Treating Medical Waste
Treating Medical Waste & Disposal
There are multiple methods for the treatment and disposal of medical and biohazard waste:
- Incineration
- Autoclaves
- Mechanical/Chemical Disinfection
- Microwave
- Irradiation
The treated waste – if sufficiently sterile – can generally be disposed with general waste in a sanitary landfill, or in some cases discharged into the sewer system. In the past, treatment of medical waste was primarily performed on-site at hospitals in dedicated medical waste facilities. Over time, the expense and regulation of these facilities have prompted organizations to hire contractors to collect, treat, and dispose of medical waste, and the percentage of medical organizations that perform their own treatment and disposal is expected to drop.
To ensure that each treatment method provides the proper environment for the destruction of biologicals, test indicators for microbiological spores measure the treatment effectiveness. Microbiological spores are the most difficult of biologicals to destroy, so when the test package cannot be cultured after treatment, the waste is considered properly treated. In treatment methods where shredding or maceration is employed, the test package is inserted into the system after the shredding process to avoid physical destruction of the test package. The test package is then retrieved from the waste after treatment.
Incineration
According to the EPA, 90% of medical waste is incinerated. Incineration is the controlled burning of the medical waste in a dedicated medical waste incinerator. Among industry folks, these units are often referred to as hospital/medical/infectious waste incinerators (HMIWIs).
The waste generally passes through the incinerator on a belt, and because most medical waste can be incinerated, the waste is not sorted or separated prior to treatment. Incineration has the benefit of reducing the volume of the waste, sterilizing the waste, and eliminating the need for pre-processing the waste before treatment. The resulting incinerated waste can be disposed of in traditional methods, such as brought to a landfill. The downside of incineration is potential pollution from emissions generated during incineration. The EPA has stringent requirements on emissions from medical incinerators. The incineration process can be applied to almost all medical waste types, including pathological waste, and the process reduces the volume of the waste by up to 90%.
Modern incinerators can provide a secondary benefit by creating heat to power boilers in the facility.
The largest concern associated with incineration is air pollution from emissions. The EPA says that at least 20% of medical waste is plastic. The biggest concern is that the incinerator may create toxic compounds. Dioxins and furans can be produced when these plastics burn. Older medical waste incinerators included no pollution control equipment. As new federal and state emission regulations are instituted that have more stringent requirements, medical incinerators are often not being replaced at the end of their service life. Over time, the amount of waste being incinerated will be reduced as other technologies replace on-site incinerators.
Another concern is incinerator ash. As incinerators are designed or retrofitted with pollution prevention equipment, more of the potentially toxic chemicals that previously ended up in emissions now remain in the ash. Incinerator ash is generally disposed of in landfills.
As additional requirements are added to the emissions for medical waste incinerators, the cost of incinerating medical waste increases, and alternative treatments have increased their market share.
Autoclaves
Autoclaves are closed chambers that apply both heat and pressure, and sometimes steam, over a period of time to sterilize medical equipment. Autoclaves have been used for nearly a century to sterilize medical instruments for re-use. Autoclaves are used to destroy microorganisms that may be present in medical waste before disposal in a traditional landfill.
Medical waste that is subjected to an autoclave is often also subjected to a compaction process, such as shredding, after treatment so that it is no longer recognizable and cannot be re-used for other purposes. The compaction process reduces the volume of the treated waste significantly. After treatment and compaction, the treated waste can be combined with general waste and disposed of in traditional manners. Waste that is treated using an autoclave is still recognizable after treatment, and therefore must be shredded after treatment to allow for disposal with general waste. Autoclaves are not recommended for the treatment of pathological waste, because of the appearance of the waste after treatment and the possibility that pathological waste may contain low levels of radioactive material or cytotoxic compounds. One problem with autoclaves is that the process can aerosolize chemicals present in the waste and depending on the design of the autoclave, these chemicals can be released into the air when the autoclave is opened.
Autoclaves can be used to process up to 90% of medical waste, and are easily scaled to meet the needs of any medical organization. Small counter-top autoclaves are often used for sterilizing reusable medical instruments while large autoclaves are used to treat large volumes of medical waste.
Steam sterilization provides generators a way to treat waste in a cost-efficient manner. The destruction of the microorganisms is highly effective, but the problem comes when transportation is required. Many landfills and general incineration facilities are reluctant to accept the waste, fearing the waste is infectious.