08 Nov From Hospital Waste to Waste-to-Energy
Categorizing Hospital Waste
Hospital waste, also known as medical waste or healthcare waste, encompasses a wide range of materials used in healthcare facilities such as hospitals, clinics, laboratories, and other medical settings. These wastes are categorized into different groups based on their potential hazard and disposal process. The main categories of hospital waste include:
- Infectious waste: this category includes infectious or potentially infectious materials such as human tissues, used syringes, needles, bandages, sharp objects, biological samples, and other waste contaminated with blood, secretions, or pathogens.
- Hazardous waste: this category comprises hazardous chemicals, expired or unused medications, chemicals used in laboratories, radiology, and other medical procedures that may contain hazardous materials.
- General waste: general waste includes non-infectious and non-hazardous materials used in hospitals, such as paper, plastic, cardboard, packaging, uncontaminated food, and other generic waste.
- Radioactive waste: radioactive waste includes materials contaminated with ionizing radiation, such as gloves or garments used in radiology, expired radiopharmaceuticals, and other radioactive substances.
- Pharmaceutical waste: this category encompasses expired or unused medications, medicine containers, unclaimed prescriptions, and other pharmaceutical-related waste.
It is essential to manage hospital waste properly to prevent the spread of infections, protect the environment, and ensure the safety of healthcare workers and the public. With this in mind, a Milan-based engineering company specializing in environmental facilities commissioned us to design and build two identical waste shredding plants for hospital waste in 60-liter cardboard boxes. The goal was to obtain, after a complex high-temperature treatment, a secondary solid fuel (CSS).
CSS can be used in existing industrial plants (cement factories, steel mills, power plants, etc.) as a replacement for traditional fuels and in waste-to-energy power plants for electricity generation: from hospital waste to waste-to-energy.
Design and Implementation of Two Hospital Waste Treatment Plants
We designed and built two shredding plants, each equipped with a 60 HP four-shaft shredder, model 4S 12/60, with 30mm selection grids to ensure controlled particle size and uniformity in the final volume of processed material.
Hospital waste is contained in 60-liter cardboard boxes and deposited in typical waste bins, attached to a bin-loader that lifts, tips, and empties the boxes into the shredder’s loading hopper.
The hopper is equipped with a large damper synchronized with the bin-loader, steam injection, and aspiration. A discharge auger beneath the shredder conveys the material to the next treatment cycle. The entire process is automated and managed by a Siemens PLC, in line with the most advanced Internet of Things and Industry 4.0 requirements.
To prevent cardboard boxes from jamming in the loading hopper, two “agitators” driven by gearmotors rotate alternately in one direction and the other, moving the boxes and preventing bridging.
The Waste-to-Energy Concept
The concept of “waste-to-energy” (WTE) refers to a process in which solid urban waste or other types of waste are used as raw materials to produce energy, typically in the form of electricity or heat. This process involves controlled combustion or gasification of waste to generate heat, which is then converted into electrical or thermal energy using turbines or other devices. The primary goal of waste-to-energy is to reduce the amount of waste destined for landfills, recover energy from renewable resources, and contribute to sustainable waste management and energy supply.
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