Hazardous waste

Hazardous Waste Disposal



The Problem With Chemical Waste

The moment you open and use a can of solvent you are a waste generator. Conservation

laboratories may only produce 10 to 15 gallons of waste each year and private

conservators only one quart, still the improper disposal of even small quantities may

cause unforeseen problems. Chemicals dumped in the back yard will filter down to the

water table. It might take years, but they will eventually pollute that water below. Some

chemicals washed down the drain produce flammable vapors which can collect in stand

pipes and explode.

The bottom line is that California does not exempt small generators and if you do not

dispose of waste properly, you are actually breaking the law and may be liable to stiff

fines for non-compliance.



Disposal Methods

In-house disposal methods should be viewed with caution. Of the following

alternatives, only a few are acceptable.

 Most chemicals may not be put into the sewage system. Untreated bleaches

(oxidizers) can react with organic material in the sewers. Sodium chlorate, for

example, when mixed with automobile brake fluid will burst into flames in 30

seconds. Solvents, heavy metals, poisons and strong acids and bases can damage

a sewer system.

 Some classes of chemicals may be neutralized and then disposed of down the

drain with large amounts of water. Only persons familiar with the chemistry of

neutralization reaction should attempt to neutralize their waste.

 Most chemical waste may not be disposed of in common garbage. Oxidizers can

react with organic waste in the garbage truck and spontaneously combust.

 Disposing of waste solvents, paints, varnishes or other chemicals in the back

yard or in an empty lot is against federal law. If caught, severe fines or a jail

sentence may be imposed.

 Burning waste solvents is illegal. Some chemical compounds (most notably

chlorinated hydrocarbons) form very persistent intermediate products when

incinerated. These can compound air pollution problems and can be toxic.

 It is legal to allow small amounts of waste solvent to evaporate. After all, solvent

evaporates whenever a varnish film is allowed to dry. When evaporating small

amounts of waste, use a fume hood or equivalent. Be mindful of fire and health

hazards. (See following paragraphs on Solvents.)

 Some large generators of waste are able to recycle their waste materials. This

solution does not apply to the small quantities of mixed waste produced by

conservators.

 Waste which cannot be disposed of through an in-house method should be

collected and containerized for removal from the lab.





The materials used by most conservators can be broadly grouped into chemical classes.

These classifications are: solvents (including paints and varnishes), detergents, acids

and alkalies, bleaches and ethyl ether. As a general rule these classes should not be

mixed together in a waste container. The possibility of chemical reaction between

incompatible materials is a genuine fire and safety hazard.



Solvents



Solvents, as a class, present a known fire and health hazard and accordingly also

present disposal and storage problems. Included in this category are: paint, varnish

and polymer residues, as well as true solvents like toluene and naptha. (Diethyl

ether is categorized with ether.) Solvent waste should be collected in glass bottles for

future removal from the lab. Glass is inert and unlike metal, will not rust through if

water is mixed in with the waste.



Small amounts of waste solvent may be allowed to evaporate in a fume hood or

equivalent.



It must be emphasized that dumping even water soluble solvents down the drain is

not an acceptable practice. Flammable vapors can collect in traps and stand pipes

creating a fire hazard.



Detergents



Only detergents can be safely and legally disposed of down the drain without prior

treatment. With the exception of triethanolamine, sewage plants are designed to

accommodate this waste. Triethanolamine should be disposed of as the waste

solvents are. Do not collect this material in a metal can if it has been mixed with

water.



Acids and Alkalies



Acids and Alkalies may be disposed of in the sewer system under certain conditions.

If the acid or base does not contain dissolved heavy metals, it may be neutralized

and then washed down the drain with plenty of water. If neutralization is possible,

protective gear such as rubber gloves, an apron and a full face shield should be worn

during the process. Acids can be neutralized with sodium bicarbonate (baking soda)

or sodium carbonate (soda ash). Alkali can be neutralized with acetic acid (vinegar),

or even better, photographic indicating stop bath (add stop until the red color is

produced.) While not recommended, if other chemicals are used for neutralization

reaction, an indicator like methyl red should be used.



Please note that waste containing dissolved heavy metals should not be disposed of

in the sewer system under any conditions. Metals such as copper, zinc, lead,

cadmium and mercury are toxic and can kill the bacteria which is introduced at the

treatment plant to work on the sewage. This reaction requires the plant to initiate a

new treatment cycle.



If neutralization is not possible, the waste must be containerized for removal.



Bleaches



The very mild and dilute bleaches used in conservation treatments should be

neutralized before disposal in the sewer system. Many of the bleaches self-neutralize

with time. Sodium perborate, hydrogen peroxide, sodium borohydride and chlorine

dioxide generating baths, each in dilute aqueous solution, should stand for an hour

in order to avoid complications in the sewer system and then be discarded.

