SOLID WASTES HANDLING
in hospitals
REPRINTED FROM PUBLIC HEALTH SERVICE PUBLICATION NO. 930-C-16
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REPRINTED FROM
environmental aspects of the hospital
HOSPITAL AND MEDICAL FACILITIES SERIES, THE HILL-BURTON PROGRAM
volume II. supportive departments
CHAPTER II. SOLID WASTES HANDLING
Ralph J. Black
U. S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
CONSUMER PROTECTION AND ENVIRONMENTAL HEALTH SERVICE
Environmental Control Administration
solid wastes program
CINCINNATI
1968
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Chapter II
SOLID WASTES HANDLING
Ralph J. Black
THE DIVERSIFIED TYPES of solid wastes that must
be stored, collected, and disposed of in the oper-
ation of medical care institutions create problems
that should be recognized early in the planning
process. Adequate facilities for the types and
amounts of waste that must be handled; the loca-
tion and design of waste chutes, and design of waste
rooms; whether separate facilities are to be pro-
vided for the disposal of surgical and autopsy
wastes; and the method of disposal are all essential
factors to consider for both new or remodeled facil-
ities. Consideration should be given to on-site
incineration or hauling for off-site disposal, with
emphasis on the placement and type of incinerator
if incineration is chosen. Suitable storage, collec-
tion, and conveyance systems must be evaluated,
keeping in mind such factors as the size of waste
containers, facilities for cart and/or container
washing, whether garbage grinders can be used, or
whether a refrigerated room must be provided for
storing the garbage until removed.
TYPES AND VOLUME
The principal types of solid wastes are: (1)
garbage, (2) paper, trash, and other dry com-
bustibles, (3) treatment room wastes, (4) surgery
wastes, (5) autopsy wastes, (6) nbncombustibles
such as cans and bottles. All containers and equip-
ment should be readily cleanable, small enough for
one man to handle easily when full, covered as
tightly as practicable until filled, and constructed
to create as little noise as possible during handling.
Ideally, collection must create a minimum of dis-
turbance, yet be scheduled frequently enough to
minimize accumulation of odors and prevent over-
loading of storage, transportation, and disposal
equipment.
Solid waste handling systems should prevent air-
borne contamination, vermin attraction, and odor
production. The system should encourage neatness
and good housekeeping, and present no safety haz-
ards to the institution or its employees. It is par-
ticularly noteworthy that studies of the micro-
biological contamination of hospital air showed tb.3
heaviest contamination in waste storage and di1-
posal areas, particularly in chute closets.1 In view
of the well-documented difficulties experienced in
controlling hospital-acquired infections, good super-
vision must assure that the most scrupulous house-
keeping standards are maintained in handitng
solid wastes.
Average weight and volume of solid wastes have
been given by several workers as between 7 and
8^2 pounds, and about 0.7 cubic foot per paoient
per day. Unfortunately, there is no reliable cur-
rent information on average refuse production. The
increasing use of disposable items has undoubtedly
altered former average figures on types and quanti-
ties and has affected incinerator loadings. The
problems inherent in safely disposing of such items
as syringes, examination gloves, catheters, emesis
basins, and petri dishes by means of outdoor stor-
age and municipal collection, involve special safety
considerations for staff, collectors, and the public.
There are legal implications as well. For example,
used syringes recovered from landfills or dumps by
children who play doctor or use them for darts, or
by narcotics addicts for less innocent purposes, may
leave the hospital liable for legal action through
failure to destroy or safely dispose of them.
Most existing data on waste type and "\ olume are
Mr. Black is chief of the Solid Wastes Engineering Sec-
tion, Special Engineering Services Branch, Division of En-
vironmental Engineering and Food Protectiou, US. Public
Health Service.
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calculated on a pounds-per-patient-per-day basis.
There are shortcomings in using the patient day as
a unit for estimation, however. It has been sug-
gested that a better correlation can be obtained by
using an equivalent population computed from
total patients, resident and part-time staff mem-
bers, and estimated visitor load. Charts II and III,
using the equivalent population basis, show the re-
sults of one waste production survey.
Single-service plastic waste receptacle liners or
moisture-proof paper bags with special holders are
preferable to unlined metal containers with their
attendant sanitizing requirements or cloth bags
which require laundering. Specially designed
Chart II. Hospital Noncombustible Wastes Production on Volume per
Capita per Day Basis*
1000
1500
Equivalent Population
I
h.
