How Healthy is your Onsite Solvent Recycling Process?

Discover a few simple and effective ways to track and improve your onsite solvent recovery process.

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CleanPlanet has been developing its Service365 model for almost a decade now, and we’ve been in hundreds of facilities that own solvent distillation equipment and seen hundreds of underperforming pieces of solvent recovery equipment.

Unfortunately, an equal number of units are not operating at all. And some companies have just stopped using their solvent recycling equipment altogether.

Our core business offers solvent recovery equipment, batch, and continuous recyclers, at no cost for the equipment. Our clients only pay for the clean, usable solvent produced; we call this program, Service365.

Included in this offer we handle the operator certification and training as well as all maintenance and repairs. We have over 100 clients on our Service365 Program. We have learned quite a bit about what it takes to keep solvent recycling equipment operating and producing clean, usable solvent.

Over the last decade, the experiences have taught us a lot about onsite solvent recycling and managing distillation equipment.

We’ve learned that onsite solvent recycling is a process. It’s more than just putting the waste solvent material in the distillation unit. Producing clean, recovered solvent is part of a process.

A thorough review of all the steps involved in an onsite solvent recovery process can be time-consuming but we’ve identified a few ways to take a quick look at your onsite solvent recycling process.

  • Solvent Waste Shipments
  • Still Bottom Drum Disposal
  • Virgin Solvent Volume Usage

The solvent waste and clean, recovered solvent materials are essentially the starting and ending points of the solvent recycling process. And that’s where to start when reviewing the recycling process.

Solvent Waste Shipments

Inspect Your Solvent Waste

Controlling what goes in the feed material collection drums increases the likelihood that the distillation process produces a better-recovered solvent product.

Inspect the feed drums for excessive solids. Most facilities that utilize onsite solvent recycling are using cleaning solvent to flush paint lines or printing presses. These facilities also produce paint and ink solids and need to be kept out of the solvent waste feed drums; this is called segregation.

Good housekeeping practices are also required. Water, rags, and other non-process materials must be kept out of the waste infeed.

Inspect Your Recovered Solvent

Regular inspections should be completed of the recycled solvent. The clean recovered solvent should be water white, crystal clear.

If the recovered solvent is tinted or discolored, your solvent recovery unit isn’t functioning correctly.

And then cleaning solvent users may choose not to use it, and instead substitute virgin solvent for cleaning processes. Using the more expensive virgin solvent will increase your facility costs.

Check to see if the cleaning solvent material users are using the recovered solvent for all cleaning processes. Excessive virgin solvent purchases may indicate that virgin solvent is being utilized for cleaning applications instead of the recovered solvent.

Also, using a virgin solvent for the cleaning process will create a domino effect of increasing the feed material volume. (The impact of substituting virgin solvent for recovered solvent will be explored in an upcoming CleanPlanet Blog).

Solvent Waste Document Review

The first thing you’ll want to do is review the waste shipment documents and determine if recyclable material has shipped out as waste. If recyclable material has been shipped out as waste, it will indicate that there is a problem with the distillation equipment or the use of the clean recovered solvent. This potentially indicates:

  • The distillation equipment is not operating
  • The distillation equipment has a mechanical problem
  • The recovered solvent is not being used, and there is an excess of cleaning solvent

Every 55-gallon drum of solvent waste that should have been recycled that leaves your facility for waste disposal has somewhere between 30 and 45 gallons of available solvent to recover. By shipping out a solvent drum for disposal instead of recycling it, it has an impact between $112 and $300 per drum shipped:

  • Low end:
    • 30 gallons of solvent x $2.00 = $60.00 value of solvent
    • 30 gallons of waste avoidance x $1.75 = $52.50 waste disposal cost avoidance
    • Total facility savings per drum = $112.50
  • High end:
    • 30 gallons of solvent x $6.00 = $180.00 value of solvent
    • 30 gallons of waste avoidance x $4.00 = $120.00 waste disposal cost avoidance
    • Total facility savings per drum = $300.00

Still Bottom Drum Disposal Content Review

Reviewing the still bottoms generated from the onsite solvent recycling process is one way of determining how well your solvent distillation equipment is operating.

