerned analyst needs to determine
if the results are still valid. This change is not necessarily applicable to
other studies where the chemistry of an analytical method is examined. In
general, the more the test studies chemistry and not merely the test procedures,
the more applicable the results are for future reference.
Another area of confusion concerns precision and accuracy. An analytical
method may be judged acceptable based on the precision of the results, while the
same method may give poor accuracy. These statistical parameters are separate
and must be tested using different experimental designs. Comparisons with the
•Ideal Method" would require that both be at acceptable levels.
In general, there is a lack of comprehensive studies to better understand
the chemistry associated with the individual test procedures. Investigations of
this nature are necessary on a continuing basis, because of the advances in ana-
lytical instrumentation and our continued improvements in understanding the de-
tails of the underlying chemistry.
Chlorine Dioxide Analytical Methods.
The iodometric method is a questionable method even for carefully controlled
research laboratory chlorine dioxide standards. In real samples where a large
number of potential interferences can exist, the method is destined to produce
erroneous results. Newer, more species specific methods are better choices.
Any method which determines concentrations by difference is potentially
inaccurate and subject to large accumulative errors--both in terms of accuracy
and precision. The subtraction of two large numbers to produce a small number
means that the errors associated with those large numbers are propagated to the
small number. The result in many cases is that the error is larger than the
smaller number, therefore, giving meaningless information. Methods such as
this, which obtain values by differences, should be avoided.
The DPD method uses the difference method in the evaluation of concen-
trations. The direct measurement of species by means of a more reliable and
accurate method to determine chlorine dioxide is needed. The same questions
raised about the DPD method for chlorine also apply here.
Ultraviolet spectrophotometry. utilizing continuous flow automated methods,
has a great potential for accurate and precise measurements with the added
advantage of ease of operation and high sample throughput. Flow injection
analysis methods (FIA) should be carefully evaluated against existing methods
for accuracy and precision. The method should be field tested and the potential
31
-------
problem of membrane reliability should be evaluated for long term operations.
Additional bench studies using continuous flow methods with chemiluminescent
detection must be carried out. The superior selectivity of this method needs to
be utilized. Comparison lab testing and field study should be carried out.
Chlorite/Chlorate Ion Analytical Methods.
The iodometric/amperometric methods are indirect determinations of chlorite
ion and cannot be recommended. The DFD method for chlorite ion can not be
recommended because it is unreliable.
The iodometric sequential methods appear to be very workable on samples
containing greater than 1 mg/L chlorite ion or chlorate ion with good precision
and accuracy resulting. The method requires considerable operator skill and
experience to obtain good precision and accuracy for samples containing less
than 1 mg/L chlorite ion or chlorate ion. The method should be field tested
with other methods using both high and low ratios of chlorate ion to chlorite
ion. The method should be used with caution on low level samples of drinking
water and/or wastewater, although direct methods requiring less specialized
skills are preferred.
Interlaboratory comparisons should be carried out for the modified
iodometric method for the direct analysis of chlorite ion and chlorate ion. The
detailed effects of various potential interferences need to be evaluated.
The argentometric titration method is to be recommended only for relatively
high concentrations of oxy-chlorine species (10-100 mg/L) but may be very useful
in establishing inter-laboratory bench mark comparisons at these high concen-
tration ranges. No such comparisons are currently available.
A highly precise, automated FIA method for low level chlorate ion needs to
be developed possibly using various masking agents such as glycine, oxalic acid,
malonic acid, and nitrite ion to initially remove other possible oxy-halogen
interfering species. The method appears to be very promising in that it can be
used to directly determine low level chlorate ion concentrations.
Difficulties With Ozone Measurements: Need For Ideal Method.
As a consequence of the nature of ozone, its continuous self-decomposition,
volatility from solution, and the reaction of ozone and its decomposition
products with many organic and inorganic contaminants in water, the deter-
mination of dissolved residual ozone is very difficult. A detailed knowledge of
the mechanism of aqueous ozone decomposition and the potential role of the
various highly reactive intermediates, is imperative in order to accurately
evaluate the analytical methods (15). In this context it should be noted that
most ozone methods are modifications of chlorine residual methods which
determine total oxidants in the solution. Therefore, ozone decomposition
products such as hydrogen peroxide and the like are also measured.
lodometry can be used as an example of the difficulties encountered in
making aqueous ozone measurements (16). Iodide ion is oxidized to iodine by
ozone in an unbuffered potassium iodide solution. The pH then is adjusted to 2
32
-------
with sulfuric acid and the liberated iodine is titrated with sodium thiosulfate
to a starch end point. The ozone/iodine stoichiometry for this reaction has been
found to range from 0.65 to 1.5. Factors affecting the stoichiometry include:
pH, buffer composition, buffer concentration, iodide ion concentration, sampling
techniques, and reaction time. The pH during the initial ozone/iodide ion
reaction and the pH during the iodine determination have been shown to markedly
alter the ozone/iodine stoichiometry. The formation of iodate ion and hydrogen
peroxide have been implicated specifically as factors affecting the ozone/iodine
stoichiometry (17). Modifications in the iodine determination include changes
in end point detection, pH, and back-titration .techniques. None of these
modifications has been demonstrated to be totally satisfactory.
The biggest difficulty in interpreting the existing ozone literature is that
no one method has been accepted as the Referee Method. Therefore, comparison
between several different methods can create false conclusions about the
accuracy of the methods. The method most often used for comparative purposes in
the research laboratory is UV measurement of ozone at 260 nm. Even with this
method there' is apparent confusion over the molar absorptivity for aqueous
ozone, with the values ranging from 2900 to 3600 M^cm"1 (16).
All analytical methods reported, particularly those of early vintage, should
be reevaluated, considering the recent information about oxidative by-products
from ozone decomposition and the ozonation process itself. Some of these
factors may not have been considered during development of the original
analytical procedures. Certainly, more detailed information and comparisons
should be available. Because of the difficulties of establishing a reliable
Referee Method we propose that the existing and future methods be compared
against an "Ideal Method". This "Ideal Method" would incorporate all of the
characteristics that are desired for an ozone method, taking into account all
other potential interferences, decomposition products, and samples originating
from various sources. Finally, automation, while not an absolute necessity, can
add to the selectivity and ideal nature of a method for ozone determination.
Ozone Measurement: Gas Phase.
The many uses of ozonation in the treatment of drinking water are controlled
by monitoring a number of parameters. Dissolved residual ozone is only one of
these parameters, and its measurement controls only disinfection conducted after
filtration, but before addition of a residual disinfectant for the distribution
system. However, it is very clear that the cost, efficiency, safety and
improvements in design of ozone water purification systems is extremely
dependent on the accurate determination of gas phase ozone. Therefore,
analytical methods must be developed that will accurately measure ozone in the
gas phase and residual ozone in the aqueous phase. At this point it is
unrealistic to believe that one single method will be acceptable for both sample
matrices.
lodometry, UV absorption and chemiluminescence are the three most common
methods employed for gas phase measurements (16). Each of these has been applied
to determine the amount of ozone present in generator exit gases, when stripped
from solution to the gas phase, or the amount of ozone in a contactor exhaust
gas.
33
-------
These techniques of monitoring concentrations in contactor exhaust gases are
quite promising as a method of controlling the production of adequate quantities
of ozone. This provides considerable savings in electrical energy costs for
ozone generation. Direct inter-comparisons of the various gas phase measurement
techniques are needed in order to evaluate accuracy.
Determination of stripped ozone in the gaseous state was reported in the
16th Edition of Standard Methods (13) for measuring ozone dissolved in water.
However, in addition to the procedure being subject to the same limitations of
UV absorption and chemiluminescence procedures in aqueous solution, the effects
of the gas stripping process itself must be taken into consideration.
Although the iodometric stripping/aqueous absorption method has been
approved in Standard Methods (13), we question the accuracy of the method. All
evidence would suggest that the method is problematic. Even though the
impurities are substantially left behind by the stripping, the actual procedure
and the continual decomposition of ozone does introduce inaccuracies into this
method. This method can be used as a relative measure of ozone for control
purposes.
This basic stripping approach followed by absorption in aqueous solution
(and colorimetric measurement) may deserve to be studied further. However, the
biggest potential problem appears to be that at high concentrations of ozone the
colorimetric compounds may react by a mechanism different from that used for
residual ozone measurements. Research should be concentrated on the reagents
that have already exhibited ozone selectivity.
lodometry (Aqueous Phase).
If the performance of ozone in a specific treatment application is not de-
pendent only on the ozone, but is instead a collective function of its reactive
decomposition products as well, then iodometry can give a representative and
reproducible reading of the total oxidants. For example, most European drinking
water treatment plants employing ozonation as the primary disinfectant, have
relied on iodometric measurements as the basis for insuring adequate
disinfection, attaining a residual "ozone" level of 0.4 mg/L in the first
contact chamber and maintaing this level for at least four minutes).
However, it is now abundantly clear that the 0.4 mg/L value is a measure of
the amount of total oxidants present, and not necessarily ozone alone.
Therefore, either the absolute level of ozone required to attain the expected
degree of disinfection is lower than 0.4 mg/L over the required period of time,
or some of the decomposition/oxidation products formed upon ozonation also have
disinfecting properties, or both. Clearly, detailed experiments need to be
carried out to demonstrate the efficacy of disinfection by the decomposition
products of ozone. Similar efficacy data for ozone decomposition products could
be developed for other uses of ozone (e.g., chemical oxidation) when measurement
of residual ozone levels must be made to control the process. Such data would
help to justify the continued use of iodometry to measure "total oxidants",
rather than only ozone.
Historically, iodometry has been used as the reference method for deter-
mining ozone, and against which other analytical procedures have been
34
-------
"standardized". It is now quite clear that because of its lack of selectivity,
the use of iodometry should be limited to that of only a control procedure. In
terms of ozonation processes, measurement-for control purposes-of the production
rate of ozone generators and bacterial disinfection/viral inactivation may be
based upon iodometry, provided the user recognizes the many limitations of the
method. The reevaluation of this method must.be carried out with the specific
goal being to define when the method is reliable and the situations where it is
not accurate.
Many authors have tactfully pointed out the many disadvantages of iodometry,
leaving it to the reader to decide whether or not to use the procedure. In a
detailed comparison of eight analytical methods for the determination of
residual ozone it was concluded (16):
"No iodometric method is recommended for the determination
of ozone in aqueous solution because of the unreliability
of the method and because of the difficulty of the com-
parison of results obtained with minor modifications in
the iodometric method itself."
Arsenic(III) Direct Oxidation.
In the direct oxidation of arsenic(III), ozone reacts with inorganic
arsenic(III) at pH 4-7, the pH is adjusted to 6.5-7 and the excess arsenic(III)
species is back-titrated with standard iodine to a starch end point. Values for
residual ozone determined by the arsenic direct oxidation method and by the
indigo method agreed within 6% of the UV values. The primary advantages of the
arsenic direct oxidation procedure are minimal interferences, good precision in
the hands of experienced operators, and apparently good overall accuracy. This
procedure continues to be recommended along with the indigo method. Additional
comparisons of this method should be made with the indigo method under various
conditions.
Syringaldazine, FACTS.
The FACTS procedure, which was developed for the selective determination of
free available chlorine (hypochlorous acid + hypochlorite ion) in the presence
of combined chlorine (chloramines), has been adapted for the determination of
residual ozone (19). In this procedure, an aqueous solution of ozone is added
to a solution of potassium iodide, and the liberated iodine is added to a 2-
propanol solution of syringaldazine at pH 6.6. The resulting color is measured
spectrophotometrically at 530 nm.
The FACTS procedure has the major advantage of providing a spectrophoto-
metric procedure for the determination of ozone. However, the major limitations
of the FACTS method are still those of the iodometric procedure. Due to the
observed changes in slope and intercept which are problems caused by the
interferences, self-decomposition of ozone, and stoichiometry, this method could
be reviewed in order to fully evaluate its potential usefulness. However,
considering the other colorimetric methods that are available further
development of the FACTS method does not seem to give any promise of the
improved selectivity that is needed.
35
-------
N,N-Diethyl-p-phenylenediamine, DPD.
The DPD procedure is based on the ozone oxidation of iodide ion present in
excess phosphate buffer at pH 6.4 to produce iodine, which then oxidizes the DPD
cation to a pink Wurster cation which is measured spectrophotometrically, or
titrated. . The interferences include all oxidants capable ©f oxidizing iodide
ion to iodine, including ozone decomposition products, halogens, and manganese
oxides (20).
One advantage of the DPD method is that determinations can be made by
ferrous ammonium sulfate (FAS) titrimetry, spectrophotometrically or by a color
comparator. Ozone concentrations of less than or equal to 2 mg/L can be
determined colorimetrically. Clearly, the procedure requires the difference of
differences and is limited by the same factors which limit iodometry, specific-
ally the presence of materials which can oxidize iodide ion to iodine.
Although evaluation of this procedure versus the standard ultraviolet and
indigo procedures would seem to be necessary to make a more educated decision
about the continued use or abandonment of this method, the recommendation is
that other colorimetric methods are considerably more reliable than DPD.
Therefore development or testing is neither recommended nor considered necessary
at this time.
Indigo Trisulfonate.
The indigo method is subject to fewer interferences than most colorimetric
methods and fewer interferences than all iodometric procedures (21-23). At pH
2, chlorite, chlorate, and perchlorate ions, and hydrogen peroxide do not
decolorize Indigo Reagent when observed within a few hours and when the
concentrations of the interferents are within a factor of 10 of that of the
ozone to be determined.
Ozone decomposition products and the products of ozonolysis of organic
solutes do not appear to interfere. However, chlorine, bromine, and iodine do
cause some interference, as do the oxidized forms of manganese. The addition of
malonic acid to the samples will mask the interference of chlorine.
For the Indigo Trisulfonate Method, it should be noted that when the
ultraviolet absorption method is used to standardize the indigo method (or anv
method) for ozone, the choice of molar absorptivity is very critical. It is
recommended that the equations of Hoigne continue to be used since they are
based on a molar absorptivity of 2950 M'lcnTl. If and when a different value
for molar absorptivity is reported and confirmed, the (calibration) equations
would have to be appropriately changed. In this manner, all current
measurements using the indigo method would continue to be comparable.
The advantages of the indigo procedure is that it is based on a measure of
discoloration which is rapid and stoichiometric. This analytical procedure is
recommended for use over any other procedure for the determination of residual
ozone. Its primary attributes are its sensitivity, selectivity, accuracy,
precision, speed, and simplicity of operation.
36
-------
The gas diffusion flow injection analysis (GD-FIA) procedure eliminates the
interference of oxidized forms of manganese, and markedly reduces the interfer-
ence of chlorine (24). Other than interference of chlorine which can be reduced
to zero by addition of malonic acid, there are no known interferences to the
determination of ozone by this GD-FIA procedure using the indigo method.
The primary advantages of the GD-FIA procedure are its accuracy,
selectivity. lack of interferences, reproducibility, and rapidity. Thus, the
•ethod is well suited for laboratory research studies and for use as an
automated analytical procedure.
More studies should be conducted with specific gas-permeable membranes,
particularly with respect to repeated and/or continuous exposure to ozone solu-
tions. The use of FIA equipment in a process control environment also must be
evaluated. The GD-FIA indigo procedure might well be adopted as the analytical
•ethod of choice.
o-Tolidine
The o-tolidine method (addition of 1-2 drops of o-tolidine solution to
ozone-containing water to develop the yellow color) is very simple, and easily
adapted to field color comparators, suitable for unskilled analysts. However,
this advantage cannot compensate for the lack of quantitation of the method, nor
for the carcinogenicity of the reagent (o-tolidine). The recommendation is to
abandon this method.
Carmine Indigo.
The carmine indigo procedure has been used in Canadian water works plants
for the past 15 years. The ozone containing water is titrated with a solution
of carmine indigo until a faint blue color persists indicating that all of the
ozone has been destroyed. Specific interferences are unknown, but any oxidant
capable of decolorizing the carmine indigo dye most likely will interfere.
Effects of interferents should be determined, as should precision, accuracy,
and effects of reagent storage and pH. The method should be studied in direct
comparison with other methods, such as the indigo and UV absorption methods.
Automation of this method could lead to improved selectivity for ozone.
Anperometry.
Vith bare electrode amperemeters, either the solution or the electrode is
rotated to establish a diffusion layer, and the electrical current measured is
directly proportional to the concentration of dissolved oxidant (25). Commer-
cial amperometric analyzers give satisfactory results provided there is no
oxidant other than ozone present in the sample. In many situations they provide
adequate monitoring of total oxidant. The bare electrode system has good
sensitivity, and is applicable as a continuous nonselective monitor for ozone.
When other oxidants such as chlorine, chlorine dioxide, bromine, and iodine are
present, the technique has difficulties. The exact nature and magnitude of
these interferences requires additional research.
37
-------
Due to the accumulation of surface impurities at the electrode surfaces, all
bare amperometric electrode systems are subject to loss of sensitivity with use.
Vith uncovered electrode surfaces, fouling has been observed to be a significant
problem as was the case in earlier tests with oxygen electrodes. Additionally,
the response is influenced by numerous surface*active agents and also halogens
and oxygen.
An improvement in the development of amperometric methods for ozone analysis
has been the application of gas-permeable membranes for increasing selectivity
and preventing electrode fouling (26-27). These Teflon membrane electrodes
exhibit less than 2% interference (in terms of current response) from bromine,
hypobromous acid, chlorine dioxide, hydrogen peroxide, nitrogen trichloride, and
hypochlorous acid (26-27).
This type of amperometric membrane sensor needs to be developed further
based on the exhibited selectivities. The most disturbing attribute is the
temperature dependence. If different membranes could maintain selectivity while
minimizing the temperature effect, this type of sensor could become highly
recommended.
The application of positive voltage potentials and the use of polymeric mem-
branes that are selectively permeable to gases has enhanced the opportunity for
selective measurement of ozone. This is a very significant improvement over
bare amperometric electrodes as well as most older colorimetric/spectrophoto-
metric and titrimetric methods. Vith an applied voltage of +0.6 V (vs SCE) at
the cathode, only the most powerful oxidizing agents can overcome the
"resistance" of this anodic voltage and cause electron flow cathodically through
the electrochemical circuit. This general approach should continue to be used
in future electrochemical developments.
Other Electrochemical Methods.
In the differential pulse polarography procedure (DPP), a predetermined
amount of phenylarsine oxide (PAO) is added in excess to an ozone solution to
reduce the levels of dissolved ozone present. Excess PAO then is measured
quantitatively by pulse polarography. The DPP method may under some
circumstances be useful in the research laboratory. The prospects of its use in
the plant or field are not as promising since a higher degree of operator skill
is required.
Potentiometry involves the cathodic reduction of dissolved ozone. The
diffusion-limiting current measured is proportional to the concentration of
ozone in the water. Further evaluation of potentiometric systems may be in
order. However, the fundamental problems of electrode fouling must be
addressed. Perhaps a combination of membranes and potentiometric detection
would produce a promising system for ozone determinations. The system appears
to have modest potential for development.,
ultraviolet Measurements.
Ultraviolet absorption measurements also can be used for residual aqueous
ozone at 258-260 nm. There is uncertainty with respect to the molar
absorptivity for aqueous ozone. In the literature, values ranging from 2900 to
38
-------
3600 M^cm'1 are reported. This uncertainty in the molar absorptivity is
critical to the future use and calibration uses of the UV methods. Clearly.
further work to verify this value is strongly recommended.
If the molar absorptivity for ozone is known unambigiously, UV absorption is
in principle an absolute method for the determination of ozone, which is not
dependent upon calibration or standardization against other analytical methods.
Therefore, it can be used for calibration of other analytical methods for ozone.
It is specific to the determination of ozone, and is applicable to measurement
in gaseous and aqueous phases.
Physical Methods.
The calorimetric method is based on the enthalpy of the catalyzed
decomposition of ozone (AH - 144.41 KJ/mole). The calorimetric determination
of ozone is calibration-independent. The technique is specific to the
determination of molecular ozone, but is applicable to measurement only in the
gas phase. However, the higher the concentration of ozone in the gas phase, the
more accurate the method appears to be, since a greater temperature difference
is observed. Potential interferents have not been reported.
The method has been shown to agree with iodometric and UV absorption pro-
cedures, particularly for the measurement of ozone in the gases exiting ozone
generators. Therefore, the procedure can be used to monitor applied ozone
dosages. Additional detailed interlaboratory comparisons need to be carried
out.
The isothermal differential pressure procedure is based on the generation of
an increased number of gas molecules during the UV destruction of ozone at
constant temperature. When this reaction is carried out isothermally in a
closed vessel, the increase in pressure of the contained gas is proportional to
the ozone concentration. In principle, this procedure achieves a totally
physical ozone measurement without requiring calibration using a chemical
method. Various automated instrumental checks such as the stored molar
absorptivity, the age of the UV light source, the zero point reading,
measurement of the flow of the test gas and the flushing gas, and the reading of
the diagnostic display are possible.
No specific comparisons are reported. However, in principle it appears that
this physical method is the best candidate for calibrating the gas phase ozone
instruments currently being used for ozonation control. As long as pure oxygen
is used for ozone generation this method would be free of interferences and
would be subject only to strict temperature control of the measurement cell.
Further study of this system would be necessary before it could be recommended
for further consideration.
General Summary and Recommendations for Ozone.
In comparing all the methods to the "Ideal Method" we find that none come
close to our ideal standard. Continued development of the various selective
aethods will, however, come closer and closer to the ideal.
39
-------
In terms of gas phase measurements, none of the existing methods can be
recommended for accurate determinations of ozone. If a relative value of the
ozone concentration is needed for control purposes, most of the methods reported
could be applicable.
The accurate determination of ozone in the aqueous phase is complicated by
the decomposition of ozone, its reactivity to the other species present, and the
by-products of the ozonation reactions. Most current methods were developed
without a clear knowledge of the associated ozone chemistry. Therefore most of
the methods are unacceptable or cannot be recommended. In particular, no
iodometric based chemistry is acceptable for the determination of aqueous ozone.
Indigo trisulfonate and arsenic(III) direct oxidation are acceptable methods.
Amperometery continues to improve -- especially as an automated control method.
The stripping techniques have some merit in terms of improved ozone
selectivity. However, automated chemical systems such as flow injection
analysis offer considerably more promise. The current GD-FIA indigo procedure
is superior for residual ozone measurements due to its selectivity for ozone.
The most important aspect of any potential new or improved ozone analytical
method will be speed of analysis and selectivity of the detection system for
only ozone. As a point of comparison, we strongly recommend that all future and
existing methods be compared against the "Ideal Method".
LITERATURE
1. Symons, J.M.; et al "Ozone, Chlorine Dioxide and Chloramines as
Alternatives to Chlorine for Disinfection of Drinking Water* in
Water Chlorination: Environmental Impact and Health Effects. Vol.
2,, Jolley, RoL.; Gorchev, H. and Hamilton, D.H., Jr., Editors, (Ann
Arbor, MI: Ann Arbor Science Publishers, Inc., 1979) pp. 555-560
and Complete Report entitled "State of the Art ..." (Cincinnati,
OH: U.S. EPA, November. 1977), 84 pp.
2. Proceedings of Seminar on "The Design and Operation of Drinking Water
Facilities Using Ozone or Chlorine Dioxide", Rice, R.G., Editor,
(Dedham, MA: New England Water Works Assoc., 1979).
3. Miller, G.W.; Rice, R.G.; Robson, C.M.; Scullin, R.L.; Kuhn. W. and
Wolf, H., "An Assessment of Ozone and Chlorine Dioxide
Technologies for Treatment of Municipal Water Supplies", U.S.
Environmental Protection Agency, EPA Project Report, EPA-600/2-
78/018, 1978, 571 pp.
4. Miltner, R.J. "Measurement of Chlorine Dioxide and Related Products",
in Proceedings of the Water Quality Technology] Conference.
(Denver, CO: American Water Works Assoc., 1976), pp. 1-11.
40
-------
5. Gordon, C. "Improved Methods of Analysis for Chlorate, Chlorite,
and Hypochlorite Ions at the Sub*mg/L Level", U.S. Environmental
Protection Agency, EPA Technical Report, EPA-600/4-85/079. October.
1985, 35 p. and Presented at AUWA WQTC, in Proc. AWUA Water Quality
Technology Conference. December. Nashville, TN, 1982, pp. 175-189.
6. Aieta, E.M.; Roberts, P.V. "Chlorine Dioxide Chemistry: Generation
and Residual Analysis" in Chemistry in Water Reuse. Vol. i.
Cooper, W.J., Editor (Ann Arbor, MI: Ann Arbor Science Publishers.
Inc., 1981). pp. 429-452.
7. Hoigne, J.; Bader, H. "Bestimmung von Ozon und Chlordioxid in Vasser
mit der Indigo-Methode" ("Determination of Ozone and Chlorine
Dioxide in Vater With the Indigo Method"). Vom Uasser, 1980, £5_,
261-280.
8. Gilbert, E.; Hoigne, J. "Messung von Ozon in Vasserwerken; Vergleich
der DPD- und Indigo-Methode" ("Ozone Measurement in Vater Treatment
Plants: Comparison of the DPD and Indigo Methods"). GFW-
Vasser/Abvasser. 1983, 124. 527-531.
9. Schalekamp, M. "European Alternatives and Experience" in Proceedings
of the National (Canadian) Conference on Critical Issues in
Drinking Water Quality. (Ottawa, Ontario, Canada: Federation of
Associations on Canadian Environment, 1984), pp. 140-169.
10. Ikeda, Y.; Tang, T-F.; Gordon, G. "lodometric Method of Determination
of Trace Chlorate Ion", Anal. Chem., 1984, !£, 71-73.
11. Emmenegger F.; Gordon, G. "The Rapid Interaction between Sodium
Chlorite and Dissolved Chlorine", Inorg. Chem., 1967, &, 633-635.
12. Aieta. E.M.; Berg. J.D. "A Review of Chlorine Dioxide in Drinking
Water Treatment*. J. Am. Vater Vorks Assoc.. 1986, IS., 62-72.
13. Standard Methods for The Examination of Vater and Vastewater. 16th
Edition. Greenberg, A.E.; Trussell, R.R.; Clesceri, L.S.; Franson,
M.A.H., Editors (Vashington, D.C.: American Public Health Assoc.,
1985), 1268 pp. and 15th Edition. Greenberg, A.E.; Connors, J.J.;
Jenkins. D.; Franson, M.A.H., Editors (Vashington, DC: American
Public Health Assoc.. 1980). 1134 pp.
14. Vhittle. G.P.; Lapteff, A., Jr. "New Analytical Techniques for the
Study of Vater Disinfection" in Chemistry of Vater Supply.
Treatment, and Distribution. Rubin, A.J., Editor, (Ann Arbor, MI:
Ann Arbor Sci. Pub., Inc., 1974), pp. 63-88.
15. Tomiyasu, H.; Fukutomi, H.; Gordon, G. "Kinetics and Mechanism of
Ozone Decomposition in Basic Aqueous Solution", Inorg. Chem., 1985,
£4.. 2962-2966.
41
-------
16. Grunwell, J.; Benga, J.; Cohen, H., Gordon, C. "A Detailed Comparison
of Analytical Methods for Residual Ozone Measurement", Ozone Sci.
Eng., 1983. I. 203-223.
17. Flamm, D.L.; Anderson, S.A. "lodate Formation and Decomposition in
lodometric Analysis of Ozone", Environ. Sci. Technol., 1975, 2,
. 660-663.
18. Rehme. K.A.; Puzak, J.C.; Beard, M.E.; Smith, C.F.; Paur, .R.J.
"Evaluation of Ozone Calibration Procedures", U.S. Environmental
Protection Agency, EPA Project Summary, EPA-600/S4-80-050,
February, 1980, 277 pp.
19. Liebermann, J., Jr.; Roscher, N.M.; Meier, E.P.; Cooper, W.J. Develop-
ment of the FACTS Procedure for Combined Forms of Chlorine and
Ozone in Aqueous Solutions", Environ. Sci. Technol.. 1980, 14,
1395-1400.
20. Palin, A.T.; Derreumaux, A. "Determination de l'Ozone Residuel dans
1'eau" ("Determination of Ozone Residual in Water"), L'Eau et
1'lndustrie. 1977, 1£. 57-60.
21. Bader, H.; Hoigne, J. "Colorimetric Method for the Measurement
of Aqueous Ozone Based on the Decolorization of Indigo
Derivatives", in Ozonlzation Manual for Water and Wastevater
Treatment. Masschelein, W.J., Editor, (New York, NY: John
Wiley & Sons, 1982), pp. 169-172.
22. Bader, H.; Hoigne, J. "Determination of Ozone in Water by the
Indigo Method", Water Research 1981, 15., 449-456.
23. Bader, H.; Hoigne, J. "Determination of Ozone in Water by the Indigo
Method; A Submitted Standard Method", Ozone: Science and Eng.,
1982, 4, 169-176.
