Recycling Your Own Solvents

The Effective Solution for Solvent Waste Handling

Using Solvents Today:

The Advantages and Responsibilities

Solvents are relied upon in a great variety of processes, from printing and manufacturing to electronics and machining, for their superior cleaning and curing properties. Industry professionals from diverse organizations continue to agree that no substitute has been found to replace solvents in such applications as coating, line flushing, reactor cleaning, stabilizing, degreasing, and parts cleaning.

Yet the use of solvents does not come without environmental responsibility. Generators of solvent waste, which is hazardous, have a "cradle to grave" liability regarding its safe disposal.

Because solvents have no substitute in many processing applications, the question most companies are asking is not whether or not to use solvents, but what should we do with our solvent waste?

This White Paper addresses that question by discussing the various options that exist, and helping you understand which options might be best for you.

Addressing the Solvent Waste Question:

What Options are Available?

Currently, the available options for solvent waste disposal include:

• Disposing of solvent waste off-site for rotary kiln or incineration destruction
• Shipping solvent waste to a TSDS (Treatment Storage and Disposal facility) for recovery
• Contracting the services of a mobile solvent recovery firm to visit your site regularly
• Investing in an on-site solvent recycling system

These four options may be combined into two categories: 1) off-site disposal or recovery, and 2) on-site recovery or recycling. If you generate a small waste stream; produce infrequent waste, are operating a short-term process, or are operating a pilot process, off-site disposal may be the most cost-effective option for you since the amount of waste generated is insubstantial to justify recovery.

However, if you generate continuous waste, you are almost certainly under regulatory and economic pressures to explore a recovery or recycling option—one of which you may already to using. In fact, EPA directives require that you reduce your waste stream through off-site recovery or on-site recycling. Moreover, both solvent recovery and recycling are clearly more cost-effective and environmentally correct than total destruction and solvent repurchase. But which action should you take—using an outside recovery service, or purchasing your own recycling equipment?

The Ramifications of Using Outside Services

Many companies turn their solvent waste over to outside sources for disposal or recovery because they believe it is a convenient option in which the waste is properly handled by professionals. While this reasoning might be valid, there are both high risks and high costs associated with using an outside service:

1. Off-site Disposal - This is the most expensive of all the options since it represents a total loss of solvent resources and incurs transportation costs both to and from the disposal facility. These costs are likely to go up as constraints continue to be placed on waste disposal facilities. From a regulatory standpoint, you are at high risk since you are liable for every drum of solvent waste that leaves your facility. If the waste hauler or the disposal facility spills the waste after it leaves your site, you are still held responsible.
2. Off-site Recovery - This option enables you to save costs through the purchase of reclaimed rather than virgin solvents. Yet transportation costs are still high, as is your liability. Your storage volume may increase since you will need to store additional drums of solvents to keep your operation running continuously. Quality is also a concern since the reclaimed solvents may be cross-contaminated by other sources.
3. Mobile Solvent Recovery - This option reduces your transportation costs, your solvent waste liability, and quality concerns. Yet you still pay for the provider’s time, equipment usage, and transportation to your site. Additionally, you must maintain a sizable solvent inventory at your facility to cover your usage between visits.

Recycling Your Own Solvents:

The Environmental and Economic Benefits



Recycling your own solvents is the most affordable, environmentally effective option of all if you generate continuous waste. In fact, recycling your own solvents has been proven to save as much as $2 or more per gallon of waste solvent than outside solvent recovery services, and enables you to reuse as much as 99% of your waste solvent.

Recycling your solvents allows you to produce a solvent blend that meets or exceeds the criteria for virgin material by distilling contaminated solvents from your operation’s waste stream.

The proven advantages of recycling your own solvents include:

• Significant reductions in removal and disposal costs
• Reduced inventory and the associated replacement costs of purchasing new solvents
• Quality control over the reclaimed solvent
• Substantial reductions in the waste solvent that leaves your facility and in the liability associated with that solvent
• EPA compliance

How it Works

Solvent recycling is accomplished by a distillation process which includes the following steps:

• A still (distillation) vessel is charged with a waste solution on a batch or continuous basis.
• A thermal oil jacket, electrically or steam heated, injects heat into the waste solvent by conductive thermal transfer.
• The still may be operated under vacuum, which lowers the boiling temperature of the solvent.
• When the solvent reaches its reduced boiling point, the solvent changes from liquid to a vapor (gas) at a controlled rate.
• The solvent, in a vapor phase, passes through the condenser which has both a condensing and a subcooling section. In the condenser, the solvent changes back to a liquid and is cooled back to ambient conditions.
• The contaminants (solids or non-volatile liquids) do not undergo a vapor phase, but stay behind as "still bottoms" to be discharged out the drain port.

