Hospitals in the United States generate approximately 4.5
million tons of medical waste each year. About 15% of this waste is considered
infectious waste. Incineration of medical waste, as with any waste, has the
advantage of being able to dramatically reduce the volume of the waste.
Disadvantages of incineration include its high costs and potential pollution hazards.
In the primary combustion chamber, waste is dried, heated, and burned in
the presence of about 80% of the stoichiometric oxygen (oxygen needed for complete
combustion). The combustion gases produced in the primary chamber proceed to the
secondary chamber. In the secondary chamber, the gases are mixed with excess oxygen
and their combustion is completed. Temperatures are controlled by air input and can
range from 1,400 to 2,000 0F. Surprisingly, these incinerators release
only 1.4 pounds of particulate matter for every ton of waste combusted. The concerns
raised in medical waste incineration revolve around the chemicals released from combusting
plastics. Chemicals know commonly as dioxins and furans result from this combustion
and are of course dangerous. The EPA (Environmental Protection Agency) reports that
20% of medical waste is plastic. I suspect that that estimate is very low. All
things considered, incineration of this type is not a bad solution, but there are better
ones.
A hospital in Pennsylvania burned their waste in a chamber with coal and limestone at
1,600 0F. The coal and limestone are good absorbing agents for many of
the formed particulates. At the same time, the hospital is burning its waste, it's
also producing energy (heat) that it can use. This is a key advantage over sending
the waste offsite....if the capital spending can be justified.
Other methods of medical waste disposal continue to be explored. The problems
associated with medical waste disposal are not as large as they sound. Overall,
there are many larger problems facing the world, but don't be surprised if a chemical
engineer helps to solve this one.
