Chemical Treatment

The obvious disadvantage of chemical treatment systems is that they consume chemicals. In addition, even if they are effective in rendering the waste noninfectious, the products of the chemical reactions they undergo are present in the waste, and may pose problems of their own. However, chemical treatment systems are convenient, and may be suitable in some situations, particularly when small quantities of waste are involved.

One of the most common constituents of chemical treatment systems is chlorine, either in the form of sodium hypochlorite solution (common bleach), or as the more powerful (and correspondingly more hazardous) gas, chlorine dioxide. These compounds are relatively cheap and effective. However, in the course of reacting with organic compounds, they tend to form objectionable byproducts such as chloroform and other persistent toxins.

The chlorine compounds work by “oxidizing” (stripping electrons from) organic compounds, including the constituents of pathogenic microorganisms. The original “oxidizer” is, of course, atmospheric oxygen. Although it is, in fact, a fairly powerful oxidizing agent, ordinary oxygen is not harmful to, andis in fact essential for the survival of, many organisms including most of the pathogens in medical waste. However, when oxygen (O2) is converted to ozone (03), a much stronger oxidizer, it becomes toxic to most life forms. Ozone can readily be generated by passing an electric arc through ordinary oxygen gas. When used in a medical waste treatment system, ozone acts as an effective sterilizer, without the tendency to generate the types of by-products found with chlorine compounds. The major problem encountered with ozone systems is the need to avoid exposure to anyone in the vicinity of the treatment system, since ozone is highly injurious to lungs.

Alkaline agents are also used in medical waste treatment, either in highly corrosive form (sodium hydroxide, or lye), or in somewhat milder form (calcium oxide, or quicklime). Alkali tends to hydrolyze (decompose) proteins, among other effects. Apart from the cost of the reagents, the major disadvantage is the risk of contact, since alkaline solutions damage skin and lungs.

Disinfectants like glutaraldehyde and peracetic acid are also used for small-scale medical waste treatment. More information on these materials can be found on the Sterilants and Disinfectants page.