United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/S2-89/029 Jan. 1990
&ER& Project Summary
Removal of DBCP from
Groundwater, Volume 1,
POE/POU Treatment Devices:
Institutional and Jurisdictional
Factors
Karl E. Longley, George P. Hanna, and Barry H Gump
The results obtained from
evaluating 10 GAC POE devices show
that whereas these GAC units
generally function very satisfactorily,
their performance can change
markedly over short periods of time.
These units require conscientious,
periodic monitoring. This unit
operation requirement was not
carried out by the owners or the
vendor; the owners generally lack the
expertise, and the vendor has no
contractual authority or responsibility
to monitor the POE GAC units.
Several Institutional models exist
for achieving the desired degree of
supervision and control over
individual or small private water
systems. Among these are the
following concepts that are not
necessarily exclusive:
1. Use existing districts or like
entities that already have a
physical system and personnel.
2. Create through legislative act or
through county ordinance, if
permitted under state law, a new
special water quality district or
sub-district for the intended
purpose.
3. Numerous other possible
models exist including
homeowner associations and
cooperative organizations.
A third party evaluation of
POE/POU treatment equipment to
verify the manufacturers' claims is an
important mechanism for providing
consumer protection. Such an
equipment testing program could be
established by legislation and
Implemented through a state
laboratory, or one or more
independent testing facilities
designated by the state and financed
by fees from equipment vendors who
wish to market their products within
the state would require the
certification of specific types of
POE/POU treatment devices that can
have an adverse effect on consumer
health if they do not properly
function.
This Project Summary was
developed by EPA's Risk Reduction
Engineering Laboratory, Cincinnati,
OH, to announce key findings of the
research project that Is fully
documented In a separate report of
the same title (see Project Report
ordering Information at back).
Introduction
Providing safe drinking water to
residents in areas of low population
density is a common problem to many
areas in California's San Joaquin Valley.
No central water treatment facilities exist
for these areas, and the costs associated
with the development of central water
treatment facilities generally are
prohibitive. A water treatment alternative
for individual homes in locations without
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access to central water treatment
facilities is the use of individual treatment
installations, commonly known as point-
of-entry/point-of-use (POE/POU) devices
depending on whether the installation of
the treatment device is on the wellhead
or at the point-of-entry into the home, or
is at the point-of-use such as attached to
a particular pipe leading to a faucet, or to
the faucet itself. Another drinking water
alternative is using bottled water, which at
best is an unhandy and inconvenient
operation, often falling short of providing
an available source of safe and
economical water. Of these alternatives,
the point-of-entry (POE) devices are the
most desirable, but their use for the
removal of organic contaminants from
drinking water is made particularly
difficult for two major reasons: (1) the
operation and maintenance requirements
for the granular activated carbon (GAC)
units; and (2) the units are typically
installed on many dispersed wellheads.
Opposition to POE/POU systems,
especially in connection with public water
supplies, has been voiced by various
public health agencies and water service
providers. They advance convincing
arguments based on their reasoning that
too many uncertainties are associated
with GAC treatment of water. First,
studies have shown that GAC may
provide a compatible environment for
bacteriological growth and, therefore, the
product water from GAC contractors may
contain high concentrations of bacteria,
their concentration apparently depending
on the feed water's temperature, flow
rate, and quality. Further, as the carbon
in a GAC treatment unit nears exhaustion,
increased concentrations of organics may
be desorbed from the carbon and appear
in the product water.
Institutional-Jurisdictional
Concerns
With the consideration of POE/POU
devices as a water treatment alternative,
numerous institutional, jurisdictional, and
technical questions must be resolved.
These questions include the following:
1. Determining what agency has
responsibility for validating the
effectiveness of the POE/POU
devices.
2. Identifying what agency has
responsibility for monitoring the
installation and use of the
POE/POU devices.
3. Determining what institutional
arrangement is desirable for
ownership and operation of the
POE/POU devices.
4. Identifying who has responsibility
for consumer related issues
including advertising practices.
Design Considerations
Evaluation of unit design must also
consider this operation characteristic in
view of the chemical matrix to be applied
to the GAC contractor. Substantial
competition for adsorption sites by the
contaminants of concern and other
organics in the source water, large
hydraulic loading, moderate to poor
adsorption to the GAC by the
contaminant(s) of interest, and significant
exhaustion of the GAC bed all contribute
to penetration of the mass transfer zone
into the carbon bed and earlier than
anticipated breakthrough of detectable
amounts of contaminant from the bed.
