Dwight Morgan

HISTORICALLY, incineration has been the primary treatment and disposal technology for medical waste. But in recent years, the availability of alternative technologies has increased due to the higher costs of incineration, the difficulty associated with permitting incinerators and the concerns over potential carcinogenic incinerator emissions.

Outsourcing the treatment and disposal of infectious regulated medical waste (RMW) has driven up total waste management costs, as the expense of transporting the material to off-site incineration facilities must now be added. At the same time, the federal Medical Waste Tracking Act (MWTA) has made waste generators rethink their decision to use off-site processes because of increased legal liability.

The biggest disadvantages of hauling waste to off-site incinerators are the inherently high cost, potential liability from improper disposal by the hauler, occupational injuries during the transfer of the waste and roadway accidents that may result in spills or injuries. The need to comply with yet another set of federal, state and local regulations for inter- and intra-state transport of RMW is another disadvantage.

Regardless of disclaimers, waste generators ultimately bear responsibility for what happens to waste once it leaves their facilities.

The problems with off-site processing, along with increased pressure to shy away from incineration, have acted as catalysts for the development and commercialization of “on-site alternative technologies.” The technologies for treatment and disposal include thermal processes, such as autoclaving; irradiative processes, including microwave sterilization; and mechanical/chemical processes. They cover both treatment (disinfection) and disposal (the reduction of waste to an unrecognizable form).

Autoclaving, or steam sterilization, has for years been used in laboratory settings to sterilize microbiological cultures. The first commercial steam sterilization process for medical infectious waste was introduced in 1978. Autoclaving has since become the most widely used alternative to incineration. However, in states covered by the MWTA, such as New Jersey and New York, wastes must not only be treated to destroy microbiological activity, but also rendered non-recognizable to prevent tracking. As a result, many companies have recently developed hybrid autoclave systems, which incorporate post- or in-process compaction or mechanical shredding.

Most health care facilities do not use the largest available autoclaves due to concerns over a “single point of failure” scenario. As such, many autoclave producers are beginning to market smaller tabletop units for use by doctor's offices and clinics. In many cases, health care facilities are installing multiple smaller autoclave units. This arrangement has become increasingly popular on the East Coast, with some restrictions.

The recognizability of compacted, autoclaved waste has led many local landfills to refuse it until shredded. Additionally, in some states, the local health departments are requiring that the sharps treated in autoclave compaction units be sealed in compaction-resistant containers when deposited in a landfill. The issues are pressuring autoclave producers to develop scalable hybrid solutions that incorporate a mechanical shredder to process the steam-sterilized waste into an unrecognizable form.

Microwave sterilization was first introduced several years ago in Germany. The systems shred waste in a controlled environment, then disinfect it using microwave radiation. The waste is wetted to facilitate heating and to reduce the risk of fire from sparking metal. The units often use computerized controls to ensure treatment and the attainment of minimum parameters for disinfection. Therefore, the systems tend to be expensive and require a dedicated skilled operator.

The third alternative medical waste treatment technology uses a combination of mechanical maceration and chemical disinfection. The solid waste is mechanically shredded to expose it to the chemical agent and to simultaneously render it unrecognizable. The residue of this process is discharged into the sewer system. The systems initially used chlorine. Reports have found chlorine bleach to be an effective disinfectant for medical waste, but less effective against spore-forming bacteria. Increasing concern over the practice of discharging untreated liquids (i.e., blood and other bodily fluids) into the sewer system makes this process an attractive alternative.

Due to rising concerns over the discharge of high levels of metals and chlorine into the sewer system, some companies have begun to incorporate biodegradable chemical agents, which provide secondary active filtration of the waste stream before discharging it.

There is no single best solution to the medical waste issue. Each alternative technology discussed here has been commercialized to address niche markets. The Medical Waste Expo and Conference in Las Vegas, to be held on April 6-7, is a good place to learn about the emerging technologies. A variety of alternative waste systems will be exhibited and discussed at the show.
— Dwight Morgan
Chief Engineer — Product Development & Engineering
MCM Environmental Technologies, Inc.
Hackensack, N.J.