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Is Industrial Solvent Recycling Profitable?

May 17, 2022

Industrial solvent disposal not only impacts the environment. It has a negative effect on your company’s bottom line, much of which can be avoided with a well-executed program of solvent recycling. This post helps you answer these important questions as you begin to develop a sustainable solvent recycling program: 

  1. What is solvent recycling? 
  2. What is an industrial solvent?  
  3. How is an industrial solvent purified for reuse?
  4. Is solvent recycling worth it relative to solvent disposal?
  5. Are there tangential benefits to solvent recycling?
  6. How long does it take to develop a solvent-recycling program?
  7. What if you don’t need or can’t use the recycled solvents?
  8. What kinds of businesses can benefit from a solvent recycling program

What is solvent recycling?

Solvent recycling begins with the careful extraction of a spent solvent from a waste-trap that’s specifically designed to collect it. For example, specific protocols must be followed to ensure that no harmful vapors escape into the workplace environment or exterior atmosphere.

Therefore, the extraction and transportation of a spent industrial solvent must be done by a company that’s licensed or  “permitted” to do so; and ensuring that’s the case is solely your responsibility as a hazardous waste generator

What is an industrial solvent?

Industrial/commercial solvents are generally considered under one of four categories:

  • Halogenated solvents
  • Non-halogenated solvents 
  • Heavy metal solvents
  • Paint solvents and residues

Halogenated solvent waste. A solvent is “halogenated” if it contains carbon and hydrogen, but where one or more of its hydrogen atoms have been replaced by a halogen. Halogens are a group of elements that share the same address on the periodic table [ VIIA (17)]. They are fluorine, chlorine, bromine, iodine, and astatine. Each is a reactive nonmetallic element that’s reactive with hydrogen. 

The key word here is reactive, which means the solvent becomes explosive, corrosive, toxic, or ignitable when in proximity to each other. Thus it’s crucial they’re kept separated during storage or transportation.

Non-halogenated solvent waste. Non-halogenated solvent wastes lack fluorine, chlorine, bromine, iodine, or astatine. Instead, they feature methanol, acetone, ethanol, ether, ethyl acetate, hexanes, or toluene. 

As they’re relatively less dangerous, the cost for their hazardous waste disposal is less expensive. Thus, you should keep them apart from halogenated solvent wastes. Otherwise, if you mix the two, the entire quantity must be treated as a halogenated substance, which needlessly increases your hazardous waste management costs.

Heavy metals solvents. These contain things like arsenic, cadmium, barium, chromium, lead, selenium, mercury, or silver, which are heavy metals implicated in gastrointestinal and kidney dysfunction, nervous system disorders, skin lesions, vascular damage, immune system dysfunction, birth defects, and cancer. 

Heavy metals also have a tendency to bioaccumulate, meaning they increase in concentration inside people and animals over time (relative to their concentration in the environment).

Paint solvents and residues. These come from oil-based paints and thinners, which contain “volatile organic compounds” (VOCs). They’re regulated by the EPA  because they vaporize when oil-based paints dry, and thus can damage the ozone layer.

If you’re using industrial paints, check out your leftover drums. If they say acrylic, epoxy, polyester, polyurethane, or polytetrafluoroethylene, then they belong to a group of resins, solvents, additives, and pigments that are particularly scrutinized by the EPA.

 Although any one of these chemical constituents mightn’t be an RCRA  listed hazardous waste, it could nonetheless be considered a characteristic waste if it exhibits corrosivity, ignitability, reactivity, and/or toxicity. 

The danger here is that it’s up to you to figure out whether your leftover industrial paint is a characteristic hazardous waste: a requirement you must meet within a specified timeframe so that the paint “characteristics” don’t change over time.

How is an industrial solvent purified for reuse?

  • Distillation. This is the most common and efficient form of recovery. A spent industrial solvent is heated in a vessel to its boiling point so that it evaporates into a gas. Contaminants with higher boiling points remain as liquids or solids at the bottom of the vessel, to be discarded either as a municipal waste or a RCRA hazardous waste. The solvent vapor is passed into a condensing chamber to be reconstituted as a liquid. Further purification might be accomplished by other processes explained below.
  • Fractionation. Here the industrial solvent is treated at different temperatures and forced through small tubes, causing it to separate from the undesired contaminant and thereby be recoverable for reapplication. 
  • Liquid-liquid extraction. This process can be used if the spent industrial solvent is immiscible with a contaminant. Placed in a separatory funnel, either the spent solvent or the contaminant will settle at the bottom of the funnel, depending on which is denser. Thus separated, the desired solvent can be recovered, and the contaminant discarded.
  • Less common methods. These include film evaporation, sorption, crystallization, and membrane separation.

 Is solvent recycling worth it relative to solvent disposal?

Saturated lacquer-thinners, acetones, chlorides, and other industrial solvents can be processed to render a percentage of their bulk into reusable products—typically as much as 80 percent. In the simplest scenario, these are returned to your facility for re-use in combination with their more-expensive virgin counterparts.

Thereby, you can realize savings across the entirety of your operation by reducing your need for virgin solvent by 80 percent, commensurately decreasing your disposal and regulatory costs.

Or another way to look at it: if you’re an LQG disposing of 1-million gallons of spent industrial solvent per month, recycling that waste so that you can reuse 80 percent of it will effectively cut your hazardous-waste stream to only 200-thousand gallons. 

Are there tangential benefits to solvent recycling?

A well-executed chemical recycling program enhances your environmental brand image, which is no small thing in today’s eco-sensitive political and legal environment. And since the recycled chemicals don’t wind up in your waste stream, they’re not counted against your generator status.

Also, you’re less likely to garner unwanted attention from the EPA if your hazardous waste generation numbers are going down rather than up, or from state and local agencies, which tend to be more restrictive and litigious than their federal counterparts.

How long does it take to develop a solvent-recycling program?

You can be recycling your spent industrial solvents about 30 days from today. A technician will take a sample of your spent solvent and perform gas chromatology to determine its chemical constituents, moisture content, suspended solids, and other waste characteristics.

If your waste is determined to be suitable for recycling, a pilot distillation will be conducted to determine the likely potency and theoretical yield of the recycled product. If this distillation is suitable for your needs, a 40-drum trial run will typically be conducted (55 gallons per drum).

What if you don’t need or can’t use recycled solvents?

In the relatively rare cases where recycled solvents cannot be reused, there are hazardous waste management companies that can broker the recovered product for you. Thus, you still realize a monetary benefit relative to the cost of traditional hazardous waste removal. 

What kinds of businesses can benefit from a solvent recycling program?

Virtually any enterprise that routinely uses significant amounts of industrial solvents can benefit from a well-executed solvent recycling program. Such solvents include but are not limited to:

  • acetone
  • denatured ethanol
  • ethyl acetate
  • ink wash
  • isopropyl alcohol (IPA)
  • lacquer thinner
  • methyl ethyl ketone (MEK)
  • methylene chloride
  • mineral spirits (150 flash)
  • n-methyl-2-pyrrolidone
  • n-propyl bromide
  • propylene carbonate
  • tetrahydrofuran (THF)

Learn more

 To find out whether your company can achieve significant comprehensive savings by implementing a chemical solvent recycling program, and to learn the best and most efficient ways to get it done, contact us today or call 888.681.8923.

And thank you for reading our blog!

And thank you for reading our blog!

Disposal of hazardous waste doesn’t have to be painful.