Waste is generated in the laboratory on a regular basis; however, not all waste is hazardous. Some chemicals can safely go in the trash or can be disposed of by pouring them down the sink. Teachers should verify the following guidelines with their local codes, as restrictions may vary.
If the teacher is disposing of approved chemicals in the trash, they should make sure they are in a tightly sealed container. Always alert maintenance staff when chemicals are in the trash to avoid any accidents. If an SDS doesn’t indicate whether or not a certain chemical can go into the trash, teachers can refer to the chemical provider for further guidance.
Find additional guidance for managing hazardous waste in these resources:
Chemical Disposal Guidelines: a Quick Reference
Trash Disposal
To be safely disposed of in regular trash, a chemical must be:
- Non-radioactive
- Not a biological hazard
- Not flammable, reactive, corrosive, toxic, or listed as hazardous per the Environmental Protection Agency (EPA)
- Not a substance that may adversely affect human or environmental health
- Not a carcinogen
Drain Disposal
Some chemicals are suitable for drain disposal. Again, if this guidance is not indicated on an SDS, teachers can refer to the chemical provider for guidance. Only small amounts of approved chemicals should be disposed of down the drain (typically no more than a few hundred grams or milliliters per day).
The general guidelines for sink disposal are as follows:
- Chemicals that meet criteria for trash disposal
- Dilute acids and bases with a pH between 5.5 and 10.5
- Compounds that are a soluble combination of the cations and anions listed below.
| Cations | |||
| Al3+ | NH4+ | Ca2+ | Cs+ |
| H+ | Li+ | Mg2+ | K+ |
| Na+ | Sr2+ | Sn2+ | Zr2+ |
| Fe2+/Fe3+ | Ti3+/Ti4+ | ||
| Anions | |||
| HCO3- | HSO3- | BrO3- | Br- |
| CO32- | ClO3- | Cl- | OH- |
| IO3- | I- | NO3- | NO2- |
| O2- | PO43- | SO42- | SO32- |
| BO33- | B4O72- | OCN- | SCN- |
Download the Disposal Quick Reference Guide for guidelines that a teacher can post in their laboratory. Note: this quick-reference guide is not exhaustive, but is helpful for day-to-day chemical disposal.
Other Disposal Tips
- Use laboratory sinks only, and never a storm drain that goes directly to a water source without treatment
- If the compound is not a pairing of a cation AND an anion on this list, it is not safe for drain disposal and needs to be disposed of by hazmat pickup. For example, AlBr3 can be disposed of down the drain. However, CuBr2 or AlF3 should be disposed of by hazmat.
- Double-check with local hazmat authorities or a reputable source such as the Flinn catalog before flushing the chemicals down the drain.
Teachers should keep a log of the contents of all hazardous waste disposal containers to avoid extra costs associated with hazmat pickup. If technicians know exactly what is in hazardous waste disposal containers, they will not have to perform expensive additional identification testing, which could be billed back to the school. All hazardous waste material should be clearly labeled as such, and the names of the contents should be spelled out with percentages.
Hazardous materials provide a unique problem for chemistry teachers, because most do not have a quick and safe way to store or dispose of them. District officials should know the next scheduled hazmat pickup and whether teachers should store hazmat materials or deliver them to a central location. A nearby college or university can also be a resource, as such institutions have more frequent pickups and could help local schools with safe disposal. Additionally, fire departments can be a resource for local chemical disposal guidelines and hazmat pickup, especially for flammables.
