Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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MACHINERY AND PROCESS FOR TREATING AND DISINFECTING
BIOMEDICAL HAZARDOUS WASTES
This invention comprises of a machine and a process for treating and
disinfecting biomedical hazardous waste.
The subject of waste disposal has become of paramount importance in allthe industrial countries in recent years. Very few members of the general
public are aware of the huge quantities of medical waste produced by
hospitals, laboratories, clinics and physicians offices. In Ontario for example
, more than 10 000 tonnes of regulated medical waste is generated annually
by the health care community. This includes blood and blood products,
cultures and stocks of infectious agents "sharps" (needles, razors etc.), as
well as pathological wastes. Due to the increase in the use of disposable
surgical products, it is anticipated that the amount of such waste will grow
significantly by the end of the decade.
The main problem with biomedical waste is that its contents, if not processed
properly are potentially contagious. There are serious health risks in
disposing of improperly treated biomedical waste directly into landfill sites
and by continuing to do so run the risk of public infection. This may take the
form of landfill predators which have been in contact with untreated
biomedical waste or by the infiltration of toxins into the groundwater.
Presently, one of the chief methods of biomedical waste disposal is
incineration. However, the use of incineration creates its own set of problems
including the expense of new incinerators to replace outdated ones,
emission of pollutants into the atmosphere, the creation of ash by-products
that are toxic and the irreversibility of the incineration process in
implementing recycling programs.
Consequently, there is mounting public concern with the present methods for
treatment of biomedical waste that necessitates the exploration of alternative
treatment solutions.
Patent application no. 2,051,445 based on PCT-90/12602 filed April 16,
1990 describes a continuous process for disinfecting biomedical waste in
which the conduction of biomedical is directed via a conveying device, then
passed through a series of microwave generators as a possible heat source
that heat the waste to a minimum temperature that is required for
disinfection of biomedical waste. The apparatus consists of a shredding
device, a conveying mechanism, a spray mechanism required to moisten
the waste and a microwave heat source. The operation of the
aforementioned system is as follows: Hazardous waste is deposited in the
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shredding mechanism to shred the waste, it is then fed through a commuting
device where the waste is then moistened and then passed through a
microwave field to heat the waste for a specific period of time and then the
waste is ejected. Given the amount of waste this machine can process as
indicated by the patent application (100-300 kg/h), it is found to be restrictive
and not economical with respect to processing time and energy consumed.
The purpose of this invention is to provide a safe, effective and more
economical process for disinfection of biomedical waste. This can be
achieved by using reliable technology on a larger scale to allow for more
waste to be disinfected per processing period. This will allow for the sharing
of the processing/disinfecting facilities by a large number of waste
generators. In addition, this will increase the affordability of waste treatmentby economies of scale. The reduction in the cost of construction of each
machine can be accentuated by the use of various industry specific parts
and components already in production to minimize the expense of custom
fabrication. The minimization of the working parts and quantity of
components in the system would increase the effficiency by requiring less
maintenance and repair costs. This can be achieved by use of the machine
set forth in this patent application.
The disinfection of biomedical waste by this process would adhere to the
following guidelines:
The waste to be treated is fed into the unit through a hopper (1 ), which may
be controlled by means of an automated lifting and tipping device or fed
through the unit manually. The hopper (2) is fitted with a sealed hydraulic
cover and a filter system (3) which removes air/aerosol from the hopper
before opening and during waste input, thus preventing contaminants from
being vented into the atmosphere.
During loading, the shredder (4) is not in operation. After closing the hopper,
the waste is fed down into the shredder by a power arm . Shredding serves
a dual purpose: it reduces the waste volume to an unrecognizable mass and
facilitates steam penetration into the waste by breaking down larger
components of the waste.
The shredded waste is then guided into a temporary internal storage bin (5)
(intermediate container) large enough to contain the entire volume of waste
to be treated in one cycle (approx. 1 metric tonne of waste per cycle). The
function of the intermediate container is to increase the efficiency of the
system by reducing the batch loading time. By allowing for one complete
cycle of waste to be ready for processing, this eliminates the time required
for shredding of waste while the disinfection chamber is idle. This waste is
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then fed into the heated disinfection chamber using a feed screw or exit
hatch mechanism (6).
While the waste is in the disinfection chamber (7) ,live steam or heated water
is then added via a steam generator (9) to obtain a controlled humidity and
to allow better heat conduction of the waste particles. In the disinfection
chamber, the waste is constantly agitated or mixed to ensure even allocation
of heat. The disinfection chamber maybe jacketed and heated by oil with the
use of an oil heater (10) and/or steam with a use of a steam generator (9) to
ensure a minimum interior chamber temperature. The temperature of the
waste reaches over 100 C and is held at that temperature for a
predetermined length of time sufficient to render inactive any dangerous
microorganisms. The advantage of the disinfection chamber being a batch
processor allows for specific attention to be given to different batches of
waste. Depending upon the source of waste, some waste need more or less
treatment time for disinfection. It is understood that general biomedical
waste would require a minimum set exposure time at minimum
temperatures. However, highly contaminated and contagious biomedical
waste may require exposure to higher levels of temperature and/or time.
While the waste is being treated, another batch of waste is shredded and
stored in the intermediate container (5) ready to be processed. After the
cycle is completed, the waste is then directed out of the disinfection chamber
via a feed screw or an exit hatch (8).
The waste in the intermediate container is then directed to the disinfection
chamber whereby the batch process begins again.
The entire process from start to finish maybe automated (ie. computer
controlled) by the Central Processing Unit (11) to ensure proper operation
and disinfection. The function of the Central Processing Unit would be to
constantly monitor the efficiency of the treatment process by first, insuring
that prior to the input of waste, the air filter is in operation and is functioning
until the hatch of the hopper is closed, second, the shredder is operating
while the waste is inputted, third, the power arm is functional, fourth, the
monitoring of the volume of waste in the intermediate storage chamber and
subsequent notification of when this chamber is at capacity at which time no
more waste would be allowed to be shredded, fifth, that it constantly
monitors the humidity and temperature via sensors in the disinfection
chamber, and/or by monitoring the inflow and outflow temperatures of the
thermal heating oils whereby any deficiency in humidity would signal the
addition of steam or water into the waste mix, and any deficiency in
temperature would signal the automatic increase in the temperature of the oil
inflow, sixth that the feed screw (8) would operate only upon the successful
completion of the disinfection cycle in the disinfection chamber, seventh,
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that once the treated waste has been removed from the disinfection
chamber, the waste in the intermediate storage chamber would then be
conducted into the disinfection chamber via feed screw ~6), and eighth, that
the machine shut's down automatically in the event of sensor or system
failure. Prior to any maintenance or repair of the equipment, the entire
system is flushed with supersaturated steam to disinfect any internal
components exposed to the infected waste material. Alternatively, the
functions may be monitored manually.
The final outcome is a hygienic waste end-product which can be stored,
transported and disposed of as innocuous domestic waste.
