30 Sep

Chemical waste disposal guide

Want to avoid violation fines and enhance lab safety when dealing with hazardous waste?

The first step to avoiding any penalties is determining if the waste produced in your laboratory is hazardous according to the jurisdiction that you are in.

In the United States for instance, failure to comply with the Resource Conservation and Recovery Act (RCRA)[1], which governs the generation, transportation, treatment, storage, and disposal of hazardous waste can result in expensive EPA violation fines.[2]

Is my chemical waste hazardous?

A chemical becomes a waste when you no longer intend to use it regardless of whether it has been used or contaminated, including expired substances, spilled chemicals, and associated absorbent materials.

Hazardous chemical waste is any material that if improperly managed or disposed of may harm human health and/or the environment. It includes solids, liquids or gases containing or contaminated with[3]:

Flammable/ignitable solvents (e.g. organic solvents)
Leachate toxic material (e.g. heavy metals, pesticides)
Corrosive material (e.g. hydrochloric acid, potassium hydroxide pellets)
Reactive material (e.g. oxidizers, cyanides, sulphides, explosives, unstable materials, and water reactive materials such as sodium metal and benzoyl peroxide)
Toxic materials including mutagenic, carcinogenic, acute or chronic toxicity substances (e.g. chloroform, ethidium bromide)
Polychlorinated biphenyls (PCBs)
Non-returnable gas cylinders

Special handling is required for:

Air or water reactive material
Ethidium bromide
Explosives
Organic peroxides
Mercury contaminated materials
PCBs
Radioactive material

Non-Hazardous waste

Non-hazardous chemicals may be disposed of down the drain or in the normal garbage with caution[4]:

Certain salts (e.g. potassium chloride, sodium carbonate)
Many natural products (e.g. sugars, amino acids)
Inert materials (e.g. non-contaminated chromatography resins and gels)
Material that does not exhibit any hazardous characteristics (ignitability, corrosivity, reactivity, or toxicity)

Mixing waste can be dangerous and costly

Compatible chemical waste should be segregated from incompatible material primarily to prevent dangerous reactions but also to decrease the cost of disposal as different hazardous wastes have different disposal methods. Non-halogenated solvents for instance are used as fuel additives in cement kilns, while halogenated solvents are incinerated at a cost two to three times higher.[5] Similarly, care should be taken not to mix non-hazardous waste with hazardous waste as this only increases the volume of the hazardous waste as well as its disposal cost.

Compatibility: Incompatible chemicals should never be mixed in a single container as this may cause fire, explosion, or the formation of toxic or flammable gases. Oxidizers and reducers for instance should be kept apart.

Container compatibility: Containers and caps must be compatible with the stored waste material (e.g. hydrofluoric acid must never be stored in glass containers and sharp material should be stored in puncture-resistant containers). Proper screw caps (corks, rubber stoppers and parafilm are unacceptable) should be used to airtight seal containers, and aging containers should be promptly disposed of. Only fill containers to about 80% capacity to prevent spillage.

How to segregate waste

Download J&K Scientific’s ‘segregating chemical waste guidelines’ for ease of disposal. A list of some common incompatible chemicals is also included.[6] As a rule of thumb, segregate waste as much as possible even within categories. Consult ‘Section 10: Stability and reactivity’ and ‘Section 13: Disposal considerations’ of the SDS or contact the Environmental Health and Safety (EHS) office if you need further guidance. Note that there may be exceptions within each chemical family.

Strive to keep precipitates, semisolids, residues, gels, etc. separate from solvent waste containers. Decantation, filtration, evaporation, or absorption may be used to separate the liquid phase.[7]

Note that laboratory waste with a combination of radioactive, biological and/or chemical material is treated as radioactive material. It may be challenging to dispose of and should be considered on a case-by-case basis.[8]

Special-handling waste should be kept isolated from any other waste

(i) Air/water reactive waste: Solids and liquids should be individually packaged in an inert or stabilizing substance.[9]

(ii) Ethidium bromide waste:

All contaminated materials (e.g. gloves, gels, etc.) should be packaged in a secure labeled container that is kept separate from other waste.

(iii) Explosive waste:

Avoid handling as it may be more dangerous than new material. Check frequently for signs of deterioration and aging (container “sweating”, bulging, crystal formation around the cap, etc.). Examples include trinitrated compounds (e.g. TNT), dry picric acid (<20% water content by weight), fulminated mercury, and heavy metal azides (e.g. lead azide). Contact EHS immediately for disposal.

(iv) Organic peroxides:

Organic peroxides are low-power (flammable) explosives that are sensitive to heat, sparks, friction, impact, and strong oxidizing and reducing agents. They should be left in their original containers if possible and not mixed with other waste. Uncleaned containers should be treated like the product itself.

