v>EPA
United States
Environmental Protection
Agency
Office of Water
Washington, D.C.
EPA 832-F-99-072
September 1999
Water Efficiency
Technology Fact Sheet
Incinerating Toilets
DESCRIPTION
Incinerating toilets are self-contained units
consisting of a traditional commode-type seat
connected to a holding tank and a gas-fired or
electric heating system to incinerate waste products
deposited in the holding tank. The incineration
products are primarily water and a fine, non-
hazardous ash that can be disposed of easily and
without infection hazard.
APPLICABILITY
Though traditional water-flushing toilets are widely
used throughout developed regions of the world,
their use is not always feasible. For example:
• In rural areas where no municipal sewage
system exists, or where installation of septic
systems is impractical or prohibitively
expensive due to shallow soils, steep slopes,
high groundwater levels, or extreme cold
weather conditions.
• For remotely located roadside rest areas,
where connection to a piped sanitary system
is impractical and the cost unjustifiable.
• For work crews operating in areas where
permanent toilets are not available.
• In marine vessels, for which discharge of
untreated waste into bodies of water is
prohibited; human wastes must either be
stored in tanks while at sea or be treated prior
to discharge.
• In areas where water is scarce due to drought
or other environmental conditions and the
need to conserve water motivates
consideration of alternative, water-free toilet
systems.
• Where community, environmental, and health
organizations have concerns regarding
existing sewage disposal practices, especially
seepage of contaminants into local water
supplies from improperly functioning septic or
other treatment systems, or exposure of
residents to improperly dumped waste
products from rudimentary collection pails
called "honey buckets."
All of these situations are potentially suited to the
use of incinerating toilets which are portable, water-
free, and sanitizing.
ADVANTAGES AND DISADVANTAGES
Often touted as a "pollution-free" technology,
incinerating toilets have some clear advantages over
many traditional methods of sewage disposal. There
are also disadvantages that should be considered.
Advantages
• Uses no water.
• Incineration cycle produces a fine, sterile ash
that can be thrown in the trash.
• Ash is space-saving; as little as one
tablespoon of ash is generated on average per
use.
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• Incinerating toilet systems are portable,
simple to install, and easy to use. Can be
installed in remote areas, either for temporary
or permanent use. Can be installed in
unheated shelters, even in freezing
temperatures.
• Relatively odorless in comparison to more
commonly used storage-in-disinfectant
portable toilets.
• In most areas, can be used in unheated
shelters without fear of freezing.
Disadvantages
• Incinerating process destroys nutrients in the
waste; ash is inadequate for replenishing soil
nutrients.
• Incinerating requires energy, resulting in
higher average energy costs for users.
• Units are not entirely pollution-free; both
portable electric generation (for remote
locations) and propane fuel burning produce
some air pollutants.
• Anti-foam agents, catalysts or other additives
are typically required for use.
• Some models cannot be used while the
incineration cycle is in progress.
DESIGN CRITERIA
Specific design criteria depend on the type of energy
used for incineration. Incinerating toilets are
designed with a chamber that receives and stores
human wastes until ready for incineration. The
incinerating chamber is typically composed of
stainless steel or a cast nickel alloy. The chamber is
accessed through a toilet seat support—part of a
housing made of non-corroding fiberglass reinforced
plastic or similar material—having a sealable
receiving opening for introduction of wastes into the
chamber. Vapor and products of combustion are
fed by blower fan to a venting system which may be
as simple as an exhaust pipe, or which may also
incorporate an afterburner or other odor control
system. Not all units can be used during the
incinerating cycle. Some units require initiation of
an incinerating cycle after each use while others
allow for multiple uses before an incineration cycle
takes place.
Electric Incinerating Toilets
The Incinolet electric incinerating toilet
(Blankenship/Research Products, 1999) is designed
with a paper-lined upper bowl that collects newly
deposited waste. To "flush," a foot pedal is pressed
causing an insulated chamber cover to lift and swing
to the side while the bowl halves separate, dropping
the paper liner and its contents into the chamber.
When the foot pedal is released, the chamber is
resealed and the bowl halves return to normal
position.
Incineration is initiated by pressing a "start" button
after each use of the toilet. The manufacturer does
not recommend using the toilet multiple times
between incineration cycles. The toilet can continue
to be used while incineration is in progress. Once
the "start" button is pressed, an electric heating unit
cycles on-and-off for 60 minutes while a blower
motor draws air from the chamber over a heat-
activated catalyst bed designed to remove odor
components. Upon leaving the catalyst bed, the air
is forced out through a vent line. Makeup air for
the chamber is drawn from the room in which the
toilet is operating. The blower motor continues to
operate after the heating cycle to cool the unit. A
complete cycle takes from 1.5 to 1.75 hours.
