Section 2: Chemical Wastes



I. Requirements for the Accumulation Area


II. Disposal Procedures for Regulated Wastes


III. Disposal Procedures for Non-Regulated Wastes


IV. Disposal Procedures for Empty Containers


V. Waste Minimization




I. Requirements for the Accumulation Area


A. Containers

Containers holding waste must be in good condition, not leaking, and compatible with the waste being stored. The container must always be closed during storage, except when it is necessary to add waste. Hazardous waste must not be placed in unwashed containers that previously held an incompatible material (see Incompatibility chart in APPENDICES).

If a container holding hazardous waste is not in good condition or if it begins to leak, the generator must transfer the waste from this container to a container that is in good condition, overpack the container, or manage the waste in some other way that prevents a potential for a release or contamination. Please contact EHS at 710-2900, if assistance is required.

A storage container holding a hazardous waste that is incompatible with any waste or other materials stored nearby in other containers must be separated from the other materials or protected from them by means of a partition, wall or other device.

All waste containers must be:

  1. Clearly labeled, with their contents indicated. Containers should be marked with the words "hazardous waste" or "spent materials", with a description of the materials in the container. EHS tags may be used to list the contents. Paint over or remove any old labels.
  2. Kept at or near (immediate vicinity) the site of generation and under control of the generator.
  3. Compatible with contents (i.e. acid should not be stored in metal cans).
  4. Closed at all times except when waste is being added to container.
  5. Properly identified with completed waste tags before pickup is requested.
  6. Safe for transport with non-leaking screw-on caps.
  7. Filled to a safe level (not beyond the bottom of the neck of the container). Over-filled bottles are:
    1. hard to pour safely,
    2. inclined to burst,
    3. apt to leak, and
    4. capable of endangering the technician through splashing or shooting up into one's face upon opening or transporting.


Note: Do not use Red bags, Sharps containers (Biohazard), or Asbestos bags for hazardous chemical waste collection.


B. Accumulation Guidelines

A generator of possible hazardous waste may accumulate up to a total of 55 gallons of waste, which may be determined to be hazardous by the Office of Environmental Health and Safety, or one quart of "listed" acutely hazardous waste (see Appendix IV) at or near the point of generation. If a process will generate more than this volume at one time, the Office of Environmental Health and Safety should be contacted in advance to arrange a special waste pick up.

Whenever possible, keep different hazardous wastes separate so that disposal options remain clearer and more cost effective. In all cases, do not mix incompatible wastes or other materials (see Appendix III) in the same container or place wastes in an unwashed container that previously held an incompatible waste or material. However, if separation is not practical, collect waste in compatible containers and try to keep it segregated into the following categories:

  1. Miscellaneous solids, e.g., grossly contaminated gloves, rags or towels, and other grossly contaminated lab equipment should be collected separately from liquid wastes.
  2. Halogenated solvents, e.g., methylene chloride, chloroform, carbon tetrachloride.
  3. Note: Disposal of non-halogenated solvents contaminated with halogens costs 4-5 times as much as non-halogenated solvents.
  4. Non-halogenated solvents, e.g., xylene, toluene, alcohols.
  5. Waste oil must be kept as uncontaminated as possible in order to be recycled. You should keep oils separate from other chemicals, particularly solvents, pesticides, and PCB's.
  6. Acids.
  7. Bases.
  8. Metal-bearing waste whether dry, flammable, corrosive or other. Specific metals of concern are arsenic, barium, cadmium, chromium, lead, mercury, nickel, selenium, silver, and thallium.
  9. Accumulate waste that is both flammable and corrosive separately from waste that is either flammable or corrosive.
  10. Special wastes, e.g., cyanide, sulfide, pesticides, oxidizers, organic acids, explosives and peroxides, should be collected individually whenever possible.
  11. Mercury and mercury containing compounds. All mixtures containing mercury in any form must be disposed of as mercury contaminated waste.



