Incinerating Hazardous Waste

Through incineration, hazardous wastes can be safely and efficiently discarded.

• By Savannah Cooper
• Apr 20, 2015

Most industrial processes produce waste, some of which can be hazardous and detrimental to public health and the environment if not managed properly. Hazardous wastes are generated in the production of cosmetics, detergents, pharmaceuticals, household paints and cleaning products, phones, televisions, garden pesticides, computers, gasoline, and even light bulbs. Hazardous wastes can be liquids, solids, contained gases, or sludges. They are the byproducts of manufacturing processing or discarded commercial products, such as cleaning fluids or pesticides.

Many companies have made significant progress in recent years to reduce or recycle hazardous wastes from their processes. However, despite their best efforts, more than 200 million tons of hazardous waste are generated each year.

A variety of businesses generate hazardous waste, including dry cleaners, automobile repair shops, hospitals, exterminators, and chemical manufacturers. In years past, hazardous waste was consigned to regular landfills, resulting in high amounts of hazardous materials seeping into the ground and nearby water sources. Today hazardous waste is often destroyed in an incinerator. Incineration not only reduces the amount of hazardous waste, but also may generate energy throughout the gases released in the process.

In the United States, modern hazardous waste incineration is a widespread and common technology. The destruction of hazardous waste in incinerators has been determined by EPA to be the Best Demonstrated Available Technology (BDAT) for most organic hazardous waste because the incineration process safely and effectively destroys the hazardous constituents in waste. When performed properly, incineration eliminates the toxic constituents in hazardous waste and reduces the volume of waste.

Hazardous waste combustors or incinerators are regulated under EPA's Clean Air Act and the Resource Conservation and Recovery Act (RCRA). By requiring reductions in emissions of some of the most hazardous air pollutants, the CAA protects human health and the environment from the harmful effects of air pollution.

Incineration converts waste into ash, flue gas, and heat. Ash is produced by the inorganic substances in the waste and may appear as solid lumps or particulates carried by the flue gas. The flue gases can be dispersed into the atmosphere, but first they must be cleaned of any gaseous and particulate pollutants. In some instances, the heat generated by the incineration process can be used to generate electric power.

Incinerators reduce the solid mass of the original waste by 80 to 85 percent and the volume by 95 to 96 percent. While incineration does not completely eliminate the need for landfilling, it does reduce the volume of waste necessary for disposal. Incineration has especially strong benefits for the treatment of specific types of waste, such as clinical wastes and hazardous wastes where pathogens and toxins can be destroyed by extremely high temperatures.

A typical hazardous waste incinerator consists of a rotary kiln, an afterburner and an air pollution control system. Both solid and liquid wastes are introduced into the rotary kiln, in which the temperature is usually higher than 1,800 degrees Fahrenheit. This extremely high temperature is maintained through the use of the heat content of liquid wastes or the introduction of supplemental fuels, such as natural gas, into the chamber. The kiln rotates slowly to ensure that the solid wastes are exposed on all sides to the high temperature in the kiln. A large fan draws the excess air into the system to increase its combustion efficiency.

In the incineration process, hazardous waste is fed semi-continuously by a ram feeder. The ram feeder can be automatically or manually cycled through a refractory lined charging into the combustion chamber. The primary combustion chamber consists of the rotary drum and a 20 MMBtu burner which is controlled and modulated by a temperature controller and temperature element placed in the ductwork between the primary and secondary combustion chambers. The ash from the primary combustion unit is discharged through a refractory-lined valve placed in the discharge bridging.

The vapor from the primary combustion chamber is pulled through refractory-lined ductwork to a secondary combustion chamber, where the vapor is oxidized at temperatures up to 2,600 degrees Fahrenheit for at least two seconds. The vapor from the secondary combustion chamber is pulled through a pre-cooler, where the temperature is reduced to approximately 1,400 degrees Fahrenheit. From the pre-cooler, the vapor is pulled through a plume eliminator, which also acts as a heat exchanger. In the plume eliminator, the fine dust particulates are removed and the vapor is cooled to approximately 700 degrees Fahrenheit. The vapor from the plume eliminator is pulled through an after-cooler, where it is further quenched prior to entering a Venturi scrubber and absorption tower, which are part of the air pollution control system.

Incinerating hazardous waste decreases the load placed on landfills and prevents potentially dangerous materials within the waste from leaching out and polluting the surrounding environment. Through incineration, hazardous wastes can be safely and efficiently discarded.

Worldwide Recycling Equipment Sales, LLC, in Moberly, Missouri, offers a variety of incinerators for hazardous waste. The Vulcan® Hazardous Waste Incinerator, for example, is a 12’ diameter x 20’ long rotary drum incinerator with an air pollution controls system. This unit consists of a ram feed system and a refractory lined rotary drum capable of operating at up to 2,600 degrees Fahrenheit. For information on Vulcan® Incinerators, visit www.getavulcan.com or contact Worldwide Recycling Equipment Sales, LLC at 660-263-7575 or wwrequip@wwrequip.com.