EPA/600/A-96/072
Water Treatment Technologies For Small Communities
Benjamin W. Lykins, Jr.
Robert M. Clark
U.S. Environmental Protection Agency
National Risk Management Research Laboratory
Water Supply and Water Resources Division
2 6 W. Martin Luther King Drive
Cincinnati, Ohio 45268
Presented At:
The 2nd EPA
National Drinking Water Treatment Technology Transfer Workshop
Kansas City, Missouri
August 12-14, 1996
-------
Water Treatment Technologies for Small Communities
by
Benjamin W. Lykins, Jr.(1) and Robert M. Clark (2)
INTRODUCTION
There are approximately 200,000 public water systems in
the United States. Approximately 31% are community water systems
which serve primarily residential areas and 91% of the population
[1]. Of the 60,000 community water systems that serve about 219
million people, 51,000 were classified as *small' or 'very
small'. The tens of thousands of very small regulated community
systems (less than 500 population served) will have difficulty in
complying with the large number of regulated contaminants or in
instituting Best Available Technology (BAT).
Regulations promulgated under the Safe Drinking Water Act
and its Amendments (SDWAA) apply to all drinking water systems
which have at least fifteen connections or regularly serve an
average of at least twenty-five individuals daily at least 60
days out of the year. Bringing small water systems into
compliance, given their current problems and the pending
regulations, will require flexibility in terms of technology
applications and institutional arrangements. The most
significant requirements for small systems in the United States
are low construction and operating costs, simple operation,
adaptability to part-time operation, low maintenance, and no
serious sludge problems. In addition to small central systems
there are numerous private homeowners, non-community, and
transient water consumers potentially at risk from contaminated
drinking water.
Small systems (<3,300 people served) are the most frequent
violators of federal regulations and accounted for nearly 89% of
the violations posted. These violations consisted of both
reporting violations and actual SDWAA Maximum Contaminant Level
(1) Chief, Water Quality Management Branch, Water Supply and
Water Resources Division, National Risk Management Research
Laboratory, U.S. Environmental Protection Agency, Cincinnati,
Ohio 45268.
(2) Director, Water Supply and Water Resources Division, National
Risk Management Research Laboratory, U.S. Environmental
Protection Agency, Cincinnati, Ohio 45268.
-------
(MCL) violations. Most of the violations fall into the
monitoring and reporting (M/R) categories. The small and very
small system violations account for approximately 6 million
consumers. In most cases, the violations are short term (less
than two months).
Because of the litany of problems associated with small
systems, many state and federal programs have been established to
assist them to come into compliance with current and anticipated
regulations. For example, programs have been established to
train 'trainers' in the latest methods and technology that are
available to aid small utilities. Another concept that is being
investigated is the xcomposite correction program' that provides
specific guidelines or rules for bringing water-treatment
facilities into compliance with some of the drinking-water
regulations. Unfortunately, for systems serving fewer than 500
people , which account for 93% of MCL and 94% of M/R violations,
these programs have achieved limited success. Most of the
problem systems are microsystems and serve 25-100 people. They
have severe financial and managerial problems and are owned and
operated by loosely organized associations which do not qualify
for or are not cognizant of finanacial assistance programs.
Frequently the operators and managers of these systems are
volunteers.
This paper will give a general overview of available
technologies for small systems and present some research
activities in the small systems area.
AVAILABLE TECHNOLOGIES
Filtration and Disinfection
The most important criteria of water treatment is to produce
drinking water safe from microbial illness (2). Both surface
water and ground water sources may be contaminated with
pathogenic microorganisms. The U.S. Environmental Protection
Agency's Surface Water Treatment Rule requires most systems
supplied by a surface water source to install and operate
approved treatment techniques which achieve at least 99.9 percent
reduction (removal and/or inactivation) of Giardia cysts and 99.9
percent reduction of enteric viruses. While ground water sources
tend to have lower levels of microbial contamination, EPA's
Groundwater Disinfection Rule will require comparable levels of
protection (inactivation) for groundwater sources(3).