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single-service cardboard cartons have also been
used successfully. (See figures 3 and 4.)
Trash chutes should discharge to a trash receiv-
ing room separate from the incinerator charging
areas, and the receiving room should have exhaust
ventilation. Chute loading doors should be located
in soiled-equipment areas or in closets separated
from corridors or clean areas. Charging doors
should be protected with electric interlock systems
to prevent the opening of more than one door at a
Figure 3. Housekeeping cart with bulk container lined
with plastic bag.
Figure 4. Trash receptacle from isolation room show-
ing impervious paper liner. Receptacles from non-
isolation rooms should also be lined.
time, and should be tightly fitted with flexible
gasketing to minimize the spread of aerosols from
the chute. Chutes and trash receiving rooms should
have adequate sprinklers for fire protection, and
incinerator operating periods should be scheduled
to minimize trash buildup in both areas. (See figure
5.)
The use of single-service container liners, paper
bags, or cardboard cartons reduces aerosol spread,
eliminates odor and noise produced in transferring
the refuse, and achieves better vector control be-
cause the metal supports or receptacles do not ac-
cumulate much gross soil. Rupture of plastic bags
of 0.0015 to 0.0020 gauge has been reported as in-
frequent even when used for cans and bottles.
Overloading, however, particularly with wet gar-
bage, inust be controlled by staff training and super-
vision. After filling, liners should be closed with
rubber bands or stapled. Paper bags are less liable
to rupture but have thus far been employed in
relatively limited quantities. (See figure 6.)
Figure 5. Trash chute receiving room should be sepa-
rate from charging area, fire sprinklered and, if pos-
sible, have hose bibs to permit periodic scrubbing.
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Figure 6. P?per bag for bulk trash collection mounted
in special holder with stapler for closing.
Plastic bags for larger (27 to 33 gallon) con-
tainers may not feed readily through waste chute
doors; the use of smaller containers and bags or
small cardboard cartons may be necessary. Metal
containers from which liners are removed should
have closely fitting lids, either detachable or of the
hinged, foot-operated type. Containers should be
constructed without open seams or crevices for
easy cleaning. The container and cart-washing
facilities should be located as close together as pos-
sible so that the same hot water and steam supply
can be used. If steam is used, it must be under
pressure to be' effective in open containers or for
carts. Whether 180° F. water or steam is used for
sanitizing, a thorough initial hot water wash with
detergent is necessary to remove the gross soil from
containers. The operation should be mechanized
as much as possible to reduce labor and to encour-
age frequent washing of this equipment. (See
figures 7 and 8.)
Although impervious liners reduce the necessary
frequency for sanitizing containers, all containers
and the carts on which they are transported should
be cleaned routinely, as frequently as facilities
permit, without waiting for accumulation of clearly
visible gross soil. Fabric hampers, if used to trans-
port sealed liners, should be laundered on alternate
days. They should never be used for carrying
pathogenic wastes.
GARBAGE DISPOSAL
Many institutions use garbage grinders. But in
some areas, local ordinances prohibit the use of
commercial, heavy-duty garbage grinders of the
type best suited to institutional use. Special agree-
ments, which sometimes include a service charge to
cover the additional sewerage treatment load, have
been negotiated between local authorities and hos-
Figure 7. Can cleaner with 180 °F. water connections.
Figure 8. Can cleaner with can positioned for cleaning.
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pital administrators. The use of grinding units for
disposing of placental wastes and other hospital
service department wastes, as well as the more cus-
tomary kitchen wastes, should be evaluated.
An approximate guide for estimating commercial
disposer capacity in kitchen uses is shown below:
Horsepower l/z % IVa 3
General capacity
Ibs/hr 200 400 1,200 2,000
Up to number of
persons per
meal 125 300 1,500 1,500 plus
The pounds-per-hour capacity is based on use of
a special mixed waste developed as a military spe-
cification.
The size of grind is important in making the dis-
charge acceptable for handling in the sewerage
treatment system. The following specifications are
based on the military specification used in table III:
1. 40 percent of discharge must pass a No. 8
sieve.
2. At least 65 percent shall pass a No. 3 sieve.
3. 100 percent shall pass a V£" sieve.
