A Pollution Prevention Guide for
Metal Fabricators

Three Rs for the 90s: Reduce Reuse Recycle

A Publication of the Delaware Department of Natural Resources and Environmental Control

Metal Fabricators

The wastes that a metal fabricating business would have to contend with might include many of the following:

• spent metalworking fluids
  
• acid/alkaline wastes
  
• halogenated and nonhalogenated solvents
  
• abrasives
  
• process solutions and rinsewater containing toxic substances
  
• contaminated wastewater treatment sludges, still bottoms, etc.
  
• empty product containers
  
• paint overspray

Businesses throughout the country have implemented waste reduction programs and found that there are many benefits to be gained from such an approach to the management of resources. Reducing the amount of waste your business generates can help you:

• reduce operating costs
  
• reduce waste disposal costs
  
• reduce long-term liability
  
• help sustain environmental quality
  
• improve workplace safety and health
  
• project a positive public image

Getting Started

Here are the steps to follow in conducting a waste audit:

• List all wastes being generated.
  
• Identify the composition and source of each waste.
  
• Identify options to reduce the generation of these substances, focusing on those waste that are most hazardous and those techniques that are most easily implemented.
  
• Compare the technical and economic feasibility of the options identified.
  
• Evaluate the results and schedule periodic reviews of the waste reduction program.

Improved Operating Procedures

• Keep storage and work areas clean and well organized, and keep all containers properly labeled.
  
• Inspect materials upon delivery, and immediately return unacceptable materials to the supplier.
  
• Keep accurate records of raw material usage so that you can measure reductions in use. Mark the purchase date on each container and adopt a “first in, first out”, policy so that older materials are used up before new ones are opened; assign someone to distribute and keep track of raw materials.
  
• Practice preventive maintenance to avoid future losses. Conduct periodic inspections of tanks, tank liners, and other equipment; repair malfunctions when they are discovered.
  
• Keep all containers covered to prevent evaporation, spillage, or drying out of contents.
  
• Keep waste streams separate for reuse, recycling, or treatment. Keep nonhazardous materials from becoming contaminated.
  
• Limit bath mixing to trained personnel.
  
• Use bench-scale testing for samples rather than in process baths.
  
• Install drip trays and splash guards to contain spills and leaks.
  
• Inspect plating racks for loose insulation that would cause increased dragout.
  
• Use dry cleanup wherever possible to reduce the volume of wastewater.

Material Substitution

• Use process chemistries that are treatable or recyclable on site.
  
• Use deionized water instead of tap water for process baths and rinsing operations; this will reduce the amount of sludge generated.
  
• Replace cyanide and barium salt baths in metals heat treating processes with alternative treatment methods, including the use of sulfate or chloride baths.
  
• Use alkaline cleaners instead of solvents in degreasing operations. Some alkaline cleaners may be treated on site and disposed of in the sanitary sewer system (with permission of the POTW).
  
• Use less toxic plating solutions. For example, use zinc instead of cadmium, and trivalent chromium instead of hexavalent chromium.
  
• Use no-rinse coatings.

Extending Process Bath Life

• Cover bath when not in use to reduce evaporation.
  
• Test process, baths for pH, metals, and other indicator parameters to determine when replenishment or treatment is in order. Replenishment (by adding necessary chemicals) or treatment (by filtration, electrolytic dummying, or other methods) can extend the useful life of the bath.
  
• Properly design and maintain racks to reduce build-up of corrosion and salt deposits which will contaminate plating solution.

Reducing Drag-out

• Minimize bath concentrations to the lower end of their operating range. This will save on materials, reduce solution viscosity and dragout, and reduce the toxicity of the bath solutions.
  
• Increase the temperature of the bath to reduce both the viscosity and the surface tension of the solution.
  
• Use non-ionic wetting agents to reduce solution surface tension.
  
• Withdraw workpieces from tanks slowly to allow maximum drainage back into the process tank.
  
• Use air knives or spray rinses above process tanks to rinse excess solution off of workpieces and into the process bath.
  