There are several specific filtration processes for
microorganism removal and chemical disinfection processes for
inactivation that have been proven over time and are generally
-------
considered effective treatment methods (Table 1)(3). Filtration
is desirable to remove not only microbes, but also turbidity
(particulate matter) and dissolved materials ("precursors") that
can consume disinfectants and produce problematic byproducts.
While it is theoretically possible to completely eliminate
microorganisms from source waters by filtration alone, the
application of disinfection treatment and maintenance of a
disinfectant residual is necessary in the distribution system to
control the regrowth of bacteria, pipeline biofilms, and
potential contamination from cross-connections.
Filtration can be accomplished using common processes such
as conventional filtration, direct filtration, slow sand
filtration, pressure filtration, diatomaceous earth (DE)
filtration, and membrane filtration, or the less widely used
technologies such as deep-bed multi-media filtration (small
pressure filters), bag filtration and cartridge filtration.
Historically, the most common processes mentioned above are most
suitable as centralized drinking water treatment facilities,
installed to serve a minimum size customer rate base via an
appropriately sized distribution system. While the common
treatment processes are successfully downsized for smaller
applications (e.g., built on-site or factory constructed package
plants installed in small communities), the other filtration
processes, deep-bed multi-media, bag and cartridge are more
suitable for the even smaller applications,
Small-Scale Conventional Treatment Systems
Conventional water treatment systems employing chemical
addition (filtration aids), coagulation, flocculation,
sedimentation, filtration and disinfection may be scaled down to
sizes appropriate for small systems. As mentioned above, they
are often the process of choice for centralized treatment due
largely to their cost effectiveness and proven track record.
Since they are custom designed to the site and for specific water
quality criteria, they require the planning and design services
of a professional engineer. When well-designed and properly
operated, these systems can meet federal and state regulations
for turbidity, filtration and disinfection, as well as minimize
particulates, disinfection byproduct precursors and some chemical
contaminants.
Slow Sand Filtration
Water treatment by slow sand filtration is one of the
earliest treatment technologies, and remains a promising
filtration method for small systems with low turbidity source
waters. It is a simple and reliable process, relatively
inexpensive to build, and can be operated by less skilled
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personnel. The process consists of percolating untreated water
slowly through a bed of porous sand, with the water influent
introduced over the surface of the filter and drained from the
bottom. Properly constructed, the filter consists of a tank, a
bed of fine filter sand, a layer of gravel to support the sand, a
system of underdrains to collect the filtered water, and a flow
control device to control the filtration rate. No chemicals are
added to aid the filtration process.
A thin, biologically active skin layer (called a
"schmutzdecke") forms on top of the filter sand during the
initial operating period. This schmutzdecke of deposits,
microorganisms and attendant biofilm must develop as part of a
maturation process before the filter will function optimally.
The biological processes in the schmutzdecke enhance removal of
contaminants, and once established, maintenance is routine and
product water is of adequate quality. No backwashing is
required, though after several weeks or months (dependent on
influent quality) the filter surface layer becomes clogged and
filter flow capacity is reduced. This lost capacity is restored
by removing (scraping off) an upper H inch (1.3 cm) layer of the
filter sand, and returning the filter to service as quickly as
possible to keep the biologically active microorganisms within
the bed alive.
A disadvantage includes the relatively large land area
required for the filter bed, necessitated by the low flow rates
per surface area for proper operation. Flow rates may be 50 to
100-fold slower than conventional systems. Because of the low
loading rates, storage for maximum peak daily demands is usually
necessary.
A packaged slow sand filter is being evaluated at EPA's Test
and Evaluation Facility (T&E) in Cincinnati, Ohio. This slow
sand filter treats enough water to serve one to two households
daily. The modular filters and storage tanks are fiberglass and
constructed off-site such that additional tanks can be installed
for higher demand situations. A filter blanket is used rather
than a schmutzdecke.