Once non-volatile portions build up to concentrated levels, the "still bottoms’ are discharged. Another production run can then be initiated.

Making the Decision:

Should You Recycle Your Solvents?

How should you decide whether recycling your own solvents is the right option for your facility? There are two steps to evaluating this option: 1) assessing your operation, and 2) assessing available recycling equipment suppliers.

Assessing Your Operations

First you must conduct a thorough evaluation of your waste stream, asking such questions as:

• What is the volume/rate of the waste stream?
• What is the current disposal cost and the projected increase in cost?
• What is the percentage of the waste stream that may be recycled?
• What are the costs of purchasing the virgin solvents?
• What solvents and contaminants make up your waste stream?

You will also need to consider your level of automation, your material handling capabilities and how they might accommodate piping, storage tanks and manpower requirements, and your safety standards. Additionally, a hazardous operation review must be conducted in order to asses the risks of the solvent recycling process and to determine sufficient safeguards.

Assessing Available Suppliers

Questions you should ask when considering prospective equipment vendors include their knowledge of current codes, experience, business focus, accreditation status, product scope, interest level and capacity to develop a solution to your problem.

Your objective is to partner with a vendor who can assist you in choosing the right recycling system, implement the system successfully, and provide training and follow-up.

Once you have assessed both your operation and the available suppliers, you are ready to proceed to the next step: the equipment selection process.

Selecting a Solvent Recycling System:

Partnering with a Professional

The selection of a solvent recycling system for your operation requires that your supplier have a complete understanding of your needs.

There are four distinct functional areas which figure prominently into the system selection process and which, when each is examined, should permit the development of a thorough understanding of your operational requirements. If you have chosen a reputable supplier with in-depth professional expertise in solvent recycling, the supplier will work with you to evaluate these four functional areas before recommending a solvent recycling system.

The first functional area, processes, requires a true understanding of your solvent waste stream, its recovery, and its ultimate use at the facility. Waste streams are unique to each facility in terms of both generation and composition.

The identification of the waste stream typically requires several levels of examination. The initial level requires the assembly of MSDS’s on the major components of the waste stream. Based on current disposal methods, a waste analysis performed by a laboratory, either third party or in-house, is necessary.

The second level of examination should be an evaluation of the waste stream’s distillation characteristics. This evaluation is one of the most fundamental steps in the identification of the waste stream. The evaluation should be conducted by a firm which is knowledgeable about testing, modeling, and the distillation process.

Operation, the human factor, refers to the specific requirements and limitations of the operator. The operator interface dictates the type of controls, the degree of automation, and specific hardware requirements. Unique facility as well as procedural stipulations may dictate the logic and control scheme specifications necessary to ensure a successful operation.

The importance of communication between the buyer and the supplier is critical in this portion of the project. Safety and automation should be the two primary concerns of the evaluation.

The third functional area is hardware. In a solvent recovery system, the hardware is the distillation processing unit. (DPU).

The DPU selection process requires both an understanding of the process and the evaluation of a number of variables. These variables include solvent characteristics such as latent heat, sensible heat, specific heat, specific gravity, percentage composition and process characteristics such as residue viscosity, material handling criteria, manpower interface, solvent volume, solids loading and logistics, and processing time.

With this set of variables, a computer modeling methodology is the best approach to proper DPU selection. Modeling allows a complete understanding of the process.

Computer Modeling



Software, the fourth area, is critical in maintaining effective performance of the recycling system. The software should minimize human interface and enhance the recovery capacity of the system.

On large scale systems, the software should provide graphic operator interface with charts and trending for system management. In addition, it should include comprehensive diagnostics. On small scale systems, it should provide redundant safeties and simplicity of operation.

Once your supplier understands your process, your operation, and your unique hardware and software needs, a proposal can be generated for a solvent recycling system that provides optimum recycling performance and complements your existing operation.