II. Disposal Procedures for Regulated Wastes


A. Waste Tags and Request for Disposal Forms

Before chemical waste can be picked up by EHS, a waste tag is required. It should be filled out by the waste generator and attached to each container. The information on the tag is used to categorize and treat the waste. Please fill them out legibly, accurately and completely.

Note: Biological Waste and Sharps containers do not require waste tags.

When your container is ready for disposal and is properly tagged, contact EHS by submitting a Waste Pickup Request to EHS.

Contents Specific, full chemical name, no formulas or abbreviations. Product names or trade names are acceptable if the manufacturer's name and address or a material safety data sheet can be supplied with the material. Vague statements such as "hydrocarbons", "organic waste", "various salts of ..." make it impossible to comply with EPA treatment standards and will delay the pick-up until sufficiently detailed information is submitted to EHS.



III. Disposal Procedures for Non-Regulated Wastes

The following checklist should be used in determining whether or not a waste may be disposed of in the sanitary sewer or municipal trash. This checklist does not apply to wastes which are radioactive or mixed in nature.

Does the material meet any of the following criteria?


If the material has not been used, does it meet any of the following criteria?


If the answer to any of the preceding questions is "yes," then the waste is regulated and must not be disposed of via sanitary sewer. Please refer to the disposal procedures outlined in Section II (Disposal Procedures for Regulated Wastes) of this chapter.

If the material is not a hazardous waste, please answer the following questions:

  • Is the material miscible in all proportions with water?


If the answer to the preceding question is "no," then the waste is prohibited by the City of Waco POTW and must not be disposed of via sanitary sewer. Please refer to the disposal procedures outlined in section II of this chapter (Disposal Procedures for Regulated Wastes).
  • Does the sum of the concentrations of the following constituents in the waste exceed 2 ppm?


    Acenaphthene 2,4-Dimethylphenol
    Acenaphthylene Dimethylphthalate
    Acrolein Di-n-butylphthalate
    Acrylonitrile Di-n-octylphthalate
    Aldrin 4,6-Dinitro-o-cresol
    Anthracene 2,4-Dinitrophenol
    Benzene 2,4-Dinitrotoluene
    Benzidine 2,6-Dinitrotoluene
    1,2-Benzanthracene 1,2-Diphenylhydrazine
    Benzo(a)pyrene alpha-Endosulfan
    Benzo(b)fluroanthene beta-Endosulfan
    1,12-Benzoperylene Endosulfan sulfate
    Benzo(k)fluoranthene Endrin
    alpha-BHC Endrin aldehyde
    beta-BHC Ethylbenzene
    delta-BHC Fluoranthene
    gamma-BHC Fluorene
    Bis(2-chloroethyl)ether Heptachlor
    Bis(2-chloroethoxy)methane Heptachlor epoxide
    Bis(2-chloroisopropyl)ether Hexachlorobenzene
    Bis(2-ethylhexyl)phthalate Hexachlorobutadiene
    Bromoform Hexachlorocyclopentadiene
    Bromomethane Hexachloroethane
    4-Bromophenylphenylether Indeno(1,2,3,c,d,)pyrene
    Butylbenzylphthalate Isophorone
    Carbon tetrachloride Methylene chloride
    Chlordane Naphthalene
    Chlorobenzene Nitrobenzene
    Chlorodibromomethane 2-Nitrophenol
    Chloroethane 4-Nitrophenol
    2-Chloroethylvinylether N-Nitrosodi-n-propylamine
    Chloroform N-Nitosodiphenylamine
    Chloromethane Parachlorometa cresol
    2-Chloronapthalene PCB-1016
    2-Chlorophenol PCB-1221
    4-Chlorophenylphenylether PCB-1232
    Chrysene PCB-1242
    4,4'-DDD PCB-1248
    4,4'-DDE PCB-1254
    4,4'-DDT PCB-1260
    1,2,5,6-Dibenzanthracene Pentachlorophenol
    1,2-Dichlorobenzene Phenanthrene
    1,3-Dichlorobenzene Phenol
    1,4-Dichlorobenzene Pyrene
    3,3'-Dichlorobenzidine 2,3,7,8-Tetrachlorodibenzo-p-dioxin
    Dichlorobromomethane 1,1,2,2-Tetrachloroethane
    1,1-Dichloroethane Tetrachloroethylene
    1,2-Dichloroethane Toluene
    1,1-Dichloroethene Toxaphene
    trans-1,2-Dichloroethene 1,2,4-Trichlorobenzene
    2,4-Dichlorophenol 1,1,1-Trichlorethane
    1,2-Dichloropropane 1,1,2-Trichlorethane
    cis-1,3-Dichloropropene Trichloroethylene
    trans-1,3-Dichloropropene 2,4,6-Trichlorophenol
    Dieldrin Vinyl chloride