Five models of the Incinolet electric toilet are
available: two for fixed locations (one four-person
capacity and one eight-person capacity); two
mobile- location units for motor homes, trailers and
boats (one four-person and one eight-person); and
a urinal (eight-person). The smaller capacity units
are designed for 120 volt service, while the larger
units require 240 volts. All models retain the same
fundamental design principles described above.
Gas-Fired Incinerating Toilets
Propane or natural gas-burning incinerating toilets
are manufactured by Storburn International, Inc.
(Storburn, 1999; Lake Geneva A&C Corp, 1977.)
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These units are equipped with a three gallon storage
chamber which can accommodate 40 to 60 uses
before initiation of an incinerating cycle. To initiate
the cycle, an anti-foaming agent is manually added
to the chamber, a pilot is lit using a built-in piezo-
electric igniter, and the burner is activated. This
procedure automatically locks down the unit so it
cannot be used while the burner is in operation. A
complete incineration cycle takes approximately 4.5
hours for a full chamber.
PERFORMANCE
Evaluation of 19 On-Site Waste Treatment
Systems in Southeastern Kentucky.
A comparative "blackwater" (human excrement
waste) treatment study, known as the Appalachian
Environmental Health Demonstration Project
(AEHDP), was conducted in southeastern Kentucky
during the 1970s (U.S. EPA 1980.) As part of the
year study, twenty prototype systems representing
several alternative treatment technologies were
installed in private residences in southeastern
Kentucky during 1970 and 1971, including six
incinerating toilets. The region used for the study
was mountainous, characterized by shallow soils,
steep slopes and high groundwater, having a
demonstrated need for alternative treatment
methods. Further, the study was performed in a
low-income area where cost of installation and
operation was a critical consideration.
Two of the six toilets used in the study were
Incinolet brand units and the remaining four were
Destroilet brand propane-fired toilets. Since the
Destroilet is no longer on the market, and was
significantly different in design from propane-fired
toilets available today, findings related to the
Destroilet are not relevant to this Fact Sheet.
Results pertaining to the Incinolet electric toilet,
however, are still pertinent.
The two users of Incinolet toilets complained of
incomplete waste incineration. Scraping of partly
burned feces from the walls of the incinerating
chamber was periodically necessary. One household
using the Incinolet deemed the operating cost
excessive, and abandoned the incinerating toilet in
favor of their outdoor privy after approximately six
months. The second household used the Incinolet
for approximately three years; however, toilet use
was intermittent over this period and the outdoor
privy was preferred because of incomplete
incineration of waste products. The second
household installed a septic system to replace both
the Incinolet and the privy. The study
acknowledges that the Incinolet manufacturer
subsequently added catalyst as an incineration aid,
but notes that the basic configuration of the unit was
unchanged.
Cold Weather Operation Study of a Storburn
Propane Combustion Toilet
Researchers from the Alaska Area Native Health
Service and from the University of Alaska,
Anchorage, conducted an examination of Storburn
propane combustion toilets whereby honey bucket
waste was collected over nearly a month and
burned in a Storburn toilet using various batch sizes
and burn cycle times (Ritz and Schroeder, 1994.)
All burn cycles were conducted while the toilet and
propane fuel tank were located outdoors, with
ambient temperatures reaching as low as -11°C.
Anti-foam reagent was added to the contents of the
combustion chamber before each cycle to prevent
boil-over of liquid waste.
The Storburn was found to effectively reduce
human wastes to ash, even at low ambient
temperatures. On the coldest day tested, the
exhaust temperature was measured going from -
11°C to 100°C (the boiling point of water) only one
minute after ignition. On average, the ash remaining
after incineration amounted to 2.23 percent of the
total weight of waste treated in the Storburn.
Moreover, microbiological examination of the
resulting ash revealed no fecal contamination. The
coldest temperatures tested did adversely impact
incineration, however, because the contents of the
propane tank could not vaporize properly. To
maintain an optimal fuel supply to the toilet, the
authors of the study recommend keeping propane
tanks sheltered or heated when used in sub-zero
conditions.
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OPERATION AND MAINTENANCE
Incinerating toilets are generally simple to operate,
either involving the press of a button to begin the
operating cycle or the activation of a burner. The
degree of maintenance required depends on the
model used. Storburn gas-fired toilets have no
moving parts and routine maintenance involves
periodic cleaning of the burner and regular removal
of ash.