Chloramine T may be diluted and washed down the drain, as it is often used in

water treatment plants. Other bleaches must be neutralized before disposal.



Ether.



Ether, diethyl ether and ethyl ether all refer to the same material. Petroleum ether

(pet ether) is not the same chemical and is handled like the solvents. Ether is terribly

dangerous because it is highly flammable and a terrific explosion hazard. Its vapor

is heavier than air and creeps along the floor. If it finds an open flame, the fire can

flash back to the container. No one should ever smoke or have an open flame near

an open can of ether.



Ether reacts with air to form shock sensitive explosive peroxides. For this reason it

should always be kept in a metal container which will inhibit the formation of

peroxides. Ether must never be stored in glass jars. Bottles of ether contaminated

with peroxides have been known to explode from unscrewing the lid. Be aware that

although metal inhibits the formation of peroxides, it does not remove existing

peroxides and new peroxides still may form.



As a general rule, ether stored without refrigeration should not be used longer than

three months after it is opened. Close attention should be paid to the expiration date

on the can. Very old cans of ether often must be disposed of by bomb squads rather

than disposal agencies.



Suspect ether can be tested for peroxides with an acidified solution of potassium

iodide. A small amount of ether would be poured into a test tube containing a small

amount of the test reagent. If a red color appears upon shaking the vial, peroxides

have formed. Be extremely careful and contact an expert at once! Also note that if

contaminated ether in any type of container is allowed to evaporate, the peroxides

will have concentrated in the container, increasing a very real explosion hazard.



To dispose of fresh ether, we recommend letting it evaporate in a safe fume hood (or

equivalent.) For large amounts, contact a disposal firm at once. For the reasons

stated above, it is not wise to save ether for lengths of time while waiting for a

scheduled removal of other waste.



As a footnote, you may be interested to know that law enforcement agencies train

dogs to follow the scent of ether because it is used in the manufacture of PCP. The

scent of ether often indicates an illicit drug operation to the authorities, so be polite

to stray dogs who come to your door.



PCBs



Another disposal problem nearly unique to the conservator, is the handling of small

amounts of PCBs (polychlorinated biphenyls), Arochlor mounting medium. It is

absolutely illegal to throw Arochlor into the garbage. Even materials contaminated

with PCB, a well documented carcinogen, must never be thrown into the garbage.

All materials including contaminated tissues, microscope slides, swabs and so on,

should be segregated and disposed of by a registered contractor.



Arochlor is categorized in California as an extremely hazardous material and

therefore waste may not be disposed of in this state by anyone other than a

registered waste hauler.



Dry Waste



Disposal of solid or dry waste is difficult to discuss in general terms, but as a rule

solid or dry materials should be kept in that state and not mixed in with liquid

waste for disposal. It may be possible to neutralize small amounts of dry waste

before disposal. Seek advice from a professional on particular disposal methods

especially for toxic and reactive materials.



Chemical Incompatibilities

Some chemicals are not compatible with others. Chemical reactions are fairly common

in waste collection containers. Incompatible materials may burst into flames

immediately or hours after mixing; emit noxious or toxic gases; or simply bubble and

fizz out of the container making a mess.

As a rule, do not mix or store the following chemical classes together:

 Acids and alkalies

 Bleaches

 Oxidizing agents

 Reducing agents

 Solvents and flammables

Learn about which materials are incompatible when mixed together and which are not.

Numerous lists and tables of incompatible chemical types have been compiled. Often

chemical and supply catalogues contain such listings.

The following are specific incompatibilities:

 Ammonia with hypochlorite bleach;

 Nitric acid with acetic acid;

 Nitric acid with sulphuric acid;

 1-Butanol with strong mineral acids;

 n-Butylamine with copper and copper alloys;

 n-n-Dimethyl formamide with halogenated hydrocarbons;

 Ethyl acetate with strong alkalies;

 Ethylene Dichloride with oxidizing materials;

 Ethylene glycol with sulphuric acid;

 MEK peroxide (hardener for polyester casting resin) with anything flammable;

 1,1,1 Trichloroethane with caustic soda and caustic potash.

Do not use these chemicals at all:

 benzene (benzine, the petroleum thinner, is safe - remember, benzine is fine,

benzene is mean);

 carbon tetrachloride;

 chloroform;

 pyridine;

 phenol (carbolic acid);

 perchloric acid;

 hydrofluoric acid (If hydrofluoric acid must be used, be aware that it is lethal and

its vapors can pass through your bones. It will eat through glass and dissolve

silicon. It is an absolute must to wear protective clothing. This acid is considered

an extremely hazardous material.)