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What is a Hazardous Waste?
In order for a material to be a "hazardous waste," it first must be a "solid waste."
Definition of Solid Waste
The term "solid waste" is defined at 40 Code of Federal Regulations (CFR) Section 261.2(a)(1) as any discarded material that is not excluded under 40 CFR Section 261.4(a) or that is not excluded by a variance granted under 40 CFR Sections 260.30 and 260.31. A solid waste can include solid materials, liquids, and contained gases. The definition of discarded material includes:
In general, materials that meet the above definition are a solid waste. However, there are many exclusions from this definition in the regulations. To determine if a material is a solid waste, the generator of that material must depend upon the regulations and not just the summary on this page. We will not delve into all the possible exclusions here, but will discuss the exclusions that are pertinent to each waste stream EPA has observed at biodiesel production facilities.
Definition of Hazardous Waste
Once it meets the definition of a solid waste, the generating facility is obligated by 40 CFR Section 262.11 to determine if the waste is hazardous. If a solid waste is listed by EPA or exhibits one of four different defined characteristics, it is a hazardous waste. Each of the listed or characteristic wastes is identified by a waste code with a letter followed by three numerals. The four characteristics that might cause a solid waste to be defined as hazardous are:
Ignitable: A liquid with a flash point of less than 60°C (140°F) in closed-cup test or a solid that can spontaneously combust or catch fire through friction or absorption of moisture under normal handling conditions and can burn so vigorously that it creates a hazard is considered ignitable. Ignitable hazardous wastes are identified with the code D001.
Corrosive: A liquid that is acidic or alkaline (basic) can be "corrosive" depending on its pH. Such wastes can readily corrode or dissolve flesh, metal or other materials. Aqueous wastes with a pH greater than or equal to 12.5, or less than or equal to 2, are corrosive. Physically solid, nonaqueous wastes are not evaluated for corrosivity. Corrosive wastes carry the waste code D002.
Reactive: A waste material that can readily explode or undergo violent reactions, or react to release toxic gases or fumes, is considered reactive. In many cases, there is no reliable test method to evaluate a waste's potential to explode, react violently, or release toxic gas under common waste handling conditions. Therefore, EPA uses narrative criteria to define most reactive wastes. The narrative criteria, along with knowledge or information about the waste properties, are used to classify waste as reactive. Reactive wastes carry the waste code D003.
Toxic: When hazardous waste is disposed in a land disposal unit, toxic compounds or elements can leach into underground drinking water supplies and expose users of the water to hazardous chemicals and constituents. EPA developed the toxicity characteristic (TC) to identify wastes likely to leach dangerous concentrations of toxic chemicals into ground water. The Toxicity Characteristic Leaching Procedure (TCLP) is used to determine if a waste will leach any of 40 different toxic chemicals in amounts above specified regulatory levels. If the leachate sample contains a concentration above the regulatory limit for one of the specified chemicals, the waste exhibits the toxicity characteristic and carries the waste code associated with that compound or element. The regulations describing the toxicity characteristic are codified in 40 CFR Section 261.24 and the TC regulatory levels appear in Table 1 of that section.
EPA developed a list of hazardous wastes and gave them specific waste codes. Listed wastes are wastes from: generic industrial processes (F-listed), certain sectors of industry (K-listed), unused pure chemical products and formulations (U-listed), and acutely toxic unused pure chemical products and formulations (P-listed). Because these wastes are dangerous enough to warrant full Resource Conservation and Recovery Act (RCRA) Subtitle C regulation based on their origin, any waste fitting one of these narrative listing descriptions in 40 CFR Part 261 Subpart D is considered a listed hazardous waste.