24. Straka, M.R.; Gordon, G.; Pacey, G.E. "Residual Aqueous Ozone Deter-
mination by Gas Diffusion Flow Injection Analysis", Anal. Chem.,
1985. 51, 1799-1803.
25. Masschelein, W.J. "Continuous Amperometric Residual Ozone Analysis
in the Tailfer (Brussels, Belgium) Plant", in Ozonization Manual
for Water and Wastevater Treatment. Masschelein, W.J., Editor, (New
York, NY: John Wiley & Sons, 1982), pp. 187-188.
26. Stanley, J.H.; Johnson, J.D. "Amperometric Membrane Electrode for
Measurement of Ozone in Water", Anal. Chem., 1979, 51. 2144-2147.
27. Stanley, J.W.; Johnson, J.D. "Analysis of Ozone in Aqueous Solution",
in Handbook of Ozone Technology and Applications. Vol. 1, Rice,
R.G. and Netzer, A., Editors (Ann Arbor, MI: Ann Arbor Sci. Pub.,
Inc., 1982), pp. 255-276.
42
-------
A GUIDE FOR EFFICIENT USE OF THIS REPORT (AND A BRIEF GLOSSARY OF TERMS)
This Report contains a very detailed review of all disinfectant residual
measurement methods. The Executive Summary is intended to give readers a brief
overview of the advantages and disadvantages of each method. To that end, Table
I (Characteristics and Comparisons of Analytical Methods) has been included to
summarize each of our findings and to recommend possible directions for future
research. In addition, Table II (Equivalent Weights for Calculating
Concentrations on the Basis of Mass) describes the equivalent weights of each of
the disinfection species in terms of the actual reactions involved in the
disinfection process.
Each chapter contains individual recommendations following the discussion of
the method. A summary of all of the recommendations is also given at the end of
each chapter. Additional help is given by means of an alphabetical Index
containing more than 2500 individual terms. Specific cross referencing for all
recommendations can be found in the Index either under the •recommendation", or,
in terms of the subject of the numbered recommendation itself.
The term Referee Method is used to describe appropriate comparisons with
existing methods and Standard Methods refers to a specifically recommended
method. The Index should be an additional aid to finding the details of
specific methods.
In this context, it should be noted that the individual literature citations
are specific to each individual chapter -• and are either numbered individually
within chapters 2 and 3, or alphabetically sequenced within chapters 4 and 5.
Chapter 4 (Indexed Reference Citations) has been included in this report in
order to assist readers in locating particular papers of interest. The 48
categories for chlorine, chloramines, and the oxy-chlorine species, along with
the additional 60 categories for ozone, should make the task of finding in-
dividual papers of interest considerably less cumbersome. Papers which describe
several methods have been included in each of the appropriate categories. All
together, the 1,400 references cited in Chapters 1-3 number more than 2,000
individual citations when distributed in the indexed form of Chapter 4.
Chapter 5 is an alphabetical listing of the individual references citations.
Finally, a detailed Index has been included in order to assist readers in
locating subjects of specific interest. We hope the readers will find these
additional chapters as useful as have we in preparing this report.
A brief Glossary follows on the next page in order to assist readers in the
various specialized terms and abbreviations used in this report. For additional
terms, the reader is referred to the Index.
43
-------
GLOSSARY
Accuracy -- the ability to determine the correct concentration
BAKI -- boric acid buffered potassium iodide method for ozone
Breakpoint -- the inorganic reaction of chlorine with ammonia nitrogen
CDFW -- chlorine demand free water
Combined Chlorine -- inorganic and organic chloramines
Detection Limit --a signal that is 3 times the noise level of the system
DOC -- dissolved organic carbon
DPD -- (N,N-diethyl-p-phenylenediamine)
FACTS •- free available chlorine test with syringaldazine
FIA -- flow injection analysis, an automated analysis procedure
Free Chlorine -- the species, C12 + HOC1 + OC1"
KI •• potassium iodide method for ozone
LCV -- leuco crystal violet
mL -- milliliter(s), standard unit of volume
Molar Absorptivity (e) reported in units of M"lcm"1
NBKI -- neutral buffered potassium iodide method for ozone
Precision =- how well the method reproducibly measures the same
concentration
Reactive Intermediate -- species such as 02", H02~, H0a, OH. 0,~, etc.
Referee Method -- the method aqainst which a working method is compared
Sensitivity -- the change in signal per unit concentration [i.e. Amps/mol]
Standard Methods -- the book, Standard Methods for the Examination of
Water and Wastewatcr published by APHA, AWWA, and WPCF
THM's -- trihalomethanes
Total Chlorine -- the combination of Free Chlorine and Combined Chlorine
TOC -- total organic carbon
TOX -- total organic halogen
44
-------
APPENDIX E
IKACTIVATIONS ACHIEVED
BY VARIOUS DISINFECTANTS
-------
MBIH
UJ'U
i.a 1.3
7.3 3.0
^0.4
9.4
O.I
1.0
i.:
1.4
1.4
1.1
;.(i
2.:
2.4
7.1
M
;
4
•J
4
7
;
3
1
1
?1
JO
10
SI
43
44
41
30
37
93
35
34
37
»
31
to
to
tl
tt
tl
7;
74
71
10
i:
34
13
17
II
11
tl
12
14
17
17
101
IN
107
IC1
112
114
lit
117
111
121
122
107
113
1:1
1:4
130
134
137
149
142
143
147
141
131
133
in
131
143
131
134
140
144
Itl
171
174
174
171
111
111
[•!
n wntits rw IUCTIVMIOI
ctsis IT rnt
»i 0.3 t
»N't.3
lei UictmtioM
0.) 1.0 I.} 7.0 7.9 1.0
77
71
10
31
32
33
34
33
33
It
37
17
31
31
33
37
to
tl
45
47
tl
70
71
72
71
74
75
74
10
14
tl
14
17
100
102
IM
104
IOI
110
III
III
114
107
113
121
124
110
113
134
131
142
144
144
141
130
132
134
143
131
137
147
144
170
174
177
110
113
lit
IM
110
140
in
in
in
114
200
203
701
713
714
Kt
773
724
771
»Nt7.0
UtttmtiKt
0.3 I.* 1.3 7.0 7.3 3.0
33
33
37
31
40
41
42
43
43
44
43
44
44
47
ts
70
74
77
71
17
14
15
17
tt
to
tl
t2
13
tl
104
111
113
111
127
125
171
130
133
135
117
131
140
131
141
141
134
131
143
It)
171
174
177
110
112
119
117
144
174
113
112
111
204
201
213
217
721
224
221
211
233
114
211
222
231
211
245
231
254
241
243
7i1
273
277
2»
pH'7.3
tW.C'ISJ
U9.ll
Uictititioni
1.0 1.3 2.0 7.3 1.0
0.4
0.4
O.I
1.0
1.7
1.4
1.4
1.1
2.0
:.2
2.4
2.4
2.1
1.0
40
43
43
47
41
41
31
32
33
33
34
35
34
34
71
13
11
t]
14
ft
IOI
101
103
107
101
110
112
113
111
121
134
140
144
141
132
133
139
140
It]
145
147
Itl
131
170
171
lit
112
117
202
204
210
214
217
770
773
724
Itl
213
724
733
740
747
293
Ttt
743
247
771
773
771
712
739
733
741
771
713
714
303
310
313
1:1
324
no
!C3
311
U; iMctmtint
0.3 1.0 1.3 2.0 2.3 S.O
47 13
3i io:
33 107
34 111
37 1!5
31 111
to 121
t? 17:
43 124
44 121
i5 1»
tt 131
17 133
17 113
147 111
132 703
1(0 714
147 772
177 710
177 734
111 741
115 747
III 731
112 733
114 731
117 243
200 244
707 270
734 714
734 303
247 371
771 333
717 344
713 334
307 347
301 370
114 377
311 313
124 JH
371 314
333 400
337 403
log UictmtiiM
0.3 1.0 1.3 7.0 7.3 1.0
94 117
M 170
43 124
tt 131
tl 13t
70 131
71 143
73 144
74 141
73 131
77 133
71 133
71 137
K 131
Itl 774
110 740
111 733
117 243
703 771
701 771
714 713
711 711
773 717
724 302
730 lOt
733 311
734 313
731 lit
771 333
300 3tO
314 371
371 114
331 407
341 411
137 471
144 417
171 443
377 43!
313 440
111 444
114 in
lit 471
Iq iMCtltrltmt
0.3 1.0 1.3 7.0 2.3 1.0
«.4
C.t
t.F
<
1.2
1.4
1.4
1.1
2
;.j
2.4
2.i
2.1
*
43
70
74
77
71
12
13
15
17
II
to
tl
12
t!
ill
140
141
134
131
143
147
170
174
177
171
112
114
114
114
211
272
231
731
743
730
734
240
743
7t1
273
774
710
7t7
2tl
214
307
317
324
134
141
347
393
391
344
3tl
373
J77
331
Itl
114
317
401
417
4C4
434
441
441
133
441
444
312
Ki
443
441
474
411
301
111
971
930
338
944
953
951
-------
mu c-7
tt VILUES (» IMCTIVITldi
t IMIU cms it FOE
CK.!t|lt
tDJCWTMTiea
£0.4
O.t
M
I
1.2
1.4
l.t
i.e
2
2.1
2.1
ocwm
(It'll
5-0.4
O.I
I
1.2
1.4
l.t
2
2.7
7.4
2.1
7.1
3
••I'll
<0.4
O.t
0
•"•4
U) laiMitttiKit
0 1
15
14
i;
IS
It
It
1»
JC
70
21
21
21
22
27
1 f
31
33
35
34
37
31
31
4C
41
41
42
42
43
44
1 ^
44
41
92
94
5i
57
51
40
41
42
43
44
4)
45
41
44
41
77
74
74
71
10
11
17
14
19
14
17
fH.7.9
lot iMctiuUo*
1.9
21
X
32
33
34
39
34
37
37
31
31
31
40
40
0.3
40
43
49
47
41
X
91
92
JJ
M
99
jj
94
97
1.1
94
41
44
44
U
70
72
74
7)
74
n
Tt
M
10
lot
1.0
W
14
to
14
•7
ti
102
104
104
101
tot
111
112
114
1.5
n
ti
tt
100
103
tot
ICI
110
112
114
lit
111
lit
121
2.0
113
121
12t
133
137
141
144
147
155
1)7
199
197
191
141
•N't.9
74
12
It
to
13
«
17
100
101
103
10)
lot
101
m
I
2.5
141
1)2
1)1
144
171
174
110
114
117
ill
m
114
lit
201
17
tt
104
101
111
114
117
111
n:
174
174
177
171
131
3.0
141
117
111
Itl
709
711
714
771
729
771
73
739
731
741
UlCtlTltlMt
1.5
170
171
139
140
14)
141
1)3
194
191
141
144
144
141
170
7.0
151
171
110
117
113
Itt
703
201
212
213
211
272
224
277
2.9
lit
214
72)
734
747
741
794
740
744
241
273
777
HI
214
3.0
731
7)7
770
711
TtO
711
X)
311
317
373
371
337
337
341
1*7.0
lO| luCtifltlMt
1.9
It
20
27
77
73
74
74
79
79
24
24
74
27
77
0.9
34
34
31
40
41
42
43
44
43
4t
44
47
47
41
I.I
31
41
43
43
44
47
41
X
91
91
92
jj
94
94
lit
1.0
47
77
74
71
17
14
*|i
II
10
tl
17
14
15
It
1.9
57
41
45
47
41
71
73
74
74
77
71
71
N
tl
1
2.1
Tt
17
It
It
17
W
17
11
101
103
104
lot
107
101
IN'I.O
2.9
n
107
101
117
119
lit
171
174
124
171
IX
137
134
134
3.1
114
173
171
134
131
147
144
141
132
194
197
191
141
143
iMCtmtlOM
I.)
101
101
114
111
123
124
171
132
134
1S7
131
141
147
144
1
2.0
13)
14)
1)7
191
144
141
177
174
171
112
119
117
110
112
fl'1.0
2.9
141
111
1*0
in
209
210
719
770
274
221
231
734
737
240
3.0
702
217
221
231
249
292
251
244
241
273
777
211
713
2M
lO| llUtittUOM
1.9
47
X
53
jj
57
91
40
41
42
43
44
49
44
44
1.0
13
too
109
110
113
lit
lit
121
174
121
171
IX
131
133
1.5
140
IX
191
144
170
174
171
112
lit
in
117
114
117
lit
7.0
Hi
200
711
711
72t
732
731
743
741
792
79t
791
743
744
7.9
233
2X
243
274
213
211
211
304
sot
319
370
374
371
337
S.O
2W
300
314
321
131
341
3)7
344
371
371
313
Sit
314
Sit
0.) M 1.9 2.1 2.9 3.0
73
79
7t
77
71
21
X
X
31
32
37
37
33
33
47
X
U
95
57
M
40
41
42
43
44
4)
44
47
70
7)
Tt
12
1)
17
n
ti
13
n
14
17
tt
100
13
100
10)
110
113
114
111
127
174
12t
121
IX
132
133
117
179
132
137
142
I4i
141
157
195
150
140
142
144
144
140
IX
1)1
149
170
175
171
IK
lit
111
112
m
117
209
-------
»nt (•}
CT MLICS F0» IMCTIWTIOI
OF tlKtlt CfSIS IT rit[
. »1 10 C
(R.CMXI U) IntctxitioM
|i}1)
Cj.4
0.4
O.I
1
1.2
1.4
1.4
1.1
2
2.2
2.4
2.4
2.1
3
tttmiff
communoN
IM/LI
£0.4
0.4
O.I
1
1.2
1.4
1.4
t |
2
2.2
2.4
2.4
2.1
3
OUMK
(ig/L)
£0.4
0.4
O.I
1
1.2
1.4
1.4
1.1
2
2.2
2.4
2.4
2.1
3
0.9
11
12
13
13
14
14
13
13
13
13
14
14
14
14
1.0
•j
29
24
27
21
21
21
M
30
31
31
37
32
33
1.3
34
37
31
40
42
43
44
43
44
44
47
41
41
41
2.1
44
41
32
14
14
17
SI
M
41
42
43
44
43
49
>H'7.S
2.3
17
42
43
47
41
71
73
73
74
n
71
M
11
12
3.0
41
74
71
11
13
U
n
10
11
13
14
14
17
n
llf iMCtitltlMI
| •>
21
23
24
23
24
24
27
21
21
21
21
21
30
30
0 Y
30
32
34
39
34
37
31
31
40
40
41
42
42
43
1 1
42
43
41
SO
91
S3
94
39
94
$7
SI
91
40
40
let
1 0
M
44
41
70
72
74
74
71
71
11
17
13
14
13
l.S
44
U
72
73
77
71
11
13
14
14
17
U
11
11
2.1
19
11
14
100
103
104
IM
110
112
114
114
III
111
121
•H.1.3
7
-------
ttflC E-4
C! VIWCS FOR lUCIIVMIM
OF IllttU CTSTS IT Fin CM.OK1K
IT 15 C
•tW.S
£-0.4
0.4
O.I
I
1.2
1.4
1.4
1.1
2
2.2
2.4
2.4
2.1
1
£0.4
C.
o.
1.
I.
2.
Ut Ir.Ktmtmi
10
to
10
10
10
10
11
11
11
15
14
17
11
11
11
11
20
20
21
21
21
22
22
a
u
24
27
21
21
21
10
10
11
11
12
12
U
11
II
15
14
17
11
11
40
41
41
42
42
41
44
•K.7.5
II
41
41
45
44
41
41
SO
SI
52
52
51
54
54
U
41
57
54
54
57
51
40
41
42
4!
44
45
45
IM iMch,,t,.M
0.5
14
15
14
17
17
II
11
11
11
11
11
20
20
20
1.0
21
10
12
n
14
15
14
17
17
II
11
11
40
49
1.5
42
45
41
50
51
51
54
55
54
57
SI
51
40
40
2.0
54
41
44
44
41
70
72
74
75
74
77
n
M
10
2.5
71
74
to
U
14
n
to
12
14
15
17
n
n
101
1.0
15
"11
14
100
10]
IM
ici
110
112
114
114
111
III
121
M.M1I
aetnw
It leg Uictiutioaf
ipg _____
IM'U 0.5
5-0.4 20
0.4 . 21
0.
•
J.
1.
;.
«
j.
2.
2.
21
21
24
25
25
24
24
27
27
21
21
21
1.0
40
4!
45
47
41
SO
SI
52
SI
54
55
55
54
$7
I.S
40
44
41
70
72
74
74
71
71
11
n
n
14
15
2.0
M
14
to
14
17
tl
102
104
104
IM
IM
111
112
114
2.5
IM
107
111
117
121
124
127
110
112
114
IP
lit
140
142
1.0
120
121
115
140
145
141
151
154
151
141
144
144
141
170
i
01
10
10
11
11
17
12
12
12
11
11
II
11
11
14
.Of IM
1 0
11
20
22
22
21
24
24
25
25
24
24
24
27
27
ictui
1 •>
21
II
12
14
15
14
14
17
U
n
it
40
40
41
tIMI
2.0
11
41
.41
45
44
47
41
50
SI
SI
52
SI
54
54
2.5
41
SI
54
54
M
51
41
42
41
44
45
44
47
41
57
41
45
47
41
71
73
74
74
77
71
71
10
11
Lot luctivitim
0.5
17
11
11
20
29
21
22
22
22
21
21
23
74
24
1.0
14
14
18
40
41
42
41
44
45
44
44
47
47
41
1.5
51
54
57
51
41
41
45
44
47
41
41
70
71
n
2.0
47
72
74
71
12
14
14
n
to
ti
n
14
15
W
pN't.O
2.5
H
11
15
11
102
105
IM
110
112
114
114
117
III
120
1.0
101
101
114
111
121
124
121
112
114
117
111
141
142
144
Lot iMCtiMtim
0.5
21
25
24
27
21
21
10
10
11
II
12
12
n
n
1.0
47
SO
51
55
57
SI
40
41
42
41
44
45
44
44
1.5
70
75
71
12
15
11
n
11
11
14
n
17
ti
IM
2.0
n
IM
105
110
11!
114
111
121
124
124
121
110
III
in
2.5
117
125
112
117
141
145
141
152
155
157
140
142
144
144
1.0
140
150
151
144
170
174
171
112
114
in
112
114
117
111
L« l-KUrtim
0.5
12
11
11
14
14
15
15
15
15
14
14
14
14
17
1.0
8
25
24
27
21
21
10
M
II
12
12
12
11
n
1.5
33
II
40
41
42
44
45
44
44
47
41
41
41
SO
2.0
47
SO
51
55
57
SI
40
41
42
4!
44
45
44
47
2.5
SI
41
44
41
71
n
74
74
n
71
M
11
12
n
1.0
70
75
71
12
15
17
n
11
11
15
14
17
tl
100
-------
IIH.E M
n VM.UES rn IMCTIVMIOI
V IIHtll CTSIS II mi CMLWIff
•«20C
CtC'M 1:; lm:ti««tiw.t
It
*m i »w i
0.4
(.1
1
i.:
1.4
1.4
I.I
2
7.7
7.4
7.4
2.1
3
0
f
4
4
4
7
7
7
7
7
11
i:
n
n
14
14
IS
i;
is
13
14
14
14
14
17
II
11
20
71
71
77
22
23
21
J4
24
;i
74
•
23
23
24
V
21
21
21
30
30
31
31
32
32
31
21
31
32
34
33
34
37
37
31
31
31
40
40
41
34
37
Jl
40
42
43
44
45
44 -
44
47
41
41
41
ON>7.3
CK.ni*E
CBuH
HlTinn
S0.4
0.4
0.1
1
1.2
1.4
1.4
1.1
7
7.7
7.4
7.4
7.1
3
MOXIIC
IM/I)
0.4
0.1
1
1.7
1.4
1.4
1.1
7
2.2
2.4
2.4
2.1
1
3
.1
.1
a
a
ii
u
14
14
14
14
13
13
19
IS
lit iMttiMUM
1.0
21
21
24
29
24
24
27
21
21
21
21
21
30
30
1.9
37
34
34
n
31
40
41
41
47
43
44
44
43
43
7.0
47
43
41
30
31
31
34
33
34
37
31
3t
40
40
»*
2.3
33
37
40
42
44
44
41
41
70
71
n
74
75
73
3.0
44
41
72
75
n
n
11
13
14
14
17
N
It
11
Lot UictmtiMi
0.9
19
14
17
11
II
It
It
It
70
70
20
21
21
21
1.0
30
32
34
33
34
37
31
31
40
40
41
47
47
41
1.3
43
41
31
31
34
34
37
31
31
40
41
42
43
44
2.0
40
44
41
70
n
74
74
n
71
11
17
n
14
IS
2.3
73
10
14
n
11
«
15
17
It
101
102
104
105
104
3.0
W
14
101
103
IM
112
114
117
111
121
121
125
124
121
1*1 luctioitiMi
0.3 1.0
14
19
14
17
17
11
II
It
It
10 It
10 20
10 20
10 20
10 20
1.3
21
23
24
23
.24
27
27
21
21
21
21
30
30
31
2.0
21
31
37
34
33
34
34
17
31
31
31
40
40
41
2.3
34
31
40
47
43
43
44
47
47
U
41
30
90
91
3.0
41
44
41
30
92
91
93
94
97
91
91
40
M
41
0.3
13
14
14
IS
19
14
14
14
17
17
17
11
II
11
1.9
17
11
20
21
21
22
22
21
21
24
24
24
23
23
lit
1.0
23
27
n
30
31
32
37
33
34
34
31
33
34
34
let
1.0
33
31
40
41
42
44
43
44
44
47
41
41
41
30
Uictmtim
1.9
a
41
43
49
44
47
41
41
30
31
32
33
33
34
1
7.0
31
34
37
91
41
43
43
44
47
U
41
70
71
n
1*1.0
2.9
43
41
71
74
77
71
II
17
14
IS
17
n
it
to
3.0
74
11
14
11
17
13
17
It
101
107
104
103
107
IN
luctiwtiMt
1.3
32
34
91
47
44
49
47
41
70
71
77
73
74
79
7.0
70
n
71
17
IS
17
Hi
tl
13
14
n
17
It
100
2.9
17
14
11
101
104
101
112
114
114
111
120
177
171
ITS
3.0
103
113
lit
171
177
111
134
117
lit
147
144
144
141
ISO
let Iucti>iti9*t
1
1
10
10
11
11
11
11
17
17
17
17
17
17
11
It
20
71
21
27
27
71
21
24
24
24
29
29
1 ,
14
21
30
Si
32
31
34
34
33
]J
34
37
jj
37
7 0
33
11
40
41
42
44
43
44
44
47
41
41
4t
X
44
47
4t
31
91
J9
34
37
91
31
40
41
42
47
3.0
3:
94
91
47
44
49
47
U
70
71
77
73
74
73
-------
TMIE E-4
CT V»ltltS rw INACTIVMIW
OF CIMDlt ttSTS IT «EE 00.0*1 IE
•I 25 C
rnffiTfitTIftM
lUHbtN 1 nm ' • •*!•
|«g'l)
~ 9.4
0.8
1
1.2
1.1
l.i
l.B
2
2.2
:.4
2.4
:.B
3
CR.3MSE
(eg/I)
<0.4
0.4
0.9
1
1.2
1.4
1.4
l.B
2
2.2
2.4
2.4
2.B
3
log
1
1
1
1
1
10
10
10
10
10
1C
11
11
5 11
log
0.1 1.0
7 14
15
14
17
17
18
IB
18
It
10 It
10 11
10 20
10 20
10 20
Inictititior.t
11
12
13
13
14
14
1!
i!
li
11
14
14
14
14
11
14
17
18
11
It
11
20
70
71
;i
71
22
22
pH«7.i
11
71
77
77
73
74
24
21
75
74
74
77
77
77
73
25
74
77
78
71
21
30
30
31
Jl
32
jj
3:
Inictivitiant
l.i
21
23
24
21
24
74
77
78
28
21
71
21
30
30
2.0
28
30
32
33
34
3!
34
J7
37
38
31
31
40
40
. ^
31
:e
40
41
43
44
41
44
47
48
48
41
10
10
1 0
42
4!
48
»
•1
13
54
!5
16
17
iB
it
4)
4,1
t 1
}
i
4
4
4
4
4
4
4
7
7
7
7
C.i
1
t
10
10
10
11
11
11
11
11
12
12
1?
12
U)
t 0
10
10
11
11
12
12
12
12
13
13
13
13
13
14
lei
1.0
17
It
It
20
20
21
22
22
22
23
23
23
24
24
Inictiutieni
14
13
14
" 17
17
18
18
It
It
11
20
20
20
20
2.0
11
20
22
22
23
24
24
21
21
24
24
:i
27
27
pH=8.0
7 ^
24
24
27
21
21
30
30
31
32
37
33
33
34
34
21
31
32
34
35
34
34
37
a
31
31
40
40
41
Inictititior.i
1.1
21
27
21
30
31
32
32
33
34
34
:i
:i
34
34
2.0
34
34
38
40
41
42
43
44
41
44
44
47
47
48
7.!
42
4}
48
M
11
13
14
55
14
57
il
it
it
M
3.0
il
14
17
it
41
43
45
44
47
48
41
70
71
72
lit l«»tlmtio.ii
0 1
4
4
7
7
7
7
7
1
1
1
1
1
1
1
1.0
12
13
13
14
14
11
11
15
li
14
14
14
14
17
I.}
11
It
20
21
21
22
22
23
23
74
74
74
25
21
2.0
23
25
24
11
78
2t
30
30
31
32
32
32
33
33
j 5
21
31
3:
34
35
34
37
38
31
31
40
41
41
47
1 0
31
31
40
41
42
44
4!
44
44
47
48
4t
41
«
CM.M1K
COKHTMTKW
(M/LI 1
<• 0.4 |0
0.4 . U
C.I U
1 12
1.7 12
1.4 12
I.
^.
•
2.
2.
2.
13
13
13
13
14
14
14
14
10,1
1.0
20
21
23
23
24
71
71
74
74
77
77
71
78
71
BtCtil
1.1
30
37
34
31
34
37
31
31
40
40
41
47
47
43
ttic.it
2.C
40
43
41
47
41
M
11
12
13
14
11
11
14
17 '
2.1
10
!3
14
it
40
42
44
41
44
47
M
41
70
71
3.C
49
44
48
70
72
74
74
78
71
11
i;
13
84
.n
pH'I.O
leg Inictivitiont
0 1
12
13
13
14
14
li
1!
15
11
14
14
14
14
17
1.0
23
2!
24
27
28
21
30
30
31
31
32
32
33
33
l.i
31
38
40
41
42
44
41
44
44
47
48
41
41
iO
2.0
47
10
13
11
17
18
40
41
42
43
44
41
44
44
7 ,
58
43
44
48
71
73
74
74
77
71
10
11
12
13
T 0
70
71
71
12
85
17
6t
11
13
14
14
17
18
100
-------
TABLE E-7
CT VALUES FOR GREATER THAN 4 LOG
INACTIVATION OF VIRUSES BY FREE CHLORINE
Temperature (C)
pH 0.5 5 10 15
6.0 31 22 16 11
6.5 38 27 20 14
7.0 47 33 25 17
7.5 56 40 30 20
8.0 67 48 36 24
8.5 80 57 43 28
9.0 93 66 50 33
TABLE E-8
CT VALUES FOR
CHLORINE DIOXIDE INACTIVATION
OF GIARDIA CYSTS pH 6-9
Temperature (C)
Removal 0.5 5 10 15
0.5 log 13 9 7 4.5
1 log 27 18 13 9
1.5 log 40.5 27 20 13.5
2 log 54 36 27 18
2.5 log 67 45 33 22.5
3 log 81 54 40 27
20 25
8 5
10 7
12 8
15 10
19 12
21 14
25 17
20 25
3 2
7 5
10.5 7
14 9
17.5 11.5
21 14
-------
TABLE E-9
CT VALUES FOR GREATER THAN 4 LOG
INACTIVATION OF VIRUSES BY CHLORINE DIOXIDE
0.5
13
Removal
0.5 log
1 log
1.5 log
2 log
2.5 log
3 log
Temperature (C)
5 10 15 20
8753
TABLE E-10
CT VALUES FOR
OZONE INACTIVATION OF
GIARDIA CYSTS pH 6-9
Temperature (C)
0.5 5 10 15 20
0.8 0.5 0.4 0.4 0.3
1.7 1 0.8 0.7 0.5
2.3 1.5 1.3 1.0 0.8
3.3 2 1.7 1.3 1.0
3.7 2.5 2.1 1.7 1.2
4.5 3 2.5 2 1.5
TABLE E-ll
CT VALUES FOR GREATER THAN 4 LOG
INACTIVATION OF VIRUSES BY OZONE pH 6-9
Temperature (C)
25
2.