As an additional benefit, this review also provides some insight into how much raw materials (ink, paint, etc.) are being wasted.

  1. There are two parts to reviewing the still bottom waste drums
    Visual inspection of the still bottom material in the drums
  2. Review of the still bottom waste disposal invoices

Visual Inspection of the Still Bottom Drums

The visual inspection of still bottom material involves opening up the still bottom drums to see how much solvent is in the drum. It will be impossible to know the exact percentage of solvent without taking a sample and using a lab to complete an analysis. The following are two quick, alternative approaches.

For liquid/sludge still bottoms:

After removing the lid on a recently produced still bottom drum and allowing it to cool down, stir the contents, so you have a homogenous mixture.

Using a Zahn Cup (widely used in both the paint and printing industries to measure viscosity) check the time the material takes to flow out of the cup.

The time will vary, depending on the type of distillation unit your facility uses, along with the solids content in your waste material.

For solid still bottoms:

Again, remove the lid on a recently produced still bottom drum that has cooled down and look for free-flowing solvent. There should not be large amounts of free-flowing solvent in your still bottom drums.

Most operators think the less liquid in the still bottom material, the better the unit is recovering the available solvent. This approach is a little misleading. By cooking the solvent waste stream down in the distillation process so that all the solvent has distilled from the waste, you may be creating some unintended consequences depending on the distillation unit:

  • Reducing the lifespan of the distillation unit due to operational demands
  • Increasing the cost of still bottom waste disposal
  • Producing more fugitive emissions due to overwhelming the condensation process
  • High energy consumption in order to extract the last bit of solvent from the solids
solvent waste and distillation machine

Still Bottom Drum Disposal Volume Review

We recommend that you review your still bottom disposal volume between two and four times a year.

An important point on still bottom drum disposal – check to make sure the material labeled as still bottom waste is only still bottom material.

Some facilities comingle still bottom disposal material with other solids or debris waste to reduce disposal costs. If this is just a top off, it will not change the number of drums generated. It will impact the volume of waste produced, depending on how volume is tracked.

For example, if you know that each discharge of your distillation equipment is 45 gallons, it will be easy to calculate your volume: 10 still bottom drums, would equal 450 gallon of still bottom material.

If your facility comingles waste with your still bottom waste, it will be important to put a process in place to identify how much of the material in the drums is actual still bottom material. A log on a clipboard may do the trick.

Establish a Baseline

If possible, plan your still bottom waste shipments with a repetitive frequency that makes reviewing your still bottom disposal volume easier.

Space and compliance requirements will need to be taken into consideration as well. If you ship your still bottom drums out once a week, once a month, every two months or every 90 days, know the expected volume of drums you normally ship out during that respective time period.

Review Waste Disposal Invoices

The first thing you should do when reviewing waste disposal invoices is to identify the still bottom waste. Most companies have a waste profile number or name associated with the still bottom material.

Once you have identified the correct line item on your waste bill for still bottom drums, check the number of drums on the invoice, adjust if necessary, and compare to the baseline.

If you log the amount of material going into and out of your distillation unit, you can compare the still bottom drums to the volume of solvent processed and the volume of solvent recovered.

Many operators will know the number of still bottom drums generated per the number of drums of recovered solvent processed or recovered. For example, one still bottom drum produced for every ten drums processed through the distillation unit.

From a volume perspective, you should know how many still bottom drums should be generated each week, month, or quarter based on the volume of solvent processed or recovered.

By completing periodic, visual inspections of your still bottom drums, you will also have an ancillary benefit of seeing how much solids you are producing.