Order only what is necessary (less than six months supply), encouraging a quick turnover of inventory. Even if a commercial inhibitor has been added by the manufacturer, organic peroxide formation can begin within six months following exposure to air. It may even commence in unopened containers that are packaged in an air atmosphere.⁸ Make sure to record when the product was received, the date opened, and its expiry date. The following materials are susceptible to forming organic peroxides[10]:

Acetals
Aldehydes
Decahydronapthalene
Dicyclopentadiene
Diethylene glycol
Acyclic ethers (e.g. diethyl ether, diisopropyl ether) and cyclic ethers (e.g. dioxane, tetrahydrofuran)
Compounds containing benzylic hydrogen atoms, especially if the hydrogen is on a tertiary carbon atom (e.g. isopropyl benzene (cumene))
Compounds containing an allylic (CH₂=CHCH₂-) motif including most alkenes
Ketones (especially cyclic ketones)
Vinyl and vinylidene compounds (vinyl acetate and vinylidene chloride)

Prior to disposal, small quantities (< 25 g) of some peroxides can be diluted with water to a concentration of 2% and then transferred to a polyethylene disposal bottle with an aqueous reducing agent (e.g. ferrous sulfate or sodium bisulfite) solution. The material can then be handled like other chemical waste, but it must not be mixed with other waste. Larger quantities (> 25 g) require special handling and only a “bomb” squad can dispose of pure peroxides.

(v) Mercury Waste:

All contaminated material (e.g. glassware, gloves, thermometer) should be collected and packaged in a leak-proof container. Elemental (liquid) mercury can go into a sealed vial or jar.[11]

(vi) PCBs:

Requires special disposal arrangements coordinated by EHS. Sources of PCBs include Aroclor transformers, the generic fluid called askarel, almost all capacitors manufactured between the 1930-1980’s, some hydraulic equipment, electromagnets, heat transfer equipment, and vapour diffusion pumps.

(vii) Radioactive waste[12]:

Solid waste must be separated from liquid radioactive waste according to specific ‘waste block’ criteria. Waste containing hazardous chemicals and/or biological agents mixed in with radioactive liquids must be inactivated or neutralized prior to disposal. If this is not possible, the EHS office must be contacted for assistance.

Lack of or improper labeling

Every institute will have a slightly different label, but hazardous waste must be labeled and should contain the following information:

Contents: The generic names of the components in the container along with approximate percentages of each component present. Abbreviations, trademark names and formulas should not be used.

Type of hazard: Here you will need to identify the hazard(s) (e.g. ignitable, toxic, corrosive, reactive, oxidizer) that best describe(s) the contents of the container.

Date: This is the date when the waste container becomes full or ready for pickup.

Contact information: The label must also include the building name, room number, and contact information of the lab manager.

Who is responsible?

It is our collective responsibility as stewards of the earth to manage laboratory waste effectively through continual ‘laboratory best practice’ training, staying up to date on national and local regulations, and replacing hazardous material with “greener” or safer chemicals as much as possible. Each person is responsible for their own waste generated.

Save money by reducing chemical waste

Consider the following steps to minimize the waste produced by your laboratory:

Optimize your methods: Choose methods that produce less waste. This may mean optimizing solvent choice or choosing reactions that use a catalyst.

Organize your laboratory: A comprehensive lab management software can be used to easily locate material and prevent excess ordering.

Implement chemical waste treatment in your lab: This is only possible for certain small-scale treatment and deactivation of products and by-products (except for neutralizations, which can be done on a larger scale). Examples include⁴:

(i) Inorganic acids and bases in aqueous solutions can be used to neutralize each other. If additional acid or base is required, sulfuric or hydrochloric acid and sodium or magnesium hydroxide can be used. Sodium bicarbonate can also act as a neutralizer. Acids and bases that are highly concentrated should be diluted to a concentration below 10% before neutralization. Nontoxic neutralization products may be flushed down the drain with copious amounts of water, but toxic products must be disposed of accordingly.

(ii) Aldehydes can be oxidized to their corresponding carboxylic acids, which are usually less toxic and volatile.

(iii) Inorganic cyanides can be oxidized to their corresponding (less toxic) cyanates with aqueous sodium hypochlorite (bleach). Hydrogen cyanide can also be converted to its corresponding cyanate in two steps: neutralization with aqueous sodium hydroxide to form sodium cyanide followed by oxidation with bleach.

Recycle solvents: Rinse solvents such as acetone can be collected and purified via distillation.[13]

Store chemicals safely: Proper chemical storage prevents the mixing of incompatible material and minimizes the chance of spillage or degradation. J&KSeal bottles are designed to prevent the degradation of air-sensitive material. Bottles are filled with an inert gas and have a metal crown cap with a pierceable resealable liner for convenient storing and dispensing.