Introduction What are Waste Minimization and Pollution Prevention? Why are Waste Minimization and Pollution Prevention Important? Purchasing Chemicals Managing Chemical Inventories Dealing with an Existing Inventory of Unwanted Chemicals Conducting Experiments Scaling Down Experiments Substituting Materials Alternatives to Wet Chemistry Reusing and Recycling Chemical Resources Segregating Waste Streams »In-Laboratory Treatment of Wastes« Working with School Administrators, Students, Other Schools, and the Community Getting More Information Appendix A—Waste Minimization Checklist

As a last line of defense in efforts to minimize waste generation, you might want to consider options for in-laboratory treatment of wastes. An important distinction exists between recycling or reclamation of chemicals and treatment of chemical waste. Reclamation or recycling generally applies to efforts to recover chemicals for re-use—either in the laboratory or elsewhere. By contrast, treatment generally applies to efforts to make waste less hazardous, followed by disposal. While treatment may be a useful activity, you should be aware that the treatment of hazardous waste may require a permit or be subject to regulation. In the laboratory setting, treatment that occurs as the last step in an experiment is technically not covered by regulation. Therefore, you will be in the best position if you can fold the following treatment options into your experiments directly. In some cases, however, you may need to accumulate wastes before treatment is practical. In this case, you should consider discussing any treatment options with state or local regulatory agencies before you implement them in your laboratory. Types of treatment techniques for rendering compounds non- or less hazardous—or in some cases reusable—include: neutralization separation fixation oxidation precipitation degradation ion exchange Another possible treatment technique—thermal treatment—is not recommended due to regulatory concerns. Neutralization of acids and bases is probably the most commonly used treatment method in educational institutions. Neutralization reduces a material’s corrosivity (acid or caustic properties) by raising or lowering the pH to a neutral range, between 6 and 9. Examples of some laboratory wastes amenable to treatment or neutralization are: phenol – with hydrogen peroxide and iron catalyst acid halides and anhydride – by hydrolyzing using sodium hydroxide solution hydroperoxide – by addition to acidified ferrous sulfate solution metal hydride – through gradual addition of methanol, ethanol, or N-butyl alcohol soluble metal fluoride – by treating aqueous metal solutions with calcium chloride solution finely divided metal – by oxidation with water aqueous solutions containing toxic metal ions, precipitate as insoluble sulfides using sodium sulfide in neutral solution oxidizing agents (e.g., hypochlorite or chromate) – by reduction using sodium bisulfite Again, before you implement any treatment methods outside of the experimental process, you should discuss your plans with state or local regulatory agencies.

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