Recycling Your Own Solvents

Yields the Best ROI

As the bar chart below indicates, recycling your own solvents yields an outstanding ROI when compared to off-site or mobile recovery. The typical ROI for companies that recover their own solvents is less than one year—and can be as little as a few months for larger companies.



Formulating Your ROI

How should you go about calculating your ROI to determine if recycling is right for you? There are many variables involved in formulating your return. They can include your corporate hazardous waste philosophy, off-site liabilities, disposal costs, solvent purchases, off-site spill liability, increased solvent inventory, record keeping requirements and manpower needs. It is difficult to evaluate their impact on your specific operation and even more difficult to assign numeric values to many of these variables.

However, the following simplified analysis—developed with the assistance of your recycling equipment supplier—can help you decide whether or not to invest in a recycling system:

1. Collect the necessary information including weekly waste generation, cost of replacement solvents, disposal costs, transportation, and any other current costs of disposal. It will be necessary to compare the proposed on-site solvent recycling with your existing mode of handling waste solvent.
2. Use a computer spreadsheet to compare the proposed on-site recycling to the existing method. This will allow you to vary certain parameters and determine their effect on your bottom line. Pay particular attention to future growth, changing costs, process changes, or other variables which might have a profound effect on the ROI.
3. Once a variable ROI has been established, it can be presented in a manner to meet the format your company prefers. The ROI is an important element in the decision-making criteria of all businesses, and it becomes a comparison value to compete against other projects in the corporate budget.

In addition to the above, the issue of quality is of prime importance to any company working toward world class status. High product quality is assured when the recycling solution is on-site and it processes only the solvents used in your facility.

Finally, by the involvement of your personnel in adopting in-house solvent recycling, you send a message that protection of the environment, stewardship of your waste, and the improvement of your bottom line are priorities. As professed by numerous Malcolm Baldridge Award winners, the road to successful continual improvement of a company’s operations requires innovation and involvement by all employees. Seldom is the effort so definitively reinforced as in the case of on-site solvent recycling.

Implementing a Solvent Recycling System

Once funding has been approved and you have contracted the purchase and the installation of the solvent recycling system, you are ready for implementation.

This includes installation inspection, equipment checklist verification, equipment commissioning system operation and operator training, specification validation, and systematic follow-up.

A vendor interested in your long-term success will have the appropriate team of people available to assist you, including customer service, field service, engineering, and the salesperson.

It is important to make sure you work toward insuring the success of the implementation phase by supporting the factory field technicians and providing the operators with the proper training. Thorough training can be of long term benefit in the overall success of the project.

Implementation is not just the start-up and warranty. It is a product stewardship responsibility that the manufacturer must commit to and support for the life of the product. Success is achieved when your solvent recycling system is operational and is recovering solvents in the manner that was prescribed in the project justification. By following the steps we have outlined in this White Paper, you will be well on the way to achieving the company’s expectations for solvent recycling as well as your goal for project success.

About PRI

Progressive Recovery, Inc. (PRI) is North America’s leading manufacturer of solvent recycling systems. The company was organized in 1980 to address the need for safe, efficient and economical solutions for reducing or eliminating hazardous waste.

With a complete line of solvent recycling systems support by engineering, design, manufacturing, quality assurance, service, and after-the-sale support, we have contributed innovative solutions to environmental waste problems at both Fortune 500 clients and privately held companies.

The key to PRI’s effectiveness has been the utilization of a methodology which allows us to truly understand each customer’s requirements and apply the optimum solvent recycling solution. Our methodology is as follows:


Understanding Your Process - PRI’s highly trained staff of lab technicians is experienced in the necessary testing of your waste stream, as well as the assembling of data you will need to determine recovery requirements.
					Understanding Your Operation - PRI can help you determine your operational requirements in light of the manpower you have available as well as assist you with a hazardous operations review.
					Assessing Your Hardware Requirements - PRI offers sophisticated modeling capabilities to determine the optimum hardware for your process, then provides selection from a full line of distillation products.
					Assessing your Software Requirements - PRI’s knowledgeable software design team is proficient in providing systems that fit your "real life" process needs, not theoretical specifications.
					For more information on solvent recycling, or to discuss your solvent waste handling requirements, contact PRI today.