- Best Practices
Is Your Solvent Waste Wasting Your Money?
Recycling your solvent waste onsite is a great way to save money. But if you aren’t tracking the still bottoms produced by your solvent recovery system then chances are you’re paying too much for disposal costs.
- The CleanPlanet Team
- January 29, 2021
Table of Contents
What are Still Bottoms ?
During the solvent recovery process solvents are separated from contaminants using distillation. Still bottoms are the residual waste material from the solvent recovery processes and are usually collected in 55-gallon drums. These drums are transported to a waste facility that bulks up the drums, where the material is used as fuel for cement kilns. If you’re recycling your solvent onsite it pays to monitor the monthly or quarterly volume of still bottom drums produced and the associated disposal cost.
Continuous or Batch Solvent Recovery Systems
There are two types of onsite solvent recycling: batch processing, and continuous processing. Batch distillation units either collect the still bottom material in bags, or the material dumps out of the distillation equipment by opening a spigot. Continuous solvent recovery units discharge the waste material from time to time as necessary as the recycling equipment continues to process solvent waste material.
Tracking Your Still Bottoms Means Tracking Your Savings
Recycling 100 drums of waste solvent will recover between 70 and 90 drums of solvent, leaving between 10 and 30 drums of still bottom material. The volume of still bottom drums produced is a good indicator of how well your distillation unit performs; the less still bottom drums generated, the better your solvent recovery unit is performing. Excessive waste from the recycling process may also be a sign of poor raw material management.
Options for tracking waste generated from the solvent recycling process:
- Utilize a specific waste profile for the still bottom material; it will be easier to track the number of still bottom drums shipped. You could either review the information in the e-manifest system or ask your waste vendor to provide a quarterly report.
- Another idea, use a dry erase board in the waste collection area that material handlers use to track still bottom drums brought into the collection area. At the end of every month, that number is provided to the EHS Manager to track a spreadsheet.
- Another idea, more costly, is to install flow meters on your distillation unit. These meters will track the quantity of material into and out of the solvent recycling unit. The difference is the still bottom material produced. CleanPlanet uses this approach to make it amazingly easy to track still bottom drums produced.
The Cost of Waste Recovery
We have seen companies producing still bottoms from their solvent recovery process pay as much as $500 per drum for disposal. Unmanaged waste disposal costs from the recycling process will reduce the savings that recycling spent solvents onsite produce. Tracking still bottom disposal cost needs to be part of your management oversight of a solvent recycling process.
If you are not currently recycling your solvent waste onsite, as a general rule, you will reduce the volume of your waste shipped by 70% to 80% and the cost of waste disposal by 40%. The still bottom drums will be more expensive to dispose of than the liquid solvent waste drums.
An example of a cost breakdown of an onsite solvent recycling process per gallon of solvent recovered:
- Unit Costs (depreciation) $1.20
- Financial Carrying Cost $0.60
- Maintenance $0.30
- Labor $0.05
- Electricity $0.08
- Still bottom disposal $0.65
Reducing Your Costs by Reducing Your Waste
The average CleanPlanet customer pays $150 per drum for the disposal of still bottoms from a continuous distillation unit. The costs will vary depending on the volume of drums shipped and geography. From a cost standpoint, this will equate to around $0.65 per gallon of recovered material produced. We have seen customers paying as much as $1.50 per gallon of recovered solvent.
It is essential to track your still bottom costs and look at the impact on the price per gallon of recovered solvent. If your onsite solvent recovery expenses are excessive, give CleanPlanet Chemical a call, we can help get those costs under control.
Better yet, if you want to avoid trying to become experts at something that is not a core competency for your facility, call CleanPlanet and ask about our Service365 Program. We’re reinventing solvent recycling.
Want to learn more about reducing hazardous waste disposal costs?
Want to learn more about reducing hazardous waste disposal costs?
