Universities typically post the disposal of used and
unwanted chemicals instructions on their Laboratory Reference Manual. An “unwanted”
chemical has a very wide definition, it can mean a chemical that has not even
been opened yet or a by-product from a chemical reaction or solvent. Sometimes
this definition also extends to mean glassware or gloves that have come in
contact with an unwanted chemical.
Before working with any chemical it is important to plan out
how you will properly dispose of them with the least amount of environmental
effects. There are many different ways to dispose of waste. Four common routes
to dispose of waste are: have a Chemical Safety Office pick them up, throw them
out in the normal trash, organize them from normal trash and pout them directly
into the dumpster, and pour them in the sanitary sewer. If unsure about which
method to use, the Chemical Safety Officer will recommend the best method
depending on the chemical in question. The Environmental Health and Science
Department will pick up chemicals, waste flammable solvents and by-products
from reactions.
The vast majority of pure unwanted chemicals should go
directly to the Chemical Safety Office. Typically, sewer disposal in the lab is
allowed for small quantities (less than a liter) of specific types of
chemicals. We saw this during out inspection of a lab, as long as the
instructor said it was okay you can pour chemicals down the drain with the
water running. If the water is not running, then it could cause the chemicals
to aerosolize and create an unsafe condition for the people in the lab. No hazardous
wastes - as defined by the EPA – can go down the drain. A hazardous waste is
defined as a waste that is dangerous or potentially harmful to our health or
the environment.
Separate and throw away in the trash is for minimally
contaminated waste that still poses a hazard risk to the average citizen
because of the toxicity of the chemicals. While items in this section can go
into a landfill with the regular trash, you want to ensure that staff that may
have to empty the trash are not accidentally exposed. This area of trash should
be collected in a trash bag separate from normal lab trash in your workplace
and labeled with contents. When the bag is filled it should be placed in a
sturdy box for disposal.
Items such as lab wipes, gloves and items not minimally
contaminated with low hazard chemicals can go in the regular trash. Items such
as glass should not go into the normal trash due to the potential danger it
could cause to the custodial staff when changing the garbage cans.
When throwing away any chemicals it is important to make
sure that any two chemicals are not incompatible with each other. If they are
incompatible it could cause a dangerous reaction which could produce harmful
by-products. For instance, never mix oxidizers with organic solvents, cyanides
with acids, azides with acids or oxidizing reagents with reducing agents.
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