Membrane Filtration
A developing technology with good prospects for small
systems is membrane filtration. While reverse osmosis (RO)
provides the highest level of membrane-based filtration
purification, other types of membrane systems may provide
suitable alternatives to RO. Semipermeable membranes can be
designed with discrete size exclusions to allow selective removal
of particulate matter including viruses and bacteria, lower-
molecular weight organic contaminants and inorganic chemicals.
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They may provide all the purification needed for specific
drinking water treatment needs, and because they operate at lower
feedwater pressures than most RO membranes, the operating costs
are lower than RO as well.
Microfiltration (MF) can remove soluble and insoluble
materials down to about 100,000 dalton molecular weight or about
0.1 micron in size. This can disinfect water of bacteria as well
as protozoa, but not of all viruses. Generally, suspended
particles and large colloids are rejected while small colloids,
macromolecules and dissolved solids pass through the membrane.
Pressure across the MF membrane is about 10 psi (0.73 k/cm2).
Ultrafiltration (UF) will remove viruses and other materials
down to about 10,000 daltons, though the molecular weight cut-off
values range from 1,000 to 10,000, or between 0.005 and 0.1
microns. UF will reject colloids, proteins, microbiological
contaminants and large organic molecules; however, all dissolved
salts and smaller molecules pass through the membrane.
Differential membrane pressures range from 10 to 100 psi (0.73 to
7.03 k/cm2) .
An ultrafiltration (UF) package plant at the T&E consists of
a bag pre-filter, optional disinfection, and UF membrane. The
unit is 3 feet wide, 7 feet tall, and 12 feet long capable of
producing approximately 15 gpm on a continuous basis. A similar
unit has been in operation at a research site in West Virginia
for over a year. This system is used to provide water to twenty-
five homes.
Nanofiltration (NF) can remove chemicals to about 200
daltons with a molecular weight cut-off of 100 to 5,000 or 0.001
to 0.005 microns, though the amount of rejection varies with
molecular structure. It is reported that salts with monovalent
anions (such as calcium chloride) have rejections of 20 to 80
percent, where salts with divalent anions (magnesium sulfate)
have rejections of 90 to 98 percent. As a result, NF systems can
remove color and total organic carbon from water, as well as
hardness, radium and total dissolved solids. Transmembrane
pressures range from 50 to 130 psi (3.5 to 9.1 k/cm2).
Reverse osmosis filtration can remove almost all inorganic
chemicals and, when used in conjunction with activated carbon,
most organic chemicals as well. Membranes usually have cut-offs
of less than 50 daltons. RO systems have been in wide use in
centralized treatment. New applications are continually being
developed, and as RO becomes more and more common, the drinking
water industry has become more comfortable with the different RO
membrane operating parameters and reliability considerations.
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Chemical Contaminant Removal
For inorganic contaminants and radionuclides, conventional
treatment alone may be effective. Reverse osmosis(RO), ion
exchange, activated alumina and granular activated carbon (GAC)
have specific applications, and aeration can be most effective
for radon removal (Table 2)(3). For most organic contaminants
currently regulated by the U.S. EPA, packed-tower aeration and
GAC have been specified as BAT. Reverse osmosis removes some
organics, and when used in conjunction with GAC, can be superior
to other single-process treatment applications. The
appropriateness of RO is dependent upon source water quality and
disinfection requirements. Table 3 shows the expected
performance for various technologies for removing organics from
drinking water (3).
As various treatment options are considered, there are
operational conditions such as operational skill required, level
of maintenance required, and energy requirements that also have
to be considered. Table 4 gives an example of these requirements
for some of the technologies discussed (1).
