Hazardous waste incineration is the burning of hazardous materials at temperatures which are high enough to destroy all of the contaminants. These wastes include soil, sludge, liquids, and gases which may be contaminated with a vast number of chemicals in substantial quantities. About 7% of the approximately 44 million tons of hazardous waste typically generated yearly in the United States is destroyed through combustion. A considerable amount of energy is used in the process. There is a potential for odors, smoke, dust, excessive noise, and hazardous substances getting into the air because of improperly performing air pollution systems.

There are two types of hazardous waste combustion units. They are incinerators, and boilers and industrial furnaces. Incinerators include rotary kilns, fluidized bed units, liquid injection units, and fixed hearth units. Industrial furnaces include cement, lime, aggregate, and phosphate kilns, as well as coke ovens, blast furnaces, etc. The EPA has established National Emission Standards for Hazardous Air Pollutants for maximum achievable control technology for an industry group or special source. (See endnote 90.)

Best Practices for Hazardous Waste Incinerators (See endnote 89)

  • • Obtain a permit from the authorizing authority by providing information on siting, design, waste streams, transportation, storage, air pollution devices, state-of-the-art technologies used, public education program, and potential hazards, types, and quantities. Also provide any other information required by the individuals granting permits. Prepare an environmental and public health impact statement.
  • • Establish a comprehensive monitoring program to detect all types of potential toxic emissions and the quantities released.
  • • Observe all rules and regulations of the state and federal government. These rules and regulations tend to change over time, and it is the obligation of the owner and operator of the incinerator facility to make all necessary changes as directed.
  • • Analyze all waste streams that have not been previously submitted for incineration at the facility. As a minimum requirement the analysis must include the heating value of the waste; halogen and sulfur content; and lead and mercury content.
  • • Monitor all instruments at least every 15 minutes to determine if various parts of the system are operating appropriately.
  • • Prior to the burning of hazardous waste, the thermal treatment process must be brought up to its normal operating condition and temperature.
  • • Use a temperature of 1600-2500°F for hazardous materials destruction depending on the type of material, quantity of material, and the contaminants. Use a time of treatment in the initial combustion chamber of 30-90 minutes also depending on the type of material, quantity of material, and the contaminants. Mixing of the waste helps make the process work better and faster.
  • • Most of the gases that are created during incineration are destroyed; however, for those that are not, they should go through a secondary combustion chamber for further heating and processing. If hazardous gases are still present, they should be trapped by the air pollution devices and then destroyed. Incineration of hazardous materials must result in the removal of 99.9999% of the contaminants.
  • • The stack plume must be observed visually at least once an hour for color and opacity to see if there are changes due to the substances being burnt and other conditions. Changes would indicate an immediate need to evaluate the system for problems.
  • • The entire thermal treatment process and all equipment must be evaluated on a daily basis as a minimum for leaks, spills, fugitive emissions, and whether or not emergency shutdown controls and system alarms are working.
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