Bed volume and depth must be sufficient
to contain the mass transfer zone for the
expected design life of the GAC unit. This
is a function of the adsorptive
characteristics and rate of application of
the chemical matrix to be applied to the
GAC unit. The hydraulic loading rate
must be constrained to a level allowing
sufficient time for adsorption of the
contaminant(s) by the GAC. This can be
accomplished by equipping each GAC
unit with a flow constrictor. Bacterial
growth on the GAC or the water quality of
the source water may contribute to rapid
clogging of the GAC unit. This requires
consideration of the need for
pretreatment of the source water before
its application to the GAC unit, and the
need for disinfecting the treated water.
Without a continuous monitoring
program, exhaustion of a GAC bed
cannot be expeditiously determined.
Consequently, isotherm data and pilot
testing data are needed that are
representative of the chemical matrix and
GAC specific to the application of each
POE unit. With this knowledge, the
theoretical bed life can be calculated, a
suitable safety factor applied to reduce
the expected life of the GAC unit (in
terms of the recommended volume of
source water applied to the unit), and an
automatic cutoff valve installed to
inactivate the unit when this
predetermined volume of water has been
applied to it.
Fresno Area Study
The study entailed the investigation of
the removal of a selected pesticide from
well water using GAC adsorption.
Dibromochloropropane (DBCP) is a
common contaminant in the
groundwaters on the eastern side ol
San Joaquin Valley because of
previous widespread application i
chemical control for nemat
infestations of vineyards and other cr
Therefore, DBCP was selected as
target chemical for this study.
Ten existing private wells southea
Fresno were monitored. These wells v
located in an area where exten
farming had been practiced. All of tl
wells were equipped with POE (
water treatment units. Inst
tional/jurisdictional arrangements v
also explored to identify feasible m<
of providing guidance for the selec
operation, and maintenance of POE (
units to ensure the provision of safe w
to the consumer.
Results and Conclusions
Central water treatment is
preferred alternative over POE/F
installations and should be given pi
consideration whenever technically
economically feasible.
The costs for the construction
operation of water treatment systi
generally vary inversely with the siz<
the system. The cost for GAC treatn
using POE devices is particul.
expensive with added representa
costs ranging from $3.00 to over $•
per 1,000 gal of treated water.
An operational and maintena
problem often not considered
POE/POU GAC units is the ultinr
disposal of the spent carbon material
operational protocol must address
problem and provide for the pro
handling and disposal of the sp
carbon in accordance with applies
hazardous waste regulations.
Because of colonization of sc
primary and opportunistic pathogens
GAC, and the high concentrations
bacteria found at times in the proc
water from the POE GAC units, th
devices are best used on waters
meet the bacteriological standards
drinking water. Post-disinfection she
be considered following POE/P
treatment for waters having question;
bacteriological quality.
POU units should be used with g
caution. While POE units can
designed to reliably and effectiv
remove organic contaminants over
extended period of time, the sr
physical dimensions of POU units v
often does not lead to safe applicat
POU units tend to be mass marketed
the purchaser is not expected to poss
the sophistication to determine if the P
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unit is suitable for the intended
application.
Results obtained from monitoring 10
POE GAG installations indicated that the
unit performance can change markedly
over short periods of time. Therefore,
these types of devices require
conscientious periodic monitoring. It was
found that this unit operation.requirement
for monitoring and maintenance was not
being carried out by the owner nor the
vendor; an owner generally lacked the
expertise, and the vendor had
no contractual authority or responsibility
to monitor the POE units.
Several models exist for achieving the
desired degree of supervision and control
over individual or small private water
systems. These include using existing
districts or like entities having an
adequate physical system and sufficient
personnel, or the creation through
legislative act or county ordinance of a
special water quality district for the
intended purpose. Examples of existing
jurisdictional bodies suitable for
administering POE/POU unit programs
are counties, towns, public or
privatewater service districts, irrigation
districts, community service districts, and
sanitation districts.
The full report was submitted in partial
fulfillment of Cooperative Agreement CR-
812227-01-3 by the California State
University, Fresno, under the sponsorship
of the U.S. Environmental Protection
Agency.
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Karl E. Longley, George P. Hanna, and Barry H. Gump are with California State
University, Fresno, CA 93740-0094.
Walter Feige is the EPA Project Officer (see below).
The complete report, entitled "Removal of DBCP from Groundwater, Volume 1,
POE/POU Treatment Devices: Institutional and Jurisdictional Factors,"
(Order No. PB 89-198 8081 AS; Cost: $15.95, subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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