MANAGEMENT OF SOLID WASTES FROM HOSPITALS:
PROBLEMS AND TECHNOLOGY
Presented at the Meeting of the National Sanitation Foundation
Steering Committee on National Conference on the Use and Disposal
of Single-use Items in Health Care Facilities,
Ann Arbor, Michigan, December 4 to 5, 1968.
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Consumer Protection and Environmental Health Service
Environmental Control Administration
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MANAGEMENT OF SOLID WASTES FROM HOSPITALS:
PROBLEMS AND TECHNOLOGY
Richard D. Vaughan*
Problems associated with the handling and disposing of solid wastes
from hospitals result essentially from the same factors that create solid
waste problems for the community as a whole: the large and growing solid
waste volumes, and the hazards these wastes pose to man and his environ-
ment.
As they apply to hospital wastes, however, these factors appear in
greatly magnified form. Obviously, the danger of disease transmission
from hospital wastes is worse than the danger from ordinary domestic
refuse; per capita waste generation is far larger for the hospital-patient
population than for the average householder and consumer. To give you
some idea of just how much larger the proportionate volume of hospital
waste is, recent studies indicate that 19 pounds of solid wastes are
generated daily for each hospital patient, while the corresponding per
capita figure for the U.S. population is 5 pounds. The 19-pound figure
*Mr. Vaughan is Chief, Solid Wastes Program, Environmental
Control Administration, Consumer Protection and Environmental
Health Service, U.S. Department of Health, Education, and Welfare.
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is perhaps more significant when it is compared with a total of only
3. 89 pounds of solid waste per patient/day, reported by the American
Public Health Association in 1955.
This startling solid waste generation increase in hospitals is
very largely the result of the wide acceptance which disposable or
single-use articles have gained in the medical, surgical, and institutional
environment, A survey conducted in 1964, for example, showed that 24
throwaway items were found in a typical surgical/obstetrical wing; 26 such
items were used in the hospital laboratory; 26 in nursing services; 29 in
the dietary department, and 13 were used by the housekeeping staff. A
survey taken today would certainly show an even greater number of
disposable items in use.
There are two reasons why disposable products have received such
strong endorsement in hospitals. One is, of course, the role these play
in control of infection. Even with well designed systems for autoclaving
and conscientious practice of sterile technique by the nursing staff, a
greater potential for infection exists with the reusable syringe, for
example, than •with its disposable counterpart.
The other reason usually given for use of disposables--economy--
may or may not be as valid. While use of disposables may result in
economies in certain areas, additional activity and expense is demanded
in other areas. Typically, the use of disposables reduces demands on
the central supply department, but imposes a much greater workload
on the receiving, storage and waste disposal operations. In one hospital,
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it was found that a storage volume of 20 cubic feet was sufficient to
maintain a six-month supply of reusable 2-cc syringes, while 100 cubic
feet (five times as much space) was required to stock disposables
(based on ten deliveries per year). Obviously, disposables required
more storeroom labor and capital investment in building and equipment.
In addition to the discard of the disposables themselves, the great increase
in bulky shipping cartons adds considerably to the solid waste volume.
Another ramification to the introduction of disposables includes
increased traffic between the central stores and the nursing stations
and departments. For more deliveries, more carts and more people
are needed. On the other hand transportation volume to and from central
supply may diminish because of fewer processed items.
The point is that the use of hospital supplies and equipment is
part of a total system, and decisions concerning whether or not to use
disposables should be made only after full analysis of the system. Such
factors as patient safety and comfort, convenience, cost, storage require-
ments, distribution, and disposal are all elements of the system, and,
accordingly, should be reviewed in relation to relative importance and
compatibility with the disposable product.
Ideally, all hospital solid waste items should be packaged when
disposed. This might be in a plastic or heavy waxed bag at the patient's
bedside, in a container at the treatment room or nursing station, or in
waste receptacles placed in the operating and delivery room. Liners or
paper containers should also be used in food preparation areas and other
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areas of the hospital. Immediate packaging of wastes will eliminate
continuous direct handling, and consequently will reduce the danger of
infection or injury to hospital employees. Packaging also eliminates
or controls generation of aerosols during the necessary handling of waste
materials.
The standard cart system for collection of solid wastes is still
used in the majority of hospitals today. Unfortunately, this system has
many undesirable features including high potential for accidents and
contamination of the hospital environment, and dependence on manpower
for movement through hospital corridors.
The gravity chute can have distinct advantages over the common
cart system of collection, although it is not without disadvantages.
Properly designed, the gravity chute allows waste material to drop
directly to a central collection room, from which it is removed to the
disposal site. In the last several years, gravity chutes have fallen into
some disfavor because of the fire hazards they present. Also, micro-
biological studies have tended to incriminate gravity chutes as contributing
to environmental contamination in the hospital.