Table III. Basis for Determining Pounds-
Per-Hour Capacity of Disposer*
Material
Uncooked beef or pork bones not over
IM:" diameter
Uncooked poultry bones
Grapefruit rinds cut in half
Green beans, cooked
Turnips, cooked
Spinach, cooked
Whole beets, cooked
Banana skins
Lettuce leaves, raw
Raw vegetable trimmings
Raw celery stalks
Corn husks
Potato peelings
Paper napkins
Approximate
Percent Drained
Weight
10
10
15
5
5
5
4
10
10
5
5
5
5
4
* Specifications Military—G-1584OB, Para. 4.1.1.1.
The unit should be approved by Underwriters
Laboratory and installed with a backflow preven-
tion device. The impellers and fly wheel should be
corrosion and jam resistant; the motor of ball-
bearing, sealed design; and the unit should have
an inlet deflector of neoprene or other approved
elastomeric material. Approved sanitary instal-
lation principles for easy cleanability and mainte-
nance should be followed.
If garbage cans are used, as they are in many
dietary facilities on nursing floors, plastic liners
are very useful in reducing the amount of gross
soil that accumulates in the cans. If garbage must
be sorted, rather than ground or incinerated, and
hauled away at the end of a shift, refrigerated
storage should be provided. This retards spoilage,
reduces odor production, and greatly reduces fly
and rodent attraction during warm weather. Out-
side storage of cither garbage or rubbish requires
containers that arc tightly covered, easily clean-
able, and positioned on a rack 12 inches off the
ground for a single rack of cans, and 18 inches
above the ground if a double rack is used. Galva-
nized pipe of lVi> inch diameter is often used to
construct racks because the pipe is durable and
easy to clean.
RUBBISH DISPOSAL
Since incineration facilities must be provided for
the disposal of infectious wastes, many institutions
have built incinerators large enough to handle all
their refuse. While enough large cardboard cartons
accumulate in large hospitals to warrant flattening
and selling them, the local demand for cardboard is
variable. Similarly, there may be a minor local
market for large-sized tin cans to be used by
nurseries to plant trees and shrubs. However, such
salvage does not significantly reduce the volume
of refuse which must be handled.
Equipment for wet grinding or pulping of refuse,
followed by dewatering of the pulp, has been intro-
duced recently. This equipment has the advantage
that both garbage and trash can be handled, and
since the slurry can be pumped easily, the extract-
ing unit can be located where removal of the de-
watered pulp is convenient. Little water is used by
these units because the extracted water is recycled.
The principal disadvantage of this method is that
a damp pulp is produced which is best disposed of
by landfilling or composting.
Such specialized problems as destruction of limb
or body casts can only be handled in heavy-duty,
high-temperature incinerator units after first
breaking the casts into small segments. One special
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problem which has occurred in institutions having
an appreciable amount of bone wastes, such as
teaching hospitals which use numbers of experi-
mental animals, is fused phosphorous deposits on
grates or bricks in combustion chambers. These
deposits, which are much harder than fused glass,
are usually removed by periodic chipping or the
replacement of some of the brickwork or grates.
HOSPITAL INCINERATOR TYPES
Two principal types of multiple-chamber in-
cinerators are currently in use—natural-draft, and
heavy-duty, high-temperature. The latter is pref-
erable because the high temperatures provide safe
disposal of pathological and laboratory wastes, wet
garbage, and other high-moisture-content mate-
rials. The obsolete flue-fed incinerator with direct
charging from the waste chute, was convenient
because it permitted loading at each floor. But it
had a high level of faulty operation and breakdown,
created aerosol contamination around flue doors,
into hallways and patient areas, and had serious
limitations on handling high-moisture wastes. The
natural-draft type offers improvement in operating
temperatures but little certainty of complete de-
struction of pathological materials. The high-
temperature type of incinerator of either grate or
solid hearth construction, with drying shelves for
wet wastes and an auxiliary heating unit to insure
temperatures of 1200° to 1800° F. is the unit of
choice.
There are various devices to aid in controlling
particulates in the gases emitted from an inciner-
ator. The settling chamber provides an additional
compartment in which fly-ash particles impinge on
the surfaces or, if large enough, settle out as the
hot gases pass through the chamber. The same
effect is usually accomplished by proper design of
a multiple chamber incinerator. Design of the
secondary combustion chamber and its flue con-
nection should afford a 90° angle, forcing a sharp
directional change in the movement of combustion
gases. The natural impingement of particles, sup-
plementing that accomplished earlier by the
baffles between the primary and secondary cham-
bers, will remove a high proportion of particulate
matter. As always, proper charging practices and
sufficiently high operational temperatures are also
necessary for good results.
