Chemical Waste FAQs

By Peter Mirtchev, Member-at-Large for the GCI and Laura Reyes, Co-Chair for the GCI

All chemists create chemical waste, it’s simply part of our job. Recently, we started a Waste Awareness Campaign to track the amount of waste being generated by our chemistry department. Aside from this, the chemical waste disposal process was a bit of a mystery. Learning how to properly sort, label, and dispose of chemical waste should be part of every chemists’ early training, but typically gets overlooked. In academic research labs, waste disposal habits tend to get passed down from one person to the next, and often stem from tradition rather than regulation. With this post, we hope to clarify some of the confusion surrounding proper disposal of different types of chemical waste.

We recently co-hosted a seminar about waste disposal with the Chemistry Students’ Union. Our speakers were Ken Greaves (Chemistry Department Supplies & Services Supervisor) and Rob Provost (Environmental Protection Manager at the UofT EH&S Office). We found that many members of the department had important questions regarding proper disposal practices and what happens to chemical waste after it is picked up. We have summarized the crucial points of the talk in Q&A format below. There’s also very useful information at this EH&S website on chemical waste. If you have other unanswered questions regarding chemical waste, leave them in the comments and we’ll get them answered for you!

Disclaimer: the information below is specific to the Department of Chemistry at the University of Toronto, and may change according to institution. Check with your own institution regarding the rules of chemical waste disposal.

Q: What are the most common types of chemical waste produced in a research laboratory?

A: Solvents. At the University of Toronto, the three most common chemicals are 1) acetone, 2) hexanes, and 3) dichloromethane. The Department of Chemistry purchases over 10,000L of acetone per year alone.

Q: What is considered ‘flammable’ waste?

A: A flammable liquid is one that has a flashpoint of 23.8°C or lower.

Q: Is a mixture of water and organic solvents considered aqueous or flammable waste?

A: If the mixture is more than 50% water, it is considered aqueous waste. If it is less than 50% water, it is considered flammable waste. If the amounts are uncertain, treat as aqueous (see below for more about the treatment of waste types).

Q: What mixtures are treated as chlorinated waste?

A: If more than 5% of a mixture is a chlorinated compound, then it is all treated as chlorinated waste. Chlorinated waste should be disposed of in glass bottles, not in flammable solvent canisters.

Q: What sort of solid waste goes into the green pails?

A: These are versatile, and can be used for any solid free chemicals, or otherwise contaminated solids (e.g. filter paper still containing a filtered product, etc). All green pails must be properly labeled, to be disposed of separately as solid chemical waste. Only non-contaminated solid waste can be aggregated into the large garbage bins located in the waste room.

Q: What information goes on waste labels?

Waste label

Sample waste label.

A: The label on all chemical waste containers should contain the name of the chemicals present (written out in words, no chemical formulas) and the approximate amount of each component as a percentage of the total volume.

Q: What do I do if I run out of room on the waste labels?

A: Often, waste labels are too small to list everything that is included. In those cases, it is most important to include whatever makes the waste mixture hazardous. This is so that the container can be safely transported between facilities.

Q: Are the contents of waste tested at any point in the disposal process?

A: No! Which is why it’s so important that all waste is properly labelled. At every point along the disposal process, the label on the bottle is what’s relied upon for proper and safe transportation, sorting, treatment, etc.

Q: What if my lab has unknown “mystery chemicals” to dispose?

A: Unknown chemicals are generally accepted for disposal as long as the proper method of transportation (e.g. air-sensitivity) can be determined.

Q: What is the fate of the different types of chemical waste we produce?

Waste Poster GCI

Waste Awareness Campaign

A: The treatment of types of waste is below, and is also nicely summarized in the poster we made for our Waste Awareness Campaign.

Acids – neutralized, then treated as regular aqueous waste.

Chlorinated organics – a small percentage is used in the cement kiln fuel blending process, while the rest is disposed of as hazardous waste.

Aqueous – processed at the water treatment facility.

Flammable – solvents with a good BTU value are used in the cement kiln fuel blending process; other solvents are either directly burned, or treated with aqueous waste in the case of water-containing mixtures.

Q: Who can I contact if I have more questions about chemical waste?

A: Your best contact is Ken Greaves (from Chemical Stores), especially for questions specific to the Department of Chemistry. If you have a general question or curiosity, feel free to also leave it in the comments and we’ll look into it for you.


3 thoughts on “Chemical Waste FAQs

  1. Chemistry isn’t going anywhere! It’s a part of life and we need it. But the potentially dangerous chemical waste must be disposed of safely and properly, and we must continue to have these types of discussions as the Chemical production industry grows and grows. Thank you so very much for sharing this! So refreshing to see schools and companies that care and are forward thinkers!

  2. Pingback: Proper Chemical Waste Disposal: Posters & Memes | The Green Chemistry Initiative Blog

  3. Pingback: Update on the Waste Awareness Campaign | The Green Chemistry Initiative Blog

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