25
0.2
0.3
0.5
0.7
0.8
1.0
0.5 5 10 15 20 25
0.8 0.5 0.4 0.4 0.3 0.2
-------
TABLE E-12
CT VALUES FOR
CHLORAMINE INACTIVATION OF GIARDIA CYSTS pH 6-9
Removal
0.5 log
1 log
1.5 log
2 log
2.5 log
3 log
0.5
>5,000
Temperature (C)
0.5 5 10 15 20
690 363 337 250 181
1,295 737 675 505 366
1,900 1,100 925 750 550
2,590 1,435 1,349 1,009 738
3,154 1,826 1,536 1,245 913
3,800 2,200 1,850 1,500 1,100
TABLE E-13
CT VALUES FOR GREATER THAN 4 LOG
INACTIVATION OF VIRUSES BY CHLORAMINES
Temperature (C)
5 10
>5,000 >5,000
25
130
260
375
532
623
750
15
>5,000
-------
APPENDIX F
BASIS FOR CT VALUES
-------
APPENDIX F
BASIS FOR CT VALUES
(from Regli, 1987)
Free Chlorine
The CT values for free chlorine in Tables E-l through E-6 are based
77 • 7
on animal infectivity data by Hibler et al. (1987), and regression analysis of
Hibler's data by Clark et al. (1987). As a safety factor, the CT values
yy • y
are defined as those needed to achieve 99.99 percent (4 log) inactivation
under experimental conditions. If this safety factor were not applied, the
CT values in the appendix would be about 25 percent lower.
77 . 7
Hibler's data were developed at temperatures of 0.5 C to 5 C, pH levels
from 6 to 8, and free chlorine concentrations between 0.44 mg/L to 4.23 mg/L.
Clark's model equation:
n 00,1-7 o°-1758 o2-7519 *. -0.1467
CT = 0.9847 C pH temp
was applied to generate CT values for chlorine concentrations from 0.4 mg/L to
3.0 mg/L, pH concentrations from 6 to 9, and temperatures from 0.5 C to 5 C.
CT values for temperatures above 5 C were estimated assuming a twofold
decrease for every 10 C. CT values for temperatures at 0.5 C were estimated
assuming a 1.5 times increase to CT values at 5 C. This general principle is
supported by Hoff (1986).
Application of Clark's model to pHs above 8, up to 9, was considered
reasonable because the model is substantially sensitive to pH (e.g., CTs at
pH 9 are over three times greater than CTs at pH 6 and over two times greater
than CTs at pH 7) . At a pH of 9 about four percent of the hypochlorous acid
fraction of free chlorine is still present. Recent data indicate that in
terms of HOC1 residuals (versus total free chlorine residuals including HOC1
and ~OC1) the CT products required for inactivation of Giardia muris and
Giardia lamblia cysts decrease with increasing pH from 7 to 9 (Leahy et al.,
1987; Rubin et al., 1987). However, with increasing pH, the fraction of free
chlorine existing as the weaker oxidant species (OC1 ) decreases. In terms of
total free chlorine residuals (i.e., HOC1 and OCl") the CT products required
for inactivation of Giardia muris cysts increase with increasing pH from 7 to
9 but less than by a factor of 2 at concentrations of less than 5.0 mg/L (see
F-l
-------
Table F-l) . Also, the significance of pH on the value of CT products
achieving 99 percent inactivation appears to decrease with decreasing
temperature and free chlorine concentration. The relative effects of pH,
temperature, and chlorine concentration, inactivation of Giardia muris cysts
appears to be the same for Giardia lamblia cysts (Rubin et al., 1987),
although not as much data for Giardia lamblia cysts as for Giardia muris cysts
is yet available for high pH and temperature values.
The CT values for the various log removals for free chlorine in Appen-
dix E were determined by extrapolation of CT 99.9 values using first order
kinetics (i.e., CTnn = 1/3 x CTon _) . This extrapolation appears reasonable
yu yy.y
based on comparison with CT values determined by Jarroll, et al. (1981).
Chlorine Dioxide and Ozone
The CT values for chlorine dioxide in Table E-8 are based on disinfection
studies using in vitro excystation of Giardia muris cysts (Leahy, 1985). CT
values at 5 C and pH 7 ranged from 7 to 18 (disinfectant concentrations
ranging from 0.1 to 5 mg/L). The highest CT value, 18, was used as a basis
for extrapolation to obtain the CT and CT values in Table E-8. First
yo 9y.9
order kinetics and a safety factor of 3 were assumed, i.e.,
CTQQ Q = 3 x CTno x 3 or 3 x 18 x 3 = 81
99.9 - 99 -
CT values at 0.5 C and 15 C were estimated, based on the same rule of thumb
multipliers assumed for free chlorine, as already discussed.
The CT values for ozone in Table E-10 are based on disinfection studies
using in vitro excystation of Giardia lamblia (Wickramanayake, G. B., et al.,
1985). CT9Q values at 5 C and pH 7 for ozone ranged from 0.46 to 0.64
(disinfectant concentrations ranging from 0.11 to 0.48 mg/L). No CT values
were available for other pHs. The highest CT value, 0.64, was used as a basis
for extrapolation to obtain the CT and CT values applying the same
90 99.9
principles as discussed for chlorine dioxide.
A much larger safety factor was applied to the ozone and chlorine dioxide
data than to the chlorine data because:
a. Less data were available for ozone and chlorine dioxide than for
chlorine;
F-2
-------
TABLE F-l
CT PRODUCTS TO ACHIEVE 99 PERCENT
INACTIVATION OF GIARDIA MURIS CYSTS BY FREE CHLORINE
Temperature
(C)
1
15
1
15
1
15
(Source: Rubin,
0.2-0.5
500
200
510
440
310
et al., 1987)
Concentration
0.5-1.0
760
290
820
220
1,100
420
(mg/L)
1.0-2.0
1,460
360
1,580
1,300
620
2.0-5.0
1,200
290
1,300
320
2,200
760
-------
b. Data available for ozone and chlorine dioxide, because of the
limitations of the excystation procedure, only reflected up to or
slightly beyond 99 percent inactivation. Data for chlorine, based
on animal infectivity studies rather than excystation procedures,
reflected inactivation of 99.99 percent. Extrapolation of data to
achieve CT values for 99.9 percent inactivation with ozone and
chlorine dioxide, versus the direct determination of CT values for
achieving 99.99 percent inactivation using chlorine, involved
greater uncertainty;
c. The CT values for ozone and chlorine dioxide to achieve 99.9 percent
inactivation are feasible to achieve; and
d. Use of ozone and chlorine dioxide is likely to occur within the
plant rather than in the distribution system (versus chlorine and
chloramines which are the likely disinfectants for use in the
distribution system). Contact time measurements within the plant
will involve greater uncertainty than measurement of contact time in
pipelines.
Chloramines
The CT values for chloramines in Table E-12 are based on disinfection
studies using preformed chloramines and jln vitro excystation of Giardia muris
(Rubin, 1987}. Table F-2 summarizes CT values for achieving 99 percent
inactivation of Giardia muris cysts. The highest CT values for achieving
99 percent inactivation at 1 C (2,500) and 5 C (1,430) were each multiplied by
1.5 to estimate the CT values at 0.5 C and 5 C, respectively, in
y y • y
Table E-12. The CT value of 970 at 15 C was multiplied by 1.5 to estimate
the CT value. The highest CT value of 1,500 at 15 C and pH 6 was not
y y•y yy
used because it appeared anomalous to the other data. Interesting to note is
that among the data in Table F-2 the CT values in the lower residual
concentration range (<2 mg/L) are higher than those in the higher residual
concentration range (2-10 mg/L). This is opposite to the relationship between
these variables which exists for free chlorine, indicating that for chlora-
mines, within residual concentrations practiced by water utilities (less than
10 mg/L), residual concentration may have greater influence than contact time
on the inactivation of Giardia cysts. No safety factor was applied to these
data since chloramination, conducted in the field, is more effective than
using preformed chloramines. Also, Giardia muris appears to be more resistant
than Giardia lamblia to chloramines (Rubin, 1987).
F-3
-------
CT Values for Inactivation of Enteric Viruses
CT values for achieving 0.5 log inactivation of Giardia lamblia are used
for indicating greater than a 4 log inactivation of enteric viruses for free
chlorine, chlorine dioxide and ozone. Since all systems are recommended to
achieve at least a 1 log inactivation (in some cases allowing for a 0.5 log
inactivation) of Giardia lamblia, CT values to achieve lower enteric virus
inactivation are not provided. The literature supports that the CT values
provided herein achieve substantially greater than a 4 log inactivation for
enteric viruses (generally by a factor of greater than 3), for which data
exists (Hoff, 1986; Payment et al., 1983; Liu et al., 1971; Sobsey et al.,
1987). The exception to this is for Coxsachie B-5 virus, but this virus has
never been associated with a waterbome disease.
The following paper presents a mathematical analysis for determining the
inactivation of Giardia lamblia by chlorine.
References
American Water Works Association. Water Chlorination Principles and
Practices, 1973.
Hibler, C. P.; C. M. Hancock; L. M. Perger; J. G. Wegrzn; K. D. Swabby
Inactivation of Giardia cysts with Chlorine at 0.5 C to 5.0 C American Water
Works Association Research Foundation, In press, 1987.
Hoff, J. Co Inactivation of Microbial Agents by Chemical Disinfectants,
EPA/600/52-86/067, U.S. Environmental Protection Agency. Water Engineering
Research Laboratory, Cincinnati, Ohio, September, 1986.
Jarroll, E. L.; A. K. Binham; E. A. Meyer Effect of Chlorine on Giardia
lamblia Cyst Viability. Appl. Environ. Microbiol., 41:483-487, 1981.
Leahy, J. G.; Rubin, A. J.; Sproul, O. J. Inactivation of Giardia muris Cysts
by Free Chlorine. Appl. Environ. Microbiol., July 1987.
Liu, O. C.; Seraichekas, H. R.; Akin, E. W.; Brashear, D. A.; Katz, E. L.;
Hill, Jr., W. L. Relative Resistance of Twenty Human Viruses to Free Chlorine
in Potomac Water. 1971.
Payment, P.; Trudel, M.; Plante, P. Elimination of Viruses and Indicator
Bacteria at Each Step of Treatment During Preparation of Drinking Water at
Seven Water Treatment Plants. Appl. Environ. Microbiol., 49:1418, 1985.
F-4
-------
TABLE F-2
CT VALUES FOR 99 PERCENT
INACTIVATION OF GIARDIA MURIS CYSTS BY MONOCHLORAMINE*
pH
6
(Rubin et al. ,
Temperature
(C)
15
5
1
15
5
1
15
5
1
15
5
1
1987)
Monochloramine
<0.2
1,500
>1,500
>1,500
>970
>970
2,500
1,000
>1,000
>1,000
890
>890
>890
Concentration (mg/L)
2.0-10.0
880
>880
>880
970
1,400
>1,400
530
1,430
1,880
560
>560
>560
*CT values with ">" signs are extrapolated from the known data.
-------
Regli, S. USEPA Disinfection Regulations. Presented at AWWA Seminar
Proceedings: Assurance of Adequate Disinfection, or CT or Not CT. Kansas
City, Missouri, June 14, 1987.
Rubin, A. J. Factors Affecting the Inactivation of Giardia Cysts by
Monochloramine and Comparison with other Disinfectants. Presented at the
DSEPA/AWWARF Conference, Cincinnati, Ohio, In press, March, 1987.
Sobsey, M D.; Fuji, T.; Shields, P. Inactivation of Hepatitus A virus and
Model Viruses in Water by Free Chlorine. Presented at USEPA/AWWARF
Conference, Cine., OH, March, 1987.
Wickramanayake, G. B.; A. J. Rubin; Sproul, O. J. Effects of Ozone and
Storage Temperature on Giardia Cysts. J.AWWA, 77(8):74-77, 1985.
F-5
-------
INACTIVATION OF GIARDIA LAMBLIA BY CHLORINE:
A MATHEMATICAL AND STATISTICAL ANALYSIS
by
Robert M. Clark
Eleanor J. Read
and
John C. Hoff
DRINKING WATER RESEARCH DIVISION
WATER ENGINEERING RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
May 21, 1987
-------
INACTIVATION OF GIARDIA LAMBLIA BY CHLORINE:
A MATHEMATICAL AND STATISTICAL ANALYSIS
by
Robert M. Clark,3 Eleanor J. Readb and John C. Hoffc
INTRODUCTION
Waterborne disease in the U.S. has been reduced by the use of sand
filtration, chlorine disinfection, and the application of Drinking
Vater Standards.* The annual number of all reported waterborne disease
outbreaks dropped from 45 per 100,000 in 1938-1940 to 15 per 100,000 in
1966-1970. The average annual number of reported outbreaks ceased to fall
around 1951, and has increased slightly for reasons unknown at this time.
Amendments to the Safe Drinking Water Act (PL 93-523) highlight the
continuing problea of waterborne disease by mandating EPA to promulgate
(a) criteria by which filtration will be required for surface water supplies
and '(b) disinfection requirements for all water supplies in the United
States. EPA's Office of Drinking Water is proposing to use the C-t (Concen-
tration times Time - disinfectant residual concentration in ng/L multiplied
by the disinfectant concentration contact time in ninutes) concept as one
of the criteria for determining when filtration might not be required. In
aDirector, Drinking Water Research Division, Water Engineering Research
Laboratory, 26 W. St. Clair Street, Cincinnati, OH 45268
"Senior Statistician, Computer Sciences Corporation, 26 W. St. Clair St.
Cincinnati, OH 45268
cMicrobiologist, Drinking Water Research Division, Water Engineering
Research Laboratory. 26 W. St. Clair Street, Cincinnati, OH 45268
-------
particular, the Office of Drinking Water is interested in applying the C«t
concept for determining the inactivation of Giardia lamblia cysts, as the
most resistant organism for which such data is available.
Among individual agents, Giardia ranks number one in causes of waterborne
illnesses and number four as an etiological agent for waterborne outbreaks,
even though it was first identified as a causative agent in the mid-1960's.*
The combination of resistance and prevalence have caused Giardia to become
a major focus in considering criteria for determining when filtration
vould be required. The Office of Drinking Water is developing criteria under
which a utility would be required to meet source water quality conditions,
maintain a protected watershed and achieve C't values which provide a
99.92 inactivation of Giardia lamblia cysts, in order to avoid filtration.
Variances from these requirements are being developed. If, for example,
a utility in addition to meeting other requirements, can demonstrate that
through effective disinfection, manifested by a sufficient C*t value, it
can reduce Giardia levels by 99.9%, then it will be exempted from surface
water filtration.
In this paper the C*t concept is applied to inactivation of G_. Lamblia
by.free chlorination of Giardia cysts. The disinfection data used are the only
G. Lamblia inactivation data available that are based on animal infectivity
rather than in vitro excystation.
THE Ot CONCEPT
In comparing the biocidal effectiveness of disinfectants, the major
considerations are the disinfectant concentration and time needed to attain
inactivation of a certain proportion of the population exposed under speci-
fied conditions. The "C't" concept that is in current use is an empirical
2
-------
equation stemming from the early work of Watson^ and is more correctly
expressed as:
K - C"t (1)
where
K - constant for a specific microorganism exposed under specific
conditions
C - disinfectant concentration
n - constant, also called the "coefficient of dilution"
t - the contact time required for a fixed percent inactivation
It is based on the van't Hoff equation used for determining the nature of
chemical reactions in which the value n determines the order of the chemical
reaction.''*
The application of this equation to disinfection studies requires
multiple experiments where the effectiveness of several variables, such
as pH, temperature, and the disinfectant concentration are examined to
determine how they affect the inactivation of raicrobial pathogens. The
disinfection concentration (C), and time (t), necessary to attain a soecific
degree of inactivation (e.g. 99Z) are plotted on double logarithmic paper.
Such a plot results in a straight line with slope n.^»6 Figure 1 illustrates
data plotted in this manner and also the significance of the value of n in
extrapolation of disinfection data.^ When n equals 1, the C*t value remains
constant regardless of the disinfectant concentration used, i.e., disinfectant
concentration and exposure time are of equal importance in determining the
inactivation rate, or the C*t product, K. If n is greater than 1, disinfectant
concentration is the dominant factor in determining the inactivation rate
while if n is less than 1, exposure tice is nore important than disinfectant
-------
10.000
UJ
i
h-
_j
o
0.01
100 '1000
DISINFECTANT CONC., (MG/L)
Figure 1. Effect of n Value on C't Values at Different Disinfectant
Concentrations (C't Values Given in Parentheses)7
-------
concentration. Thus, the value of ir is a very important factor in determining
the degree to which extrapolation of data from disinfection experiments is
Q
valid. In addition, Morris0 pointed out that the evaluation of n is valid
only if the original experimental data follow Chick's Law which is normally
not the case. Morris8 further cautioned as follows:
"Watson's law must be regarded as purely empirical, handy
for coordination and interpolation but dangerous with respect to
extrapolation. Even the form has no basic justification. So
the relation is uninstructive with regard to mechanisms of
germicidal action. Intuitively a value of (n) equal to unity
seems natural; indeed, in most instances where appropriate
studies of aqueous disinfectants have been made the values found
for (n) fall within the range 0.8 to 1.2. For such cases the
deviations from unity seem more likely to be the result of
experimental aberration than to be true variations.
Greater reproducible deviations are observed with a nuaber
of germicide-microbe systems, however, ranging from 0.5 up to
2.0. Nothing is known so far about the meaning of these values.
Yet, their occurrence makes it difficult practically to compare
the relative potencies of disinfectnats for these will shift
with concentrations."
FACTORS AFFECTING C't
The destruction of pathogens by chlorinacion is dependent on a number
of factors, including water temperature, pH, disinfectant contact time,
degree of mixing, turbidity, presence of interfering substances, and con-
centrations of chlorine available. The pH especially, has a significant
effect on inactivation efficiency because it determines the species of
chlorine found in solution.
The impact of temperature on disinfection efficiency is also signifi-
cant. For example, Clarke's^ work in virus destruction by chlorine indicates
that contact time oust be increased two to three tines when the temperature
is lowered 10*C. Disinfection by chlorination can inactivate Ciardia
cysts, but only under rigorous conditions. Most recently, Hoff et al.
-------
concluded that (1) these cysts are among the most resistant pathogens
known, (2) disinfection at low temperatures is especially difficult, and (3)
treatment processes prior to disinfection are important.
Jarroll £t^£l»11 have shown that 99.8 percent of Giardia cysts can be
killed by exposure to 2.5 mg/L of chlorine for 10 minutes at IS'C at pH 6,
or after 60 minutes at pH 7 or 8. At 5°C, exposure to 2 mg/L of chlorine
killed 99.8 percent of all cysts at pH 6 and 7 after 60 minutes. While it
required 8 mg/L to kill the same percentage of cysts at pB 6 and 7 after 10
minutes, it required 8 mg/L to inactivate cysts to the same level at pH 8
after 30 minutes. C*t values for 99% inactivation of Giardia lamblia by free
chlorine at different temperatures and pHs are shown in Table 1. 'Cyst
viability following the chlorine contact time was determined by in vitro
excystation. Inactivation rates decreased at lower temperatures and at
higher pHs as indicated by the higher C-t values.
TABLE 1. C-t VALUES FOR 99Z INACTIVATION OF GIARDIA
LAMBLIA CYSTS BY FREE CHLORINE3
Temp
(°C)
5
15
25
pH
6
7
8
6
7
8
6
7
8
Disinfectant
Concentration
(mg/1)
1.0-8.0
2.0-8.0
2.0-8.0
2.5-3.0
2.5-3.0
2.J-3.0
1.5
1.5
1.5
Range
Time
(min)
6-47
7-42
72-164
7
6-18
7-?.l
< 6 ~
< 7
< 8
C-t
47-84
56-152
72-164
18-21
18-45
21-52
< 9
<10
<12
Mean
C-t
65
97
110
20
32
37
- < 9
<10
<12
No. of
Exp.
4
3
3
2
2
2
• 1
1
1
Calculated from Jarroll et al.11
-------
Quantification of the combined" effects of pH, temperature and disin-
fectant concentrations require special techniques which take into account the
interaction of these variables so they can be described by a single value.
In the following section, cyst inactivation data from animal infectivity
studies conducted by Hibler12 are described and the results of statistical
analysis of this data are presented to show what effects the interaction of
chlorine concentration, pH and temperature have on the inactivation of Giardia
cysts.
ANIMAL INFECTIVITY DATA
The cysts of G. lanblia are among the most resistant to disinfection and
chlorine is the most frequently used disinfectant in the U.S. This has led
to widespread examination of C*t values for Giardia and chlorine. One of the
nost important studies to examine the effect of chlorine on Giardia cysts was
conducted by Dr. Charles Hibler at Colorado State University.*- Dr. Hibler
acquired G. lamblia isolates fron several human sources and maintained them
by passage in mongolian gerbils. Cysts obtained from these animals were used
to develop C«t values for 99.99 percent inactivation of Giardia cysts with
chlorine at temperatures of .5, 2.5 and 5*C and at pH values of 6, 7 and 8.
In these experiments clean G. lamblia cysts at a concentration of 1.02 x
10^ cysts/nL were exposed to selected chlorine concentrations at appropriate
pH and temperature. At specified time intervals for each temperature and pH
condition, chlorine activity was stopped by the addition of sodium thio-
sulfate. The treated cyst suspension was centrifuged, the supernatant poured
off and the cysts rcsuspcndcd in a small volume of buffer. Each of 5 gcrblls
was fed 5 x 10^ of the concentrated chlorino exposed cysts.
-------
Equal numbers of positive control animals were each orally inoculated with 50
unchlorinated cysts maintained and buffered at the sane temperature and nH as
the chlorine exposed cysts. After 6-7 days animals were exaained to determine
the number per group infected. Since the test animals had each received a
dose of 5 x 10* cysts and since infectivity studies with unchlorinated cysts
showed that approximately 5 cysts usually constituted an infective dose, the
following assumptions were made depending on the infectivity patterns occurring
in the animals receiving chlorine exposed cysts. If all five animals were
infected, then it was assumed that the C't had produced less than 99.992
inactivation and if no animals were infected, then it had produced greater
than 99.99Z inactivation. It is impossible to determine the exact level of
inactivation for these results. If, however, 1-4 animals were infected then
it was assumed that the level of cysts was about 5 per aniaal since soae were
infected and some were not. The C't values for this breakthrough group vere
then considered to produce 99.99% inactivation and these data were used in
the statistical analysis.
STATISTICAL ANALYSIS
Table 2 summarizes Hibler's data for the different experimental conditions
examined. Column 1 in Table 2 shows the chlorine concentration in ng/L to
which cysts were exposed before being fed to the gerbils and Column 2 shows the
number of experiments at that chlorine concentration which yielded 1-4 infected
gerbils out of 5. Column 3 shows the mean cyst exposure time and Column 4
contains mean C-t values that are the product of the chlorine concentration
and cyst exposure time.
In order to analyze these data a regression model that incorporates the
variables of concentration, pH and temperature was developed. This nodel is
as follows:
t - RCa pHb tcnpc (2)
3
-------
TABLE 2. C*t VALUES FOR 99.99 PERCENT INACTIVATION
(1 TO k OF 5 GERBILS INFECTED) AT DIFFERENT TEMPERATURES AND pHs
Chlorine
Concentration
(oR/L)
0.56
0.72
0.75
1.12
1.33
1.51
2.09
2.55
2.90
3.08
3.32
3.32
3.56
3.93
0.53
0.81
0.92
1.26
1.84
2.07
2.59
2.84
3.64
3.80
0.44
0.62
0.78
0.98
1.19
1.56
1.87
1.99
2.05
2.15
2.36
2.93
3.01
3.47
Mean
Cyst
Number of Exposure
of
Time
Experiments (minutes)
pH -
1
2
1
1
1
2
2
2
1
. 3
2
2
2
3
PH -
2
1
1
1
1
1
1
2
3
2
pH -
1 -
1
1
1
3
3
1
3
2
3
1
1
3
2
6 Temperature -
300.0
208.5
272.0
157.0
138.0
99.0
• 66.0
85.0
39.0
85.0
42.5
71.0
42.5
58.5
6 Temperature "
222.0
186.0
71.0
112.0
78.0
68.0
82.0
38.5
55.3
17.5
6 Temperature •
287.0
202.0
224.0
128.0
126.0
53.3
35.0
25.0
71.0
73.7
53.0
43.0
52.7
52.0
Keen
C't
from data
(minutes)
0.5'C
166.5
150.1
204.0
175.8
183.5
149.5
137.9
216.8
113.1
- 263.3
141.1
236.1
151.3
229.9
2.5°C
117.7
150.7
65.0
141.1
143.1
140.8
212.4
109.3
201.4
66.5
5'C
124.8
125.2
174.7
125.4
149.9
83.2
65.5
49.8
145.6
158.4
125.1
126.0
153.5
180.4
Predicted
C't
(minutes)
136.1
142.5
143.5
154.0
158.7
162.3
171.8
178.0
182.0
184.0
186.4
186.5
188.7
192.0
106.6
114.9
117.4
124.2
132.6
135.5
140.9
143.2
149.6
150.7
93.0
99.0
103.1
107.3
111.0
116.4
120.2
— 121.5
122.2
123.2
125.2
130.1
130.7
134.0
-------
Table 2 (Cont'd)
Chlorine
Concentration
Mean
Cyst
Number of Exposure
of
Time
(ng/L) Exuerinents (minutes)
0.51
0.52
0.73
0.75
0.82
1.51
1.98
2.14
2.78
3.11
4.00
4.01
4.05
0.64
0.78
1.04
1.08
1.65
2.06
2.09
2.25
2.53
2.98
3.37
3.47
3.81
4.23
-
0.73
1.08
1.36
1.57
2.22
2.51
2.61
2.69
3.00 —
3.14
3.15
3.16
3.31
4.C3
pH -
1
1
1
1
2
1
1
1
1
1
1
1
1
pH -
1
1
1
1
1
1
1
1
1
1
1
1
1
1
pH -
1
1
1
1
1
1
1
1
1
1
1
2
1
1
7 Temperature -
600.0
300.0
400.0
400.0
333.5
200.0
130.0
126.0
109.0
' 93.0
75.0
75.0
75.0
7 Temperature •
350.0
334.0
250.0
244.0
155.0
121.0
127.0
55.0
89.0
93.0
103.0
66.0
58.0
75.0
7 Temperature «
227.0
152.0
106.0
106.0
66.0
67.0
60.0
63.0
54.0
56.0
67.0
47.0
67.0
50.0
Mean
C't
from data
(minutes)
0.5°C
303.6
156.0
292.0
300.0
271.8
302.0
256.8
269.6
303.0
289.?
300.0
300.8
303.8
2.5°C
224.0
260.5
260.0
263.5
255.8
249.3
265.4
123.8
225.2
277.1
347.1
229.0
221.0
317.3
5°C
165.7
164.2
144.2
166.4
146.5
168.2
156.6
169.5
162.0
175.8
211.1
148.5
221.8
204.0
•
Predicted
C-t
(minutes)
204.7
205.7
218.3
219.3
222.6
248.1
260.0
263.7
276.2
281.7
294.4
294.5
295.0
•
168.5
174.4
183.5
184.7
199.7
206.9
207.4
210.1
214.5
220.8
225.6
226.7
230.5
234.8
155.7
166.8
173.7
178.2
189.4
193.5
194.8
195.9
199.6
201.3
201.4
201.5
203.1
210.7
10
-------
Table 2 (Cont'd)
Chlorine
Concentration
"umber
of
Mean
Cyst
of Exposure
Time
(ms/L) Experiments (minutes)
0.49
0.51
0.75
1.10
1.25
2.05
2.06
2.66
3.03
3.25
0.50
0.66
0.73
1.01
1.15
1.22
1.62
1.90
2.04
2.25
2.59
2.87
3.02
3.24
0.48
0.76
0.95
1.29
1.49
1.81
1.91
2.06
3.00
3.02
3.67
pH -
2
3
2
1
3
2
3
1
2
3
pH - 8
3
2
2
2
1
3
1
1
1
1
1
1
1
1
pH -
1
1
2
2
1
1
1
1
1
3
1
8 Temperature -
593.0
311.0
250.0
395.0
294.0
' 191.0
. 193.7
132.0
173.5
133.3
Temperature • 2
390.3
342.0
431.0
231.0
207.0
212.7
217.0
195.0
128.0
130.0
135.0
126.0
109.0
54.0
8 Temperature •
417.0
263.0
288.0
241.5
235.0
213.0
137.0
180.0
95.0
116.0
95.0
Mean
C't
from data
(minutes)
0.5°C
290.6
158.6
187.5
434.5
367.5
391.6
399.0
351.1
525.7
433.3
.5°C
195.2
225.7
314.6
233.3
238.1
259.5
351.5
370.5
261.1
292.5
349.7
361.6
329.2
175.0
5°C
200.2
199.9
273.6
311.5
350.2
385.5
261.7
370.8
285.0
350.3
348.7
Predicted
C-t
(ninutes)
293.9
296.0
316.7
338.8
346.5
378.0
378.3
395.7
404.9
409.9
232.9
244.6
249.0
263.6
269.7
272.5
286.4
294.5
298.2
303.4
311.0
316.7
319.5
323.5
208.9
226.5
235.5
248.6
254.9
263.8
266.3
269.9
288.3
288.6
298.7
1!