  • Does the waste contain any of the following constituents at levels greater than the specified amount?


    Copper 1.9 mg/L
    Nickel 1.6 mg/L
    Zinc 2.3 mg/L
    Fluorides 65 mg/L
    Cyanides 1.0 mg/L
    Manganese 6.1 mg/L


  • Is it extremely toxic or a known carcinogen or mutagen?


If the answers to the two preceding questions are "yes," then the waste is prohibited by the City of Waco POTW and must not be disposed of via sanitary sewer. Please refer to the disposal procedures outlined in section II of this chapter (Disposal Procedures for Regulated Wastes). Otherwise, the material is acceptable for sanitary sewer disposal if it is a liquid or for trash disposal if it is a solid. The discharge of wastes to the sanitary sewer should be accompanied with copious amounts of water a good rule of thumb is to use a 100-fold excess of water when discharging wastes to the sanitary sewer.

Examples of Non-Regulated Chemicals

The following are examples of nonhazardous chemicals which may be disposed of either in the general trash (for solids) or the sanitary sewer (for liquids). For a more complete list, please consult Appendix I.


Adenosine 3'-monophosphate, sodium salt
Albumin, bovine, methylated
Bacto peptone; Peptone
Carbachol chloride
Glutamic acid
Sodium citrate



IV. Disposal Procedures for Empty Containers

Disposal procedures for empty containers depends on the previous contents and the efficiency of emptying them. Containers of pourable contents must be completely emptied. Containers of thick or solidified materials must be scraped out or drained until no more than one inch of material remains in the bottom of the container or no more than 3% of the original weight of the contents remains, whichever is less. Chemical containers that meet these criteria are considered empty and may be disposed of given the following provisions:

  • if the container labels are made unreadable by affixing an "Empty" sticker over the previous label.
  • if the container cap is removed and discarded in the normal trash, and
  • if the sole active ingredient of the previous contents was not acutely hazardous (see list of acutely hazardous waste in Appendix IV).


If containers are not or cannot be emptied, or if they contained acutely hazardous waste, submit them to EHS as waste in accordance with the procedures described in these procedures. You can also utilize a used container to hold waste for pick up if the waste is compatible with the residue in the container, the label is defaced, and the container is in good condition and not leaking.

Containers that held compressed gases are to be picked up intact by EHS. Empty cylinders should be tagged in the same manner as other waste, with the previous contents listed and the notation (EMPTY) on both the tag and the Waste Pickup Request.



V. Waste Minimization


A. Methods for Treating Hazardous Wastes in the Laboratory

Scientific and engineering research and teaching activities in academic institutions can result in the generation of relatively small quantities of a wide variety of waste and surplus chemicals. The small-scale treatment and deactivation of these sorts of chemical products and by-products as part of the experimental plan (i.e., as part of the routine procedure) is one approach that can be used to address the problem of waste minimization at the laboratory level. Several texts have been published that deal with this issue - two particularly good examples are:

  1. George Lunn and Eric Sansone. 1994. Destruction of Hazardous Chemicals in the Laboratory, 2nd Edition. Frederick, Maryland: Wiley-Interscience Publications.
  2. Margaret A. Armour. 1991. Hazardous Laboratory Chemicals - A Disposal Guide. Edmonton, Alberta, Canada: CRC Press.
B. Five Examples of Reagent Substitutions that Result in Less Hazardous and/or Less Costly Waste