• Install drainage boards between process tanks and rinse tanks to route drag-out back into the process tank.
  
• Use dedicated drag-out tanks after using process baths to capture drag-out.
  
• Install rails above process tanks to hang workpiece racks for drainage prior to rinsing.
  
• Rack parts properly to maximize drainage.

Conserving Rinse Water

• Install automatic flow controls.
  
• Spray rinse the workpieces as they emerge from the process tank.
  
• Install multiple rinse tanks in a counter-current series system.
  
• Agitate the rinsing bath either mechanically or with air.

Reducing Paint Wastes

Here are some suggestions for reducing these wastes:

• Purchase paint in bulk, so as to reduce the number of paint cans requiring disposal. If this is not practical, purchase. the paint in the smallest amount required; this will minimize the amount of residual remaining in the can.
  
• Waste associated with paint application can be reduced by
  
• Changing the method of application. Roller and flow coating machines and electro coating systems are much more efficient than conventional spray systems.
  
• Finding safer substitutes for conventional solvent-based systems. Water-based, radiation-cured, and powder coatings are three systems that eliminate or greatly reduce the use of volatile solvents in the paint application process. They also reduce the amount of paint overspray requiring disposal.
  
• Clean-up wastes can be reduced by careful scheduling of the paint operations. Scheduling all batches of the same color to be done on the same day or during the same part of the day can reduce the number of cleanups required. When different colors will be applied on the same day, try to do the lightest colors first and move progressively to the darker colors.

Reusing and Recycling Other Wastes

• Reuse or recycle excess, off-specification materials and samples taken for quality control testing.
  
• Segregate and reuse dust emissions in the production process.
  
• Distill waste solvents, and regenerate catalysts.
  
• Find as many ways to reuse paper as you can (as note pads, poster paper, etc.).
  
• Recycle as many of the company’s waste materials as possible. Corrugated cardboard, computer and office paper, aluminum, ferrous metals, and plastic and glass containers are some commonly recycled items. DNREC’s Pollution Prevention Program (739-3822) may be able to help you find recyclers for various materials.
  
• Recycle lube oils.

Getting the Job Done

Management can demonstrate its commitment to waste reduction by:

• Providing employees with training in waste reduction techniques and practices -- including periodic “refresher courses” to increase employees’ awareness of the importance of waste reduction.
  
• Involving the employees in designing and implementing waste reduction measures.
  
• Establishing incentives to encourage workers to use waste reduction techniques and to suggest changes in design or operating procedures that would further reduce waste generation.

Following Up

Here are some ways to keep the waste reduction program vital:

• When buying new equipment, look for equipment will minimize both the amount of toxic materials used. and the amount of waste produced.
  
• Reassess the company’s operations and waste handling practices periodically with an eye to avoiding the temptation of slipping back into old, more wasteful ways of doing things and to identify additional waste reduction possibilities.
  
• Publicize the firm’s commitment to waste reduction. Customers will feel good about doing business with a company that is environmentally responsible.

Sources of Additional Help

• The Northeast Industrial Waste Exchange may be able to help you find companies that can use your wastes. You can call the Exchange directly at 315-422-6572 and identify yourself as a Delaware business, or call the Pollution Prevention Program.

• The Delaware Manufacturing Alliance is a private, non-profit corporation which is dedicated to improving the quality, productivity, and profitability of Delaware manufacturers, and to serving as a prime service resource for the state’s new and existing manufacturers. The DMA can be reached at (302) 452-2520.

• A Waste Reduction Self-Evaluation Manual has been developed by the Department of Natural Resources and Environmental Control to assist small and medium-sized businesses in implementing waste reduction programs. Copies of the manual can be obtained by calling the Pollution Prevention Program at 739-3822.

• The Delaware Pollution Prevention Program in the Department of Natural Resources and Environmental Control (302) 739-3822 provides technical assistance, information resources, as well as assistance with other services that are available to your business.

The Department of Natural Resources and Environmental Control is an equal opportunity employer. No person or group shall be excluded from participation, denied any benefits, or subjected to discrimination on the basis of race, color, national origin, or handicap.