-------
where
t - time to 99.99Z inactivation as determined from animal infectivity
C • concentration of disinfectant
pH • pH at which experiment was conducted
temp - temperature at which experiment was conducted
R,a,b,c - constants determined from regression
A log transform of equation 2 yields:
log (t) - log (R) + a log (C) + b log
-------
Equation (5) can be shown to be equivalent to equation (1) (Watson's
Law) by dividing both sides of equation (5) by "Ca~ which yields:
C~a't - R pHb tempc (6)
Assume a constant pH • pH and a constant temp - temp
K - R pHb tempc (7)
C-a-t - K
where
-a - n in equation (1)
EXTRAPOLATIONS
Equation (5) should be used only over the ranges for which it was derived:
0.44 og/L £ C £ 4.23 mg/L; 6 £ pH £ 8; 0.5*C £ temp £ 5*C; inactivation level
of 99.992. However there are well established kinetic principles that can be
applied to the results from equation (5). For example, as indicated by Clarke^,
and Hoff7 the C-t value decreases to 1/2 the previous value with every 10*C
increase in temperature.
Extrapolations from one C-t value at a given Inactivation level to a
different C-t value at another inactivation can also be cade based on first
order kinetics. It is a well known fact that the inactivation of micro-
organisms by disinfectants can be considered as having the characteristics of
the first order chemical reaction, the disinfectant and the oicroorganlsm
constituting the reactants.7 This has generally been expressed in turns of
Chick's Law which may be written.as follows:
In N/No - -rt (8)
where N/No is the fraction of the original number of organisms remaining at
tine t, and r is the proportionality constant. To illustrate the extrapolation
procedures assume an inactivation level of 90% at time tj. Using equation (8)
13
-------
yields:
In 0.10 - rti (9)
Assuming another inaetivation level of 99% at time t2 and using equation
(8) yields:
In 0.01 - rt2 (10)
If we assume Watson's law with a value of n - 1 then at tj and t2^
C'tl - K! (11)
Making the appropriate substitutions into equations :(9) and (10) yields:
In 0.10 KI
- - — (13)
In 0.01 *2
-2.3026 KT
(1A)
-4.6052 K2
or
K2 - 2 K! (15)
A general relationship that relates Ot values at different inaetivation
levels is:
In (Ni/Nj,) Ki
- -- - (16)
In (Nj/No: Kj
where N^ is the number of organism left at time tj- and Nj is the number of
organisms left at time tj . Table 3 summarizes the multiplication factors to
be applied, assuming first order kinetics, to convert a value of K^ to an
equivalent value of K.
-------
TABLE 3. MULTIPLICATION FACTORS TO CONVERT C-t VALUES FROM ONE
INACTIVATION LEVEL Kj_ TO INACTIVATION LEVEL Kj
From
Inactivation
Level i
to Inactivation
Level j
Multiplyer for
90
99
99.9
99.99
90
99
99.9
99.99
1/2
1/3
1/4
2.0
2/3
1/2
3.0
1 1/2
3/4
4.0
2.0
1 1/3
Using these veil established principles it should be possible to fix chlorine
concentrations, pH and teoperature to determine a value for C*t. Then using
kinetic principles an extrapolated C»t can be calculated for.the desired temp-
erature conditions. Another extrapolation that can be made is to estimate
the C't levels that would be required for different levels of inactivation,
for a given temperature, pH and concentration.
For example, if one wishes to use equation (5) to calculate the C*t
values required at a temperature of 5°C, a pH of 6 and a concentration
level of 4.5 mg/L of chlorine at 99 percent inactivation, one could perform
the following calculation:
In equation (5) if C - 4.5 mg/L, pH - 6 and temp - 5°C
then C-t (4.5; 6; 5; 99.99) - 0.9847 (4.50.1758)(62.7519)(5-0.1467)
or C-t (4.5; 6; 5; 99.99) - 140.3
Assuming first order kinetics the C*t value at 99 percent using Table 3
would be:
C't (4.5; 6; 5; 99.0) - 1/2 [C't ^4.5; 6; 5; 99.99)]
- 70.1
15
-------
This value is very close to the value expected from Table 1.
Another example of extrapolation would be to calculate the Ot value
for a chlorine concentration of 1»5 mg/L, pH of 6, and a temperature of
25°C for an inactivation level of 99 percent. Assume in equation (5)
C - 1.5 mg/L, pH - 6 and temp - 5°C
then Ot (1.5; 6; 5j 99.99) - 115.6
From Table 3:
Ot (1.5; 6; 5; 99.0) - 1/2 [Ot (1.5; 6; 5; 99.99)] - 57.8
If we assume thez for each 10°C increase in temperature the Ot decreased by
1/2 then:
Ot (1.5; 6; 25; 99.0) - 1/4 [Ot (1.5; 6; 5; 99.0)] - 14.4 •
Checking Table 1 for this condition yields a Ot less than 9 which is
consistent with the previous calculation. Table 4 compares the values in
Table 1 with the predicted values usin<; equation (5).
TABLE 4. COMPARISON OF IN VITRO EXCYSTATION Ot VALUES FOR 99Z INACTIVATION
OF GIARDIA LAMBLIA CYSTS VERSUS PREDICTIVE EQUATION
Temp
CO .
5
15
25
PH
6
7
8
6
7
8
6
7
8
Mean Disinfectant
Concentration
(=>g/i)
4.5
5.0
5.0
2.75
2.75
2.75
1.5
1.5
1.5
Mean
Ot
(in vitro)
65
98
110
20
32
37
<9
<10
<12
Estimated
C-t
(equation 5)
70.1
109.2
157.7
32.2
49.2
71.0
14.5
22.1
31.9
16
-------
From Table A It appears thafC't values derived by equation (5) from the
animal infectivity data are more conservative than the comparable in_ vitro
excystation data.
SUMMARY AND CONCLUSIONS
Amendments to the Safe Drinking Water Act clearly spell out Congress'
intent to require that all surface water suppliers in the U.S. install
filtration, or practice adequate disinfection to protect the health of
their customers. Giardia has been identified as one of the leading causes
of waterborne disease outbreaks in the U.S. Giardia is also one of the
most resistant organisms to disinfection by free chlorine. Therefore,
EPA's Office of Drinking Water has adopted the C-t (Concentration tines
Time) concept to quantify the inactivation of Giardia cysts by disinfection.
If a utility can assure that a large enough C*t can be maintained to ensure
adequate disinfection then it nay not be required to install filtration.
In this paper an equation has been developed that can be used to
predict C*t values for inactivation of Giardia by tree chlorine based on
the interaction of concentration, tecperature and pH. The parameters for
this equation have been derived from a set of animal infectivity data
produced by Dr. Charles Hibler of Colorado State University. This equation
provides a systematic mechanism for extrapolating C*t values within the
temperature ranges of 0.5-5°C at pH levels of 6, 7, S. Extrapolations
outside this range can be accomplished by applying well known kinetic
-principles with caution. The predictive equation yielded values that
compared favorable with the data in Table 1.
17
-------
ACKNOWLEDGEMENTS
The authors would like to acknowledge the following: Huiling Feng
from the Computer Sciences Corporation for her assistance in the analysis
of the data in this paper; Dr. Alfred Dufour and Mr. Stig Regli of EPA
for their helpful suggestions; and, Patricia Pierson and Diane Routledge
for their assistance in preparing this oanuscript.
13
-------
REFERENCES
1. Craun, G.F. "Waterborne Outbreaks fron Glardia" In Giardia and giardiasis.
Editor: Erlandson Planum Publishing Corporation (In press).
2. Watson, H. E. 1908. A note on the variation of the rate of disinfection
with change in the concentration of the disinfectant. J. Hyg. ^:536-592.
3. Berg, G., S. L. Chang, and E. K. Harris. 1964. Devitalization of micro-
organisms by iodine. 1. dynamics of the devitalization of enteroviruses
by elemental iodine. Virol. 22:469-481.
4. Fair, G. M., J. C. Geyer, and D. A. Okua. 1968. Water and Wastewater
Engineering. Vol. 2. Water purification and wastewater treatment and
disposal. John Wiley and Sons, Inc., New York, NY.
5. Fair, G. M., J. C. Morris, and S. L. Chang. 1947. The dynamics of water
chlorination. J. New Eng. Water Works Assoc. 61:285-301.
6. Fair, G. M., J. C. Morris, S. L. Chang, II Weil, and R. ?. Burden. 1943.
The behavior of chlorine as a water disinfectant. J. Aa. Water Works
Assoc. 4£:1051-1061.
7. Hoff, J. C., "Inactivation of Microbial Agents b>- Chemical Disinfectants"
EPA/600/2-86-067.
8. Morris, J. C., 1970. "Disinfectant Chemistry and Biocidal Activities"
in Proceedings of the National Specialty Conference on disinfection,
American Society of Civil Engineers, New York, NY.
9. " Clarke, N. A., G. Berg, P. W. Kabler, and L. L. Chang. "Hunan Enteric
Viruses in Water: Source, Survival, and Removability". International
Conference on Water Pollution Research, Landar, September, 1962.
10. Hoff, J. C., E. W. Rice, and F- W. Schaefer III, "Disinfection and the
Control of Waterborne Giardiapts", In proceedings of the 1984 Specialty
Conference, Environmental Engineering Division, ASCE, June 1984.
11. Jarroll, E. L., A. K. Bingham, and E. A. Meyer. "Effect of Chlorine on
Giardia Lamblia cyst Viability". Applied and Environcental Microbiology,
Vol. 41, pp. 483-487, February, 1981.
12. Hibler, C. P., Hancock, C. M., Perger, L. M., Wegrzn, J. G. and Swabby,
K. D., Inactivation of Giardia Cysts with Chlorine at 0.5'C to 5.0°C.
- American Water Works Association Research Foundation, (in press).
-19-
-------
APPENDIX G
PROTOCOL FOR DEMONSTRATING
EFFECTIVE CHLORINE-AMMONIA DISINFECTION
-------
APPENDIX G
PROTOCOL FOR DEMONSTRATING
EFFECTIVE CHLORINE-AMMONIA DISINFECTION
The chloramine CT values presented.in this manual are based upon the use
of preformed chloramines. However, under field conditions, chloramination as
a treatment process involves the addition of free chlorine and ammonia either
concurrently, or sequentially. The order of addition and timing between
adding each component is determined by needs of the utility. The relative
effectiveness will be influenced by the order of addition, the chlorine to
ammonia ratio and water pH and temperature. As a result of these various
methods of application, chloramination, as conducted in the field, may be more
effective than using preformed chloramines. Consequently, systems which
currently utilize chloramines as a primary disinfectant may not be able to
meet the CT requirements for preformed chloramines yet may wish to demonstrate
their effectiveness under local conditions rather than switch to an alternate
disinfectant. This appendix presents procedures for demonstrating effective
inactivation of Giardia and viruses by chloramine disinfection.
Giardia Cysts
Test Procedure
The tests can be conducted in a stirred batch reactor. Use of this type
of system rather than a flowthrough pilot plant makes it possible to reduce
the number of cysts used and simplifies disposal problems. The use of G_^
lamblia cysts is recommended because G^ lamblia is the pathogen of direct
concern. It is not possible to simulate mixing efficiency of the treatment as
practiced but effective mixing is assumed.
1. Taken from information provided by J. Hoff, USEPA.
G-l
-------
To 500 ml of raw source water, maintained in a stirred beaker at the
lowest temperature experienced by the utility, 350,000 G^ lamblia cysts '
cleaned by the method described by Bingham et al. (1979) or Sauch (1984) are
added. Following this, chlorine and ammonia are added, the sequence and
timing of addition, concentration, and contact time simulating the chloramina-
tion process used by the utility. At the end of the contact time, sufficient
sodium thiosulfate to neutralize the residual disinfectant is added to the
reactor. The cysts are separated from the suspending liquid, resuspended in a
small volume, and counted as described by Hoff, Rice, and Schaefer (1985). A
sufficient volume of the concentrated cysts to provide 50,000 cysts is intro-
duced into each of 5 Mongolian gerbils by stomach tube. The volume that can
be administered by this route is limited to 0.5 ml/animal. The animals are
held in individual cages for seven days and fecal specimens are examined for
the presence of cysts daily beginning on day four. The presence of cysts
indicates that sufficient viable cysts to initiate infection remained after
disinfectant contact.
The £._ lamblia cysts used must be from a human isolate adapted to infect
Mongolian gerbils. The cysts are produced in specific pathogen-free gerbils,
as described by Hibler, et al. (in press). Cysts used in the experiments
should be stored under refrigeration and should be less than five days old.
Infectivity of cysts not exposed to disinfectant should be determined either
by inoculating gerbils with low numbers of cysts as described by Hibler (in
press), or by performing an ID5Q tritration as described by Hoff, Rice and
Schaefer (1985). As a disinfectant control, the disinfectant residual remain-
ing at the end of the contact time should be determined in a separate reactor
chloraminated in the same manner but not containing cysts. This should be
compared with the residual present at the end of the contact period in the
operating system and the two should be the same.
2. Excess cysts are included to allow for losses during laboratory
manipulation and for counting.
G-2
-------
Interpretation of Results
The available data indicate that the ID for G. lamblia cysts is approx-
50 ^~"~ —"*"""""—~^
imately 5 cysts (Rendtorff, 1954; Hibler et al., in press). Since each animal
is fed 50,000 cysts previously exposed to disinfectant, absence of infection
in all of the five animals would indicate that viable cysts had been reduced
by 99.99 percent or more. This is one order of magnitude higher than the 99.9
percent inactivation level required and thus provides some margin of safety.
If any of the animals fed disinfectant-exposed cysts become infected, the
chloramination process or contact time should be altered to provide more
effective disinfection. The test should be repeated at least three times
under the same conditions and should be performed again and repeated any time
changes are made in the disinfection process. The CT value should be deter-
mined by multiplying the contact time in minutes by the disinfectant residual
(mg/L) present at the end of the contact time. For each 10 C increase in
temperature above the minimum the CT value can be reduced to half the previous
value either by reducing the contact time or disinfectant concentration,
provided that; if the disinfectant concentration is changed, the addition
sequence and the ratio of chlorine to ammonia is not changed.
Enteric Viruses
Test Procedure
It is suggested that bacteriophage MS2 of Escherichia coli be used as a
disinfection model for drinking water systems which rely upon chloramines as
an alternative disinfectant. The reasons for selecting MS2 phage include its
chemical and physical similarities to members of the genus Enterovirus, which
includes Human enterovirus 72 (hepatitis A virus) and its lack of pathogenic-
ity. Also, published research data on members of the genus Levivirus, to
which MS2 belongs, suggest that they may be expected to respond to chlorine-
based disinfection treatments in a manner biochemically similar to those of
the genus Enterovirus. The MS2 bacteriophage can easily be prepared in high
titer and the procedure for its assay is both simple and rapid. The media and
3. Taken from information provided by C. Hunt, HERL USEPA.
G-3
-------
procedures for preparing and assaying bacteriophage MS2 are listed at the end
of this appendix. The method for coliphage assay listed in "Standard Methods"
would not be adequate for this purpose, as the host bacterium given is not
suitable for MS2.
The bench scale chloramination procedure used for the virus inactivation
test should be the same as described for Giardia. The treatment plant person-
nel should first perform this test on a sample of unseeded raw water to
determine the inactivation efficiency for indigenous phages. On the same
dates as this test is performed, with as little elapsed time as possible, the
same test should be performed on a batch of raw water which has been seeded
with MS2 bacteriophage at an initial titer of from 10 to 10 plaque forming
units per mL. The inactivation efficiency can then be calculated according to
the following formulas
(raw seeded - raw unseeded) - (finished seeded - finished unseeded) .„
% inactivation = ; — —— x 100
(raw seeded - raw unseeded)
The assay procedure and bacterial host used in titering both the seeded MS2
and indigenous bacteriophages should be identical.
Interpretation of Results
The calculated percent inactivation of viruses can be used for comparison
with the required inactivation efficiency. As a margin of safety, the batch
test should yield 99.999 percent inactivation; one order of magnitude greater
than required for compliance. If this efficiency is not attained, the chlora-
mination process or contact time should be altered to provide more effective
disinfection. As with Giardia, the test should be repeated at least three
times under the same conditions and should be performed again and repeated any
time changes are made in the disinfection procedure.
G-4
-------
Materials and Assay Method
A. Mi croorgani sms
1. Bacteriophage MS2: Bacteriophaoe catalog number 15597-B1,
American Type Culture Collection.
2. Bacterial Host: Escherichia coli catalog number 15597, Ameri-
can Type Culture Collection.
B. Culture Media
1. Growth and Maintenance of Bacterial Host
a. TYE(5) Broth
10.0 g Bacto Tryptone'
1.0 g yeast extract
1.0 g glucose
8.0 g NaCl
2.0 ml 1 M CaCl
Dissolve in distilled water to a total volume of 1.0 L,
then add 0.3 ml of 6 M NaOH.
This medium should be sterilized either by autoclaving or
filtration, and then stored at a temperature of approxi-
mately 4 C. It is used in preparing bacterial host
suspensions for use in viral assays.
b. TYE Agar
Same formulation as for TYE Broth plus addition of 15 g
microbiological grade agar prior to sterilization.
This medium should be sterilized by autoclaving (which
will also serve to solubilize the agar) and then used to
prepare slant tubes for maintenance of bacterial host
stock cultures. Prepared slant tubes should be stored
under refrigeration at a temperature of approximately 4 C.
4. American Type Culture Collection, 12301 Parklawn Drive, Rockville,
Maryland 20852.
5. Tryptone-Yeast Extract.
6. Difco Laboratories, 17177 Laurel Park Drive, Levonia, Michigan
48214. Bacto and Tryptone are trade names. Similar items may be
available from other suppliers.
G-5
-------
2, Media and Diluent for Bacteriophage Assays
a. Bottom Agar
10.0 g Bacto Tryptgne
15.0 g Bacto Agar
2.5 g NaCl
2.5 g KC1
1.0 ml 1 M CaCl2
Dissolve in distilled water to a total volume of 1.0 L.
This medium should be sterilized by autoclaving (which
will also serve to solubilize the agar) , then used for
pouring into Petri dishes to form a sturdy bottom layer of
agar medium. This bottom layer serves as an anchoring
substrate for the top agar layer. This medium should be
stored at a temperature of approximately 4 C until used in
pouring bottom agar layers in Petri dishes. Immediately
prior to this use the medium would need to be liquified by
heating.
b. Top Agar
10.0 g Bacto Tryptone
1.0 g yeast extract
1.0 g glucose
6.0 g Bacto Agar
8.0 g NaCl
1.0 ml 1 M CaCl
Dissolve in distilled water to a total volume of 1.0 L.
This medium should be sterilized by autoclaving (which
will also serve to solubilize the agar). It should then
be stored at a temperature of approximately 4 C until
needed for use in bacteriophage assays. Immediately prior
to use in assays, this medium will need to be liquified by
heating, and then cooled to and maintained at a tempera-
ture of 45 C.
c. Salt Diluent for Bacteriophage Samples
8.5 g NaCl
2.0 ml 1 M CaCl
™*" ^
Dissolve in distilled water to a total volume of 1.0 L.
This diluent should be sterilized either by autoclaving or
filtration. It may then be stored at room temperature.
G-6
-------
This diluent should be used as necessary for preparing
dilutions of samples containing bacteriophage prior to
their being assayed.
C. Growth and Maintenance of Bacterial Host Cultures
and Bacteriophage Stock Suspensions
1. Preparation of Bacterial Host Stock Cultures
Host bacteria are inoculated onto TYE Agar slant tubes, incu-
bated for 24 hours at 37 C to allow bacterial growth, and then
refrigerated at 4 C. At monthly intervals the cultured bacter-
ial host should be transferred to a new TYE Agar slant, as
above, so as to maintain adequate viability.
2. Bacteriophage Stock Suspensions
Inoculate between 5 to 10 Petri dishes of host bacteria with
bacteriophage as you would do for the plaque assay procedure
described below. The bacteriophage suspension inoculated for
this technique should represent a sufficiently low dilution so
as to yield assay plates on which the host bacterial "lawn"
demonstrates nearly complete lysis following 6 to 8 hours of
post-inoculation incubation at 37 C.
Following this incubation, add between 2 to 3 ml of sterile TYE
Broth to the surface of the Top Agar layer in each Petri dish.
Then, using a sterile rubber spatula, gently scrape off the Top
Agar layers and combine them in a large centrifuge tube. Add
to this pool of top agar layers an amount of TYE Broth suffi-
cient to yield a total volume of 40 ml. To this mixture add
0.2 g of EDTA (disodium salt) and 0.026 g of lysozyme (crystal-
lized, from egg white). This mixture should then be incubated
at room temperature, approximately 23 C, for 2 hours with
occasional vortex mixing. The entire mixture should next be
centrifuged for 15 minutes at 3000G. Carefully then remove the
upper, fluid layer and sterilize it by passage through a filter
that has first been pretreated by passing a small volume of TYE
Broth through it. Use of positive pressure and a 0.22 urn pore
size filter for this step is considered important. The TYE
Broth used for pretreatment is discarded. The virus-containing
filtrate constitutes a viral stock suspension for use in
subsequent testing and assays. The viral stock suspension may
be stored frozen.
D. Performance of Bacteriophage Assay
A two-week supply of Petri dishes (100 x 15 mm) may be poured with
Bottom Agar ahead of time and refrigerated at 4 C. The amount of
Bottom Agar added per dish should be approximately 15 ml. Eigh-
teen hours prior to beginning a phage assay, a bacterial host
G-7
-------
suspension should be prepared by inoculating 5 ml of TYE Broth with
a small amount of bacteria taken directly from a slant tube culture.
The broth containing this bacterial inoculum should then be incubat-
ed overnight (approximately 18 hours) at 37 C immediately prior to
use in bacteriophage assays as described below. This type of broth
culture should be prepared freshly for each day's bacteriophage
assays. If necessary, a volume greater than 5 ml can be prepared in
a similar manner.
On the day of assay, a sufficient amount of Top Agar should be
melted and then maintained at 45 C in a waterbath. Test tubes
(13 x 100 mm) should be placed in a rack in the same waterbath and
allowed to warm, following which 3 ml of Top Agar is added to each
tube. The test tubes containing Top Agar are next inoculated with
the bacteriophage samples (0.5 to 1.0 ml of sample per tube) plus
0.1 ml of the overnight bacterial host suspension. The bacterio-
phage samples should be diluted appropriately in salt diluent prior
to inoculation. The test tubes containing Top Agar, bacteriophage
inoculum, and bacterial host suspension should then be agitated
gently on a vortex mixer, and the contents of each poured onto a
hardened Bottom Agar layer contained in an appropriately numbered
dish. The Petri dishes should then quickly be rocked to spread the
added material evenly, and placed on a flat surface at room tempera-
ture while the agar present in the added material solidifies
(approximately 15 minutes). The dishes should finally be inverted
and incubated at 37 C for a minimunr of 6 hours. The focal areas of
viral infection which develop during this incubation are referred to
as "plaques" and, if possible, should be enumerated immediately
after the incubation. If necessary, the incubated Petri dishes can
be refrigerated at 4 C overnight prior to plaque enumeration.
References
Adams, H. H. Bacteriophages. Interscience Publishers, New York, 1959.
American Public Health Association; American Water Works Association;
Water Pollution Control Federation. Standard Methods for the Examination
of Water and Wastewater, 16th ed., pp. 1033-1036, 1985.
Bingham, A. K.; Jarroll, E. L.; Meyer, E. A. Giardia sp.; Physical
factors of excystation in-Vitro, and excystation vs. eosion exclusion as
determinants of viability. Exp. Parasitol. 47,204-291, 1979.
Cramer, W. N.; Kawata, K.,° Kruse, C. W. Chlorination and iodination of
poliovirus and f^. J. Water Poll. Control Fed., 48:61-76, 1976.
Grabow, W. O. K.; Gauss-Muller, V.; Prozesky, O. W.; Deinhardt, F.
Inactivation of hepatitis A virus and indicator organisms in water by
free chlorine residuals. Appl. Environ. Microbiol., 46:619-624, 1983.
G-8
-------
Hibler, C. P., Hancock, C. M., Perger, L. M., Wegrzyn, J. G.;
Swabby K. D.. Inactivation of Giardia cysts with chlorine at 0.5 C to
5.0 C. American Water Works Association Research Foundation Research
Report, (In press, 1987).
Hoff, J. C., Rice, E. W. ? Schaefer,, F. W. III. Comparison of animal
infectivity and excystation as measures of Giardia muris cyst inactiva-
tion by chlorine. Appl. Environ. Microbiol. 50:1115-1117, 1985.
Hoff, J. C. Inactivation of microbial agents by chemical disinfectants.
EPA-600152-86-067, U. S. Environmental Protection Agency. Water Engineer-
ing Research Laboratory, Drinking Water Research Division, Cincinnati,
Ohio, September, 1986.
Mathews, R. E. F. Classification and nomenclature of viruses. Inter-
virology, 17:1-199, 1982.
Olivieri, V. P., Donovan, T. K.; Kawata, K. Inactivation of virus in
sewage. In: Proceedings of the National Specialty Conference on Disin-
fection. American Society of Civil Engineers, New York, NY, pp.
265-685, 1971.
Olivieri, V. P.; Kruse, C. W.; Hsu, Y. C.; Griffiths, A. C.; Kawata, K.
The comparative mode of action of chlorine, bromine and iodine on f
bacterial virus. In: Disinfection; Water and Wastewater. Johnson, J.
D., ed., Ann Arbor Science, Ann Arbor, MI. pp. 145-162, 1975.
Rendtorff, R. C. The experimental transmission of human intestinal
protozoan parasites. II. Giardia lamblia cysts given in capsules. Am.
J. Hyg. 59:209-220, 1954.
Safe Drinking Water Committee. The Disinfection of Drinking Water. In:
Drinking Water and Health, National Academy Press, Washington, DC.,
2:5-137, 1980.
Sauch, J. (1984) - already referenced in Guidance Manual.
Shah, P. and McCamish, J. Relative Resistance of Poliovirus 1 and
Coliphages f and T2 in Water. Appl. Microbiol., 24:658-659, 1972.
G-9
-------
APPENDIX H
SAMPLING FREQUENCY FOR TOTAL COLIFORMS
IN THE DISTRIBUTION SYSTEM
-------
APPENDIX H
COLIFORM MONITORING REQUIREMENTS
Surface Water
(1 2)
With Disinfection Only (No Filtration) '
25-500 persons: 5 samples/month
- 501-3,300 persons: 5 samples/month
- over 3,300 persons: Monitoring frequency specified in Table H-l
With Filtration and Disinfection
- 25-500 persons: 5 samples/month OR a sanitary survey every 5 years
and one sample/month
501-3,300 persons: 5 samples/month OR a sanitary survey every
3 years and 3 samples/month
- over 3,300 persons: Monitoring frequency specified in Table H-l
Notes:
1. In compliance with 40 CFR Part 141, Subpart H.
2. System must collect at least one coliform sample near the first
customer on each day that a turbidity measurement, as required in
40 CFR Part 141.74, exceeds 1 NTU.
H-l
-------
TABLE H-l
COLIFORM MONITORING FREQUENCY BY POPULATION SERVED
Served
25- 3,300
3,301- 5,800
5,801- 6,700
6,701- 7,600
7,601- 8,500
8,501-10,000
10,001-15,000
15,001-20,000
20,001-25,000
25,001-30,000
30,001-35,000
35,001-40,000
40,001-45,000
45,001-50,000
50,001-55,000
55,001-60,000
60,001-65,000
65,001-70,000
70,001-75,000
75,001-80,000
80,001-85,000
Samples/Month
Served
Note:
5
6
7
8
9
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
(1)
85,001- 90,000
90,001- 95,000
95,001- 100,000
100,001- 200,000
200,001- 300,000
300,001- 400,000
400,001- 500,000
500,001- 600,000
600,001- 700,000
700,001- 800,000
800,001- 900,000
900,001-1,000,000
1,000,001-1,200,000
1,200,001-1,400,000
1,400,001-1,600,000
1,600,001-1,800,000
1,800,001-2,000,000
2,000,001-2,500,000
2,500,001-3,000,000
3,000,001-3,500,000
3,500,001-4,000,000
over 4,000,000
Samples/Month
90
95
100
130
160
180
200
220
240
260
. 280
300
320
340
360
380
400
420
440
460
480
500
1. Unless reduced by the State as provided in 40 CFR 141.21(a). State
may permit systems serving 25-300 persons to reduce monitoring to
1 sample/month and systems serving 301-500 persons to reduce
monitoring to 3 samples/month if:
a. sanitary survey results every 3 years are satisfactory
b. system has not had a waterborne disease outbreak
c. system has record of compliance with the coliform MCLs and
monitoring requirements
-------
APPENDIX I
MAINTAINING REDUNDANT
DISINFECTION CAPABILITY
-------
APPENDIX I
REDUNDANT DISINFECTION CAPABILITY
In reviewing water disinfection facilities for compliance with redundancy
requirements, the following items should be checked:
I. General
A. Are the capacities of all components of both the primary system and
the redundant system equal to or greater than the design values?