The pneumatic refuse collection system is an interesting new
development that may be used increasingly in newly constructed hospitals.
With this system, charging doors are located at or near the waste source
and bagged waste is transported pneumatically to a central collection
point, an incinerator, or to the transport vehicle. This system reduces
the amount of physical handling required for solid waste removal, and
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may eliminate the need for collection rooms, such as required with
conventional systems. Possibly the most advanced pneumatic solid
waste collection system for any hospital in the United States is being
installed in California in a Los Angeles County hospital. One of the
particularly interesting features of this installation involves filtration
of air discharged from the collection system to assure that there will
be no microbiological contamination of the surrounding environment.
The wet pulping system is also receiving increasing attention
as a desirable waste collection system. The pulping device, similar
to a garbage grinder, reduces most wastes, including paper, tissue,
and plastics to a pulp or slurry, which is then piped to an extractor
near the hospital loading dock where it is dewatered for transport to
the ultimate disposal site. Several pulping units may be located at
strategic places throughout the hospital facility, or pulping may be
accomplished by a central unit. In the latter case the advantages of
pulping would seem to be diminished by the necessity for auxiliary
transport system to carry solid wastes to the central unit. Pulping
reduces waste to 15 percent of its original volume. The weight, however,
is significantly greater than that of the original material because of the
residual water content. This weight/volume relationship obviously has
important implications for the cost of final disposal. If hauling rates
to the ultimate disposal site are based on weight, then pulping may
prove comparatively expensive. On the other hand, if rates are based
on volume, then pulping may have a cost advantage over other collection
systems.
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The Federal solid wastes program is supporting research at the
University of Pennsylvania to apply the technology of solids transport
in pipes to collection and removal of domestic solid wastes, and results
of this work should have direct application in improvement of hospital
pulping systems. The question has been raised whether hazardous
aerosols are created around the pulping device, and there is need for
further research in this area.
Most hospitals have some incineration facility for disposal of
infectious wastes; many institutions have built incinerators large enough
to handle and reduce all of their solid refuse. Although the flue-fed
incinerator permits the convenience of direct charging from waste chutes
on each hospital floor, this type is now obsolete for a number of reasons:
pollution of our air resources, frequency of breakdown, aerosol contam-
ination around flue doors, and serious limitations on handling wastes
with high moisture. Two types of multiple-chamber incinerators are
now in common use: the natural draft incinerator, and the heavy-duty,
high-temperature incinerator. Of these, the heavy-duty, high-temperature
type is preferable because it assures safe disposal of pathologic and
laboratory wastes at temperatures which may range from 1, 200° to
1,800° F. There are many and various features to be considered in
incinerator design, such as the iron grate, solid hearth, step-grate,
drying shelf, auger feed, auxiliary fire, etc. The optimal combination
of these features •will vary from one hospital to another, and is in large
measure a function of the proportion and quantity of dry refuse, wet
refuse, and pathologic waste that must be handled.
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Disposal of radioactive wastes is a growing problem as
radioisotopes receive increased use in diagnostic procedures and treat-
ment. The Solid Wastes Program has sponsored research at Harvard
University to evaluate the feasibility of incinerating low-level radio-
active wastes in lieu of burial or discharge with dilution to sewers.
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This study considered the release rates of tritium, C, and S from
a solid waste matrix and determined their distribution between flue gases,
residue, furnace linings, and duct surfaces. Several types of incinerators
were examined and the mechanized steam boiler incinerator appeared to
be most satisfactory.
Disposable items are, of course, frequently made of plastic
materials, and these can cause serious operational difficulties in
incineration. Melted plastic tends to clog incinerator grates, and
polyvinyl chlorides have corrosive effects on firewalls. Incidentally,
these effects from plastics are not limited to hospital incinerators, but
cause similar problems in municipal plants. Hospital incinerators do,
however, have a unique problem in that phosphorus from bones will glaze
brickwork in the combustion chamber. Phosphorus deposits raise the
floors of grates or brick unevenly, making them difficult to clean. If
not periodically chipped away, these deposits may shut off the supply of
air through the grates. The problem is particularly manifest in university
research hospitals where large numbers of experimental animals are used.
Several alternatives have been proposed for solving the problem of
disposal of plastic wastes. One suggestion is that they be dissolved and
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poured down the drain. Although at present, various plastics require
different solvents, advances in fluorine chemistry promise the avail-
ability of a universal solvent, and, when available, this may become
a practical solution.
Another possibility is that plastics might be melted into mold
pans in relatively low-temperature ovens. When cooled, the cast
blocks of plastic could be landfilled or transported to a specially con-
structed incinerator for destruction. The melting-down process would
trap most infective material within the plastic mass, and surfaces of
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the block could be disinfected. These alternatives both have the disad-
vantage of requiring separation of plastics from the rest of the hospital
refuse.