PERFORMANCE OF EXISTING SMALL SYSTEMS
A joint field study was conducted by the American Water
Works Association and the United States Environmental Protection
Agency to evaluate existing small community systems utilizing
package plant technology (4). A geographic and technological
cross-section of 48 package plant systems were evaluated through
an examination of historical water quality and financial records,
site visits, and analysis of raw and finished water quality
samples taken during the visits. Results indicated that most of
the systems were performing adequately; however, a few were
exceeding turbidity or inorganic contaminant standards.
Standardized levels of operator certification, use and knowledge
of technical assistance, and good management practices were
lacking in many of the systems. In addition, several would have
difficulty meeting portions of the Disinfectant and Disinfection
Byproducts Rule or the Enhanced Surface Water Treatment Rule.
INTERNATIONAL ACTIVITIES
In 1993, a new technology initiative, Environmental
Technology Initiative (ETI), was developed to yield environmental
benefits and increase exports of "green" technologies (5). One
of the components of ETI is the U.S. Technology for International
Environmental Solutions (U.S. TIES) program. This program was
-------
designed to enlist greater participation of the U.S. private
sector in achieving U.S. environmental objectives overseas.
Three drinking water projects have been initiated by EPA's
Water Supply and Water Resources Division in Cincinnati, Ohio.
These projects were selected for countries where it appeared that
the greatest potential for success and creation of a market for
U.S. products would occur. These three projects are located in
Ecuador, Mexico, and China. Each of these countries has similar
types of drinking water concerns with problems that are also
unique to their country. Below is a description of the
demonstration sites and the treatment that will be used at these
sites.
ECUADOR
• Hospital Rodriguez Zambrano in Manta - The existing water
system at the hospital consisted of a two inch diameter line
which goes into two 66,000 gallon tanks. Chlorination was
done in these tanks by the addition of liquid chlorine
(Chlorox). Aeration was used to mix the liquid chlorine. A
swimming pool-type color comparator was used to monitor the
chlorine residual. Immediately after chlorine addition,
high residual levels were detected which quickly dissipate
to non-detectable levels.
Water from the tanks was pumped by three 20 HP pumps through
a four inch diameter pipe and distributed with a 60 psi pressure
system. Water usage at the hospital is variable with a maximum
of 26,000 gal/day. The hospital has 220 beds with an average of
8,672 patients/year and 594 employees. The number one disease in
Manta is diarrhea. The number one disease causing death is
malnutrition and the fifth is diarrhea.
Modification of treatment consists of using one of the
existing 66 gallon tanks for raw water accumulation and storage.
The second tank is used for storage of disinfected water. An
ozone system is located between the two tanks with ozone inducted
to the raw water supply as it flows from one tank to the other.
Two backwashing filters containing sand, anthracite, and garnet
media are used for particle removal prior to the second tank.
Chlorine is injected prior to entering two existing pressure
tanks.
* Monteoscuro - This community has 150 families with 120
connected to a water system served by a well. The well is
one year old and the water is described as salty. There is
a 13,000 gallon storage tank 3,800 yards from the well.
This community has a state-supported medical center that has
been in operation since 1984. Diarrhea is very common among
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the families who are members of the clinic and good records
are kept on these families.
The water supply at Monteoscuro contains a significant
particulate load that has to be reduced. This has been
accomplished by using a manual backwashing filter containing
sand, anthracite, and garnet media. After filtration, primary
disinfection of the water supply is done by using a Teflon coil
UV unit. The UV unit is located at the protected wellhead area
and powered from the same source as the existing pump, thus
ensuring that when electricity is available to pump water from
the well to the existing storage tank, it is also available for
the UV unit. Post-disinfection with chlorine provides a residual
in the distribution system.
A majority (60% to 70%) of the Monteoscuro residents
currently boil their water for disinfection. Propane fuel is
used at a cost of approximately $1.20 per household every three
weeks. This amounts to about $20.80 per household per year.
