Electrocoat Addition

Ask an Expert From: Products Finishing, , from Hixson Inc.

Posted on: 9/1/2003

Question: We currently have a five-stage zinc phosphate washer and are powder coating various metal parts for original equipment manufacturers.

Question:

We currently have a five-stage zinc phosphate washer and are powder coating various metal parts for original equipment manufacturers. We are seeing more requests from these customers for electrocoat finishes. What would be the environmental impact on our operation if we added an e-coat operation? D.A.

Answer:

Your question could easily had been the topic for a 40-minute presentation at the recent 2004 Electrocoat Conference, sponsored by the Electrocoat Association (www.electrocoat.org), but let me make several pertinent comments. Overall, a powder coat system generates less pollution than an electrocoat system, especially air pollution, however, an e-coat system is a very low emitter of air pollutants as compared to conventional wet paint systems using compliance coatings and no add-on pollution control systems.

Since you apparently have a wastewater pretreatment system for your washer, we would still recommend several changes. First, you need to make sure that your wastewater pretreatment system can handle the small flow from the electrocoat rinse stages as well as the regenerant wastes if you plan to use ion exchange with on-site regeneration in order to produce the high quality water needed for electrocoat. Second, we recommend that you discuss these changes with your wastewater chemical supplier since changes in your coagulant and/or polymer chemistry may be needed to handle the electrocoat wastes. Lastly, we recommend that you seriously consider installing a batch treatment tank to handle any waste paint and ultrafilter cleaning wastes; these typically require much different treatment chemistries than used in your wastewater pretreatment system.

If your facility is located in an ozone attainment area, an electrocoat system could likely be permitted without add-on pollution control, such as an afterburner. In fact, within recent years, low VOC (volatile organic compounds) and low HAP (hazardous air pollutant) electrocoat formulations have been successfully developed and commercialized; the emissions from these coatings can be low enough, depending upon use, that air pollution permitting may not be required. We have several clients whose emissions from their electrocoating operations are so low that they are exempt from air pollution permitting.

While an electrocoat’s actual and potential-to-emit (24 hrs/day, 365 days per year at maximum production) VOC emissions can be below the major source designation (up to 100 tons per year depending upon the level of ozone, aka smog, non-attainment) threshold, the actual or potential-to-emit emission of hazardous air pollutants (HAPs), such as glycol ethers, may exceed the major source threshold of 10 tons/year for a single HAP and 25 tons/year for all HAPs. As a major source, you would be required to obtain a Title Five permit from USEPA or your state. However, it has been our experience that most electrocoat operations, especially now with the low HAP e-coat formulations, are able to demonstrate that actual emissions are below these thresholds, and can opt out of the Title Five permit by capping their emissions below the major source thresholds through a federally enforceable state operating permit (FESOP).

Lastly, if the electrocoat paint contains significant lead concentration, the paint filters will likely fail the Toxicity Characteristic Leaching Procedure (TCLP) test for lead and must be disposed of as a RCRA hazardous waste. Unfortunately, you would not be able to place these filters into the cure oven so as to “lock” the lead into the cured paint resin in order to pass the TCLP—lead test procedure; USEPA regulations consider this “treatment” of a hazardous waste and requiring a hazardous waste treatment permit. Fortunately, low lead and no lead e-coat formulations are available and may be able to meet your specifications.

 


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