Individual Waste Streams: A waste stream generated from a laboratory procedure or shop process should not be combined with other chemical wastes. The fewer the number of chemicals associated with a waste, the more economical is the disposal method for that waste. If this is not practical, the Safety Officer should be consulted about which wastes can be combined.
Non-Halogenated Flammable Solvents: Non-halogenated flammable solvents are sent to an incinerator or recycler and must be free of heavy metals and reactive materials, e.g. sodium metal. Disposal of solvents to the sanitary sewer is limited to low-toxicity solvents, miscible in water, diluted to non-flammable concentrations.
Halogenated Solvents: Halogenated solvents are disposed of separately and must not be combined with flammable non-halogenated solvents. Examples of halogenated solvents include methylene chloride, chloroform, and carbon tetrachloride
Acids and Bases: Acids with a pH of greater than five can be diluted and discharged to the sanitary sewer. Small volumes of bases can be discharged to the sanitary sewer, but followed by flushing with copius volumes of water. Acids and bases containing heavy metals must not be disposed to the sewer system.
Oils: Oil is sent to a recycler. Only trace quantities of oils associated with cleaning and washing operations should be released to the sanitary sewer. Oil wastes from vacuum pumps, transformers, motors, etc., should be accumulated for pick-up. Oily rags should be sent to a cleaning service.
Biocides: Concentrated solutions are not to be released to the sanitary sewer. Disposal is to be limited to one gallon of "working strength" solution per laboratory per day. This applies primarily to germicides and occasional disposal of pesticides. Chemicals which are persistent in the environment should be released only in trace quantities.
Sodium Azide: Solutions containing sodium azide, commonly used as a preservative in many in-vitro diagnostic products and with automatic blood cell counters, can be discharged to the sanitary sewer if done so with generous amounts of water and where drain lines are lead and copper-free. The accumulation of lead and/or copper azide in the drain pipes can produce a potentially explosive situation.
Toxic, Carcinogenic, Oxidizer, and Explosive Waste: Are picked up for disposal.
Compressed Gas Cylinders: Containing hazardous gas should be shipped back to the vendor.
Needles and Syringes: Must not be put in the regular trash. They should be accumulated in suitable hard wall containers. Needles and syringes contaminated with infectious agents must be autoclaved or otherwise decontaminated.
Infectious and Radioactive Waste: These guidelines do not apply to infectious or radioactive waste. Consult the Safety Officer for these types of waste.
Drain Disposal of Chemicals: Limited quantities (generally not more than a few hundred grams or milliliters) can be disposed of in the sanitary sewer, but never in a storm sewer system. The disposal should be performed by flushing with at least lOO-fold excess water at the sink, so that the chemicals become highly diluted. Only those compounds that are water soluble to at least 3% and present a low toxicity hazard are suitable for drain disposal. The following list comprises compounds that are suitable for drain disposal. In general, compounds that are not listed are not suitable.*
Alkanols with less than 5 carbon atoms, t-Amyl alcohol, Alkanediols with less than 8 carbon atoms, Glycerol, sugar and sugar alcohols,
Alkoxyalkanols with less than 7 carbon atoms, 2-Chloroethanol
Aliphatic Aldehydes with less than 5 carbon atoms
RCONH2 and RCONHR with less than 5 carbon atoms
RCONR2 and less than 11 carbon atoms
Aliphatic amines with less than 7 carbon atoms
Aliphatic diamines with less than 7 carbon atoms
Alkanoic acids with less than 6 carbon atoms, Alkanedioic acids with less than 6 carbon
atoms, Hydroxyalkanoic acids with less than 6 carbon atoms, Aminoalkanoic acids with
less than 7 carbon atoms,
Ammonium, sodium, and potassium salts of the above acid classes with less than 21 carbon atoms
Chloroalkanedioic acids with less than 4 carbon atoms
Ester with less than 5 carbon atoms, Isopropyl acetate
Ketones with less than 6 carbon atoms
Sodium or potassium salts of most are acceptable
This list comprises water-soluble compounds of low-toxic-hazard cations and low-toxic-hazard anions. Compounds of any of these ions that are strongly acidic or basic should be neutralized before disposal down the drain.
Cations: Al3+,Ca2+, Cu2+, Fe2+, Fe3+, H+, K+, Li+, Mg2+, Na+, NO3-, NH4+, PO43- , Sn2+, SO42-, Sr2+, SCN-, Ti3+, Ti4+, Zn2+, Zr2+
BO33-, B4O72-, Br-, I-, CO32-, Cl-, HSO3-, OCN-, OH-
*This material is from "Prudent Practices for Disposal of Chemicals from laboratories". National Academy Press