Assuming there are 78 households (120 households times 65%) that
boil their water, the total costs to the community per year is
$1,622.40. One might think that the use of UV is an expensive
alternative. By using the above information and assuming that
eight UV bulbs costing $50 per bulb is used and assuming that the
average bulb life is one year, the annual UV bulb replacement
costs will not exceed $400 for the community. Also, electrical
consumption will be low; about the equivalent of eight 40 watt
light bulbs. Therefore, by using UV, disinfection cost should be
reduced by over 50%.
MEXICO
* Jilotepec - This water system serves a population of
approximately 3, 500 people with a flow of approximately
120 gpm. The town is served by two separate distributions:
a) surface water which is approximately 40%, and b) spring
water which is approximately 60% of the water supply in
town.
Jilotepec is in a valley and the water that is supplied
comes from the mountains overlooking Jilotepec. The surface
water that would be treated in this project flows from a small
impoundment area to a tank that is several hundred feet higher in
elevation than the town. The current treatment is chlorination
only. This particular site provides a challenge to logistics of
getting treatment package technology up the side of a mountain as
there is not a roadway compatible for vehicular traffic. The
surface water is very susceptible to changing conditions during
the rainy season and appeared to be moderately turbid during the
initial site visit. Water is chlorinated as it enters a tank and
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then is provided to the town via a gravity feed system.
Treatment will consist of modular filtration followed by
chlorination.
* Ixhuacan de los Reyes - The community of Ixhuacan de los
Reyes is suppled with water from Rio San Jose. This
community of approximately 2,600 people has a water demand
of approximately 85 gpm. Water from the river, which is
located higher in elevation than Ixhuacan, flows by pipeline
down the side of the mountain and enters a rectangular
presedimentation tank that is split into two chambers which
would allow operation of either side individually or
parallel. From this first presedimentation tank the water
then flows into a second rectangular sedimentation basin and
flows by gravity several hundred yards down the side of the
mountain into a typical stone storage tank. No chemical
treatment occurs until chlorine is added at this point and
the water then flows from the outlet of the stone tank to
the city of Ixhuacan. Treatment will consist of modular
filtration followed by chlorination.
• Francisca I Madero Public Elementary School- The Francisca I
Madero Public Elementary School is located in a small suburb
near Cordoba and serves approximately 300 children who
attend the school daily. The water supply for the school is
a hand-dug well, approximately 30 feet deep, five feet in
diameter and has a stone or brick interior wall. It is
covered but not sealed to prevent foreign material from
entering the well. This water then is pumped from the well
to rooftop cisterns which is open to airborne contamination.
This provided pressure for the system inside the school.
Currently, the children are advised to bring water or
beverages from their homes.
The treatment for the school will consist of using a MIOX
electro-chemical unit to disinfect the drinking water.
CHINA
The proposed on-site demonstrations will be performed in
collaboration with the Institute of Environmental Geology under
the Ministry of Geology and Natural Resources, the People's
Republic of China. It is initially agreed that when these on-
site demonstration proposals are approved, the Institute of
Environmental Geology will seek Chinese grants to perform the
necessary analytical work either in their own laboratories or
local universities such as the Geological Sciences graduate
school. In addition, with the small community demonstrations, an
epidemiological study comparing the health rates of the case
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study site vs. nearby communities with untreated water will be
conducted by local graduate students.
One demonstration project is expected to take place in Zibo
City in the Shandong Province to demonstrate the removal of
industrial organics. Another demonstration may include the City
of Chifeng where the raw water is contaminated with fluoride,
agricultural chemicals, and industrial wastes.
SUMMARY
Providing safe adequate drinking water for small systems in
the United States is no easy task. Appropriate treatment
technology is determined in part by the costs, availability and
proven effectiveness of the technology itself, and in part by the
sum of the regulatory requirements specific to the localities in
which these systems reside. The range of regulatory requirements
includes both state and federal drinking water regulations as
well as local and regional requirements for drinking water,
wastewater, air quality, land use and construction. In addition,
public perceptions, attitudes and interests can affect treatment
choice. Both in-house and extramural research have been
developed to evaluate and improve small systems treatment
technology, taking other factors mentioned above into
consideration.
