The legislation states that hazardous medical waste at infectious risk must be packaged in a double container:
Moreover, inside the same containers, rigid containers destined for cutting and / or pungent waste are collected once they are filled.
The plant is provided with a loading trolley that can be fed from above, with an automatic system, introducing inside it single-use containers “as-is” and / or the contents of the re-usable containers.
The filling of the trolley starts the preparation phase of the waste for the subsequent dispatch to the sterilization phase.
The two phases are batch processes that can take place simultaneously, so during the sterilization process it is possible to start the preparation of a new waste load.
In this way we avoid:
The infected waste, loaded into the inlet bin after initial weighing, is lifted and overturned in the hopper. Once the loading operation is completed, the hopper is closed before the beginning of the next phase.
The shredding takes place by means of a 4-axis knives shredder, equipped with an automatic anti-blocking system. The shredded waste is downloaded under the shredder through a grid that allows to obtain the desired size. During the operation, a sodium hypochlorite solution is nebulized inside the loading hopper, in order to sanitize the hopper itself and to reduce the lifting of powders.
The shredded waste is stored in a compartment which feeds the conveyor screw to the sterilization chamber. The storage compartment, in addition to homogenising the shredded mass, regulates, through level sensors, the introduction of new waste into the hopper.
The automatic preparation cycle is carried out by keeping the loading hopper in depression to avoid the spilling of emission components.
The flow aspirated by the filter group is treated by:
This emission treatment system allows the flow to complies with the standards set for air in the workplace. Since these standards are more restrictive than those foreseen for emissions into the atmosphere, the conveyance can take place both in the environment where the system is installed, and outside.
The waste accumulated in the storage compartment is assigned to the sterilization chamber through the transfer cochlea. Filling sensors in the storage compartment
allow to check the complete emptying through a PLC terminal which allows the management of the solenoid valves through a pneumatic circuit driven by a compressor.
The sterilization process was conducted through a heating cycle. The combination of fluxing and agitation allows the penetration of saturated steam throughout the treatment mass. By means of this system, it is possible to reach, within the mass of the waste, the maximum conditions obtainable equal to 165 ° C at 6 bar of pressure, with a reduction of the bacterial load such as to guarantee an S.A.L. (Sterility Assurance Level) not less than 10-6, as evidenced by the efficiency test issued by the University of Bari. The time / automatic cycle conditions are defined during the configuration of each individual plant according to: waste problems treated, moisture level, operating potential, etc.
Moreover, inside the sterilization chamber, a housing is provided in which will be introduced the bioindicators, in the form of vials containing a strip of spores of Geobacillus Stearothermophilus, useful to comply with the provisions of UNI 10384/94.
After the sterilization phase, the chamber pressure is lowered through a valve suitable for the steam escaping, which is recovered and condensed through a chiller. This allows re-use in the following cycles. Then, a depression is created to guarantee the evaporation of residual moisture. This evaporation also implies a cooling of the waste.
Before proceeding with the uloading of the sterilized waste, an appropriately designed cochlea is positioned automatically, using PLC management, under the sterilization chamber to receive the waste in exit. The cochlea is then activated to transfer the waste into a final container. Once the unloading phase is complete, the cochlea returns to the initial position. The process is completely managed by a PLC.
The plant is installed on a self-supporting frame made of steel sections that allows a simple and quick installation. It has a size of about 1170L x 710D x 600H (cm), with a consumption per cycle of treatment depending on the types and quantities of treated waste.
The technology, on the edge of the panel, provides an integrated printer in order to store the most important parameters of the cycle:
Finally, the report aims to relieve the operator who performs the operation from any possible responsibility.
Test carried out by the Department of Biomedical Sciences and Human Oncology of the University of Bari “Aldo Moro”, which confirmed the compliance with the provisions of the UNI 10384/94 standard.
Professor Giuseppe Signorile claims:
“no spore survived in the various monitored cycles”.
In compliance with the provisions of art. 11 of the D.P.R. 254/2003, sterilized sanitary waste, classified using the CER code 191210 – waste derived fuel (CDR),
“…waste can be sent to CDR production plants or directly used as a means of producing energy…”
The waste exiting the plant, sterile and reduced in volume in fine size, can be easily packaged, stored in temporary storage and sent directly to plants that can use it to produce energy, in plants of CDR / CSS that exploit the high calorific value to improve the quality of their fuel.
As part of the project evaluation, will be evaluated the hypothesis to equip the plant with an energy recovery system of the RDF produced, which may eventually receive coded 191210 waste from other production plants. In this way it is considered possible a high energy recovery to be used on site to feed the waste management and sterilization process.