Within the broad theme of pollution prevention, earlier chapters of this book consider various management strategies to reduce the formation of waste during laboratory operations. These include reducing the scale of laboratory operations, cataloging and reusing excess materials, and recycling chemicals that can be recovered safely. Clearly, the best approach to laboratory waste is to not generate it. However, this ideal situation is seldom attained in the laboratory. Therefore, this chapter considers methods for dealing with the waste that is generated during laboratory operations and for accomplishing its ultimate disposal.
The earlier chapters are directed primarily at enhancing the safety of laboratory workers and visitors and focus on the laboratory environment. However, discussing prudent practices for disposal of waste requires a broader perspective. When waste is eventually removed from the laboratory, it affects individuals other than those who acquired or generated it, and, ultimately, society as a whole. Waste is disposed of by three routes: (1) into the atmosphere, either through evaporation or through the volatile effluent from incineration; (2) into rivers and oceans via the sewer system and wastewater treatment facilities; and (3) into landfills. Occasionally, waste has to be held indefinitely at the laboratory site or elsewhere until acceptable modes of disposal are developed. The laboratory worker who generates waste has an obligation to consider the ultimate fate of the materials resulting from his or her work. The high cost of disposal of many materials, the potential hazards to people outside the laboratory, and the impact on the environment are all important factors to be considered.
Because of the potential adverse impact on the public through pollution of the air, water, or land, society invariably regulates waste disposal. Disposal of household waste is usually regulated by municipalities, while hazardous waste disposal is regulated at the federal level and often also by states and municipalities. The focus in this chapter is on the disposal of waste that may present chemical hazards, as well as those multihazardous wastes that contain some combination of chemical, radioactive, and biological hazards. Many of the disposal solutions outlined in this chapter have been designed to take advantage of the fact that there is a normal stream of nonhazardous waste generated in the laboratory and other parts of the institution. In some instances, waste that is classified as hazardous can be modified to permit disposal as nonhazardous waste, which is usually a less expensive and less cumbersome undertaking. The scientist who generates hazardous waste must make decisions consistent with the institutional framework for handling such materials.
Generally, waste is defined as surplus, unneeded, or unwanted material. It is usually the laboratory worker or supervisor who decides whether to declare a given laboratory material a waste. However, specific regulatory definitions must be taken into account as well. Even the question of when an unwanted or excess material becomes a waste involves some regulatory considerations. Whereas some institutions have created glossaries of terms to label waste materials as co-products or surplus reagents, regulations state that a material may be declared a waste if it is ''abandoned" or is considered "inherently wastelike." Spilled materials, for example, often fall into these latter categories. Therefore, it is not necessarily up to the generator to decide whether or not a material is a waste.
Once material becomes a waste by a generator's decision or by regulatory definition, the first responsibility for its proper disposal rests with the laboratory worker. These experimentalists are in the best position to know the characteristics of the materials they have used or synthesized. It is their responsibility to evaluate the hazards and assess the risks associated with the waste and to choose an appropriate strategy to handle, minimize, or dispose of it. As discussed earlier in this volume (see Chapter 3, section 3.B), there are numerous sources of information available to the laboratory worker to guide in the decision making, including those required under various Occupational Safety and Health Administration (OSHA) regulations.
Because proper disposal requires information about the properties of the waste, it is recommended that all chemicals used or generated be identified clearly. In general, they must be retained in clearly marked containers, and if they have been generated within the laboratory, their source must be defined clearly on the container and ideally in some type of readily available notebook record. In academic laboratories where student turnover is frequent, it is particularly important that the materials used or generated be identified. This practice can be as important for small quantities as it is for large quantities of material.
It is usually quite simple to establish the hazardous characteristics of clearly identified waste. Unidentified materials present a problem, however, because treatment disposal facilities are prohibited from accepting materials whose hazards are not known. In those cases when the identity of the material is not known, it is possible to carry out simple tests to determine the hazard class into which the material should be categorized. Because the generator may be able to apply some gen-