Some systems may have two or more units which provide design levels
of the disinfectant when all are in operation. In these cases, an
additional unit is needed as backup during the downtime of any of
the operating units. The backup must have a capacity equal to or
greater than that of the largest on-line unit.
B. Are adequate safety precautions being followed, relative to the type
of disinfectant being used?
C. Are redundant components being exercised or alternated with the
primary components?
D. Are all components being properly maintained?
E. Are critical spare parts on hand to repair disinfection equipment?
F. Is there duplication of components of the system which are
indispensible for disinfecting the water?
II. Disinfectant Storage
A minimum of two storage units capable of being used alternately should
be provided. However, it is not necessary for both systems to have full
design capacity.
A. Chlorine
Storage for gaseous chlorine will normally be in 150-lb cylinders,
2,000-lb containers, or larger on-site storage vessels.
1. Is there automatic switchover equipment if one cylinder or
container empties or becomes inoperable?
2. Is the switching equipment in good working order, (manually
tested on a regularly scheduled basis), and are spare parts on
hand?
1-1
-------
3. Are the scales adequate for at least two cylinders or
containers.
Bo Hypochlorite
Storage of calcium hypochlorite or sodium hypochlorite is normally
provided in drums or other suitable containers. Redundancy requirements are
not applicable to these by themselves, so long as the required minimum storage
quantity is on hand at all times.
C. Ammonia
Anhydrous ammonia is usually stored in cylinders as a pressurized liquid.
Aqua ammonia is usually stored as a solution of ammonia and water in a hori-
zontal pressure vessel.
1. Is the design storage volume divided into two or more usable
units?
2. Is automatic switching equipment in operation to change over
from one unit to another when one is empty or inoperable?
3. Are there spare parts for the switching equipment?
III. Generation
Ozone and chlorine dioxide are not stored on-site. Rather, because of
their reactivity* they are generated and used immediately.
It is recommended that for the redundancy requirement for these disinfec-
tants to be satisfied that there are two generating units, or two sets of
units, capable of supplying the design feed rate. In systems in which there
is more than one generation system to provide the design capacity, a standby
unit should be available for times the on-line units need repair. The backup
unit should have a capacity equal to or greater than the units it may replace.
A. Chlorine Dioxide
Chlorine, sodium chlorite, or sodium hypochlorite should be stored in
accordance with storage guidelines previously described.
B. Ozone
Are all generation components present and in working order for both the
primary and the redundant units (whether using air or oxygen)?
C. Common
Is switchover equipment and automatic start-up installed and operable to
change from the primary generating unit(s) to the redundant unit(s)?
1-2
-------
IV. Feed Systems
Redundancy in feed systems requires two separate units, or systems, each
capable of supplying the design feed rate of disinfectant. If more than one
unit is used to provide the design feed rate, a third unit should be available
to replace any of the operating units during times of malfunction. The
replacement unit must, therefore, have a capacity equal to or greater than
that of the largest unit which it may replace. This requirement applies to
all disinfection methods, and is best implemented by housing the primary and
redundant components in separate rooms, enclosures, or areas, as appropriate.
In reviewing these systems for redundancy, the following components
should be checked:
A. Chlorine
1. Evaporators
2. Chlorinators
3. Injectors
B. Hypochlorite
1. Mixing tanks and mixers
2. Chemical feed pumps and controls
C. Ozone
1. Dissolution equipment, including compressor and delivery piping
systems
D. Chlorine Dioxide
1. Chlorine feed equipment
2. Sodium chlorite mixing and metering equipment
3. Day tank and mixer
4. Metering pumps
5. If a package CIO unit is used, two must be provided
E. Chloramination
1. Chlorine feed equipment
2. Ammonia feed equipment, including applicable equipment for
either:
a. Anhydrous ammonia (gas)
b. Aqua ammonia (solution)
1-3
-------
V. Residual Monitoring
The surest method of checking the past performance of a disinfection
facility for continuous operation is by continuous monitoring and recording.
To ensure continuous monitoring, it is suggested that duplicate continuous
monitors are present for backup in the event of monitor failure. However, if
there is a failure in the monitoring system for indicating that a continuous
residual is being maintained, this would be a violation of a monitoring
requirement, not a treatment requirement.
A. Chlorine
1. Does the facility have a continuous monitor for chlorine
residual at the disinfection system site with an alarm or
indicator to show when the monitor is not functioning? For
added assurance, the provision of a backup monitoring unit is
also recommended.
2. Is there instrumentation in place to automatically switch from
one monitor to the other if the first one fails?
B. Hypochlorite
Same as for chlorine system.
C. Ozone
1. Does the facility have a continuous ozone monitor with
automatic switchover capability and alarms?
2, Does the facility have a continuous ozone residual monitor with
automatic switchover capability and alarms?
D. Chlorine Dioxide
1. Does the facility have a continuous chlorine dioxide monitor
with automatic switchover capability and alarms?
2. Does the facility have a continuous chlorine dioxide residual
monitor with automatic switchover capability and alarms?
E. Chloramination
1. Does the facility have a continuous ammonia monitor with
automatic switchover capability and alarm?
2. Does the facility also have a continuous chlorine residual
monitor on-site with automatic switchover capability and
alarms?
1-4
-------
VI. Power Supply
A permanently installed standby generator, capable of running all elec-
trical equipment at the disinfection station, and equipped for automatic
start-up on power failure, must be on-site and functional.
Alternatives to a standby generator, such as a feed line from a different
power source, are acceptable if they can be shown to have equal reliability.
VII. Alarms
Indicators and alarms, both local and remote, must be capable of promptly
alerting operating and supervisory personnel of problem conditions.
A. Local
Lights, buzzers, and horns should be installed and functioning to alert
on-site personnel to problem conditions.
B. Remote
Indications of major problems should also be relayed to a central control
panel which is manned 24 hours per day and whose operators can notify response
personnel instantaneously.
C. Problem Conditions
A minimum list of problem conditions which should have indicators and
alarms, both locally and at a 24-hour per day switchboard, is as follows:
1. Disinfectant leak
2. Feeder pump failure
3. Power outage
4. Generator or alternate power source on
5. Disinfectant residual less than setpoint value
VIIII. Facility Layout
Maximum reliability is ensured when redundant units are separated from
primary units. The type of separation should be appropriate to the type of
potential malfunction. For example, any area within a building subject to a
chlorine leak should have primary components separated from redundant compo-
nents by an airtight enclosure, i.e., separate rooms of varying sizes.
1-5
-------
IX. Separate Facility
Under certain conditions, such as location of a disinfection facility in
an area of high earthquake potential, the most reliable means of providing
redundant facilities may be to house them in a completely separate structure
at a different site.
1-6
-------
APPENDIX J
WATERSHED CONTROL PROGRAM
-------
APPENDIX J
WATERSHED CONTROL PROGRAM
The following is a guideline for documenting a watershed control program.
All systems are expected to conduct the basic elements of a watershed control
program. However, the scope of the program should increase as the complexity
and size of the watershed/system increases. The program could be more or less
comprehensive than this outline, and will be determined on a case-by-case
basis by the utility and the Primacy Agency.
A. Watershed Description
1. Geographical location and physical features of the watershed.
2. Location of major components of the water system in relation-
ship to the watershed.
3. Hydrology: Annual precipitation patterns, stream flow charac-
teristics, etc.
4. Agreements and delineation of land use/ownership.
B. Identification of the Watershed Characteristics
and Activities Detrimental to Water Quality
1. Naturally Occurring:
a. Effect of precipitation, terrain, soil types and land
cover
b. Animal populations (describe) — include a discussion of
the Giardia contamination potential, any other microbial
contamination transmitted by animals
c. Other - any other activity which can adversely affect
water quality
2. Man-Made:
a. Point sources of contamination such as wastewater treat-
ment plant, industrial discharges, barnyard, feedlots, or
private septic systems
b. Nonpoint Source of Contamination:
1) Road construction - major highways, railroads
J-l
-------
2) Pesticide usage
3) Logging
4) Grazing animals
5) Discharge to ground water which recharges the surface
source
6) Recreation activities
7) Potential for unauthorized activity in the watershed
8) Describe any other human activity in the watershed
and its potential impact on water quality
It should be noted that grazing animals in the watershed may
lead to the presence of Cryptosporidium in the water. Crypto-
sporidium is a pathogen which may result in a disease outbreak
upon ingestion. Mo information is available on its resistance
to various disinfectants, therefore grazing should not be
permitted on watersheds of non-filtering systems. The utility
should set priorities to address the impacts in B.I. and 2.,
considering their health significance and the ability to
control them.
C. Control of Detrimental Activities/Events
Depending on the activities occurring within the watershed, various
techniques could be used to eliminate or minimize their effect.
Describe what techniques are being used to control the effect of
activities/events identified in B.I. and 2. in its yearly report.
Example:
Activity; Logging in the watershed.
Management Decision; Logging effects are unacceptable, there-
fore, do not allow logging in watershed.
Procedure; Buy out all logging rights within the watershed.
Monitoring; Periodically tour watershed to ensure no logging
is conducted.
Controlled logging may sometimes be more cost effective. Measures
should, however, be taken to:
- Limit access
J-2
-------
- Ensure cleanup
- Control erosion
Example:
Activity; Point sources of discharge within the watershed.
Management Decision; Eliminate those discharges or minimize
their impact.
Procedures; Actively participate in the review of discharge
permits to alert the reviewing agency of the potential (actual)
impacts of the discharge and lobby for its elimination or
strict control.
Monitoring; Conduct special monitoring to ensure conditions of
the permit are met and to document adverse effects on water
quality.
D. Monitoring
1. Routine: Minimum specifications for monitoring several raw
water quality parameters are listed in Section 3.1. Describe
when, where and how these samples will be collected. These
results will be used to evaluate whether the source may con-
tinue to be used without filtration.
2. Specific: Routine monitoring may not provide information about
all parameters of interest. For example, it may be valuable to
conduct special studies to measure contaminants suspected of
being present (Giardia, pesticides, fuel products, enteric
viruses, etc.). Frequent presence of either Giardia or enteric
viruses in raw water samples prior to disinfection would
indicate an inadequate watershed control program. Monitoring
may also be useful to assess the effectiveness of specific
control techniques, and to audit procedures or operational
requirements instituted within the watershed. Utilities are
encouraged to conduct additional monitoring as necessary to aid
them in controlling the quality of the source water.
E. Management/Operations
1. Management
a. Organizational structure
b. Personnel and education/certification requirements
2. Operations
a. Describe system operations and design flexibility.
J-3
-------
b. The utility should conduct some form of ongoing review or
survey in the watershed to identify and react to potential
impacts on water quality. The scope of this review should
be documented and agreed upon by the utility and Primacy
Agency on a case-by-case basis.
c. Specifically describe operational changes which can be
made to adjust for changes in water quality. Examples
Switching to alternate sources; increasing the level of
disinfection; using settling basins. Discuss what trig-
gers, and who decides to make, those changes.
3. Annual Report: As part of the watershed program, an annual
report should be submitted to the Primacy Agency. The contents
of the report should:
a. Identify special concerns that occurred in the watershed
and how they were handled (example: herbicide usage, new
construction, etc.).
b. Summarize other activities in the watershed such as
logging, hunting, water quality monitoring, etc.
c. Project what adverse activities are expected to occur in
the future and describe how the utility expects to address
them.
F. Agreements/Land Ownership
The goal of a watershed management program is to achieve the highest
level of raw water quality practicable. This is particularly
critical to an unfiltered surface supply,.
1. The utility will have maximum opportunity to realize this goal
if they have complete ownership of the watershed. Describe
efforts to obtain ownership, such as any special programs or
budget. When complete ownership of the watershed is not
practical, efforts should be taken to gain ownership of
critical elements, such as, reservoir or stream shoreline,
highly erodable land, and access areas to water system
facilities.
2. Where ownership of land is not possible, written agreements
should be obtained recognizing the watershed as part of a
public water supply. Maximum flexibility should be given to
the utility to control land uses which could have adverse
effect on the water quality. Describe such agreements.
3. Describe how the utility ensures that the landowner complies
with these agreements.
J-4
-------
APPENDIX K
SANITARY SURVEY
-------
APPENDIX K
SANITARY SURVEY
The SWTR requires that a sanitary survey be conducted each year.
Section 3 presents guidelines for an •annual survey which is conducted to
ensure that the quality of the water and service is maintained. In addition,
it is recommended that a more comprehensive survey such as contained in this
appendix be conducted every 3 to 5 years. This time period is suggested since
the time and effort needed to conduct the comprehensive survey makes it
impractical for it to be conducted annually.
The sanitary survey involves three phases, including planning the survey,
conducting the survey and compiling the final report of the survey, as will be
presented in the following pages.
1. Planning the Survey
Prior to conducting or scheduling a sanitary survey, there should be
a detailed review of the water system's file to prepare for the
survey. The review should pay particular attention to past sanitary
survey reports and correspondence describing previously identified
problems and their solutions. These should be noted, and action/in-
action regarding those problems should be specifically verified in
the field. Other information to review includes: any other corre-
spondence, water system plans, chemical and microbiological sampling
results, operating reports, and engineering studies. This review
will aid in the familiarization with the system's past history and
present conditions, and the agency's past interactions with the
system.
The initial phase of the water quality review will be carried out
prior to conducting the survey as well, and will consist of review-
ing the water system's monitoring records. Records should be
reviewed for compliance with all applicable microbiological, inor-
ganic chemical, organic chemical, and radiological contaminant MCLs,
and also for compliance with the monitoring requirements for those
contaminants. The survey will provide an opportunity to review
these records with the utility, and to discuss solutions to any MCL
or monitoring violations. The survey will also provide an oppor-
tunity to review how and where samples are collected, and how field
measurements (turbidity, chlorine residual, fluoride, etc.) are
made. Points to cover include:
K-l
-------
a. Is the system in compliance with all applicable MCLs (organic
chemical, inorganic chemical, microbiological, and radio-
logical)?
b. Is the system in compliance with all monitoring requirements?
The pre-survey file review should generate a list of items to check
in the field, and a list of questions about the system. It will
also help the survey or plan the format of the survey and to
estimate how much time it may take. The next step is to make the
initial contact with the system management to establish the survey
date(s) and time. Any records, files, or people that will be
referenced during the survey should be mentioned at the outset.
Clearly laying out the intent of the survey up front will greatly
help in managing the system, and will ensure that the survey goes
smoothly without a need for repeat trips.
2. Conducting the Survey
The on-site portion of the survey is the most important and will
involve interviewing those in charge of managing the water system as
well as the operators and other technical people. The survey will
also review all major system components from the source(s) to the
distribution system. A standard form is frequently used to ensure
that all major components and aspects of each system are consis-
tently reviewed. However, when in the field, it is best to have an
open mind and focus most attention on the specifics of the water
system, using the form only as a guide. The surveyor should be
certain to be on time when beginning the survey. This consideration
will help get the survey started smoothly with the operator and/or
manager.
As the survey progresses, any deficiencies that are observed should
be brought to the attention of the water system personnel, and the
problem and the corrective measures should be discussed. It is far
better to clarify technical details and solutions while standing
next to the problem than it is to do so over the telephone. Points
to cover include:
a. Is the operator competent in performing the necessary field
testing for operational control?
b. Are testing facilities and equipment adequate, and do reagents
used have an unexpired shelf life?
c. Are field and other analytical instruments properly and regu-
larly calibrated?
d. Are records of field test results and water quality compliance
monitoring results being maintained?
e. Conduct any sampling which will be part of the survey.
K-2
-------
Also, detailed notes of the findings and conversations should be
taken so that the report of the survey will be an accurate
reconstruction of the survey.
Specific components/features of the system to review and some
pertinent questions to ask are:
A. Source Evaluation
1. Description: based on field observations and discussion
with the operator, a general characterization of the
watershed should be made. Features which could be
included in the description are:
a. Area of watershed or recharge area.
b. Stream flow.
c. Land usage (wilderness, farmland, rural housing,
recreational, commercial, industrial, etc.).
d. Degree of access by the public to watershed.
e. Terrain and soil type.
f. Vegetation.
g. Other.
2. Sources of contamination in the watershed or sensitive
areas surrounding wells or well fields should be identi-
fied. Not only should this be determined by physically
touring and observing the watershed and its daily uses,
but the surveyor should also actively question the water
system manager about adverse and potentially adverse
activities in the watershed. An example of types of
contamination includes:
a. Man Made.
1. Point discharges of sewage, stormwater, and
other wastewater.
2. On-site sewage disposal systems.
3. Recreational activities (swimming, boating,
fishing, etc.).
4. Human habitation.
5. Pesticide usage.
K-3
-------
6. Logging.
7. Highways or other roads from which there might
be spills.
8. Commercial or industrial activity„
9. Solid waste or other disposal facilities.
10, Barnyards, feed lots, turkey and chicken farms
and other concentrated domestic animal activity.
11. Agricultural activities such as grazing,
tillage, etc., which affects soil erosion,
fertilizer usage, etc.
12. Other.
b. Naturally Occurring.
1. Animal populations, both domestic and wild.
2. Turbidity fluctuations (from precipitation,
landslides, etc.).
3. Fires.
4. Inorganic contaminants from parent materials
(e.g., asbestos fibers).
5. Algae blooms.
6. Other.
This list is by no means all inclusive. The surveyor
should rely principally on his observations and
thorough questioning regarding the unique properties
of each watershed to completely describe what may
contaminate the source water.
3. Source Construction.
a. Surface Intakes.
1. Is the source adequate in quantity?
2. Is the best quality source or location in that
source being used?
3. Is the intake protected from icing problems if
appropriate?
K-4
-------
4. Is the intake screened to prevent entry of
debris, and are screens maintained?
5. Is animal activity controlled within the immedi-
ate vicinity of the intake?
6. Is there a raw water sampling tap?
b. Infiltration Galleries.
1. Is the source adequate in quantity?
2. Is the best quality source being used?
3. Is the lid over the gallery watertight and
locked?
4. Is the collector in sound condition and main-
tained as necessary?
5. Is there a raw water sampling tap?
c. Springs.
1. Is the source adequate in quantity?
2. Is there adequate protection around the spring
such as fencing to control the area within 200
feet?
3. Is the spring constructed to best capture the
spring flow and exclude surface water infiltra-
tion?
4. Are there drains to divert surface water from
the vicinity of the spring?
5. Is the collection structure of sound construc-
tion with no leaks or cracks?
6. Is there a screened overflow and drain pipe?
7. Is the supply intake located above the floor and
screened?
8. Is there a raw water sampling tap?
d. Catchment and Cistern.
1. Is source adequate in quantity?
K-5
-------
2, Is the cistern of adequate size?
3. Is the catchment area protected from potential
contamination?
4. Is the catchment drain properly screened?
5. Is the catchment area and cistern of sound
construction and in good condition?
6. Is catchment constructed of approved non-toxic,
non-leaching material?
7. Is the cistern protected from contamination —
manholes, vents, etc?
8. Is there a raw water tap?
e. Other Surface Sources.
1. Is the source adequate in quantity?
2. Is the best possible source being used?
3. Is the immediate vicinity of the source pro-
tected from contamination?
4. Is the structure in good condition and properly
constructed?
5. Is there a raw water sampling tap?
4. Pumps, Pumphouses, and Controls,,
a. Are all intake pumps, booster pumps, and other pumps
of sufficient capacity?
b. Are all pumps and controls operational and maintained
properly?
c. Are check valves, blow off valves, water meters and
other appurtenances operated and maintained properly?
d. Is emergency power backup with automatic start-up
provided and does it work (try it)?
e. Are underground compartments and suction wells
waterproof?
f. Is the interior and exterior of the pumphouse in good
structural condition and properly maintained?
K-6
-------
g. Are there any safety hazards (electrical or mechan-
ical) in the pumphouse?
h. Is the pumphouse locked and otherwise protected
against vandalism?
i. Are water production records maintained at the
pumphouse?
5. Watershed Management (controlling contaminant sources):
The goal of the watershed management program is to ident-
ify and control contaminant sources in the watershed (see
Section 3.3.1 of this document, "Watershed Control Pro-
gram" ). Under ideal conditions each source of contamina-
tion identified in 2 will already have been identified by
the utility, and some means of control instituted, or a
factual determination made that its impact on water
quality is insignificant. To assess the degree to which
the watershed management program is achieving its goal,
the following types of inquiries could be made:
a. If the watershed is not entirely owned by the util-
ity, have written agreements been made with other
land owners to control land usage to the satisfaction
of the utility? Are appropriate regulations under
the contract of state/local department of health in
effect?
b. Is the utility making efforts to obtain as complete
ownership of the watershed as possible? Is effort
directed to control critical elements?
c. Are there means by which the watershed is regularly
inspected for new sources of contamination or tres-
passers where access is limited?
d. Are there adequately qualified personnel employed by
the utility for identifying watershed and water
quality -problems and who are given the responsibility
to correct these problems?
e. Are raw water quality records kept to assess trends
and to assess the impact of different activities and
contaminant control techniques in the watershed?
f. Has the system responded adequately to concerns
expressed about the source or watershed in past
sanitary surveys?
g. Has the utility identified problems in its yearly
watershed control reports, and if so, have these
problems been adequately addressed?
K-7
-------
Identify what other agencies have control or juris-
diction in the watershed. Does the utility actively
interact with these agencies to see that their
policies or activities are consistent with the
utility's goal of maintaining high raw water quality?
B. Treatment Evaluation
1. Disinfection.
a. Is the disinfection equipment and disinfectant
appropriate for the application (chloramines, chlor-
ine, ozone, and chlorine dioxide are generally
accepted disinfectants)?
b. Are there back-up disinfection units on line in case
of failure, and are they operational?
c. Is there auxiliary power with automatic start up in
case of power outage? Is it tested and operated on a
regular basis, both with and without load?
d. Is there an adequate quantity of disinfectant on hand
and is it properly stored (e.g., are chlorine cylin-
ders properly labeled and chained)?
e. In the case of gaseous chlorine, is there automatic
switch over equipment when cylinders expire?
f. Are critical spare parts on hand to repair disin-
fection equipment?
g. Is disinfectant feed proportional to water flow?
h. Are daily records kept of disinfectant residual near
the first customer from which to calculate CTs?
i. Are production records kept from which to determine
CTs?
j. Are CTs acceptable based on the level of treatment
provided (see Surface Water Treatment Rule for
filtered sources, and Section 3.2.2 of this guidance
manual for unfiltered sources, to determine the
appropriate CT)?
k. Is a disinfectant residual maintained in the dis-
tribution system, and are records kept of daily
measurements?
K-8
-------
1. If gas chlorine is used, are adequate safety pre-
cautions being followed (e.g., exhaust fan with
intake within six inches of the floor, self-contained
breathing apparatus that is regularly tested, regular
safety training for employees, ammonia bottles and/or
automatic chlorine detectors)? Is the system
adequate to ensure the safety of both the public and
the employees in the event of a chlorine leak?
2. Other.
a. Are other treatment processes appropriate and are
they operated to produce consistently high water
quality?
b. Are pumps, chemical feeders, and other mechanical
equipment in good condition and properly maintained?
c. Are controls and instrumentation and adequate for the
process, operational, well maintained and calibrated?
d. Are accurate records maintained (volume of water
treated, amount of chemical used, etc.)?
e. Are adequate supplies of chemical on hand and pro-
perly stored?
f. Are adequate safety devices available and precautions
observed?
Sections of a sanitary survey pertaining to systems
containing filtration facilities have been omitted, as
this section of the guidance document pertains to non-
filtering systems.
C. Distribution System Evaluation
After water has been treated, water quality must be protected
and maintained as it flows through the distribution system to
the customer's tap. The following questions pertain to the
water purveyor's ability to maintain high water quality during
storage and distribution.
1. Storage.
a. Gravity.
1. Are storage reservoirs covered and otherwise
constructed to prevent contamination?
2. Are all overflow lines, vents, drainlines, or
cleanout pipes turned downward and screened?
K-9
-------
3o Are all reservoirs inspected regularly?
4. Is the storage capacity adequate for the system?
5o Does the reservoir (or reservoirs) provide
sufficient pressure throughout the system?
6. Are surface coatings within the reservoir in
good repair and acceptable for potable water
contact?
7. Is the hatchcover for the tank watertight and
locked?
8. Can the reservoir be isolated from the system?
9. Is adequate safety equipment (caged ladder, OSHA
approved safety belts, etc.) in place for
climbing the tank?
10. Is the site fenced, locked, or otherwise pro-
tected against vandalism?
11. Is the storage reservoir disinfected after
repairs are made?
12. Is there a scheduled program for cleaning
storage reservoir sediments, slime on floor and
side walls.
b„ Hydropneumatic „
1, Is the storage capacity adequate for the system?
2. Are instruments, controls, and equipment ade-
quate, operational, and maintained?
3. Are the interior and exterior surfaces of the
pressure tank in good condition?
4. Are tank supports structurally sound?
5. Does the low pressure cut in provide adequate
pressure throughout the entire system?
6. Is the pump cycle rate acceptable (not more than
15 cycles/hour)?
2o Cross Connections.
a. Is the system free of known uncontrolled cross
connections?
K-10
-------
b. Does the utility have a cross connection prevention
program, including annual testing of backflow preven-
tion devices?
c. Are backflow prevention devices installed at all
appropriate locations (wastewater treatment plant,
industrial locations, hospitals, etc.)?
3. Other.
a. Are proper pressures and flows maintained at all
times of the year?
b. Do all construction materials meet AWWA or equivalent
standards?
c. Are all services metered and are meters read?
d. Are plans for the system available and current?
e. Does the system have an adequate maintenance program?
- Is there evidence of leakage in the system?
- Is there a pressure testing program?
Is there a regular flushing program?
- Are valves and hydrants regularly exercised and
maintained?
- Are AWWA standards for disinfection followed
after all repairs?
- Are there specific bacteriological criteria and
limits prescribed for new line acceptance or
following line repairs?
- Describe the corrosion control program.
- Is the system interconnected with other systems?
D. Management/Operation
1. Is there an organization that is responsible for providing
the operation, maintenance, and management of the water
system?
2. Does the utility regularly summarize both current and
long-term problems identified in their watershed, or other
parts of the system, and define how they intend to solve
the problems i.e., is their planning mechanism effective;
do they follow through with plans?
K-ll
-------
3. Is the budget and financing satisfactory to provide
continuous high quality service, and allow for future
replacements and improvements?
4. Are customers charged user fees and are collections
satisfactory?
5. Are there sufficient personnel to operate and manage the
system?
6. Are personnel (including management) adequately trained,
educated, and/or certified?
7. Are operation and maintenance manuals and manufacturers
technical specifications readily available for the system?
8. Are routine preventative maintenance schedules established
and adhered to for all components of the water system?
9. Are sufficient tools, supplies, and maintenance parts on
hand?
10. Are sufficient operation and maintenance records kept and
readily available?
11. Is an emergency plan available and usable, and are em-
ployees aware of it?
12. Are all facilities free from safety defects?
When the survey is completed, it is always preferable to
briefly summarize the survey with the operator(s) and manage-
ment. The main findings of the survey should be reviewed so it
is clear that there are not misunderstandings about find-
ings/conclusions. It is also good to thank the utility for
taking part in the survey, arranging interviews with employees,
gathering and explaining their records, etc. The information
and help which the utility can provide are invaluable to a
successful survey, and every attempt should be made to continue
a positive relationship with the system.
3. Reporting the Survey
A final report of the survey should be completed as soon as possible
to formally notify the system and other agencies of the findings.
There is no set or necessarily best format for doing so, and the
length of the report will depend on the findings of the survey and
size of the system. Since the report may be used for future compli-
ance actions and inspections, it should include as a minimum:
1) the date of the survey; 2) who was present during the survey;
3) the findings of the survey; 4) the recommended improvements to
identified problems; and 5) the dates for completion of any improve-
ments. Any differences between the findings discussed at the
K-12
-------
conclusion of the survey and what's included in the final report
should be discussed and clarified with the utility prior to sending
out the final report. In other words, the utility should be fully
aware of the contents of the final report before receiving it.
K-13
-------
APPENDIX L
SMALL SYSTEM CONSIDERATIONS
-------
APPENDIX L
SMALL SYSTEMS CONSIDERATIONS
Introduction
Under the provisions of the SWTR, systems with fewer them 500 service
connections may be eligible for an exemption. Guidance on the requirements
for an exemption is provided in Section 9. For systems which are not eligible
for an exemption, compliance with the SWTR is mandatory. It is recognized
that the majority (approximately 75 percent) of people in the United States
are served by a relatively small number of large systems. However, most water
systems in the United States are small. For small systems, compliance with
the various provisions of the SDWA has traditionally been a problem. Records
show small systems have a disproportionately higher incidence of drinking
water quality and monitoring difficulties. The reasons for these difficulties
can generally be broken down into the following three categories:
- Economics
- Treatment Technologies
- Operations (lack of qualified personnel)
Small water systems typically face severe economic constraints. Their
lack of operating revenues results in significant limitations on their ability
to respond to the requirements of the SDWA. These systems cannot benefit from
the economies of scale which are available to larger systems.