A second device for particulate removal is the
liquid scrubber or gas washer, operated on these
basic principles:
a. Wet impingement—Particulates impinge on
baffles with water flowing over their surfaces.
b. Water sprays—Spray jets in the flue breech-
ing wash the gases in passing.
c. Water curtain—A continuous curtain is di-
verted by baffles through which the flue gases pass.
Particulate removal devices are designed more
for air-pollution control than as safety devices to
prevent emission of pathogens. Adequate destruc-
tion of pathogens is only accomplished by suffi-
ciently high temperatures in auxiliary burning
units, and particulate removal should never be
viewed as a substitute for high-temperature de-
struction.
Heavy-duty incinerators can be equipped with a
heat-exchange coil to provide hot water or steam
for sterilizing waste cans. In many cases, irregular
incinerator operating schedules and the relatively
low BTU value of refuse, even if no high-moisture
material is incinerated, offer marginal benefits.
However, one author indicated that in a "fairly
large" hospital, heat recovery could mean a saving
of $100 or more per month.2 The determination to
make the added capital investment necessary to
recover waste heat should be evaluated by a quali-
fied mechanical engineer after data on average
waste composition have been collected. Local air
pollution control requirements always should be
investigated before installing or modifying an
incinerator installation. Detailed operating instruc-
tions should be mounted on the incinerator control
panel or nearby wall. The manufacturer's repre-
sentative should review operating procedures with
the engineer or foreman responsible for incinerator
operation and maintenance.
Classification systems have been suggested for
incinerator types to furnish some guidance in select-
ing appropriate units.3'4
OPERATIONAL AND SAFETY
CONSIDERATIONS
In organizing solid wastes disposal work, super-
vision must be strict and constant, with the respon-
sibility delegated to one individual. Housemen
performing collection and storage work should be
carefully trained in protective techniques neces-
sary for the proper handling of pathogenic wastes,
such as the use of gloves, gown, filter mask; meth-
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ods of handling containers to minimize aerosol
spread; and proper closure techniques if liners are
used. All wastes from infectious disease cases, in-
cluding food wastes, should be placed in clearly
marked plastic or paper bags and incinerated. Only
trained personnel, wearing gloves or other protec-
tive items, if necessary, should handle these wastes.
Pathogenic wastes from treatment rooms, burn
dressing rooms, autopsy wastes, items such as
sputum cups and tissues from tuberculosis wards,
pathogenic laboratory wastes, and experimental
animal tissues all require careful handling of waste
receptacle liners, together with strict observation
of protective techniques by collecting personnel.
Scheduling of collection must depend on local
conditions, but refuse should be removed at fre-
quent intervals in as sanitary and as quiet a man-
ner as possible. Since no firm scheduling of refuse
removal from operating and delivery rooms is
feasible, frequent checking with supervisors is
necessary to provide adequate service. If only one
service hall and entrance in the building is avail-
able, the food facilities are frequently located
nearby. In such cases, refuse removal should be
scheduled during periods of the lowest level of food
preparation and service. To minimize aerosol haz-
ards and relieve hallways and service elevators of
extra traffic, no collection should be scheduled dur-
ing mealtimes. If flue-fed incinerators are still
being used, particular attention must be given to
training housemen and others handling wastes not
to empty noncombustible or pathological wastes
into the chutes. Waste receptacle liners must not be
overloaded to the point that the bags are ruptured
by forcing them through hopper doors. Liners
should be routinely used in kick-buckets in surgery
and delivery rooms. Proper training of housemen
in the use of waste-can liners or cartons makes it
unnecessary to use nursing personnel trained in
isolation and protective techniques to handle in-
fectious waste disposal. (See figures 9, 10, and 11.)
Medicines which contain alcohol, empty con-
tainers with residual hydrocarbon products, trash
saturated with inflammable liquids, and pathogenic
wastes all constitute safety hazards if spilled in the
incinerator charging process or thrown into a
closed-down but still hot incinerator chamber.
Transparent face shields are used routinely to pro-
tect the eyes of municipal incinerator stokers, and
should be used by hospital incinerator operators.
