WHAT ARE MY POLLUTION PREVENTION OPTIONS?

What is Pollution Prevention? As stated in the Pollution Prevention Act of 1990, Congress has declared it to be the nation's policy that, wherever feasible, pollution should be prevented or reduced at the source. The Act states that source reduction is more desirable than waste management and pollution control. Source reduction is defined as any practice that reduces the amount of any hazardous substance entering the waste stream or otherwise released into the environment prior to recycling, treatment, or disposal. Therefore, you must also consider wastewater, hazardous waste, and solid waste effects and regulations as well as air in selecting any method of control.

What are my options? This regulation allows for pollution prevention measures to be used when complying with the requirements of the regulation. There are two source reduction alternatives available. The first is the use of chemical fume suppressants to inhibit chromium emissions at the source--the electroplating or anodizing tank. The second source reduction technique involves the use of a trivalent chromium electroplating process instead of the traditional hexavalent chromium (chromic acid) process.

Even though add-on pollution control measures are not considered source reduction measures, the add-on pollution control techniques described in the regulation (i.e., composite mesh-pad systems and packed-bed scrubbers) have a pollution prevention aspect. These pollution control measures allow closed-loop recycling of all collected chromium as well as concentration of process rinsewaters for some decorative chromium plating operations.

Which method should I use? There are advantages and disadvantages associated with each pollution prevention method that you should consider before selecting a method. The advantages and disadvantages are summarized below. In general, the advantages of a method and the benefits of pollution prevention to the owner or operator outweigh the disadvantages.

Fume suppressants. Fume suppressants are used widely and effectively in decorative chromium electroplating and chromic acid anodizing operations and less frequently in hard chromium electroplating operations. The disadvantages of using fume suppressants are:

• some wetting agents have a tendency to aggravate pitting and
• foam blankets that are too thick entrap hydrogen gas, which poses an explosion hazard.
  

The advantages of using fume suppressants are:

• minimization of plating solution evaporation losses;
• a very low-cost of chromium emission control;
• no impact on energy consumption; and
• no impact on solid waste generation.
  

Trivalent chromium process. Trivalent chromium processes are very effective in reducing chromium emissions from decorative chromium electroplating operations. Disadvantages of using trivalent chromium processes are:

• careful rinsing is required to minimize bath contamination;
• the finish of satin nickel may appear more gray than blue; and
• post treatment may be required to passivate unplated areas for corrosion resistance.

While there are some disadvantages and problems associated with the use of trivalent chromium processes, most can be overcome with process adjustments (e.g., careful rinsing to minimize bath contamination). The advantages of using trivalent chromium processes are:

• lower toxicity than hexavalent chromium;
• reduced waste disposal problems and costs compared to use of hexavalent chromium;
• provides better covering and throwing power than hexavalent chromium;
• eliminates "burning;" and
• provides enhanced corrosion resistance compared to hexavalent chromium.
  

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