Methods for Chemical Waste Disposal

The disposal of chemical and hazardous waste is very complex and heavily regulated in most areas to avoid threats to the environment and human health. Given the extreme danger posed by the improper disposal of some chemical wastes, only a few disposal methods are legally permitted in most areas, with the processes for each one clearly defined by law.

On-site Preparation

• The process of chemical waste disposal begins at the source. Most producers of chemical waste, such as laboratories, factories or processing plants, have an internal policy for the treatment of chemical waste. Although these policies can be more or less rigorous depending on the nature and amount of the chemical waste produced, most have a few steps in common: isolation, labeling, storage and retrieval. Waste is first separated by type, then placed in a specific, sealed and labeled container with complete information on the type and amount of waste contained and, finally, retrieved by a certified disposal agent after temporary storage in a designated safe place in the building.

Treatment and Incineration

• Several types of chemical waste can undergo treatment to reduce the toxicity or volume of waste. Treatments can include chemical neutralization or, more commonly, incineration, a process by which chemical waste is exposed to extremely high temperatures in order to combust harmful agents, reduce the volume of waste or reduce the environmental danger posed by the waste. In most cases, incineration still leaves some volume of dangerous waste that requires final disposal.

Land Disposal

• Land disposal refers to the long-term or permanent placement of chemical waste in subterranean or surface holding facilities. These facilities, which can include landfills, surface impoundments, waste piles or injection wells, are usually sealed facilities that keep waste from entering the surrounding earth, bodies of water or subterranean waters. Landfills, for instance, carve away pieces of land and refill them with wastes in sealed containers, while surface impoundments store wastes above ground in safe containers. Waste piles, simply piles of waste above ground, are used for less toxic wastes and usually have a safety perimeter, while injection wells, commonly used for liquid chemical wastes, are deep sealed wells into which wastes are injected.

Chemical Waste Recycling

• Certain types of chemical waste can be recycled to reduce the final amount of waste generated. Chemical wastes can either be reused directly, as is the case with emission control dust that can be reinserted into a zinc smelting furnace without processing, or reclaimed, meaning that the waste needs some chemical processing before it can be reused. Spent solvents, for example, can be treated to recover acetone. Chemical waste recycling not only reduces the environmental impact of chemical production, but can have economic benefits as it takes advantage of useful byproducts.