AMIRAULT Et Al 2003 Activated Carbon Treatment of Drinking Water Supplies PDF
AMIRAULT Et Al 2003 Activated Carbon Treatment of Drinking Water Supplies PDF
AMIRAULT Et Al 2003 Activated Carbon Treatment of Drinking Water Supplies PDF
Types of Units
Activated carbon filters come in both point-of-entry (POE)
units and point-of-use (POU) units. POE and POU devices
refer to the location where the device is installed. POE units
treat all the water coming into the house. POU units treat
water at specific areas, i.e. installed below the kitchen sink to
treat only tap water in the kitchen. POU units include pour
through, faucet mount, in-line, and line bypass.
T H E S TAT E O F R H O D E I S L A N D D E PA R T M E N T O F H E A LT H A N D T H E U N I V E R S I T Y O F R H O D E
I S L A N D C O O P E R AT I V E E X T E N S I O N D E PA R T M E N T O F N AT U R A L R E S O U R C E S S C I E N C E
Point-of-Entry
Nonhousehold uses
Treated
water to
household
plumbing
Water meter
Point-of-Use
In-Line
Hot
Activated
carbon
filter
Cold
Line-Bypass
Treated
Tap
Water
Hot
Cold
Faucet-Mount
Hot
Activated
carbon
filter
Cold
Pour-Through
Untreated water
Activated
carbon
filter
Unit Effectiveness
The effectiveness of an activated carbon unit
depends on the extent of contact between the
carbon and the untreated water. During regular
operation of any device, channels form within the
carbon filter, allowing some water to bypass the
filtering material, short-circuiting treatment. Since
treatment depends on the carbon granules
adsorbing the chemical contaminants, these
channels decrease the contact time and the
effectiveness of the carbon filter unit. A
disadvantage of block carbon is that if it is
unevenly compressed when manufactured,
irregular flow patterns may affect the
effectiveness of contaminant removal.
There are two main procedures to determine how
much a carbon filter can adsorb: the iodine test
and the phenol test. The iodine number is defined
as the amount of iodine (in milligrams) adsorbed
by one gram of carbon under a certain set of
conditions. The larger the number, the more the
carbon filter can adsorb. Phenol is another
measure of effectiveness. The lower the phenol
number, the better the carbon is at removing
organics. When comparing home carbon devices,
pay attention to these values.
Please keep in mind that manufacturers tend to
report the best removal rate for their product. The
values are frequently the amount the unit will
remove at the beginning of use for a single
contaminant at moderate concentrations. Units
having a larger bed volume of carbon usually
remove a greater quantity of contaminants. Some
types of activated carbon will remove specific
Maintenance
Regardless of the quality of the equipment purchased, it will not
perform satisfactorily unless maintained in accordance with the
manufacturers recommendations for maintenance, cleaning, and
part replacement. Keep a log book to record equipment
maintenance and repairs.
Most activated carbon filter units need to have the carbon
changed periodically. For small specialty units, the entire unit is
normally replaced. Cartridge filters are the easiest to change.
Before purchasing a unit, consider the ease of opening the filter
housing and the amount of space required to change the filter.
Service periods vary greatly. Small units with heavy loads of
contaminants may need replacement monthly or more often,
while a six-month service interval is frequently advised for the
cartridge filters. Since some filters treat up to a particular
amount of water, a water meter installed on the filter can help
judge when carbon replacement is necessary.
Depending on the type and concentration of the contaminant
being removed, some carbon filters may require special
hazardous waste handling and disposal, which can be costly. An
example would be carbon filters used to remove radon in drinking
water. It is important to establish beforehand how handling and
disposal will work and whether alternative treatment methods or
locating alternative water sources (such as installing a new well
in a new location, tying into a public water supply if available, or
using bottled water) would be more effective in the long run.
Other Considerations
Ensure the system you choose is installed and operated
according to the manufacturers instructions. After installation,
retest both the raw water (prior to treatment) and the treated
water at a state certified laboratory to ensure it is working
properly and removing the contaminants. You should continue to
test the quality of both the raw and treated water annually or
more frequently (quarterly or semi-annually) if high levels of
contaminants are present in the raw water. Frequent testing will
also help you determine how well your treatment system is
working and whether maintenance or replacement of
components may be necessary.
Product Certification
NSF, International is a non-profit organization that sets
performance standards for water treatment devices. Because
companies can make unsubstantiated statements regarding
product effectiveness, the consumer must evaluate test results
of the device to determine if claims are realistic. Products that
have been tested or evaluated by NSF and meet their minimum requirements are entitled to display the NSF listing
mark on the products or in advertising literature for products. Manufacturers and models that meet NSFs standard are
included in a listing published twice a year. For more information contact NSF at: 800-NSF-MARK or
http://www.nsf.org/water.html
This factsheet is one in a series on drinking water wells, testing, protection, common contaminants, and home water
treatment methods. Contact the URI Home*A*Syst Program for more information.
University of Rhode Island Cooperative Extension Home*A*Syst Program
Offers assistance, information, and workshops on private well water protection. 401-874-5398 www.uri.edu/ce/wq
RI Department of Health, Office of Drinking Water Quality
Offers assistance, information on testing and state certified laboratories.
401- 222-6867 http://www.health.ri.gov/environment/dwq/Home.htm
For a listing of HEALTHs certified private laboratories in Rhode Island http://www.health.ri.gov/labs/instate.htm
US EPA New England website: http://www.epa.gov/ne/eco/drinkwater/
US Environmental Protection Agency. For a complete list of primary and secondary drinking water standards:
http://www.epa.gov/safewater
RI Department of Environmental Management, Office of Water Resources
Maintains listing of registered well drillers, information on well location and construction.
401-222-4700 http://www.state.ri.us/dem/programs/benviron/water/permits/privwell/index.htm
This project is a
collaboration of
the staff at
HEALTH and
the University
of Rhode Island
Cooperative
Extension
Water Quality
Program.
NSF International
For information on water treatment systems, NSF International has tested and certified treatment systems since 1965.
800-NSF-MARK http://www.nsf.org/water.html
Water Quality Association
The Water Quality Association is a not-for-profit international trade association representing the household,
commercial, industrial, and small community water treatment industry. For information on water quality contaminants
and treatment systems. www.wqa.org
This project is a collaboration of the staff at the Rhode Island Department of Health: Richard Amirault,
Gary Chobanian P.E., Dana McCants, and the University of Rhode Island Cooperative Extension Water Quality Program:
Alyson McCann, Holly Burdett, Brianne Neptin.
Issued in furtherance of Cooperative Extension work and Acts of May 8 and June 30, 1914. Jeffrey Seemann, Dean and
Director, College of the Environment and Life Sciences. The University of Rhode Island U.S. Department of Agriculture,
and local governments cooperating. Cooperative Extension in Rhode Island provides equal opportunities in programs
and employment without regard to race, sex, color, national origin, sex, or preference, creed or disability. This is
contribution number 3969 of the College of the Environment and Life Sciences, University of Rhode Island.
Funding for this project is supported by HEALTH.