The second difficulty facing the small systems has been the lack of
appropriate treatment technologies. Although methods for removing most of the
contaminants .known to occur in drinking water are available, many of these
technologies have only recently been scaled down for the smaller systems.
The third problem which has traditionally plagued small systems is the
lack of well trained operators. This deficiency is the result of many com-
bined factors. First of all, many of these operators are employed only on a
part-time basis or if they are employed on a full-time basis they have a
myriad of additional duties. In addition, the operator's technical background
may be limited as well. This results from the low salary of the position,
which is uninviting to qualified operators. Also, in spite of the requirement
L-l
-------
of retaining certified operators upheld-in many states, it seems to be diffi-
cult to enforce this requirement in small systems.
The purpose of this appendix is to provide assistance to the Primacy
Agency in defining the problems and potential solutions typically associated
with small systems. It is beyond the scope of .this document to provide an
indepth dicussion of the needs of small systems. However, over the past
several years the needs of the small water systems have been recognized to be
of primary concern and numerous workshops, seminars and committees have been
attempting to more clearly define workable solutions. A partial listing of
the papers, reports and proceedings which discuss problems and solutions
pertaining to small systems beyond that which is possible in this manual is
presented in the reference list of this appendix.
Economics
One of the most severe constraints of small systems is the small economic
base from which to draw funds. Certain treatment and services must be pro-
vided for a community regardless of how few people are served. Thus, as the
number of connections to the system decrease, the cost per connection in-
creases. The economic limitations of small utilities makes it difficult to
provide needed upgrading of existing facilities or an adequate salary to
maintain the employment of a qualified operator to monitor and maintain the
system. Adding to the severity of the economic hardships of small systems is
the fact that many of the small water systems are privately owned, with
private ownership increasing as system size decreases. The ownership of the
plant presents difficulties since privately owned systems are subject to rate
controls by the local public utility commission, are not eligible for public
grants and loans, and may find commercial loans hard to obtain.
Financing options for small systems include; federal and state loan and
grant programs, federal revenue sharing and revenue bonds (for municipal
systems) and loans through the United States Small Business Administration
(SBA) and use of industrial development bonds or privatization (for private
utilities). These options are explained in greater detail in the "Guidance
Manual - Institutional Alternatives for Small Water Systems" (AWWA, 1986).
L-2
-------
The following paragraphs will explain some existing options which may ease the
hardship of financing small water treatment facilities.
The major cause of small system difficulties arises from the lack of
funds and resources. It is therefore in the best interest of small utilities
to expand their economic base and the resources available to them, to achieve
the economies of scale available to larger systems. Regionalization is the
physical or operational union of small systems to effect this goal. This
union can be accomplished through the physical interconnection of two or more
small systems or the connection of a smaller system to a pre-existing larger
system. Water supply systems can also join together for the purchase of
supplies, materials, engineering services, billing and maintenance. The union
of the small systems increases the population served, thereby dispersing the
operational costs and decreasing the cost per consumer.
The creation of utility satellites is another form of regionalization. A
satellite utility is one which taps into the resources of an existing larger
facility without being physically connected to, or owned by, the larger facil-
ity. The larger system may provide any of the following for the smaller
system:
1. Varying levels of technical operational, or managerial assistance on
a contract basis.
2. Wholesale treated water with or without additional services.
3. Assuming ownership, operation and maintenance responsibility when
the small system is physically separate with a separate source.
The formation of a satellite offers many advantages for both the
satellite and the parent utility. These advantages include: an improved
economy of scale for satellites, an expanded revenue base for the parent
utility, provisions of needed resources to satellites, the retention of the
satellites' local autonomy, improved water quality management of the
satellite, improved use of public funds for publicly owned satellites.
In order to create a more definite structure for the union of resources
of water treatment facilities, water districts may be created. Water
districts are formed by county officials and provide for the public ownership
of the utilities. The utilities in any given district would combine resources
and/or physically connect systems so that one or two facilities would provide
L-3
-------
water for the entire district. The creation of water districts creates
eligibility for public monies, has the potential for economies of size,
facilitates the takeover or contract services with publicly owned non-commun-
ity systems and small privately owned systems, and offers a tax advantage.
Drawbacks include subjection to politics, a strong local planning effort is
needed for success, and competition with private enterprises.
The centralization of utilities can be taken one step further through the
creation of county utilities or even state utilities. The government will
create a board which may then act to acquire, construct, maintain and operate
any public water supply within its district, the system may provide water on
its own or purchase water from any municipal corporation. The board may adopt
and administer rules for the construction, maintenance, protection and use of
public water supplies and the fixation of reasonable rates for water supplies.
The cost of construction and/or upgrading of facilities may be defrayed
through the issuance of bonds and/or property assessment. As with all the
alternatives, the creation of government control of the utilities has its
advantages and disadvantages. The advantages include: the creation of
central management, creation of economy of scale for utilities, eligibility
for public grants and loans, savings through centralized purchasing, manage-
ment, consultation, planning and technical assistance, and possible provision
for pool of trained operators. The disadvantages include the subjectivity to
politics, the slow response caused by bureaucracy, and competition to private
contractors.
Treatment Technologies
The high cost of available treatment technologies has limited their use
in small water supply systems. Recently prefabricated package plants and
individual treatment units have been developed to lessen these costs. At the
present time, the treatment technologies which are available to enable systems
to comply with the Safe Drinking Water Act are identified to be the following!
- Package plants
- Slow-sand filters
- Diatomaceous earth filters
- Cartridge filtration
A brief discussion of each treatment method is provided below.
L-4
-------
Package Plants
Clarification and filtration units which require minimal assembly in the
field can now be manufactured. To minimize required operator skill level and
operational attention, the equipment should be automated. Continuous effluent
turbidity and disinfectant residual monitoring systems with alarms and
emergency shutdown provisions are features that safeguard water quality and
should be provided for unattended plants.
Slow-Sand Filters
Slow-sand filters are applicable to small water supply systems. Their
proven record of effective removal of turbidity and Giardia cysts makes them
suitable for application where operational attention is minimal. Since no
chemicals other than a disinfectant are needed, and no mechanical equipment is
involved, the required operator skill level is the lowest of the filtration
alternatives available to small systems.
Diatomaceous Earth Filters
Diatomaceous earth (DE) pressure and vacuum filters can be used on
relatively low turbidity surface waters (less than 1 to 2 NTU) for removal of
turbidity and Giardia cysts. DE filters can effectively remove particles as
small as 1 micron, but would require coagulating chemicals and special filter
aids to provide significant virus removal.
Cartridge Filters
Cartridge filters using microporous ceramic filter elements with pore
sizes as small as 0.2 urn may be suitable for producing potable water, in
combination with disinfection, from raw water supplies containing moderate
levels of turbidity, algae, protozoa and bacteria. The advantage to a small
system, is, with the exception of chlorination, that no other chemicals are
required. The process is one of strictly physical removal of small particles
by straining as the water passes through the porous membranes. Other than
occasional cleaning or membrane replacement, operational requirements are not
complex and do not require skilled personnel.
Selection of a Filtration Technology
The criteria for selection of a filtration technology for a small commun-
ity are essentially the same as those for a larger community. That is, the
utility must first screen the complete list of available alternatives to
L-5
-------
eliminate those which are either not technically suited to the existing
conditions (Table 4-1) or not affordable by the utility. Remaining alterna-
tives should then be evaluated based on both cost (capital, annual, and
life-cycle) and non-cost bases (operation and maintenance, technical require-
ments versus personnel available; flexibility regarding future needs; etc.).
In these evaluations it should be noted that even though automated package
plants are cost-competitive with slow sand filters, their operation require-
ments to achieve optimum performance could be complicated. Also, the
maintenance requirements for package plants would be mechanically and
electrically oriented and might require a maintenance agreement with the
manufacturer.
During the process of installing the treatment system, interim measures
should be taken to ensure the delivery of a reasonably safe water to the
consumers. In addition to the available interim measures listed in
Section 9.3, temporary installation of mobile filtration plants may be
possible. These trailer-mounted units are sometimes available from state
agencies for emergencies, but more often may be rented or leased from an
equipment manufacturer.
Modification of Existing Filtration Systems
Small treatment systems that are already in existence should comply with
the performance criteria of the SWTR. If the systems are not found to be
performing satisfactorily, modifications to the existing process may be
required. Improvement in treatment efficiency depends on the type of filtra-
tion system in use. Operation of slow sand filters could be checked for bed
depth, short-circuiting, excessive hydraulic loading, and for the need to pre-
treat the raw water. Infiltration galleries, or sometimes, roughing filters
ahead of a slow sand filter may provide for better performance by reducing the
solids load on the filters. However, the design criteria and costs for this
alternative have not yet been defined. Site specific studies may be required
before roughing filters could be used to achieve compliance with the regula-
tions. Diatomaceous earth (DE) filters should be checked for appropriate
precoat and body feed application, hydraulic loading, grade (size) of DE being
used, and possible need for chemical pretreatment. Package plants would have
to be checked process-by-process, similar to the system used for a
L-6
-------
conventional plant. Other filtration processes would have to be checked for
hydraulic loading rate, appropriateness of the filter material (pore size),
and possible need for additional pretreatment.
Disinfection
Disinfection (CT) requirements for small systems can be met in several
different ways. The most obvious method of maintaining a disinfectant
residual in the distribution system is to add disinfectant at one or more
additional locations. An alternate method is to increase the disinfectant
dose at the existing application point(s). The latter alternative, however,
may increase disinfectant byproducts, including THMs, in the system.
If it is a relatively short distance between the treatment system and the
first customer, additional contact time can be provided so that the
disinfectant dose does not have to be increased beyond desirable residuals.
Two specific methods of increasing contact time for small systems are
1) installing a pressure vessel or closed storage vessel, baffled to provide
adequate contact time, or 2) constructing a looped pipeline, on the finished
water line between the filtration-disinfection system and the first customer.
The feasibility of either of these methods would depend on system specifics
that include size, physical conditions, and cost.
If it is not practical to provide additional storage time to achieve the
desired CT, an alternate, more effective disinfectant may be used. An
alternate disinfectant may provide a sufficient CT without altering the system
configuration.
Operations
Water treatment facilities need to be operated properly in order to
achieve maximum treatment efficiencies. There is currently a lack of well
trained operators at many small treatment plants. The main cause is lack of
awareness of the importance of correct plant operation, lack of training
programs, lack of enforcement of the requirement for employment of a certified
operator and lack of funds to employ such an operator.
Small systems may wish to implement a circuit rider/operator program. In
this program a qualified, certified, experienced operator works for several
water supply systems. The rider can either directly operate the plants, or
L-7
-------
provide technical assistance to individual plant operators, by acting as a
trainer through on-the-job supervision. The latter would be preferable since
it could create a pool of well trained operators.
The main cause of inadequately trained operators is the lack of well
established training programs. Until such training programs are begun,
systems must depend on other training means, such as seminars and books. One
resource which may be helpful in running the plant is "Basic Management
Principles for Small Water Systems - An AWWA Small-Systems Resource Book",
1982.
Most package plant manufacturers' equipment manuals include at least
brief sections on operating principles, methods for establishing proper
chemical dosages, instructions for operating the equipment, and troubleshoot-
ing guides. An individual who studies these basic instructions and receives
comprehensive start-up training should be able to operate the equipment
satisfactorily. These services are vital to the successful performance of a
package water treatment plant and should be a requirement of the package plant
manufacturer. The engineer designing a package plant facility should specify
that start-up and training services be provided by the manufacturer, and also
should consider requiring the manufacturer to visit the plant at 6-month and
1-year intervals after start-up to adjust the equipment, review operations,
and retrain operating personnel. Further, this program should be ongoing and
funds should be budgeted every year for at least one revisit by the package
plant manufacturer.
Another way for small systems to obtain qualified plant operation would
be to contract the services of administrativet operations, and/or maintenance
personnel from a larger neighboring utility, government agencies, service
companies or consulting firms. These organizations could supply assistance in
financial and legal planning, engineering, purchasing accounting and collec-
tion services, laboratory support, licensed operators or operator training,
treatment and water quality assurance, regulatory liaison, and/or emergency
assistance. Through the contracting of these services the utility provides
for the resources needed, improves water quality management and retains its
autonomy. However, if and when the contract is terminated, the utility
returns to its original status.
L-8
-------
References
American Water Works Association. Basic Management Principles for Small Water
Systems, 1982.
American Water Works Association. Design and Construction of Small Water
Systems, 1984.
Kelly, Gidley, Blair and Wolfe, Inc. Guidance Manual - Institutional
Alternatives for Small Water Systems. AWWA Research Foundation Contract
79-84, 1986.
L-9
-------
APPENDIX M
PILOT STUDY PROTOCOL
FOR ALTERNATE FILTRATION TECHNOLOGY
-------
APPENDIX M
If a system desires to use an alternate filtration technology, then the
system must demonstrate through pilot testing that the alternate technology
can meet the performance criteria for virus and Giardia removal and/or
inactivation. However, pilot testing for virus removal is not required if the
water to be disinfected has a turbidity less than 1 NTU and sufficient CT is
provided to achieve 4-log virus inactivation. Alternate technologies may
include demonstrated technologies operating outside the range of accepted
design criteria.
This appendix provides a recommended protocol for evaluating alternate
filtration methods through pilot testing. This protocol is divided into
sections:
- Pilot Plant
- Testing Program
- Monitoring and analyses.
Pilot Plant
The primary consideration in design of the pilot plant is to adequately
simulate the treatment provided by the full scale facility. Criteria which
should be considered in the pilot plant design include but are not limited to
the parameters in the following list.
Treatment Process Criteria
Rapid Mix Number of Stages
Detention Time
Mixing Intensity
Flocculation Number of Stages
Detention Time
Mixing Intensity(ies)
Sedimentation Unit Type (plate, tube, etc.)
Loading Rates
Filtration Media type and size
Media depth
Loading Rate
Operation Mode (constant rate,
declining rate)
Chemical Addition Location
Dosage
M-l
-------
Testing Program
In developing a pilot testing procedure or study to evaluate an alternate
filtration technology, seasonal water quality variations should be reviewed in
order to establish the annual worst case water quality conditions for an
individual source water. The water quality parameters which should be re-
viewed include:
- Total and/or Fecal Colifonns
- Heterotrophic plate count
- Turbidity
- Temperature
- pH
- Color
- Chlorine demand
As a minimum, pilot testing should be conducted when the source exhibits
its worst case annual conditions. However, it is preferable to perform
testing under all seasonal water quality conditions.
The design of pilot plant studies will depend on a variety of factors
including the technology being evaluated and individual site constraints. Any
pilot study should include consideration of the following (Thompson, 1982) •
- Definition of purpose of study
- Identification of end product of study
- Collection of available background information
- Acquisition of additional information required
- Establishment of size of pilot plant and available space
- Determination of who will operate pilot plant
- Ascertainment of how it should be operated
- Establishment of life of pilot plant
- Determination of frequency and location of sample collection and
analysis
- Modification of pilot plant (if required)
- Revision of goals and budget if necessary
- Preparation of design and construction of pilot plant based on above
- Recording of all pilot plant data
1.Additional information on the design of specific pilot studies can be
found in the following references:
- Overview of Pilot Plant Studies. (Thompson, 1982)
- Water Treatment Principles and Design, James M. Montgomery.
- Al-Ani, C.SoU., Filtration of Giardia Cysts and Other Substances:
Volume 3. Rapid Rate Filtration (EPA/600/2-85/027).
M-2
-------
Performance of critical data analysis
- Reporting of Substantiated Conclusion
Monitoring Requirements
The purpose of the pilot testing program is to demonstrate that the
alternate filtration technology can meet the performance criteria for virus
and Giardia removal/inactivation outlined in section 5. The monitoring
locations and frequency should therefore be selected to comply with these
requirements. For example, filter effluent turbidity should be monitored
continuously or, at a minimum every four hours. Disinfectant residual should
also be monitored as outlined in Section 5.
References
J. C. Thompson, "Overview of Pilot Plant Studies in Proceedings AWWA
Seminar on Design of Pilot-Plant Studies," May 16, 1982.
M-3
-------
APPENDIX N
PROTOCOL FOR DEMONSTRATION
OF EFFECTIVE TREATMENT
-------
APPENDIX N
PROTOCOL FOR DEMONSTRATION
OF EFFECTIVE TREATMENT
Based upon the requirements of the SWTR, the minimum turbidity perfor-
mance criteria for systems using conventional treatment or direct filtration
is filtered water turbidity less than or equal to 0.5 NTU in 95 percent of the
measurements taken each month. However, at the discretion of the Primacy
Agency, filtered water turbidity levels of less than or equal to 1 NTU in 95
percent of the measurements taken every month may be permitted on a case-by-
case basis if the system can demonstrate by on-site studies that it is achiev-
ing effective removal and/or inactivation of Giardia lamblia cysts, or removal
of cyst-sized particles. This appendix presents a protocol which can be used
by the Primacy Agency to evaluate these demonstrations.
There are two approaches which can be taken to demonstrate effective
removal and/or inactivation of Giardia cysts:
- Provide sufficient disinfection
- Perform pilot filtration tests
With the first approach it is necessary to provide 3-log Giardia inacti-
vation through disinfection. This should be done by satisfying the disinfec-
tion criteria presented in Section 3, including the requirements for disinfec-
tion system redundancy expanded in Appendix I. For example, a system utiliz-
ing ozone disinfection at pH 7 and a temperature of 10 C, should provide a CT
of at least 2.5 mg/L-min (see Table E-10). Auxiliary ozonation equipment
would also be required including air preparation units, ozone generators and
ozone monitors. If all of these criteria are satisfied, the Primacy Agency may
choose to allow the systems filtered water turbidities to exceed 0.5 NTU.
However, the turbidity must still remain below 1 NTU in 95 percent of the
samples analyzed each month and must never exceed 5 NTU.
The second approach to demonstrating adequate reduction and/or inactiva-
tion of Giardia is through pilot scale filtration tests. Prior to performing
the tests it is necessary to demonstrate that the pilot facilities simulate
full scale plant performance in terms of typical operating parameters includ-
ing chemical types and dosages, detention times (confirmed by tracer studies),
N-l
-------
mixing intensities, and loading rates (filtration and sedimentation). The
water quality parameters which should be monitored for comparison to the full
scale plant should include turbidity, color, oxidant demand and pH.
These tests can be performed with particles equivalent in size to Giardia
cysts. To provide a margin of safety in correlating the pilot and plant scale
results, the pilot studies must demonstrate sufficient reduction that, when
combined with the inactivation provided by disinfection, a 99.99 percent
reduction and/or inactivation of Giardia cysts is achieved. For example, if a
filtration plant provides 2 log inactivation of Giardia through chlorine
addition (in accordance with the criteria described in Section 5) and pilot
studies indicate that treatment will remove 99 percent of Giardia sized
particles, the Primacy Agency may decide that the effluent turbidity limit of
0.5 NTU can be raised to 1.0 NTU in 95 percent of the samples taken each
month.
N-2
-------
APPENDIX O
PROTOCOLS FOR POINT-OF-USE
DEVICES
-------
UNITED STATES
ENVIRONMENTAL PROTECTION AGENCY
Registration Division
Office of Pesticide Programs
Criteria and Standards Division
Office of Drinking Water
GUIDE STANDARD AND PROTOCOL FOR
TESTING MICROBIOLOGICAL WATER PURIFIERS
Report of Task Force
Submitted April, 1986
Revised April, 1987
-------
CONTENTS
Page
PREFACE
1. GENERAL O-l
2. PERFORMANCE REQUIREMENTS O-6
3. MICROBIOLOGICAL WATER PURIFIER TEST PROCEDURES O-8
APPENDIX O-l SUMMARY FOR BASIS OF STANDARDS AND O-21
TEST WATER PARAMETERS
APPENDIX 0-2 LIST OF PARTICIPANTS IN TASK FORCE O-29
APPENDIX O-3 RESPONSE BY REVIEW SUBCOMMITTEE TO O-31
PUBLIC COMMENTS
-------
1. GENERAL
1.1 Introduction
The subject of microbiological purification for waters of unknown micro-
biological quality repeatedly presents itself to a variety of governmental and
non-governmental agencies, consumer groups, manufacturers and others. Exam-
ples of possible application of such purification capabilities include:
- Backpackers and campers
- Non-standard military requirements
- Floods and other natural disasters
- Foreign travel and stations (however, not for extreme contamination
situations outside of the U.S.)
- Contaminated individual sources, wells and springs (however, not for
the conversion of waste water to microbiologically potable water)
- Motorhomes and trailers
Batch methods of water purification based on chlorine and iodine disin-
fection or boiling are well known, but many situations and personal choice
call for the consideration of water treatment equipment. Federal agencies
specifically involved in responding to questions and problems relating to
microbiological purifier equipment include:
- Registration Division, Office of Pesticide Programs (OPP), Environ-
mental Protection Agency (EPA): registration of microbiological
purifiers (using chemicals);
- Compliance Monitoring Staff, EPA: control of microbiological
purifier device claims (non-registerable products such as ultra-
violet units, ozonators, chlorine generators, others);
- U.S. Army Medical Bioengineering Research and Development Laboratory
(USAMBRDL), U.S. Army Natick Research and Development Center and
other Army and military agencies: research and development for
possible field applications;
- Criteria and Standards Division, Office of Drinking Water (ODW),
EPA: Consideration of point-of-use technology as acceptable tech-
nology under the Primary Drinking Water Regulations; consumer
information and service;
0-1
-------
- Drinking Water Research, Water Engineering Research Laboratory
(WERL), EPA? responsible for water treatment technology research;
- Microbiology Branch, Health Effects Research Laboratory (HERL), EPA;
responsible for study of health effects related to drinking water
filters.
A number of representatives of the above mentioned agencies provided
excellent participation in the task force to develop microbiological testing
protocols for water purifiers. Major participation was also provided by the
following:
- A technical representative from the Water Quality Association;
- A -technical representative from the Environmental Health Center,
Department of Health and Welfare of Canada; and
- An associate professor (microbiology) from the University of
Arizona.
1.2 Basic Principles
1.2.1 Definition
As set forth in EPA Enforcement Strategy and as supported by a Federal
Trade Commission (FTC) decision (FTC v. Sibco Products Co., Inc., et al.,
Nov. 22, 1965) , a unit, in order to be called a microbiological water
purifier, must remove, kill or inactivate all types of disease-causing micro-
organisms from the water, including bacteria, viruses and protozoan cysts so
as to render the processed water safe for drinking. Therefore, to qualify, a
microbiological water purifier must treat or remove all types of challenge
organisms to meet specified standards.
1.2.2 General Guide
The standard and protocol will be a general guide and, in some cases, may
present only the minimum features and framework for testing. While basic
features of the standard and protocol have been tested, it was not feasible to
conduct full-fledged testing for all possible types of units. Consequently,
protocol users should include pre-testing of their units in a testing rig,
including the sampling techniques to be used. Where users of the protocol
find good reason to alter or add to the guide in order to meet specific
operational problems, to use an alternate organism or laboratory procedure, or
to respond to innovative treatment units without decreasing the level of
0-2
-------
testing or altering the intent of the protocol, they should feel free to do
so. For example, the OPP Registration Division might find it necessary to
amend the guide somewhat for different types of treatment units. Another
example would be ultraviolet (U.V.) units, which may have specific require-
ments in addition to the guide protocol.
1.2.3 Performance-Based
The standard will be performance-based, utilizing realistic worst case
challenges and test conditions and use of the standard shall result in water
quality equivalent to that of a public water supply meeting the
microbiological requirements and intent of the National Primary Drinking Water
Regulations.
1.2.4 Exceptions
A microbiological water purifier must remove, kill or inactivate all
types of pathogenic organisms if claims are made for any organism. However,
an exception for limited claims may be allowed for units removing specific
organisms to serve a definable environmental need (i.e., cyst reduction units
which can be used on otherwise disinfected and microbiologically safe drinking
water, such as a disinfected but unfiltered surface water containing cysts.
Such units are not to be called microbiological water purifiers and should not
be used as sole treatment for an untreated raw water.)
1.2.5 Not to Cover Non-Microbiological Reduction Claims
The treatment of water to achieve removal of a specific chemical or other
non-microbiological substances from water will not be a part of this standard.
National Sanitation Foundation (NSF) Standards 42 (Aesthetic Effects) and 53
(Health Effects) provide partial guides for chemical removal and other claims
testing.
1.2.6 Construction and Information Exclusions
While the standard recommends safe, responsible construction of units
with non-toxic materials for optimum operation, all such items and associated
operational considerations are excluded as being beyond the scope of the
standard. Included in the exclusion are materials of construction, electrical
and safety aspects, design and construction details, operational instructions
and information, and mechanical performance testing.
0-3
-------
1.2.7 Research Needs Excluded
The guide standard and protocol must represent a practical testing
program and not include research recommendations. For example, consideration
of mutant organisms or differentiation between injured and dead organisms
would be research items at this time and not appropriate for inclusion in the
standard.
1.2.8 Not to Consider Sabotage
Esoteric problems which could be presented by a variety of hypothetical
terrorist (or wartime) situations, would provide an unnecessary complication,
and are not appropriate for inclusion in the standard.
1.2.9 Continuity
The guide standard and protocol will be a living document, subject to
revision and updating with the onset of new technology and knowledge. It is
recommended that the responsible authorities for registration and drinking
water quality review potential needs every two to three years and reconvene
the task force upon need or upon request from the water quality industry, to
review and update the standard and testing protocol.
1.3 Treatment Units Coverage
1.3.1 Universe of Possible Treatment Units
A review of treatment units that might be considered as microbiological
purifiers discloses a number of different types covering treatment principles
ranging from filtration and chemical disinfection to ultraviolet light ra-
diation.
1.3.2 Coverage of This Standard
In view of the limited technical data available and in order to expedite
the work of the task force, the initial coverage is limited, on a priority
basis, to three basic types of microbiological water purifiers or active
components with their principal means of action as follows:
1.3.2.1 Ceramic Filtration Candles or Units (may or
may not contain a chemical bacteriostatic agent)
Filtration, and adsorption, and chemical anti-microbial activity if a
chemical is included.
0-4
-------
1.3.2.2 Halogenated Resins and Units
Chemical disinfection and possibly filtration. (Note: While not
included in this guide standard, halogen products for disinfection or systems
using halogen addition and fine filtration may be tested using many of its
elements, i.e., test water parameters, microbiological challenge and reduction
requirements, analytical techniques and other pertinent elements.)
1.3.2.3 Ultraviolet (UV) Units
UV irradiation with possible add-on treatment for adsorption and filtra-
tion (not applicable to UV units for treating potable water from public water
supply systems).
1.3.3 Application of Principles to Other Units
While only three types of units are covered in this standard, the princi-
ples and approaches outlined should provide an initial guide for the testing
of any of a number of other types of units and/or systems for the microbiolog-
ical purification of contaminated water.
0-5
-------
2, PERFORMANCE REQUIREMENTS
2ol Microbiological Water Purifier
In order to make the claim of "microbiological water purifier/" units
must be tested and demonstrated to meet the microbiological reduction require-
ments of Table 1 according to the test procedures described in Section 3
(Appendix O-l) for the specific type of unit involved.
2.2 Chemical Health Limits
Where silver or some other pesticidal chemical is used in a unit, that
chemical concentration in the effluent water must meet any National Primary
Drinking Water Maximum Contaminant Level (MCL), additional Federal guidelines
or otherwise be demonstrated not to constitute a threat to health from con-
sumption or contact where no MCL exists.
2.3 Stability of Pesticidal Chemical
Where a pesticidal chemical is used in the treatment unit, the stability
of the chemical for disinfectant effectiveness should be sufficient for the
potential shelf life and the projected use life of the unit based on manufac-
turer's data. Where stability cannot be assured from historical data and
information, additional tests will be required.
2.4 Performance Limitations
2.4.1 Effective Lifetime
The manufacturer must provide an explicit indication or assurance of the
unit's effective use lifetime to warn the consumer of potential diminished
treatment capability either through:
a. Having the unit terminate discharge of treated water, or
b. Sounding an alarm, or
c. Providing simple, explicit instruction for servicing or replacing
units within the recommended use life (measurable in terms of volume
throughput, specific time frame or other appropriate method)„
0-6
-------
TABLE 1
MICROBIOLOGICAL REDUCTION REQUIREMENTS
Klebsiella terrigena, a common coliform, was selected as the challenge
organism to represent the coliform group. Poliovirus 1 (LSc) and rotavirus
(Wa or SA-11) are common environmental viruses and show resistance to
different treatment processes, thereby providing good challenges for the virus
group. Giardia was selected as the cyst challenge representative because of
its widespread disease impact and its resistance to chemical disinfection.
The use of 4-6 micron particles or beads for testing the occlusion filtration
of cysts has been demonstrated to be an accurate and practical substitute for
the use of live cyst challenges. It is included as an option where
disinfection or other active processes are not involved.