ACKNOWLEDGMENTS
The authors thank Patricia Williamson and Carmen F. Adevoso
for typing this paper.
This paper has been reviewed in accordance with the U.S.
Environmental Protection Agency's peer and administrative review
policies and approved for presentation and publication. Mention
of trade names or commercial products does not constitute
endorsement or recommendation for use by the USEPA.
-------
REFERENCES
1. Clark, R.M., Goodrich, J.A., and Lykins, Jr., B.W.,"Package
Plants for Small Water Supplies - the US Experience",
J. Water SRT-Aqua, Vol. 43, No.l,pp 23-34, 1994.
2. Lykins, Jr., B.W"Innovative Technologies for Treating
Drinking Water for Small Communities", presented at the
International Seminar on Ecological Effective Technologies
for Water and Wastewater Treatment", Vologda, Russia,
September 1993.
3. Macler, B.A., Goodrich, J.A., Robberson, W.M., and
Clark, D.,"Treatment Technology for Small Drinking Water
Systems in the U.S.", presented at the 3rd U.S.-Japan
Governmental Conference on Drinking Water Quality
Management, Cincinnati, Ohio, September 1992.
4. Campbell, S., Lykins, Jr., B.W., Goodrich, J.A., Post, D.,
and Lay T.,"Package Plants for Small Systems: A Field
Study", J. American Water Works Association, Vol. 87,
No. 11, pp. 39-47, November 1995.
5. Lykins, Jr., B.W.,"Utilization of Small Systems Treatment in
Latin America and China", presented at the Water Quality
Association's 22nd Annual Convention and Exhibition,
Indianapolis, Indiana, March 1996.
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TABLE 1. TREATMENT TECHNOLOGIES SUITABLE FOR FULL-SCALE
CENTRAL USE BY SMALL SYSTEMS
Technology
Advantages
Disadvantages
Filtration
Slow Sand
Operational simplicity
and reliability, low
cost, ability to achieve
greater than 99.9
percent Giardia cyst
removal
Not suitable for water
with high turbidity,
requires large land
areas
Diatomaceous
Earth
Compact size, simplicity
of operation, excellent
cyst and turbidity
removal
Most suitable for raw
water with low
bacterial counts and
low turbidity (less
than 10 NTU), requires
coagulant and filter
aids for effective
virus removal,
potential difficulty in
maintaining complete
and uniform thickness
of diatomaceous earth
on filter septum
Reverse Osmosis
Membrane
Extremely compact,
automated
Little information
available to establish
operating parameters.
Most suitable for raw
water with less than 1
NTU; usually must be
preceded by high levels
of pretreatment, easily
clogged with colloids
and algae, short filter
runs, concerns about
membranes failure,
complex repairs of
automated controls,
high percent of water
lost in backflushing
Rapid Sand/Direct
Filtration Package
Plants
Compact, treats a wide
range of water quality
parameters and variable
levels
Chemical pretreatment
complex, time-
consuming, cost
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TABLE 1. TREATMENT TECHNOLOGIES SUITABLE FOR FULL-SCALE
CENTRAL USE BY SMALL SYSTEMS (CONTINUED)
Technology
Advantages
Disadvantages
Disinfectant
Chlorine
Very effective; has a
proven history of
protection against
waterborne disease,
widely used, variety of
possible application
points; inexpensive,
appropriate as both
primary and secondary
disinfectant.
Potential for harmful
halogenated by-products
under certain
conditions
Ozone
Very effective. No THMs
formed.
Relatively high cost.
More complex operations
because it must be
generated onsite.
Requires a secondary
disinfectant, other by-
products .
