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Abstract

This paper focuses on the terminal treatment technologies for used subcutaneous injection needles, deeply analyzing the principles, efficacy, and comparative advantages of mainstream harmless technologies such as high-temperature incineration, steam sterilization, and microwave disinfection. It also explores the resource recovery technology paths, challenges, and prospects for recovering stainless steel and plastic materials from the needles, demonstrating the innovation in medical waste management driven by technology.

Key Words

Used subcutaneous injection needles; Hazardous waste treatment; High-temperature incineration; Resource recovery; Medical waste disposal technology

Body

When the used subcutaneous injection needles are sealed in the sharps container and leave the medical institution, their final destination is a professional disposal facility. Here, a series of technical goals are clearly defined: to completely eliminate their biological hazards and to maximize the recycling of materials. Currently, decontamination is the primary and mandatory requirement, while resource utilization is the cutting-edge direction for the industry's pursuit of sustainable development.

Analysis of Mainstream Harmless Technologies

High-temperature incineration method: This is currently the mainstream and most reliable technology for handling infectious/injurious waste, including needles. Its core advantage lies in thorough destruction and harmless treatment. At temperatures ranging from 850°C to 1200°C, all pathogens such as hepatitis B and HIV on the needle surface are completely inactivated within seconds. The metal of the needle (mainly austenitic stainless steel) oxidizes under high temperature, and the plastic components undergo complete pyrolysis and combustion. Modern incinerators are equipped with secondary combustion chambers, quenching towers, activated carbon injection, bag dust removal, and other exhaust gas purification systems, which can effectively control the emissions of acidic gases, heavy metals, and dioxins. However, this method has high investment and operation costs, and completely dissipates the resource value of the materials.

High-temperature steam sterilization method: This method is suitable for sorted medical waste mainly consisting of plastic products. For needles, they need to be crushed or melted for destruction after thorough sterilization. Steam penetrates the waste under high pressure and causes the microbial proteins to denature and coagulate through wet heat (usually 134°C, above 0.2 MPa, for 30-45 minutes). Its advantage is that the operating cost is relatively low and there is no problem of smoke pollution. However, the challenge is that stainless steel needles may damage the sterilization equipment, and it is necessary to ensure that the steam can effectively penetrate the inner part of the tightly packed sharp containers, with extremely high requirements for the standardization of the operation process.

Microwave disinfection method: It uses high-frequency microwaves to cause the water molecules inside the waste to vibrate rapidly and generate heat from the inside out, achieving internal and external sterilization. It is usually combined with crushing technology. This method is energy-saving and has a short processing cycle. However, it also faces problems such as reflection of microwaves by metal components (needles), potential ignition, and equipment wear.

Exploration of Resource Recycling Technology

Under the condition of ensuring harmless treatment, recovering resources from discarded needles has significant environmental and economic value. The technical approach usually follows the sequence of "first harmless treatment, then resource utilization" or "combining harmless treatment and resource utilization".

Metal Recycling: The main material of the needle is high-quality 304 or 316L medical stainless steel, which has a high recycling value. The technical route includes: ① After incineration, the metal residues can be sorted from the slag through magnetic separation and other methods, and then recycled for smelting. ② After sterilization with steam or microwave and complete reshaping, the metal fragments can be separated through fine mechanical sorting (such as vibrating screens, eddy current sorting, optical sorting), and sent to specialized steel mills for regeneration as scrap steel. Recycling 1 ton of stainless steel can save approximately 1.6 tons of standard coal compared to producing it from iron ore.

Plastic Recycling: The plastic components of the syringe and the sleeve (mostly PP or PE) can be processed through harmless treatment, then crushed, cleaned, and melted into granules for downgraded use in the production of non-medical and non-food-contact plastic products, such as benches, toolboxes, industrial pallets, etc.

However, resource recycling faces severe challenges: Firstly, there is a strict requirement for health and safety, ensuring "zero pollution" in the recycling process, and public acceptance is crucial; Secondly, the sorting technology has high costs and purity requirements; Thirdly, a stable and traceable industrial chain from recycling to regeneration and utilization needs to be established. Despite numerous difficulties, with the deepening of the "circular economy" concept and the advancement of sorting technology, especially as regions such as the European Union incorporate medical waste plastics into their circular economy strategies, and used needles have transformed from "hazardous waste" to "urban mines", the transition from technical concept to commercial practice is gradually moving towards reality, representing an important direction for the industry's future green transformation.