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Pollution Prevention and Control Technologies for Plating Operations
Section 3 - Chemical Recovery
3.8 MESHPAD MIST ELIMINATORS
3.8.2 Development and Commercialization
Meshpad mist eliminators have been manufactured for more than 30 years (ref. 403) and applied to chromium plating for more than 20 years (e.g., PS 253). However, use of this technology for plating applications only recently became widespread. Until the past few years, most hard chromium shops either had no emission control, used chevron mist eliminators or used wet scrubbers. Most decorative platers relied on fume suppressants and most chromic anodizers either had no controls or used either wet scrubbers or fume suppressants. In 1992, data were presented on the relative uses of these technologies (see Exhibit 3-65) (ref. 213).
The results from the Users Survey show that 86% of the mist eliminator units for which the purchase date was given were installed since 1988 and 71% since 1990. These data and those from the literature indicate that use of mist eliminators is expanding at a very significant rate. The reason for this change may be due to the recognized advantages of this technology over other competing technologies plus regulatory requirements.
The high efficiency and recovery potential of meshpad mist eliminators was documented by the Navy in the mid-1980's. That work concluded that the meshpad mist eliminator proved to be more effective than a wet scrubber on chromic acid mists and that it produced a concentrated, low volume chromic acid stream with potential for recycle. Further, the Navy concluded that it was a simpler device, compared to the wet scrubber (ref. 404).
The State of California undertook regulatory development efforts in the mid-1980's to control chromium emissions from plating and anodizing (ref. 405). California enacted strict rules on chromic acid emissions in 1988 (ref. 406). EPA generated and compiled performance data for control measures during the mid-to late 1980's (ref. 46). Included in these efforts were detailed studies of meshpad mist eliminators (ref. 407, 408). These research efforts also showed that high efficiency levels were attained by the meshpad mist eliminator.