Ultraviolet
Radiation
Very effective for
viruses and bacteria,
readily available, no
known harmful residuals,
simple operation and
maintenance for high
quality waters
Inappropriate for
surface water, requires
a secondary
disinfectant
Organic Contaminant
Removal
Granular Activated
Carbon
Effective for a broad
spectrum of organics
Spent carbon disposal
Packed Tower
Aeration
Effective for volatile
compounds
Potential for air
emissions issues
Diffused Aeration
Effective for volatile
compounds/radionuclides
Clogging, air
emissions, variable
removal efficiencies
Advanced Oxidation
Very effective
By-products
Reverse Osmosis
Broad spectrum removed
Variable removal
efficiencies,
wastewater disposal
Inorganic Contaminant
Removal
Reverse Osmosis
Highly effective
Expensive waste removal
Ion Exchange
Highly effective for
some inorganics
Expensive waste removal
Activated Alumina
Highly effective for
some inorganics
Expensive waste removal
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TABLE 2. REMOVAL EFFECTIVENESS FOR NINE PROCESSES BY INORGANIC CONTAMINANT
Contaminant
Treat merit
Ag
As
As111
Av
Ba
Cd
Cr
Cr111
Crvl
F
Hg
Hg'°'
Hg11'
no3
Pb
Ra
Rn
Se
Selvi
Selml
U
Conventional
treatment
H
-
M
H
L
H
-
H
H
L
-
M
M
L
H
L
-
-
M
L
M
Coagulation -
aluminum
H
-
-
H
-
M
-
H
-
-
M
-
-
-
H
-
-
-
-
-
-
Coagulation - iron
M
-
-
H
-
-
-
H
H
-
-
-
-
-
-
-
-
-
-
-
-
Lime softening
-
-
M
H
H
H
-
H
L
M
-
L
M
L
H
H
-
-
M
I.
H
Reverse osmosis
& electrodialysis
H
-
M
H
H
H
H
-
-
H
H
-
-
M
H
H
-
H
-
-
H
Cation exchange
-
L
-
-
H
H
-
H
L
L
-
-
-
L
H
H
-
L
-
-
H
Anion exchange
-
-
-
-
M
M
-
M
H
-
-
-
-
H
M
M
-
H
-
-
H
Activated alumina
-
-
H
-
L
L
-
-
-
H
-
-
-
-
-
L
-
H
-
-
-
Powdered activated
ca rbon
L
-
-
-
L
M
-
L
-
L
-
M
M
I,
-
L
-
-
-
-
-
Granular activated
carbon
-
-
-
-
L
M
-
L
-
L
-
H
H
L
-
L
H
-
-
-
-
Aeration
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
H
-
-
-
-
H = High = > 80% removal
M = Medium - 20-80% removal
L = Low = < 20% removal
xs-" = indicate no data were provided
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TABLE 3. PERFORMANCE SUMMARY FOR TECHNOLOGIES EXAMINED
Removal e
f f iciency*
Organic
Compounds
Regulatory
phase
GAC
Packed-
tower
aeration
Reverse
osmosis
Ozone
oxidation
(2-6 ppm)
Conventional
treatment
VOCs
Alkanes
Carbon tetrachloride
1.1-Dichloroethane
1,1,1-Trichloroethane
1.2-Dichloropropane
Ethylene dibromide
Dibromochloropropane
I
I
I
II
II
II
++
++
++
++
++
++
++
++
++
++
++
+
++
+
++
++
+
NA
-
-
Alkenes
Vinyl chloride
1, 1-Dichloroethylene
cis-1, 2-Dichloroethylene
trans-1,2-Dichloroethylene
Trichloroethylene
I
I
II
II
I
+
++
++
++
++
++
++
++
++
++
NA
NA
NA
+
++
++
++
++
+
-
Aromatics
Benzene
Toluene
Xylenes
Ethylbenzene
Chlorobenzene
o-Dichlorobenzene
p-Dichlorobenzene
Styrene
I
II
II
II
II
II
I
II
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
NA
NA
++
+
NA
NA
++
++
++
++
+
+
+
++
-
PESTICIDES
Pentachlorophenol
2, 4-D
Alachlor
Aldicarb
Carbofuran
Lindane
Toxophene
Heptachlor
Chlordane
2,4,5-TP
Methoxychlor
II
II
II
II
II
II
II
II
II
II
II
++
++
++
++
++
++
++
++
++
++
++
++
++
++
NA
NA
NA
NA
++
++
++
NA
NA
NA
NA
NA
NA
++
+
++
NA
++
NA
+
NA
+
NA
NA
NA
NA
NA
NA
OTHER
Acrylamide
Epichlorohydrin
PCBs
II
II
II
NA
NA
++
++
NA
NA
NA
NA
NA
NA
NA
NA
'++ = Excellent (70-100%). Excellent removal category for carbon indicates that the
compound has been demonstrated to be adsorbable onto GAC, either in full- or
pilot-scale application or in the laboratory. The data suggest that GAC can
be a cost-effective technology.