Any introduction of material into the incinerator
after routine operating hours should be closely su-
pervised. When pathological remains which have
been preserved in alcohol are incinerated, additional
air must be provided to keep down the heat and
smoke generated. The operating temperature should
be brought up to about 1700° F. by auxiliary
burners and blowers when starting to incinerate a
new load of wastes. After the load is charged, the
fuel supply should be cut off, but the blowers should
be left running to provide sufficient air for good
combustion.
In new installations, facilities for vacuum clean-
ing incinerators, rather than sweeping and shovel-
ing, should be investigated. One municipal-sized
operation reported a reduction in work force from
6 to 2 men and cleaning time reduced from 36 to
5 hours a week. Additionally, the vacuum process
eliminates the need for workmen to use the pro-
tective clothing and respirators required by the
manual process.5
Safety controls required on gas-fired incinera-
Figure 9. Bulk waste can with plastic
liner for wastes from isolation area.
Smaller individual can liners from
patient rooms are placed in lined larger
can.
Figure 10. Houseman closing neck of
liner before fastening. Note that proper
sized liner cuff permits enough slack for
adequate closure without compressing
waste inside.
Figure 11. Both fastened liner and tight-
fitting can lid are tagged with warning
tag to protect subsequent handlers and
insure adequate disposal of infectious
wastes.
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tors should be (1) draft indicators, (2) pilot light
solenoid, (3) low voltage release relay on blower,
and (4) damper interlock. All these safeguards
should be in series with a solenoid shut-off valve
in the gas supply line, which will operate upon
failure of any of the safety components.
Routine safety inspections by insurance inspectors
should be encouraged, since their training makes
them sensitive to any installation where a foresee-
able set of circumstances might cause accidents
or fire.
Some routine operating instructions which pro-
long incinerator life are:
1. Clean grates and ash pits daily.
2. Keep all draft passages clean.
3. Operate dampers weekly. Pulleys may cease
to function because of ash dust.
4. Keep cans, bottles, and other noncombustibles
out of the incinerators.
5. Ventilate furnace well before lighting to re-
duce explosion hazards from accumulated fumes.
6. Don't overload furnace.
7. Keep materials stirred and loose, exposing
them to air so they will burn readily.
8. Give a smoking fire more air.
9. Don't strike brickwork with bars or rakes.
10. Learn what types and amounts of wastes
may safely be burned without overheating the
brickwork.6
REFERENCES
1. Greene, V. W.. et al. "Microbiological Contamination of
Hospital Air; I. Quantitative Studies, II. Qualitative
Studies," Applied Microbiology, 10: 561-566 and 10:
567-571, November 1962.
2. Deming, Emily C. "How To Remove Waste To Remove
Hazards," Modern Hospital, 91: 130, Oct. 1958.
3. Mohr, Orpha. "The Selection of Incinerators for Hos-
pital Use," Hospital Management, 85: 118, February
1958.
4. Incinerator Institute of America. Incinerator Standards.
New York: The Institute, April 1963.
5. "Incinerator Vacuum Cleaner Cuts Labor Costs," The
American City, 71: 136, March 1956.
6. Koppenhauer, 0. E. "Incinerator of Hospital Wastes,"
Hospitals, 35: 91, May 1, 1961.
ADDITIONAL READING
Bond, R. G., and Michaelsen, G. S. Bacterial Contamina-
tion from Hospital Solid Wastes. (Final Report, PHS
Research Grant EF-00007-04) University of Minnesota.
Cadmus, R. R. "One-Use Waste Receptacles Minimize
Infection Spread," Hospitals, 32: 82-84, Dec. 16, 1958.
Hurst, Valerie, et al. "Hospital Laundry and Refuse Chutes
as Source of Staphylococcic Cross-Infection," JAMA.
167: 1223-1229, July 5, 1958.
James, P. E. Equipment and Methods for HeaL-Treating
Garbage for Hog Feed (U.S. Dept. of Agri. Program Aid
No. 370), November 1958.
Los Angeles County Air Pollution Control District. Multi-
ple-Chamber Incinerator Design Standards for Los Angeles
County. Los Angeles: The District, 1960.
Paul, R. C. "Disposables in Hospital Plant Operation Func-
tions." Presented to The Invitational Conference on
Utilization of Disposables in Hospitals, American Hospital
Association, Chicago, 111., 1964.
Vincent, C. L. "Careful Use of Plastic Liners Eliminates
Need for Cloth Bags," Modern Sanitation
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