Minimum
Required
Reduction
Influent
Challenge*
Organism Challenge* Log
Bacteria:
Klebsiella terrigena
(ATCC-33257)
Virus:
a. Poliovirus 1 (LSc)
(ATCC-VR-59) and,
b. Rotavirus (Wa or SA-11)
(ATCC-VR-899 or VR-2018)
Cyst (Protozoan): Giardia***
a. Giardia muris or
Giardia lamblia
or
b. As an option for units or
components based on occlusion
filtration: particles
or spheres, 4-6 microns
(Testing according to National Sanitation Foundation Standard 53 for cyst
reduction will be acceptable.
10 /100 ml
1 x 10 /L
1 x 10 /L
106/L
10?/L
99.9999
99.99**
99.99**
99.9
99.9
The influent challenges may constitute greater concentrations than
would be anticipated in source waters, but these are necessary to
properly test, analyze and quantitatively determine the indicated
log reductions.
-------
TABLE 1
MICROBIOLOGICAL REDUCTION REQUIREMENTS (Continued)
** Virus types are to be mixed in roughly equal 1 x 10 /L
concentrations and a joint 4 log reduction will be acceptable.
*** It should be noted that new data and information with respect to
cysts (i.e., Cryptosporidium or others) may in the future
necessitate a review of the organism of choice and of the challenge
and reduction requirements.
-------
2.4.2 Limitation on Use of Iodine
EPA policy initially developed in 1973 and reaffirmed in 1982 (memo of
March 3, 1982 from J. A. Cotruvo to G. A. Jones, subject: "Policy on Iodine
Disinfection") is that iodine disinfection is acceptable for short-term or
limited or emergency use but that it is not recommended for long-term or
routine community water supply application where iodine-containing species may
remain in the drinking water.
0-7
-------
3= MICROBIOLOGICAL WATER PURIFIER TEST PROCEDURES
3.1 Purpose
These tests are performed on ceramic filtration candles or units, halo-
genated resins and units and ultraviolet (UV) units in order to substantiate
their microbiological removal capabilities over the effective use life of the
purifier as defined in Table 1 and, where a pesticidal chemical is used, to
determine that said chemical is not present in the effluent at excessive
levels (see Section 3.5.3.4, Appendix 0).
3.2 Apparatus
Three production units of a type are to be tested, simultaneously, if
feasible; otherwise, in a manner as similar to that as possible.
Design of the testing rig must parallel and simulate projected field use
conditions. For plumbed-in units a guide for design of the test rig may be
taken from "Figure 1: Test Apparatus-Schematic" (p. A-2 of Standard Number 53
"Drinking Water Treatment Units — Health Effects," National Sanitation
Foundation). Otherwise, the test rig must be designed to simulate field use
conditions (worst case) for the unit to be tested.
3.3 Test Waters — Non-Microbiological Parameters
In addition to the microbiological influent challenges, the various test
waters will be constituted with chemical and physical characteristics as
follows:
3.3.1 Test Water #1 (General Test Water)
This water is intended for the normal non-stressed (non-challenge) phase
of testing for all units and shall have specific characteristics which may
easily be obtained by the adjustment of many public system tap waters, as
follows:
a. It shall be free of any chlorine or other disinfectant residuali
b. pH — 6.5 --8.5;
c. Total Organic Carbon (TOC) 0.1 - 5.0 mg/Lf
d. Turbidity 0.1-5 NTU;
O-8
-------
e. Temperature 20 C * 5 C; and
f. Total Dissolved Solids (TDS) 50 - 500 mg/L.
3-3.2 Test Water #2 (Challenge Test Water/Halogen Disinfection)
This water is intended for the stressed challenge phase of testing where
units involve halogen disinfectants (halogen resins or other units) and shall
have the following specific characteristics:
a. Free of chlorine or other disinfectant residual;
b. (1) pH 9.0 * .2, and
(2) for iodine-based units a pH of 5.0 " .2 (current information
indicates that the low pH will be the most severe test for virus
reduction by iodine disinfection);
c. Total Organic Carbon (TOC) not less than 10 mg/L;
d. Turbidity not less than 30 NTU;
e. Temperature 4 C " 1 C; and
f. Total Dissolved Solids (TDS) 1,500 mg/L * 150 mg/L.
3.3.3 Test Water #3 (Challenge Test Water/Ceramic Candle
or Units With or Without Silver Impregnation)
This water is intended for the stressed challenge phase of testing for
the indicated units but not for such units when impregnated with a halogen
disinfectant (for the latter, use Test Water #2). It shall have the following
specific characteristics:
a. It shall be free of any chlorine or other disinfectant residual;
b. pH 9.0 * .2;
c. Total Organic Carbon (TOC) — not less than 10 mg/L;
d. Turbidity — not less than 30 NTU;
e. Temperature 4 C * 1 C; and
f. Total Dissolved Solids (TDS) — 1,500 jng/L * 150 mg/L.
3.3.4 Test Water #4 (Challenge Test Water for Ultraviolet Units)
This water is intended for the stressed phase of testing for UV units and
shall have the following specific characteristics:
0-9
-------
a. Free of chlorine or other disinfectant residual;
b. pH 6.5 - 8.5;
c. Total Organic Carbon (TOG) •— not less than 10 mg/L;
d. Turbidity •— not less than 30 NTU;
e. Temperature 4 C * 1C;
f. Total Dissolved Solids (TDS) — 1,500 mg/1 " 150 mg/L;
g. Color U.V. absorption (absorption at 254 run) — Sufficient para-
hydroxybenzoic acid (PHBH) to be just below the trigger point of the
warning alarm on the U.V. unit. (Note that Section 3.5.1.1 provides
an alternative of adjusting the U.V. lamp electronically, especially
when the U.V. lamp is preceded by activated carbon treatment.)
3.3.5 Test Water t5 (Leaching Test Water for Units Containing Silver)
This water is intended for stressed leaching tests of units containing
silver to assure that excess levels of silver will not be leached into the
drinking water. It shall have the following specific characteristics:
a. Free of chlorine or other disinfectant residual;
b. pH — 5.0 * 0.2;
c. Total Organic Carbon (TOC) —• approximately 1.0 mg/L;
d. Turbidity — 0.1 - 5 NTU;
e. Temperature — 20 C * 5 C; and
f. Total Dissolved Solids (TDS) — 25 - 100 mg/L.
3.3.6 Recommended Materials for Adjusting Test Water Characteristics
a. pH: inorganic acids or bases (i.e., HC1, NaOH);
b. Total Organic Carbon (TOC): humic acids;
c, Turbidity: A.C. Fine Test Dust (Park No. 1543094)
from: A.C. Spark Plug Division
General Motors Corporation
1300 North Dort Highway
Flint, Michigan 48556;
d. Total Dissolved Solids (TDS): sea salts, Sigma Chemical Co., S9883
(St. Louis,MO) or another equivalent source of TDS;
0-10
-------
e. Color U.V. Absorption: p-hydroxybenzoic acid (grade: general
purpose reagent).
3.4 Analytical Methods
3.4.1 Microbiological Methods
Methods in this section are considered "state-of-the-art" at the time of
its preparation and subsequent improvements should be expected. Methods used
for microbiological analyses should be compatible with and equal to or better
than those given below.
3.4.1.1 Bacterial Tests
a. Chosen Organism: Klebsiella terrigena (ATCC-33257).
b. Method of Production: Test organism will be prepared by overnight
growth in nutrient broth or equivalent to obtain the organism in the
stationary growth phase (Reference: Asburg, E.D., Methods of
Testing Sanitizers and Bacteriostatic Substances In: Disinfection,
Sterilization and Preservation, Seymour S. Block, ed., pp. 964-980,
1983) . The organism will be collected by centrifugation and washed
three times in phosphate buffered saline before use. Alternatively,
the organisms may be grown overnight on nutrient agar slants or
equivalent and washed from the slants with phosphate buffered
saline. The suspensions should be filtered through sterile Whatman
Number 2 filter paper (or equivalent) to remove any bacterial
clumps. Mew batches of organisms must be prepared daily for use in
challenge testing.
c. State of Organism: Organisms in the stationary growth phase and
suspended in phosphate buffered saline will be used.
d. Assay Techniques: Assay may be by the spread plate, pour plate or
membrane filter technique on nutrient agar, M.F.C. or m-Endo medium
(Standard Methods for the Examination of Water and Wastewater, 16th
edition, 1985, APHA). Each sample dilution will be assayed in
triplicate.
3.4.1.2 Virus Tests
a. Chosen Organisms: Poliovirus type 1 (LSc) (ATCC-VR-59), and Rota-
virus Strain SA-11 (ATCC-VR-899) or WA (ATCC-VR-2018).
b. Method of Production: All stocks should be grown by a method
described by Smith and Gerba (in Methods in Environmental Virology,
pp. 15-47, 1982) and purified by the procedure of Sharp, et al.
(Appl. Microbiol., 29:94-101, 1975), or similar procedure (Berman
and Hoff, Appl. Environ. Microbiol., 48:317-323, 1984), as these
methods will produce largely monodispersed virion particles.
O-ll
-------
c. State of the Organism: Preparation procedure will largely produce
monodispersed particles,
d. Assay Techniques? Poliovirus type 1 may be grown in the BGM, MA-104
or other cell line which will support the growth of this virus. The
rotaviruses are best grown in the MA-104 cell line. Since both
viruses can be assayed on the MA-104 cell line, a challenge test may
consist of equal amounts of both viruses as a mixture (i.e., the
mixture must contain at least 1.0 x 10 /mL of each virus). Assays
may be as plaque forming units (PFU) or as immunofluorescence foci
(IF) (Smith and Gerba, In: Methods in Environmental Virology,
pp. 15-47, 1982). Each dilution will be assayed in triplicate.
3.4.1.3 Cyst Tests
a. Chosen Organism
1. Giardia lamblia or the related organism, Giardia muris, may be
used as the challenge cyst.
2. Where filtration is involved, tests with 4-6 micron spheres or
particles have been found to be satisfactory and may be used as
a substitute for tests of occlusion using live organisms (see
Table 1). Spheres or particles may only be used to evaluate
filtration efficacy. Disinfection efficacy can only be evalu-
ated with the use of viable Giardia cysts.
b. Method of Production: Giardia muris may be produced in laboratory
mice and Giardia lamblia may be produced in Mongolian gerbils;
inactivation results based on excystation measurements correlate
well with animal infectivity results.
c. State of the Organisms Organisms may be separated from fecal
material by the procedure described by Sauch (Appl. Environ.
Microbiol., 48:454-455, 1984) or by the procedure described by
Bingham, et al. (Exp. Parasitol., 47:284-281, 1979).
d. Assay Techniques: Cysts are first reconcentrated (500 ml., minimum
sample size) according to the method of Rice, Hoff and Schaefer
(Appl. Environ. Microbiol., 43:250-251, 1982). The excystation
method described by Schaefer, et al. (Trans., Royal Soc. of Trop.
Med. & Hyg. 78:795-800, 1984) shall be used to evaluate Giardia
muris cyst viability. For Giardia lamblia cysts, the excystation
method described by Bingham and Meyer (Nature, 277:301-302, 1979) or
Rice and Schaefer (J. Clin. Microbiol., 14:709-710, 1981) shall be
used. Cyst viability may also be determined by an assay method
involving the counting of trophozoites as well as intact cysts
(Bingham, et al., Exp. Parasitol., 47:284-291, 1979).
0-12
-------
3.4.2 Chemical and Physical Methods
All physical and chemical analyses shall be conducted in accordance with
procedures in Standard Methods for the Examination of Water and Wastewater,
16th Edition, American Public Health Association, or equivalent.
3.5 Test Procedures
3.5.1 Procedure - Plumbed-in Units
a- 1- Install three production units of a type as shown in Figure 1
and condition each unit prior to the start of the test in
accordance with the manufacturer's instructions with the test
water without the addition of the test contaminant. Measure
the flow rate through each unit. The unit shall be tested at
the maximum system pressure of 60 psig static and flow rate
will not be artificially controlled.
2. Test waters shall have the defined characteristics continuously
except for test waters 2, 3 and 4 with respect to turbidity.
The background non-sampling turbidity level will be maintained
at 0.1-5 NTU but the turbidity shall be increased to the
challenge level of not less than 30 NTU in the following
manner:
- In the "on" period(s) prior to the sampling "on" period.
- In the sampling "on" period when the sample actually will
be taken. (Note: at least 10 unit void volumes of the 30
NTU water shall pass through the unit prior to actual
sampling so as to provide adequate seasoning and uni-
formity before sample collection.)
b. 1. Use appropriate techniques of dilution and insure continual
mixing to prepare a challenge solution containing the bacterial
contaminant. Then spike test water continuously with the
influent concentration specified in Table 1.
2. Use appropriate techniques to prepare concentrated virus and
Giardia suspensions. Feed these suspensions into the influent
stream so as to achieve the influent concentrations specified
in Table 1 in the following manner:
- In the "on" period(s) prior to the sampling "on" period.
- In the sampling "on" period when the sample actually will
be taken. (Note: at least 10 unit void volumes of seeded
water shall pass through the unit prior to sampling so as
to provide adequate seasoning and uniformity before sample
collection.)
0-13
-------
c. Purge the system of the uncontaminated water with a sufficient flow
of contaminated test water. Start an operating cycle of 10 percent
on, 90 percent off with a 15 to 40 minute cycle (Examples 3 minutes
on, 27 minutes off) with the contaminated test water. This cycle
shall be continued for not more than 16 hours per day (minimum daily
rest period of 8 hours). The total program shall extend to 100% of
estimated volume capacity for halogenated resins or units and for
10-1/2 days for ceramic candles or units and U.V. units.
d. Sampling: Samples of influent and effluent water at the specified
sampling points shall be collected as shown below for the various
units; these are minimum sampling plans which may be increased in
number by the investigator. All samples shall be collected in
duplicate from the flowing water during the sampling "on" portion of
the cycle and they shall be one "unit void volume" in quantity (or
of appropriate quantity for analysis) and represent worst case
challenge conditions. Effluent samples shall usually be collected
near the middle of the sampling "on" period (or the whole volume
during one "on" period) except for samples following the specified
"stagnation" periods, for which sampling shall be conducted on the
first water volume out of the unit. Each sample will be taken in
duplicate and shall be retained and appropriately preserved, if
required, for chemical or microbiological analysis in the event
verification is required. (For units where the volume of a single
"on" period is insufficient for the required analysis, samples from
successive "on" periods may be accumulated until a sufficient volume
has been collected.)
l(a). Sampling Plan: Halogenated Resins or Units (Non-iodine Based)
Tests
Test Point
(% of Estimated
Capacity)
Start
25%
50%
After 48 hours
stagnation
Influent
Background
General
Active
Agent/
Residual
X
X
X
Microbiological
X
X
X
60%
75%
After 48 hours
stagnation
100%
Chal-
lenge
PH -
9.0 ' 0.2
X
X
X
X
X
X
X
X
0-14
-------
Kb). Sampling Plan: lodinated Resins or Units
Test Point
(% of Estimated
Capacity)
Start
25%
50%
After 48 hours
stagnation
Tests
General
Influent
Background
X
Active
Agent/
Residual
X
X
X
Microbiological
X
X
X
60%
75%
After 48 hours
stagnation
Chal-
lenge
PH -
9.0 ' 0.2
X
X
X
X
90%
100%
After 48 hours
stagnation
Chal-
lenge
pH -
5.0 * 0.2
X
X
X
X
2. Sampling Plan: Ceramic Candles or Units and U.V. Units
Tests
Test Point
Start
Day 3
Day 6
Test
Water
General
Influent
Background
(middle)
(middle)
After 48 hours
stagnation
Microbiological
X
X
X
Day 7 (middle)
Day 8 (near end)
After 48 hours
stagnation
Day 10-1/2
Chal-
lenge
X
X
X
X
(Note: All days are "running days" and exclude stagnation periods. When
the units contain silver, a leaching test shall be conducted as shown in
Section 3.5.1.e and silver residual will be measured at each microbiological
sampling point.)
O-15
-------
Leaching Tests for Silverized Unitss Where the unit contains
silver, additional tests utilizing Test Water #5 will be conducted
as follows:
Tests
Influent
Test Point Background Silver/Residual
Start X X
Day 2 X
After 48 hours
stagnation X
f. Alternate Sampling Plans:
1. Since some laboratories may find it inconvenient to test some
units on a 16 hour on/8 hour off cycle, two alternates are
recognized:
- Go to a shorter operational day but lengthen the days of
test proportionally
- Use up to 20 percent "on"/80 percent "off" for a propor-
tionally shorter operational day
2. Sampling points must be appropriately adjusted in any alternate
sampling plan.
g. Application of Test Waters: The application of test waters is
designed to provide information on performance under both normal and
stressed conditions? it should be the same or equivalent to the
followings
1. a. Halogenated Resins or Units (Non-iodine based) —•
First 50% of test period: Test Water 1 (General)
Last 50% of test period: Test Water 2 (Challenge)
(pH - 9.0 * 0.2)
b. lodinated Resins or Units —
First 50% of test period: Test Water 1 (General)
Next 25% of test period: Test Water 2 (Challenge)
(pH - 9.0 ' 0.2)
Last 25% of test period: Test Water 2 (Challenge)
(but with pH - 5.0 * 0.2)
2. Ceramic Candles or Units —
First 6 days of testing: Test Water 1 (General)
Last 4-1/2 days of testing: Test Water 3 (Challenge)
0-16
-------
3. Ultraviolet (U.V.) Units —
First 6 days of testing:
Last 4-1/2 days of testing:
h. Analyses and monitoring:
Test Water 1 (General)
Test Water 4 (Challenge)
1. Microbiological sampling and analysis shall be conducted of the
specified influent and effluent sampling points during each
indicated sampling period.
2. Test Water Monitoring: The specified parameters of the various
test waters (see Section 3.3) will be measured and recorded at
each microbiological sampling point; the specified parameters
will be measured at least once on non-sampling days when the
units are being operated.
3. Background chemical analyses of influent water shall be con-
ducted at least once at the start of each test period to
determine the concentration of the U.S. EPA primary inorganic
contaminants, secondary contaminants and routine water para-
meters, not otherwise covered in the described test waters.
4. In addition, quality assurance testing shall be conducted for
the seed bacteria under environmental conditions on the first
and last days of testing to make sure that there is no signifi-
cant change over the test day. Populations will be measured
(for example, as dispersed in the supply tank) at the beginning
and end of the test day to detect possible incidental effects
such as proliferation, die-off, adsorption to surfaces, etc.
Relatively stable bacterial seed populations are essential to
an acceptable test program.
5. When a unit contains a halogen or silver, the active agent
residual will be measured in the effluent at each microbiologi-
cal test (sampling) point.
6. Silver will additionally be measured three times in the efflu-
ent as specified in Section 3.5.I.e.
Neutralization of Disinfection Activity: Immediately after col-
lection, each test sample must be treated to neutralize residual
disinfectant. For halogen- and silver-based disinfectants this may
be done by addition of thioglycollate-thiosulfate neutralizer
solution (Chambers, et al., J. Amer. Water Works Assoc., 54:208-216,
1962). This solution should be prepared daily. All results are
invalid unless samples are neutralized immediately upon collection.
0-17
-------
j= Special Provisions for Ceramic Candles or Units:
1. Provisions for slow flow: Ceramic units may be subject to
clogging and greatly reduced flow over the test period. An
attempt should be made to maintain manufacturer rated or
claimed flow rates, but even at reduced flows the sampling
program set forth in Section 3.5.1.d.2 shall be maintained.
2. Cleaning of ceramic units: Units should be cleaned according
to manufacturer's directions. Two cleanings should occur
during the period of test (in order to prove the unit's
durability through the cleaning procedure). However, near the
time of microbiological sampling, the units should not be
cleaned until after the sampling. Further, no anti-microbial
chemical (for cleaning or sanitizing) may be applied to the
units during the test period unless the manufacturer specifies
the same as part of routine maintenance.
k. Halogenated units or U.V. units with mechanical filtration processes
separate from the microbiological disinfection components shall have
the mechanical filtration components replaced or serviced when
significant flow reduction (clogging) occurs in accordance with the
manufacturer's instructions in order to maintain the test flow rate.
Units with non-removable mechanical filtration components will be
run until flow is below that considered acceptable for consumer
convenience. (If premature clogging presents a problem, some
specialized units may require a customized test plan.)
1. Special Provisions for Ultraviolet (U.V.) Units:
1. The units will be adequately challenged by the prescribed test
watersi consequently they will be operated at normal intensity.
However, where the U«V0 treatment component is preceded by
activated carbon treatment, the output of the U.V. lamp shall
be adjusted electronically, such as by reducing the current to
the lamp or other appropriate means, to be just above the alarm
point. This option shall be available for use under other U.V.
configurations, at the choice of the persons responsible for
testing, as an alternative to the use of the U.V. absorbent,
p-hydroxybenzoic acid.
2. Fail/safe: Units will provide and will be tested for fail/safe
warnings in the event of water quality changes or equipment
failures which may interfere with its microbiological purifica-
tion function.
3. Cleaning: Manufacturer's guidance with respect to cleaning
will be followed.
0-18
-------
3.5.2 Procedure; Non-Plumbed Units
a. General: The basic procedures given in Section 3.5.1 shall be used
with necessary adaptations to allow for the specific design of the
unit. In any event, the testing procedures shall provide a test
challenge equivalent to those for plumbed-in units.
b. Test conditions and apparatus should be adapted to reflect proposed
or actual use conditions in consultation with the manufacturer,
including flow rate and number of people to be served per day. In
some cases variable flow or other non-standard conditions may be
necessary to reflect a worst-case test.
3.5.3 Acceptance and Records
3.5.3.1
To qualify as a microbiological water purifier, all three production
units of a type must continuously meet or exceed the reduction requirements of
Table 1, within allowable measurement tolerances for not more than ten percent
of influent/effluent sample pairs, defined as follows:
Virus: one order of magnitude
Bacteria: one order of magnitude
Cysts: one/half order of magnitude
The geometric mean of all microbiological reductions must meet or exceed
the requirements of Table 1. An example is given as follows:
- Unit: iodinated resin.
- Number of sample pairs over the completed test program:
10 per unit — 3 units « 30.
- Number of allowable sample pairs where log reduction is insuffi-
cient: 10% of 30 = 3 sample pairs.
- Allowable minimum log reductions in these 3 pairs:
Bacteria - 5 log
Virus - 3 log
Cyst - 2-1/2 log
- Conclusion: If the geometric mean of all reductions meets or
exceeds the requirements of Table 1, the indicated insufficient
sample pairs will be allowed.
0-19
-------
3.5.3.2 Records
All pertinent procedures and data shall be recorded in a standard format
and retained for possible review until the report of results has been com-
pletely accepted by review authorities, in no case for less than a year.
3.5.3.3 Scaling Up or Down
Where a manufacturer has several similar units using the same basic
technology and parallel construction and operation, it may sometimes be
appropriate to allow the test of one unit to be considered representative of
others. Where any serious doubt exists, all units of various sizes may
require testing. A "rule of three" is suggested as a matter of judgment.
Scaling up to three times larger or on-third, based on the size of either the
test unit or of its operative element, may be allowed. However, for UV units,
any size scale-up must be accompanied by a parallel increase in radiation
dose.
3.5.3.4
Where silver or some other chemical is used in the unit, concentrations
in the effluent water must meet any National Primary Drinking Water Maximum
Contaminant Level (MCL), additional Federal guidelines, or otherwise must not
constitute a threat to health where no MCL exists.
O-20
-------
APPENDIX O-l
SUMMARY FOR BASIS OF STANDARDS AND TEST WATER PARAMETERS
A- Microbiological Reduction Requirements
1. Bacteria
Current standards for the microbiological safety of drinking
water are based on the presence of colifonn bacteria of which
Klebsiella is a member. Members of the genus Klebsiella are also
potential pathogens of man (Vlassof, 1977). Klebsiella terrigena is
designated as the test organism since it is commonly found in
surface waters (Izard, et al., 1981).
Experience with the use of colifonn bacteria to estimate the
presence of enteric bacterial pathogens in drinking water as per-
formed over the last 75 years indicates a high degree of reliabil-
ity. Required testing of more than one bacterial pathogen appears
unjustified since viral and Giardia testing will be required.
Enteric viruses and Giardia are known to be more resistant to common
disinfectants than enteric bacterial pathogens and viruses are more
resistant to removal by treatments such as filtration. Thus, any
treatment which would give a good removal of both virus and Giardia
pathogens would most likely reduce enteric bacteria below levels
considered infectious (Jarroll, et al., 1981; Liu, et al., 1971).
The concentration of coliform bacteria in raw sewage is approx-
imately 10 /100 ml. Concentrations in polluted stream waters have
been found to exceed 10 per 100 ml (Gulp, et al., 1978, Table 10).
Based on the over 10 /100 ml concentrations observed in highly
polluted stream water and a target effluent concentration of less
than 1/100 ml, a 6 log reduction is recommended.
2. Virus
In the United States concentrations of enteroviruses are esti-
mated to range from 10 -10 /liter in raw sewage (Farrah and Schaub,
1971). Based on this observation it is estimated that, natural
waters contaminated with raw sewage may contain from 10 to 10
enteric viruses per liter.
There are currently no standards for viruses in drinking water
in the United States. However, EPA has proposed a non-enforceable
health-based recommended maximum contaminant level (RMCL) of zero
for viruses (EPA, 1985). Several individuals and organizations have
developed guidelines for the presence of viruses in drinking water
and various experts have proposed standards (WHO, 1979, 1984; Berg,
1971; Melnick, 1976). It has generally been felt that
0-21
-------
drinking water should be free of infectious virus since even one
virus is potentially infectious and suggested standards are largely
based on technological limits of our detection methodology„ Guide-
lines suggested by the World Health Organization (1984) and others
recommend that volumes to be tested be in the order of 100-1,000
liters and that viruses be absent in these volumes.
Assuming a target effluent level of less than one virus in 100
liters of water and a concentration of 10 enteric viruses in 100
liters of sewage-contaminated waters, the water purifier units
should achieve at least 4 logs of virus removal.
The relative resistance of enteric viruses to different dis-
infectants varies greatly among the enteric viruses and even among
members of the same group (i.e., enteroviruses). For example, while
f2 coliphage is one of the most resistant viruses to inactivation by
chlorine it is one of the most susceptible to inactivation by ozone
(Harakeh and Butler, 1984). Ionic conditions and pH can also affect
the relative resistance of different viruses to a disinfectant
(Engelbrecht, et al., 1980). On this basis it is felt that more
than one enteric virus should be tested to ensure the efficacy of
any disinfection system. Poliovirus type 1 (Strain LSc) was chosen
as one of the test viruses because it has been extensively used in
disinfection and environmental studies as representative of the
enterovirus family. It is recognized that it is not the most
resistant virus to inactivation by chlorine, but is still resistant
enough to serve as a useful indicator. Rotavirus is selected as the
second test enteric virus since it represents another group of
enteric viruses in nucleic acid composition and size. It is also a
major cause of viral gastroenteritis and has been documented as a
cause of water borne gastroenteritis (Gerba, et al., 1985). The
human rotavirus or the similar Simian rotavirus may be used in the
test procedure. A net 4-log reduction for a joint challenge of
1 x 10 /L each for poliovirus and rotavirus is recommended.
3. Cysts (Protozoan)
Over the past several years, giardiasis has consistently been
one of the most frequently reported waterborne diseases transmitted
by drinking water in the United States (Craun, 1984). EPA has
proposed a RMCL of zero for Giardia (EPA, 1985). Its occurrence has
generally been associated with treatment deficiencies including
either inadequate or no filtration. Giardiasis has not been known
to occur from drinking water produced by well-operated filtration
treatment plants. De Walle, et al. (1984), in a study of filtration
treatment plant efficiencies, cited percent removals for Giardia in
pilot plant tests as follows:
- Rapid filtration with coagulation-sedimentation: 96.6-99.9%?
- Direct filtration with coagulation: 95.9-99.9%.
0-22
-------
From this research and from the lack of Giardia cases in
systems where adequate filtration exists, a 3-log (99.9%) reduction
requirement is considered to be conservative and to provide a
comparable level of protection for water purifiers to a
well-operated filtration treatment plant.
Data on environmental levels for cysts in natural waters is
limited because of the difficulties of sampling and analysis.
Unpublished data indicate very low levels from less than 1/L to less
than 10/L. Here a 3-log reduction would provide an effluent of less
than 1/100 L, comparable to the recommended virus reduction require-
ments .
Either Giardia lamblia or the related organism, Giardia muris,
which is reported to be a satisfactory test organism (Hoff, et al.,
1985) , may be used as the challenge organism. Tests will be con-
ducted with a challenge of 10 organisms per liter for a 3-log
reduction.
Where the treatment unit or component for cysts is based on the
principle of occlusion filtration alone, testing for a 3-log reduc-
tion of 4-6 micron particles or spheres (National Sanitation Founda-
tion Standard 53, as an example) is acceptable. Difficulties in the
cyst production and measurement technologies by lesser-equipped
laboratories may require the use of such alternative tests where
applicable.