+ = Average (30-69%)
- = Poor (0-29%)
NA = Data not available, or compound has not been tested by EPA Water Supply and
Water Resources Division
-------
TABLE 4. OPERATIONAL CONDITIONS FOR TREATMENT TECHNOLOGIES
Requirements
Technology
Operational
skills
Maintenance
Energy-
Granular activated carbon
Medium
Low
Low
Packed column aeration
Low
Low
Varies
Slow sand filtration
Low
Low
Low
Diatomaceous earth
Low
Medium
Medium
Reverse osmosis
Low
Medium
High
Chlorine
Low
Low
Low
Ozone
High
Medium
Varies
uv
Low
Low
Low
-------
4
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA/600/A-96/072
4. TITLE AND SUBTITLE
Water Treatment Technologies for Small
Communities
6. PERFORMING ORGANIZATION CODE
3. RECIPI
5. REPORT DATE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO
Benjamin W. Lykins, Jr. and Robert M. Clark
PERFORMING ORGANIZATION NAME ANO AODRESS
Water Supply and Water Resources Division
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12,
NaPfion
NSOR1N
STM ? PfiXragMrc ^KStt-ch
Office of Research
U.S. Environmental
Cincinnati, Ohio
Laboratory
and Development
Protection Agency
45268
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
EPA/600/14
15. supplementary notes Presented at: 2nd EPA National Drinking Water Treatment Technology
Transfer Workship, Kansas City, Missouri, August 12-14, 1996
Project Officer - Ben W. Lykins, Jr. (513)569-7460
16. ABSTRACT
Because of the litany of problems associated with small systems, many state and
federal programs have been established to assist them to come into compliance with
current and anticipated regulations. For example, programs have been established to
train 'trainers' in the latest methods and technology that are available to aid small
utilities. Another concept that is being investigated is the 'composite correction
program' that provides specific guidelines or rules for bringing water-treatment
facilities into compliance with some of the drinking-water regulations. Unfortunately,
for systems serving fewer than 500 people , which account for 93% of MCL and 94% of M/R
violations, these programs have achieved limited success. Most of the problem systems
are microsystems and serve 25-100 people. They have severe financial and managerial
problems and are owned and operated by loosely organized associations which do not
qualify for or are not cognizant of finanacial assistance programs. Frequently the
operators and managers of these systems are volunteers. This paper gives a general
overview of available technologies for small systems and present some research activities
in the small systems area.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c. COSATl Field/Group
Regulatory
Drinking Water
Small Systems
Package Plant Treatment
Microorganisms
18. DISTRIBUTION STATEMENT
19. SECURITY CLASS (This Report)
21. NO. OF PAGES
20. page/
22. PRICE
RELEASE TO PUDLIC
EPA Form 2220-1 (R.v. 4-77)
UNCLASSIFIED
PREVIOUS EDITION IS OBSOLETE
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