Hospital incinerators, as well as others, must operate under
increasingly stringent air pollution control regulations. But whether
the air pollution control device consists of a settling chamber or liquid
scrubber, the controls are not designed to prevent emission of pathogens.
Adequate destruction of pathogens is only accomplished by sufficiently
high temperatures, and air pollution control devices should never be
viewed as a substitute for high-temperature destruction of pathogenic
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•wastes.
In many cases, irregular incinerator operating schedules may make
heat recovery impractical; nevertheless, some large hospitals have been
able to recover incinerator heat for beneficial purposes. In particular,
heavy-duty incinerators can be equipped with a heat-exchange coil to
provide hot water or steam for sterilizing waste cans.
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From 7 to 10 percent of hospital solid wastes are not incinerable,
and these, plus incinerator fly ash and residues, must be ultimately
disposed of. In most instances, ultimate disposition will be by sanitary
landfill. The Federal Solid Wastes Program has conducted considerable
research on the sanitary landfill process in an effort to improve this
technique and minimize health hazards from solid waste disposal. All
landfills, particularly including those receiving hospital wastes, should
be so engineered that there is no danger of groundwater pollution. The
term sanitary landfill implies an adequate daily earthcover over the
excavated area, and this may be especially important in landfills which
receive hospital wastes.
While composting is not a widely used method of disposal in the
United States, we may reasonably expect to see at least some increase
in amounts of waste disposed of by this method. In cooperation with the
Tennessee Valley Authority, the Federal solid wastes program is operating
an experimental compost plant at Johnson City, Tennessee. Although the
plant receives and processes most of the solid •wastes from commercial
and domestic sources in Johnson City, it has been necessary also to
refuse to accept wastes from the local hospital. In the initial stages of
the plant's operation these wastes were accepted, but it was soon found
that discarded hypodermic needles presented unmanageable hazards to
the "pickers, " who manually separate the compostable from noncompost-
able material, and these needles, being difficult to separate, •would
sometimes turn up in the finished compost product.
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Another form of solid waste disposal that is sometimes practiced
involves separation of food wastes for feeding to swine. There are
several attendant problems with this procedure, not the least of which
is maintaining the overall sanitation level of the pig farms. In order
to avoid transmission of vesicular exanthema and other diseases, most
states now require that garbage wastes be cooked before feeding to
animals. Also, and from the hospital's point of view, the waste
separation procedure or dual waste collection system may be less
convenient than a system -which can receive all wastes.
There appears to be no uniformity of interest displayed by states
in regulating the handling and disposal of hospital solid wastes. In most
cases, the regulations and ordinances that do exist are issued by the
cities and local authorities to protect the refuse collectors. In many
instances hospital solid wastes enter the municipal waste stream, some-
times at the point of transport to the ultimate disposal site or, if transport
is furnished by a private collector, then at the city-owned landfill or
incinerator. There is, however, an increasing tendency for regulations
governing hospital waste management to apply to the handling of wastes
while they are still on the hospital premises.
Other administrative/legal issues now being raised concern the
propriety of user charges to hospitals for the unusual burden they may
place on municipal disposal facilities. These issues may be resolved
differently in different communities, and changing technology will
undoubtedly have a bearing on decisions in this area. For example,
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the possibility of grinding hospital wastes and discharging them directly
to the sewer is being studied. If this method is widely adopted there
might well develop a special users' charge to offset expenses of the
increased burden to the sewage treatment facility.
There is no easy answer to the problem of disposing of hospital
solid wastes, and there is no single answer to this problem. Different
economics prevailing in different communities, for example, may dictate
different collection and disposal technologies. Hospital size and char-
acteristics of refuse will determine the optimum incinerator type and
whether or not heat recovery units are practical.
The hospital administrator can assist in mitigating the waste
problem by opting for disposable items only after careful consideration
of their desirability within the total systems concept.
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REFERENCES CITED
1. Oviatt, V. R. Waste handling--an old problem. Paper presented at
Joint Session, Annual National Environmental Sanitation Maintenance
Exposition, Institute of Sanitation Management, Oct. 10, 1967,
Washington.
2. Holbrook, J. A. Disposables require new disposal methods. Modern
Hospital, 107(1) :126-130, July 1966.
3. Rayner, H. M. On the disposal of disposables. Canadian Journal of
Public Health, 58(4):177-179, Apr. 1967.
4.. Black, R. J. Solid wastes handling. In Environmental aspects of the
hospital, v. 2. Supportive departments. Public Health Service
Publication No. 930-C-16. Washington, U.S. Department of
Health, Education, and Welfare, 1967. p. 25.
5. Falick, J. Waste handling in hospitals. Architectural fc Engineering
News, 7(11):46-53, Nov. 1965.
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