Maintaining Solvent distillation machine

Virgin Solvent Usage Volume

Prior to discussing virgin solvent usage, it is essential to note that most facilities using an onsite solvent recycling system use both virgin and recovered solvent. The virgin solvent is utilized for production processes like cutting of paints or viscosity control of inks. Recovered solvent from the recycling process is primarily used for cleaning applications.

One of the more interesting experiences we’ve had visiting facilities that utilize an onsite solvent recovery system, is seeing how much virgin solvent is used for cleaning applications. No one likes talking about this dirty secret.

When you ask people in the front of the building (Management) if they use any virgin solvent in their cleaning processes, the answer is always a resounding “NO, NEVER, that’s why we bought a solvent distillation unit!” But when you go to the back of the facility, where reality lives, you will find that almost all facilities use virgin solvent for cleaning processes.

The reason virgin solvent ends up being used for cleaning applications is varied:

  • Solvent distillation equipment has mechanical issues and is not producing recovered solvent
  • Operator(s) are unavailable, or on leave, so the solvent recovery unit is not producing recycled solvent
  • The virgin solvent is easily accessible
  • The recovered solvent is in a remote part of the facility
  • The quality of the recycled product is viewed as inferior because it is tinted or grey
  • Operators don’t know which material to use
  • Inadequate container labeling of the recovered solvent

Monitor your virgin solvent usage and make sure virgin solvent is not used for cleaning applications as long as you have recovered solvent available, of course.

Once you have a virgin solvent usage baseline, track it to production volumes. If the virgin solvent volume being used is out of line, the above list will give you some direction.

Keeping the distillation equipment running will reduce virgin solvent usage. A Preventative Maintenance Program may help improve your distillation equipment’s uptime. Training backup operators will ensure continuity when primary solvent recovery operators are unavailable.

Accessibility of the correct solvent can make all the difference. We have seen simple things like labeling – “Recovered Solvent: Use for all Cleaning,” have a significant impact on reducing virgin solvent usage.

The most formidable challenge for many facilities is the quality of the recovered solvent. Making sure the distillation unit produces clean, water-white solvent is easier said than done.

There are several things you can do to get the users of the recycled solvent onboard. If water white recovered solvent is being produced, show them that material. Possibly compare the recycled solvent and virgin solvent visually by using two mason jars.

You can also show them how the recycled solvent cleans by doing some test cleaning. The best way is to make sure you quality control the recovered solvent and only use water-white solvent.

This will be the most effective way of increasing the likelihood that employees use the recycled solvent for cleaning applications.

CleanPlanet Chemical's Service365 Program

We have learned a healthy solvent recycling process is a useful tool for reducing waste generation, waste disposal and solvent costs, and impacting environmental sustainability.

When we implement a Service365 Onsite Solvent Recovery Program at a new client, we look at the entire process from the point the solvent waste is generated to the clean, usable recovered solvent is produced.

All we do is onsite solvent recycling; it’s our only job. We have learned how to build a program that addresses the historical shortcomings of onsite solvent recycling.

Distillation equipment uptime and yield are two driving forces for us as a company. We focus on those two things every day for our clients. The equipment has to be operating for us to make money. One of the best ways for us to increase our company’s value is to improve the yield for our customers.

As our client’s partner, we want the client to recover the most solvent out of their waste stream. More recovered solvent means more savings for our clients and more billing for us.

Managing a solvent distillation process seems simple; unfortunately, most companies don’t have the time to invest to maximize the value their onsite solvent recycling system could provide. Most of our prospects and clients have told us solvent recycling is not a priority. As a result, it is treated as such, and the promised value of an onsite solvent recycling promise isn’t sustained.

CleanPlanet’s Service365 makes onsite solvent recovery a priority at your facility without you having to manage the process; that’s what we do. If you review your current onsite solvent recycling process and find opportunities for improvement, give us a call.


CleanPlanet partners with its customers to ensure they are maximizing their onsite chemical recycling. Our advanced solvent distillation technology allows our customers to recover more chemical than any other distillation unit. If you’re struggling with an underperforming distillation unit reach out to our team to see how we can help.


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