Maintenance for the electric incinerating toilet
involves:
• Regular emptying of the ash collection pan.
• Cleaning of the outer stainless steel surfaces
including the bowl halves.
• Periodic (every 90 days) cleaning of the
blower motor with occasional replacement of
the blower wheel.
• Cleaning and lubrication of the foot pedal
mechanism.
• Removal of bits of paper and dust from the
combustion chamber.
• Annual inspection of the catalyst.
COSTS
According to Incinolet product literature (Research
Products/Blankenship), a four-user electric
incinerating toilet costs $2,300; an eight-user toilet
costs $2,700. The purchase cost of a propane-
burning Storburn is $2,550; a natural gas-burning
unit costs is $2,590. Vent kits for both types of
toilet are not included in these costs.
The cost of electricity varies widely according to the
location of service. Domestic retail energy prices
can vary from $0.05 to $0.15 per kilowatt-hour.
The Incinolet electric toilet is claimed by the
manufacturer to use 2 kw-h per cycle. Assuming
four users, each using the toilet every 1.5 hours for
a use period of 10 hours, the electric toilet would
consume approximately 53 kw-h of energy per day,
or about 1,600 kw-h per month. At $0.10 per kw-
h, this amounts to $160.00 per month or $1,920
annually.
According to the manufacturer, maintenance costs
for the Incinolet include $0.08 per bowl liner used
(one per use), a new heating coil every one to three
years ($89.10 each), and a new blower fan every
two years ($8.95 each). Using the same
assumptions for frequency of use and replacing parts
every two years, the annual maintenance cost is
approximately $828.
Assuming a total purchase and installation cost of
$4,000, for a 10-year service life, the average annual
cost (including purchase, installation, operation and
maintenance averaged over 10 years) is $3,148 in
1999 dollars for the Incinolet electric toilet.
Ritz and Schroeder performed a life-cycle cost
analysis for the Storburn propane toilet (Ritz and
Schroeder, 1994.) The authors calculated the
annual operational cost per adult to be $233.60 and
the average annual maintenance cost to be $150.
Assuming a purchase and installation price of
$4,000, the annual cost for four adult users
averaged over a 10-year service life is $1,484 in
1994 dollars. In 1999 dollars (assuming 5 percent
inflation per year), this figure is equivalent to
$1,894. Since this estimate reflects unit operation
under cold-weather conditions, it may be assumed
that this represents the high end of the cost range;
the unit would require less energy for each burn
cycle when used indoors or in warmer climates, with
correspondingly lower energy costs.
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REFERENCES
Lake Geneva A & C Corp, 1977. Store and
Burn Incinerating Toilet and Method.
United States Patent US4051561.
The mention of trade names or commercial products
does not constitute endorsement or recommendation
for use by the U.S. Environmental Protection
Agency.
Research Products/Blankenship. Incinolet
Electric Incinerating Toilet product
literature. Internet site at http:/www.
incinolet.com, accessed June 1999.
Ritz, P. and Schroeder, H.P., 1994. "Life
Cycle Cost Analysis of a Storburn Propane
Combustion Toilet." Paper presented at the
8th International Cold Regions Conference,
Fairbanks, Alaska.
Storburn International. Storburn
International Inc. Gas-Fired Incinerating
Toilet product literature. Internet site at
http://www3.sympatico.ca/storburn/,
accessed June 1999.
U.S. Congress, Office of Technology
Assessment, 1994. An Alaskan Challenge:
Native Village Sanitation. OTA-ENV-591,
U.S. Government Printing Office,
Washington, DC.
U.S. EPA, 1980. Evaluation of 19 On-Site
Waste Treatment Systems in Southeastern
Kentucky. EPA 600/2-80-101, U.S. EPA,
Washington, DC.
ADDITIONAL INFORMATION
Storburn International, Inc.
47 Copernicus Blvd., Unit #3
Brantford, Ontario, Canada N3P 1N4.
Contact: David Gabriel, Owner
Contact: Julie-Ann Friedrich
Research Products/Blankenship (Incinolet)
2639 AndjonDr.
Dallas, TX 75220
Contact: Carol McFarland
Dr. Herbert Schroeder
Associate Professor of Civil Engineering
University of Alaska
3211 Providence Dr.
Anchorage, AK 99508
For more information contact:
Municipal Technology Branch
U.S. EPA
Mail Code 4204
401 M St., S.W.
Washington, D.C., 20460
IMTB
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MUNICIPAL TECHNOLOGY
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