To enhance safety and minimize the environmental consequences of an experiment, careful thought should be given to the materials to be used and the scale of the experiment. Traditionally, chemists have chosen reagents and materials for experiments to meet scientific criteria without always giving careful consideration to waste minimization or environmental objectives. In synthetic procedures, overall yield and purity of the desired product were usually regarded as the most important factors. Material substitution emerged as an important consideration in manufacturing process design because of the large quantities of chemicals involved. The following questions should now be considered when choosing a material to be used as a reagent or solvent in an experimental procedure:

  • Can this material be replaced by one that will expose the experimenter, and others who handle it, to a lower order of potential hazard?
  • Can this material be replaced by one that will reduce or eliminate the generation of hazardous waste and the consequent cost of waste disposal?

The following examples illustrate applications of these principles to common laboratory procedures:


  1. Phosgene is a highly toxic gas used as a reagent in many organic transformations. Its use requires proper precautions to deal with the containment of the gas and the handling and disposal of cylinders. Commercially available substitutes such as diphosgene (trichloro-methyl)chloroformate, a liquid, or triphosgene bis(trichloromethyl)carbonate, a low-melting solid, can often be substituted for phosgene by appropriate adjustment of experimental conditions or can be used to generate phosgene only on demand. Both chemicals are highly toxic themselves, but they offer a means to avoid the problems associated with handling a toxic gas.
  2. Many widely used reagents contain toxic heavy metals, such as chromium and mercury. Waste containing these materials cannot be incinerated and must be handled separately for disposal. Thus, substitution of other reagents for heavy metal reagents will almost always be beneficial with respect to hazard and waste minimization. Chromic acid cleaning solutions for glassware can be replaced by proprietary detergents used in conjunction with ultrasonic baths. Various chromium (VI) oxidants have been important in synthetic organic chemistry, but their use can often be avoided through the substitution of organic oxidants. The Swern oxidation of alcohols (oxalyl chloride/DMSO) produces relatively innocuous byproducts, which can be handled with other organic waste. Other oxidation reagents tailored to the specific needs of a given transformation are available.
  3. Fluorine and fluorinating reagents such as perchloryl fluoride are among the most demanding of reagents to handle because of their high reactivity and toxicity. Accordingly, there has been considerable incentive to develop substitutes for these materials. One example is F-TEDA-BF4, or 1-chloromethyl-4-fluoro-1,4-diazonia[2.2.2]bicycloctane bis(tetrafluoroborate). This reagent can be substituted for more hazardous reagents in many fluorination procedures.
  4. Organic solvents for liquid-liquid extraction or chromatography can often be replaced by other solvents with significant benefit. Benzene, once a widely used solvent, is now recognized as a human carcinogen and must be handled accordingly. Toluene can often serve as a satisfactory substitute. Diethyl ether is a flammable solvent whose handling must take into account its tendency to form explosive peroxides. Methyl t-butyl ether offers only slight advantages over diethyl ether with respect to flammability, but its greatly reduced tendency to form peroxides eliminates the need to monitor peroxide formation during handling and storage.
  5. The technology for handling supercritical fluids has developed rapidly in recent years. Supercritical carbon dioxide can replace organic solvents for high-performance chromatography and is beginning to find use as a reaction medium. While supercritical solvents require specialized equipment for handling, they offer the potential benefit of large reductions in organic solvent waste.
  6. Mercury thermometers are widely used and easily broken, which results in worker exposure to mercury, release of the vapors to the environment, and increased waste disposal costs as all of the cleanup material must be disposed of as mercury contaminated waste. Substitution of alcohol thermometers for mercury thermometers eliminates these problems. Thermometers containing alcohol are as accurate and have as wide a temperature range as mercury thermometers, and the waste from the cleanup of broken alcohol thermometers can be thrown in the regular trash. Moreover, the breakage of alcohol thermometers does not expose the lab personnel to poisonous vapors.



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