B. Microbiological Purifier Test Procedures
1. Test Waters
a. The general test water (test water #1) is designed for the
normal, non-stressed phase of testing with characteristics that
may easily be obtained by the adjustment of many public system
tap waters.
b. Test water #2 is intended for the stressed phase of testing
where units involve halogen disinfectants.
1. Since the disinfection activity of some halogens falls
with a rising pH, it is important to stress test at an
elevated pH. The recommended level of 9.0 * 0.2, while
exceeding the recommended secondary level (Environmental
Protection Agency, 1984) is still within a range seen in
some natural waters (Environmental Protection Agency,
1976). However, for iodine-based units, a second stress-
ful condition is provided — a pH of 5.0 * 0.2 since
current information indicates that the disinfection
activity of iodine falls with a low pH (National Research
Council, 1980). While beneath the recommended secondary
0-23
-------
level (Environmental Protection Agency, 1984) a pH of 5.0
is not unusual in natural waters (Environmental Protection
Agency, 1976).
2o Organic matter as total organic carbon (TOC) is known to
interfere with halogen disinfection. While this TOC is
higher than levels in many natural waters, the designated
concentration of 10 mg/L is cited as typical in stream
waters (Culp/Wesner/Culp, 1978).
3. High concentrations of turbidity can shield microorganisms
and interfere with disinfection. While the recommended
level of not less than 30 NTU is in the range of turbidi-
ties seen in secondary wastewater effluents, this level is
also found in many surface waters, especially during
periods of heavy rainfall and snow melt (Culp/Wesner/Culp,
1978).
4. Studies with Giardia cysts have shown decreasing halogen
disinfection activity with lower temperatures (Jarroll,
et al., 1980); 4 C, a common low temperature in many
natural waters, is recommended for the stress test.
5. The amount of dissolved solids (TDS) may impact the
disinfection effectiveness of units that rely on displace-
able or exchange elements by displacement of halogens or
resins, or it may interfere with adsorptive processes.
While TDS levels of 10,000 mg/L are considered unusable
for drinking, many supplies with over 2,000 mg/L are used
for potable purposes (Environmental Protection Agency,
1984). The recommended level of 1,500 mg/L represents a
realistic stress challenge.
c. Test water #3 is intended for the stressed phase of testing of
ceramic filtration candles or units with or without silver
impregnation.
1. Since viruses are typically eluted from adsorbing media at
high pHs (Environmental Protection Agency, 1978) it may be
concluded that a high pH will provide the most stressful
testing for a ceramic-type unit; consequently, the high
natural water pH of 9.0 is recommended.
2. Expert opinion also holds that organic material will
interfere with adsorption of viruses. Thus, a high total
organic carbon level of not less than 10 mg/L is recom-
mended.
3. Turbidity may enhance the entrapment and removal of
microorganisms but it also may stimulate "short-
circuiting" through some units. A turbidity level of
0-24
-------
30 NTU will provide stress at time of sampling but the
non-sampling level of 0.1-5 NTU will allow routine opera-
tion of units.
4. Expert opinion holds that low water temperatures and high
TDS would most likely interfere with virus reduction by
adsorption; consequently, a 4 C temperature and 1,500 mg/L
TDS are recommended.
d. Test water #4 is intended for the stressed phase of testing for
ultraviolet (UV) units.
1. In general, high TOC, turbidity and TDS and low tempera-
ture are considered most stressful for UV, and the in-
dicated challenge levels are the same as for test
water #2.
2. The pH is not critical and may range from 6.5 to 8.5.
3. In order to test the UV units at their most vulnerable
stage of operation, a color challenge (light absorption at
254 nm) is to be maintained at a level where UV light
intensity is just above the unit's low intensity warning
alarm point. However, an alternate to the absorption
challenge is provided through adjusting the light intensi-
ty output of the UV lamp electronically by reducing
current to the lamp, or other appropriate means, to be
just above the alarm point; this approach would be
particularly necessary where the UV lamp is preceded by
activated carbon treatment.
e. Test water #5 is intended for the stressed leaching tests of
units containing silver. Low pH, TOC, turbidity, and TDS and
higher temperature are felt to be the characteristics associ-
ated with increased leachability. The recommended pH of
5.0 * .2, while being beneath the recommended secondary range
of 6.5-8.5 (Environmental Protection Agency, 1984) is still
found in some natural waters.
2. Test Procedures
The plan for testing and sampling is designed to reveal unit
performance under both "normal" and "stressed" operating conditions.
The stressed phase would utilize a set of water quality and opera-
tions conditions to give the units a realistic worst case challenge.
Testing plans for a specific model might involve modifications to
the recommended plan; more samples could be taken and analyzed; more
units could be studied. The principle of demonstrating adequate
performance even under realistic worst case conditions should be
maintained and the final selected test procedures should be agreed
as between investigators and reviewers or regulators.
0-25
-------
While some aspects of the testing procedures have been utilized
in actual experiments, the proposed protocol has not been verified
or utilized for the various units that may be considered. Conse-
quently, investigators and users of this protocol may find reasons
to alter some aspects through their practical experience; needed
changes should be discussed and cleared with involved reviewers/-
regulators .
0-26
-------
REFERENCES;
Berg, G. Integrated approach to the problem of viruses in water. J. ASCE,
Sanit. Eng. Div. 97:867-882, 1971.
Culp/Wesner/Culp. Guidance for planning the location of water supply intakes
downstream from municipal wastewater .treatment facilities. EPA Report, Office
of Drinking Water. Washington, DC, 1978.
Craun, G. F. 1984. Waterbome outbreaks of giardiasis: Current status. In:
Giardia and giardiasis. D. L. Erlandsen and E. A. Meyer Eds., Plenum Press,
New York, pp. 243-261, 1984.
DeWalle, F. B.; J. Engeset; Lawrence, W. Removal of Giardia lamblia cyst by
drinking water treatment plants. Report No. EPA-600/52-84-069, Office of
Research and Development, Cincinnati, OH, 1984.
Engelbrecht, R. S. , et al. Comparative inactivation of viruses by chlorine.
Appl. Environ. Microbiol. 40:249-256, 1980.
Environmental Protection Agency. Quality criteria for water. Washington, DC,
1976.
Environmental Protection Agency. National secondary drinking water
regulations. EPA-570/9-76-000, Washington, DC, 1984.
Environmental Protection Agency. National primary drinking water regulations;
synthetic organic chemicals, inorganic chemicals and microorganisms; Proposed
rule. Federal Register, Nov. 13, 1985.
Farrah, S. R., and S. A. Schaub. Viruses in wastewater sludges. In: Viral
Pollution of the Environment, G. Berg, Ed. CRC Press, Boca Raton, Florida.
pp. 161-163, 1983.
Gerba, C. P.; Rose, J. B.; Singh, S. N. Waterbome gastroenteritis and viral
hepatitis. CRC Critical Rev. Environ. Contr. 15:213-236, 1985.
Harakeh, M.; Butler, M. Inactivation of human rotavirus, SA-11 and other
enteric viruses in effluent by disinfectants. J. Hyg. Camb. 93:157-163, 1984.
Hoff, J. C.; Rice, E. W.; Schaefer, F. W. Comparison of animal infectivity
and excystation as measures of Giardia muris cyst inactivation by chlorine.
Appl. Environ. Microbiol. 50:1115-1117, 1985.
Izard, D.; Farragut, C.;Gavini, F.; Kersters, K.; DeLey. J.; Leclerc, H.
Klebsiella terrigena, a new species from water and soil. Intl. J. Systematic
Bacteriol. 31:116-127, 1981.
0-27
-------
Jakubowski, W. Detection of Giardia cysts in drinking water. In: Giardia
and Giardiasis, Erlandsen, S. L.; Meyer, E. A. Eds., Plenum Press, NY.
pp. 263-286, 1984.
Jarroll, E. L.; Bingham, A. K0; Meyer, E, A. Giardia cyst destructions
Effectiveness of six small-quantity water disinfection methods. Am. J. Trop.
Med. 29:8-11, 1980
Jarroll, E. L,,; Bingham, A. K.; Meyer, E. A. Effect of chlorine on Giardia
cyst viability. Appl. Environ. Microbiol. 43:483-487, 1981.
Liu, O. C., et al. Relative resistance of 20 human enteric viruses to free
chlorine in Potomac River water. Proceedings of 13th Water Quality Conference
Snoeyink, V.; Griffin, V. Eds., pp. 171-195, 1971.
Melnick, J. L. Viruses in water. In: Viruses in Hater Berg, G.;
Bodily, H. L.; Lennette, E. H.; Melnick, J. L.; Metclaf T. G., Eds. Amer.
Public Hlth. Assoc., Washington, DE, pp. 3-11, 1976.
National Research Council. The disinfection of drinking water, In: Drinking
Water and Health, Volume 2. Washington, DC, pp. 5-137, 1980.
National Sanitation Foundation. Drinking water treatment units: Health
effects. Standard 53. Ann Arbor, MI, 1982.
Vlassoff, L. T. Klebsiella. In: Bacterial Indicators/Health Hazards
Associated with Water Hoadley, A. W.; Dutka, B. J., Eds. American Society for
Testing and Materials, Philadelphia, PA. pp. 275-288, 1977.
World Health Organization. Human Viruses in Water, Technical Support
Series 639, World Health Organization, Geneva, 1979.
World Health Organization. Guidelines for Drinking Water Quality. Volume 1.
Recommendations. World Health Organization, Geneva, 1984.
0-28
-------
APPENDIX O-2
LIST OF PARTICIPANTS; TASK FORCE ON GUIDE STANDARD AND PROTOCOL FOR
TESTING MICROBIOLOGICAL WATER PURIFIERS
Stephen A. Schaub, Chairman — U.S. Army Medical Bioengineering Research and
Development Laboratory (USAMBRDL), Fort Detrick, Maryland 21701, FTS:
8/935-7207 — Comm: 301/663-7207.
Frank A. Bell, Jr., Secretary — Criteria and Standards Division, Office of
Drinking Water (WH-550), Environmental Protection Agency, Washington,
D.C. 20460, Phone: 202/382-3037.
Paul Berger, Ph.D. — Criteria and Standards Division, Office of Drinking
Water (WH-550), Environmental Protection Agency, Washington, D.C. 20460,
Phone: 202/382-3039.
Art Castillo — Disinfectants Branch, Office of Pesticide Programs (TS-767CO,
Environmental Protection Agency, Washington, D.C. 20460, Phone: 703/557-
3695.
Ruth Douglas — Disinfectants Branch, Office of Pesticide Programs (TS-767C),
Environmental Protection Agency, Washington, D.C. 20460, Phone: 703/557-
3675.
Al Dufour — Microbiology Branch, Health Effects Research Laboratory/
Environmental Protection Agency, 26 W. St. Clair Street, Cincinnati, Ohio
45268, Phone: FTS: 8/684-7870 — Comm: 513/569-7870.
Ed Geldreich — Chief, Microbiological Treatment Branch, Water Engineering
Research Laboratory, Environmental Protection Agency, 26 W. St. Clair
Street, Cincinnati, Ohio 45268, Phone: FTS: 8/684-7232 -- Comm:
513/569-7232.
Charles Gerba — Associate Professor, Department of Microbiology and
Immunology, University of Arizona, Tucson, Arizona 85721, Phone:
602/621-6906.
John Hoff — Microbiological Treatment Branch, Water Engineering Research
Laboratory, Environmental Protection Agency* 26 W. St. Clair Street,
Cincinnati, Ohio 45268, Phone: FTS: 8/684-7331 — Comm: 513/569-7331.
Art Kaplan — Office of Research and Development (RD-681) Environmental
Protection Agency, Washington, D.C. 20460, Phone: 202/382-2583.
Bala Krishnan — Office of Research and Development (RD-681) Environmental
Protection Agency, Washington D.C. 20460, Phone: 202/382-2583.
0-29
-------
John Lee — Disinfectants Branch, Office of Pesticide Programs (TS-767C)
Environmental Protection Agency, Washington, D.C. 20460, Phone;
703/557-3663.
Dorothy Portner -- Disinfectants Branch, Office of Pesticide Programs
(TS-767-C), Environmental Protection Agency, Washington, D.C. 20460,
Phone: 703/557-0484.
Don Reasoner — Microbiological Treatment Branch, Water Engineering Research
Laboratory, Environmental Protection Agency, 26 W. St. Clair Street,
Cincinnati, Ohio 45268, Phones 312/654-4000.
P. Reguanthan (Regu) ~ Everpure, Inc., 660 N. Blackhawk Drive, Westmont,
Illinois 60559, Phone: 312/654-4000.
David Stangel — Policy and Analysis Branch, Office of Compliance Monitoring,
Environmental Protection Agency, Washington, D.C., Phone: 202/382-7845.
Richard Tobin ~ Monitoring and Criteria Division, Environmental Health
Center, Department of Health and Welfare of Canada, Tunney's Pasture,
Ottawa, Ontario, K1A OL2, Canada, Phone: 613/990-8982.
0-30
-------
APPENDIX 0-3
RESPONSE BY REVIEW SUBCOMMITTEE(1) TO PUBLIC COMMENTS ON GUIDE STANDARD
AND PROTOCOL FOR TESTING MICROBIOLOGICAL WATER PURIFIERS
A. Recommendation for the use of Giardia lamblia cysts as a replacement for
Giardia muris cysts as the protozoan cyst test organisms.
Recommendation;
The subcommittee concurs with the recommendation and further endorses the
use of Giardia lamblia as the preferred cyst test for evaluation of all
treatment units and devices. Obviously the use of the protozoan orga-
nisms of actual health concern in testing is most desirable. Anyone
finding the Giardia lamblia strain feasible for testing and cost-
effective to work with is encouraged to use same instead of Giardia
muris.
B. Substitution of 4-6 micron bead or particle tests as an alternate option
instead of the Giardia cysts for evaluating devices that rely strictly on
occlusion filtration for microbiological removal: Several commenters
criticized the use of beads or particles (e.g., A.C. fine dust) and
recommended only use of live Giardia cysts for performance tests.
Discussion;
The subcommittee recognizes and favors the use of the natural human
parasite, Giardia lamblia, but was not aware of any convincing scientific
data which would disallow the optional use of testing with beads or
particles for units or devices using only occlusion filtration to remove
microorganisms. Previous development of the National Sanitation Standard
(NSF) 53 (1982) requirement for cyst reduction (using 4-6 micron parti-
cles as cyst models) was based on engineering and scientific opinion and
experimental evidence at that time. Specifically, Logsdon used
radioactive cyst models in the initial phase of a study of removal
efficiencies for diatomaceous earth filters? subsequent experiments with
Giardia muris cysts confirmed the efficacy of the diatomaceous earth
filters. Further studies by Hendricks and DeWalle with Giardia
lamblia cysts also showed comparable reduction efficiencies for
diatomaceous earth filters.
l.S.A. Schaub; F.A. Bell, Jr.; P. Berger; C. Gerba; J. Hoff;
P. Regunathan; and R. Tobin. [Includes additional revision pursuant to
Scientific Advisory Panel review (Federal Insecticide, Fungicide, and
Rodenticide Act).]
0-31
-------
Subsequently confirmatory parallel testing results have been developed
vis-a-vis 4-6 micron particles as compared to Giardia lamblia cysts.
Specifically, two. nnits listed by NSF for cyst reduction (using 4-6
micron particles) have also been tested and listed for 100% efficiency
reduction (using Giardia lamblia cysts) by Hibler :
1. Everpure Model QC4-SC
2. Royal Boulton Model F303.
Again we prefer the use of the human pathogen, Giardia lamblia; however,
no experimental data has been provided regarding the lack of validity or
of failure in previous tests utilizing beads or particles of 4-6 microns.
In most cases the bacterial or viral challenges to occlusion filters ill
represent a greater problem in terms of microbiological reduction
requirements than will cysts. Therefore, without substantiation of
deficiencies, the use of 4-6 micron beads or particles is considered to
be as feasible as the use of live cysts for routine performance testing
of water filtration (occlusion) devices.
Recommendation;
Recommend retaining the optional use of 4-6 micron particles or beads for
cyst reduction testing in occlusion filtration devices only.
References;
Logsdon, G. S., et al. Alternative Filtration Methods for Removal
of Giardia Cysts and Cyst Models, JAWWA, 73(2)111-118, 1981.
Logsdon, G. S.; Hendricks, D. W., et al. Control of Giardia Cysts
by Filtration; The Laboratory's Rose. Presented at the AWWA Water
Quality Technology Conference, December, 1983.
DeWalle, et al. Removal of Giardia lamblia Cysts by Drinking Water
Treatment Plants, Grant No. R806127, Report to Drinking Water
Research Division, U.S. EPA (ORD/MERL), Cincinnati, Ohio.
(4)
National Sanitation Foundation, Listing of Drinking Water Treatment
Units, Standard 53. May, 1986.
Hibler, C. P. An Evaluation of Filters in the Removal of Giardia
lamblia. Water Technology, pp. 34-36. July, 1984.
C. Alternate assay techniques for cyst tests (Jensen): Proposed alterations
in cyst tests include a different method for separating cysts from fecal
material and an assay method involving the counting of trophozoites as
well as intact cysts. Both alterations have been used by Bingham, et al.
(Exp. Parasitol., 47:284-291, 1979).
0-32
-------
Recommendation;
These alterations appear to be reasonable laboratory procedures, support-
ed by a peer-reviewed article and will be included in the Report as
options for possible development and use by interested laboratories.
D. The use of pour plate techniques as an option for Klebsiella terrigena
bacteria analyses.
Recommendation;
The pour plate technique adds a heat stress factor to the bacteria which
constitutes a possible deficiency. However, it is a recognized standard
method and probably will not adversely affect the Klebsiella terrigena.
Consequently, it will be added to the Report as one of the acceptable
techniques.
E. Option of using Escherichia coli in lieu of Klebsiella terrigena for the
bacterial tests.
Discussion;
Appendix O-l, Section A.I. of the Guide Standard and Protocol sets forth
the basis for selection of K. terrigena as the test bacteria. The
selection was made along pragmatic line emphasizing the occurrence of K.
terrigena in surface waters and that it would represent the enteric
bacteria. It was also pointed out that the tests with virus and Giardia
were expected to be more severe than the bacterial tests. For comprehen-
siveness, bacterial tests were included in the protocol but were not felt
to be as crucial as the virus and Giardia tests.
E. coli, or any number of other generally accepted indicator bacteria,
could be used for the test program if they were shown to have good
testing and survival characteristics (equivalent to K. terrigena) by the
interested research laboratory.
Recommendation:
The intent of the Guide Standard and Protocol is to provide a baseline
program subject to modification when properly supported by an interested
laboratory. Consequently, any laboratory could propose and with proper
support (demonstrating challenge and test equivalency to K. terrigena)
use Escherichia coli or one of the other enteric bacteria. This idea
will be included in revised working in Section 1.2.2, "General Guide."
F. Performance requirements for Giardia cysts and virus in relation to the
EPA-Recommended Maximum Contamination Levels (RMCLs) of zero.
Discussion;
The RMCLs of zero for Giardia and viruses which have been proposed by EPA
are health goals. They are no enforceable standards since to assure the
0-33
-------
presence of "no organisms" would require an infinite sample. The
rationale for the recommended performance requirements for Giardia cysts
and virus is set forth in Sections A.2 and A. 3 of Appendix fc.C /We feel
that these requirements together with the application of realistic worst
case test conditions will provide a conservative test for units resulting
in treated effluent water equivalent to that of a public water supply
meeting the iricrobiological requirements and intent of the National
Primary Drinking Water Regulations.
Recommendation;
Retain recommended performance (log reduction) requirements for cyst and
virus reduction.
G. Rotavirus and its proposed assay: One commenter states that the rota-
virus tests are impractical because Amirtharajah (J. AWWA, 78 (3):34-49,
1976) cites "no satisfactory culture procedures available for analysis of
these pathogens and, therefore, monitoring would not be feasible."
Discussion;
Section 3.4.1.2, "Virus Tests" of the Report, presents means for cul-
turing and assaying rotaviruses. This means for doing the rotavirus
tests are available and are practical for application in the laboratory.
Dr. Amirtharajah was referring to the field collection, identification in
the presence of a wide variety of microorganisms, and quantification as
not being "satisfactory." Laboratory analysis of rotaviruses is practi-
cal but their field monitoring may not yet be feasible.
Further, the selection of both poliovirus and rotavirus as test viruses
was necessitated by the fact that the surface adsorptive properties and
disinfection resistance of the various enteric viruses have been shown to
differ significantly by virus group and by strains of a specific virus.
While all enteric viruses and their strains could not be economically
tested, it was determined by the task force that at least two distinctly
different virus types should be tested to achieve some idea of the
diversity of removal by the various types of water purifiers. Polio and
rota viruses have distinctly different physical and chemical charac-
teristics representative of the viruses of concern. Polioviruses are
small single stranded RNA viruses with generally good adsorptive proper-
ties to surfaces and filter media while rotaviruses are over twice as
large, are double stranded RNA and in some studies have been found to
possess less potential for adsorption onto surfaces or filter media.
These two viruses also have been demonstrated to have somewhat different
disinfection kinetics.
Recommendation;
Retain the rotavirus test requirements.
H. Definition of microbiological water purifier: One general comment
requested redefinition based on "lack of any virus removal "requirement
0-34
-------
in the EPA primary drinking water regulations, so that no virus reduction
requirement should be included. Also, it was claimed that the separation
of purifiers from non-purifiers would be a "disservice to consumers and
other users."
Discussion;
Viruses are recognized in the EPA regulations vis-a-vis a proposed recom-
mended maximum contaminant level of zero. Since virus monitoring for
compliance with a possible MCL is not yet feasible, a treatment require-
ment is necessary. Virus control will be considered in the Safe Drinking
Water Act filtration and disinfection treatment regulations. The reduc-
tion of viruses by treatment is discussed by Amirtharajah (J. AWWA,
78:3:34-49, 1986).
With respect to consumers and other users, we feel that the current
definition is appropriate and necessary. The average consumer cannot be
expected to know the difference between viruses, bacteria and cysts, or
when a raw water will or will not contain any of these organisms. In
order to protect the average consumer, the subject units either alone or
with supplementary treatment, should be able to cope with all of the
specified organisms.
Recommendation;
Retain the current definition for microbiological water purifier.
I. Coverage of units: Several comments related to the coverage of units.
These questions are addressed individually as follows:
1. Ultraviolet units that are used for supplemental treatment of water
from public water system taps would not be covered. We agree that
such units are not covered and parenthetical language has been
included in Section 1.3.2.3 to clarify this point.
2. A special status should be given to units which remove Giardia and
bacteria but not virus. Specifically, the meaning of Section 1.2.4,
"Exceptions," was addressed. The "Exceptions" section was specif-
ically developed to relate to the problem of public water systems
having disinfection but no filtration on a surface supply. Cysts
alone have been found to survive disinfection treatment and could be
present in such treated waters. In this case an effective cyst
filter serves an independent, beneficial purpose and should not be
required to be a microbiological water purifier. However, such a
unit should not be used as sole treatment for untreated raw water.
Additional parenthetical language has been added to Section 1.2.4.
3. The entire treatment unit or system should be tested, not just a
single component. We agree but believe that it is sufficiently
clear without providing additional language.
0-35
-------
4. The protocol should be expanded to cover units for the reduction of
TCE, EDB and other chemical pollutants. We felt that the introduc-
tion of non-microbiological claims to the standard would make it
large, unwieldy and duplicative of an existing third-party standards
and testing program (see Section I»2o5)°
J. Alleged preference of National Sanitation. Foundation (NSF) over other
laboratories for conducting the microbiological water purifier testing
protocol. The comment indicated that we were giving NSF preferential
treatment "to the detriment of other laboratories well qualified to
perform the required protocol."
Discussion;
We have made appropriate references to existing standards (#42 and #53)
developed by the NSF standards development process. Standard 53, the
health effects standard, was developed by a broadly based Drinking Water
Treatment Units Committee, including representatives from local, State
and Federal health and environmental agencies, universities, professional
and technical associations, as well as water quality industry
representatives. It was adopted in 1982 and the only test from it
utilized in our Report has been substantiated as described in Part B of
this "Response."
Nowhere in our report have we advocated NSF (or any other laboratory) as
the prime or only laboratory for implementing "the required protocol."
Recommendation;
No action needed.
K. Instruction concerning effective lifetime, One comment described an
alternate means for determining lifetime where a ceramic unit is
"brushed" to renew its utility and is gradually reduced in diameter. A
gauge is provided to measure diameter and to determine when replacement
is needed.
Recommendation;
Where a manufacturer provides a satisfactory "other" means of determining
lifetime, this should be accepted. Appropriate words have been added to
Section 2.4.I.C.
L. Ceramic candles should not be cleaned during testing because some
consumers would not clean them and this would provide the "worst case
test." One comment asserted this point.
Discussion;
There is some truth to this proposition. However, the other approach may
also have validity. Frequent brushing may reduce filtration efficiency.
0-36
-------
In any event, where a manufacturer prescribes filter cleaning and how to
do it, and provides a gauge to determine lifetime, we feel the testing
program is bound to follow the manufacturer's directions.
Recommendation;
No change needed.
M. Scaling up or down. One comment points out that one or more manufac-
turers may vary size of treatment units by increasing or decreasing the
number of operative units rather than the size of the operative unit.
The comment suggests allowing scaling based on size "of operative unit.
Recommendation;
We agree with the comment and have added clarifying words to Sec-
tion 3.5.3.3.
N. Turbidity level of "not less that 30 NTU" for ceramic candles or units.
One comment states that "Such levels are impossible to utilize in testing
mechanical filtration devices which will clog entirely or require such
frequent brushing as to render the test impossible as a practical
matter."
Discussion;
We recognized the potential "clogging problems" in Section 3.5.1.a(2)
where the 30 NTU water is only to be applied immediately before and
during each sampling event; the non-sampling turbidity level, which will
be applied over 90% of the "on" time, is currently set at no less than
10 NTU.
Turbidity levels of 30 NTU are commonly found in surface waters during
heavy rainfall or snow melt. Treatment units may be used under these
circumstances, so this challenge level should be retained. However, most
usage will occur under background conditions so the non-sampling
turbidity levels should be 0.1-5 NTU.
Recommendations;
1. Retain sampling turbidity level of not less than 30 NTU, and
2. Change non-sampling turbidity to 0.1-5 NTU. Appropriate wording
changes have been introduced in Section 3.5.1.a(2) and in Appen-
dix O-l, Section B.
0. Chlorine in test water #5. One comment asserts that chlorine "tends to
increase silver ion leaching activity" and that a high chlorine level
should be included in the silver leaching test; but no reference or
evidence, however, is provided to back this assertion.
0-37
-------
Discussion;
We have no compelling evidence or reason to expect that chlorine will
enhance the leaching of silver. However, the prescribed low pH and TDS
levels will provide a clearly severe test for silver leaching.
Recommendations
No change needed.
P. Unnecessary difficulty and expense of test protocols. Several comments
were made under this general heading. These comments are outlined and
discussed as follows:
1. Too many sampling events are required; sampling of a few units at
start, middle and finish should be satisfactory: The committee has
carefully laid out the standard and protocol and we feel the minimum
sampling plan must be maintained for the consumers' health pro-
tection.
2. Three units are too many to study; parallel testing of two units
should be satisfactory: For consumer protection, the Disinfectants
Branch, Office of Pesticide Programs, has traditionally required the
testing of three units. The committee recognizes the additional
cost involved in testing a third unit but feels that this will
provide a minimum level of assurance to prevent infectious disease
and recommends retention of the 3-unit requirement.
3. The protocol requires large tanks and microbiological reseeding on a
daily basis s We feel that the tank size requirements are not
extreme and can be met by an interested laboratory. With respect to
reseeding, it should be pointed out that virus and cyst seeding need
only be conducted immediately before and during the sampling "on"
period (see Section 3.5.1.b(2)), equivalent to less that 10% of the
"on" time. This "spot" seeding for viruses and cysts recognized the
expense and difficulty of maintaining large populations of these
organisms. Continuous seeding was provided for bacteria because
they are easier to grow and maintain and might have the capacity to
grow through some units, given enough time and opportunity.
4. Challenge levels of contaminants are too high compared to known
environmental conditions and the required log reductions exceed Safe
Drinking Water Act requirements: As explained in a footnote to
Table 1, Section 2, the influent challenges may constitute greater
concentrations than would be anticipated in source waters. These
levels are necessary to test properly for the required log reduc-
tions without having to utilize sample concentration procedures
which are time/labor intensive and which may, on their own, intro-
duce quantitative errors to the microbiological assays. As men-
tioned in Part I of this paper, the log reductions for bacteria,
virus and Giardia have been suggested for public water system
0-38
-------
treatment in a paper by Amirtharajah (1986, JAWWA, 78:3:34-49). The
reductions in the microbiological purifier standard are entirely
compatible with the reductions cited for public water supply
treatment.
0-39
------- |